tag:theconversation.com,2011:/global/topics/biological-age-30963/articlesBiological age – The Conversation2023-11-13T03:02:44Ztag:theconversation.com,2011:article/2163642023-11-13T03:02:44Z2023-11-13T03:02:44ZInsecure renting ages you faster than owning a home, unemployment or obesity. Better housing policy can change this<p>People’s experiences of private rental housing are linked to faster biological ageing, our recent <a href="http://dx.doi.org/10.1136/jech-2023-220523">research</a> finds. </p>
<p>While chronological ageing happens at the same speed for everyone, biological ageing varies greatly. It depends on the lives we lead and the risks we’re exposed to. Biological age reflects the gradually accumulating damage to cells and tissues in the body.</p>
<p>Our research explored associations between pace of ageing and many aspects of housing and other social determinants of health. Our strongest finding about housing was that people living in a privately rented home tended to age faster than those who owned their home outright. Every year of private renting was associated with an extra 2.4 weeks of ageing on average. </p>
<p>Our findings also suggest being a private renter has a greater effect on biological age than being unemployed (adding about 1.4 weeks of ageing per year), obesity (about 1 week), or being a former smoker (about 1.1 weeks). </p>
<p>The insecurity of private renting appears to be the key factor in its biological ageing effect. The good news is that policies that improve housing security can redress this. </p>
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Read more:
<a href="https://theconversation.com/the-insecurity-of-private-renters-how-do-they-manage-it-77324">The insecurity of private renters – how do they manage it?</a>
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<h2>How do we measure biological age?</h2>
<p>Faster ageing is associated with poorer health. Outcomes include <a href="https://elifesciences.org/articles/54870">poorer</a> physical and cognitive function and a higher risk of chronic illness and even <a href="https://onlinelibrary.wiley.com/doi/10.1111/acel.12421">early</a> <a href="https://www.aging-us.com/lookup/doi/10.18632/aging.101020">death</a>.</p>
<p>To measure ageing, we use an indicator of <a href="https://theconversation.com/difficult-childhood-experiences-could-make-us-age-prematurely-new-research-102807">DNA methylation</a>. This is an epigenetic process – a way in which the environment can affect how our genes are expressed. By analysing the locations of DNA methylation across a person’s DNA, we can estimate their pace of biological ageing.</p>
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Read more:
<a href="https://theconversation.com/difficult-childhood-experiences-could-make-us-age-prematurely-new-research-102807">Difficult childhood experiences could make us age prematurely – new research</a>
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<p>It’s hard to get the data for this sort of analysis. We needed blood samples that have gone through complex processing to estimate biological ageing, as well as survey data on many aspects of people’s lives. We controlled for income and health behaviours, among other things.</p>
<p>The data we used describe the <a href="https://www.understandingsociety.ac.uk/documentation/health-assessment">British</a> population, but our findings are directly transferable to Australians. Given the <a href="https://www.aihw.gov.au/reports/australias-welfare/home-ownership-and-housing-tenure">increasing numbers of renters</a> in Australia, many in insecure housing, our findings are directly relevant to our current housing debate.</p>
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Read more:
<a href="https://theconversation.com/more-rented-more-mortgaged-less-owned-what-the-census-tells-us-about-housing-185893">More rented, more mortgaged, less owned: what the census tells us about housing</a>
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<p>The experiences of private renting are similar in Britain and <a href="https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Community_Affairs/Worseningrentalcrisis/Interim_Report">Australia</a>. Short tenancy agreements (<a href="https://www.abs.gov.au/statistics/detailed-methodology-information/information-papers/new-insights-rental-market">12 months</a> on average in Australia) mean insecurity is a feature of private renting in both nations. </p>
<p>No-fault/no-grounds/no-cause evictions in some states further undermine renters’ security. Even renters who do everything right can be evicted at short notice.</p>
<h2>Insecure housing is bad for your health</h2>
<p>We found no negative effects for people renting social housing. In both Britain and Australia, <a href="https://www.gov.uk/government/collections/english-housing-survey">social renters</a> have far greater security of tenure than private renters. This suggests it is not renting itself that is related to faster ageing, but specifically the insecurity of private renting. </p>
<p>These findings are important for Australian housing policy. The social housing sector – managed by state or community providers – has shrunk. Today <a href="https://www.ahuri.edu.au/analysis/brief/what-right-level-social-housing-australia">less than 4%</a> of households are in social housing. </p>
<p>Governments have edged away from publicly provided social housing. They prefer to subsidise renters in the private sector.</p>
<p>The role of private rental housing has also changed in both countries. Rather than being a form of housing in which a relatively small number of people live in for a short time while studying or starting their career, more people are living in privately rented homes for longer. As access to both <a href="https://theconversation.com/australias-social-housing-system-is-critically-stressed-many-eligible-applicants-simply-give-up-183530">social housing</a> and <a href="https://theconversation.com/more-rented-more-mortgaged-less-owned-what-the-census-tells-us-about-housing-185893">home ownership</a> becomes harder, many will probably rent for life. </p>
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<p>This means more people are exposed to housing insecurity and the negative health impacts for longer.</p>
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Read more:
<a href="https://theconversation.com/stability-and-security-the-keys-to-closing-the-mental-health-gap-between-renters-and-home-owners-179481">Stability and security: the keys to closing the mental health gap between renters and home owners</a>
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<h2>What does this mean for policy?</h2>
<p>Public debate and health messaging often <a href="https://doi.org/10.1093/pubmed/fdy045">focus on individual</a> behaviours and characteristics such as smoking and obesity. Our research emphasises how important housing is for people’s health. It’s also an area where policy changes can make a big difference.</p>
<p>The insecurity of private renting in Australia and Britain is not inherent to private renting itself. It’s a result of policy choices that:</p>
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<li>emphasise housing <a href="https://theconversation.com/explainer-the-financialisation-of-housing-and-what-can-be-done-about-it-73767">as an asset</a></li>
<li><a href="https://theconversation.com/shh-dont-mention-the-public-housing-shortage-but-no-serious-action-on-homelessness-can-ignore-it-124875">minimise the state’s role</a> in providing or regulating housing</li>
<li>do little to <a href="https://theconversation.com/do-tenancy-reforms-to-protect-renters-cause-landlords-to-exit-the-market-no-but-maybe-they-should-194900">protect renters</a>. </li>
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<p>This approach can change, and the appetite for change appears to be increasing. There are efforts to end no-fault/no-grounds evictions in both Australia and Britain. </p>
<p>State governments have talked about ending no-grounds evictions. <a href="https://www.rentersrights.org.au/no_grounds_evictions">New South Wales</a> has yet to do anything about it. Despite <a href="https://theconversation.com/how-5-key-tenancy-reforms-are-affecting-renters-and-landlords-around-australia-187779">reforms in other states</a>, they still <a href="https://www.tenants.org.au/blog/end-fixed-term-evictions-are-unfair-no-grounds-evictions-part-2">permit</a> no-grounds evictions when fixed-term leases end.</p>
<p>Scotland has adopted a new model of tenancy that does not permit no-fault evictions with few exceptions – to allow landlords to sell the property, for example. The UK government has been talking about ending such evictions since <a href="https://www.insidehousing.co.uk/comment/comment/open-ended-prs-tenancies-the-quickest-change-of-government-housing-policy-in-recent-memory-61043">2019</a>, but progress has been slow. </p>
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<p>However, there are glimmers of hope. The <a href="https://indaily.com.au/news/2023/08/16/albanese-hails-deal-with-states-for-housing-shortage/">Australian government</a> is paying <a href="https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Community_Affairs/Worseningrentalcrisis/Interim_Report">more attention</a> to renters’ needs. <a href="https://www.cbs.sa.gov.au/news/no-cause-evictions-to-be-banned-in-south-australia">South Australia</a> is working to end no-grounds evictions for both fixed and periodic tenancies. In NSW, the new government has <a href="https://www.theguardian.com/australia-news/2023/jul/21/renter-evicted-ndis-shower-rail">promised to end such evictions</a>. </p>
<p>In the UK, the <a href="https://bills.parliament.uk/bills/3462/stages">Renters (Reform) Bill</a> finally had its second reading on October 23.</p>
<p>Private renting can work <a href="https://theconversation.com/renting-rights-what-england-can-learn-from-fairer-systems-around-the-world-103779">better for tenants</a>, but shouldn’t be the only option for people who don’t own their homes. Our finding that renting social housing was no different to outright ownership lends weight to calls for greater support for social housing. Housing should be good for everyone’s health, whether or not they own their home.</p><img src="https://counter.theconversation.com/content/216364/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma Baker receives funding from the Australian Research Council, the National Health and Medical Research Council, and the Australian Housing and Urban Research Institute. She holds a voluntary board position with Habitat for Humanity. </span></em></p><p class="fine-print"><em><span>Meena Kumari receives funding from the Economic and Social Research Council (ES/T014083/1; ES/S012486/1). </span></em></p><p class="fine-print"><em><span>Amy Clair does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>People age differently depending on the lives they lead. DNA testing shows every year of living in a privately rented home add 2.4 weeks of ageing compared to those who own their home.Amy Clair, Lecturer, Australian Centre for Housing Research, University of Adelaide, and Research Associate, ESRC Research Centre on Micro-Social Change, University of EssexEmma Baker, Professor of Housing Research, University of AdelaideMeena Kumari, Professor of Biological and Social Epidemiology,, University of EssexLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2156112023-11-06T10:30:24Z2023-11-06T10:30:24ZYour biological age predicts dementia and stroke regardless of your actual age – new study<figure><img src="https://images.theconversation.com/files/557607/original/file-20231105-27-bb4wsv.jpg?ixlib=rb-1.1.0&rect=10%2C31%2C6939%2C4594&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/concept-image-on-age-characters-young-2274077339">tomertu/Shutterstock</a></span></figcaption></figure><p>As we journey through life, the risk of developing chronic diseases, including cancer, heart disease and neurological disorders, increases significantly. However, while we all grow older chronologically at the same pace, biologically, our clocks can tick <a href="https://doi.org/10.1038/s41591-023-02296-6">faster or slower</a>. Relying solely on chronological age – the number of years since birth – is inadequate to measure the body’s internal biological age.</p>
<p>This discrepancy has prompted scientists to find ways to determine a person’s <a href="https://doi.org/10.1016/j.cell.2023.08.003">biological age</a>. One way is to look at “<a href="https://www.nature.com/articles/d41586-022-00077-8">epigenetic clocks</a>” which consider chemical changes that occur in our DNA as we age. Another approach uses <a href="https://doi.org/10.1007/s11357-021-00480-5">information from medical tests</a>, such as blood pressure, cholesterol levels and other physiological measurements.</p>
<p>By using these “biomarkers”, researchers have discovered that when a person’s biological age surpasses their chronological age, it often signifies <a href="https://doi.org/10.1038/s43587-021-00044-4">accelerated cell ageing</a> and a higher susceptibility to age-related diseases. </p>
<p>Our new research suggests your biological age, more than the years you’ve lived, may predict your risk of dementia and stroke in the future. </p>
<p><a href="https://doi.org/10.1093/brain/awad252">Previous studies</a> have shed light on this association but they were often limited in scale. This has left gaps in our understanding of how biological ageing relates to various neurological disorders, including Parkinson’s disease and motor neuron disease.</p>
<p>To bridge this gap, our study, <a href="https://doi.org/10.1136/jnnp-2023-331917">published in the Journal of Neurology, Neurosurgery and Psychiatry</a>, examined over 325,000 middle-aged and older British adults. We investigated whether advanced biological age increases the future risks of developing neurological diseases, including dementia, stroke, Parkinson’s disease and motor neuron disease.</p>
<p>To assess biological age, we analysed 18 biomarkers collected during medical checkups conducted between 2006 and 2010. These included blood pressure, blood glucose, cholesterol levels, inflammation markers, waist circumference and lung capacity. </p>
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<img alt="A man reading his own blood pressure." src="https://images.theconversation.com/files/557608/original/file-20231105-21-98b0vn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557608/original/file-20231105-21-98b0vn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557608/original/file-20231105-21-98b0vn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557608/original/file-20231105-21-98b0vn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557608/original/file-20231105-21-98b0vn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557608/original/file-20231105-21-98b0vn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557608/original/file-20231105-21-98b0vn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A number of biomarkers were measured, including blood pressure.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hypertension-older-age-senior-black-man-2066841269">Pro-stock Studio/Shutterstock</a></span>
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<p>We then followed participants for nine years to see who developed neurological diseases. Those with older biological ages at the study’s start had significantly higher risks of dementia and stroke over the next decade – even after considering differences in genetics, sex, income and lifestyle.</p>
<p>Imagine two 60-year-olds enrolled in our study. One had a biological age of 65, the other 60. The one with the more accelerated biological age had a 20% higher risk of dementia and a 40% higher risk of stroke.</p>
<h2>Strong association</h2>
<p>It is worth noting that while advanced biological age showed a strong association with dementia and stroke, we saw a weaker link with motor neuron disease and even an opposite direction for Parkinson’s disease.</p>
<p>Parkinson’s disease often exhibits unique characteristics. For instance, although smoking typically <a href="https://doi.org/10.7554/eLife.59479">accelerates ageing</a>, it paradoxically exerts a <a href="https://doi.org/10.1212/WNL.0000000000009437">protective effect</a> against Parkinson’s disease.</p>
<p>Our findings show that biological ageing processes probably contribute substantially to dementia and stroke later in life. Together with our previous research showing a significant association between <a href="https://doi.org/10.1038/s41416-023-02288-w">advanced biological age and cancer risks</a>, these results suggest that slowing the body’s internal decline may be key to preventing chronic diseases in late life.</p>
<p>Assessing biological age from routine blood samples could someday become standard practice. Those with accelerated ageing could be identified decades before dementia symptoms arise. While currently incurable, early detection provides opportunities for preventive lifestyle changes and close monitoring.</p>
<p>For example, research starts to suggest that biological age may be slowed down or even reversed by <a href="https://doi.org/10.18632/aging.202913">lifestyle intervention</a> including exercise, sleep, diet and nutritional supplements.</p>
<p>Replicating our results in diverse groups of people is next step. We also hope to unravel connections between genetic background, biological ageing and other major diseases, such as diabetes and heart diseases.</p>
<p>For now, monitoring internal ageing processes could empower people to delay cognitive decline, providing hope for a healthier and more fulfilling life in later years.</p><img src="https://counter.theconversation.com/content/215611/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sara Hägg receives funding from the Swedish Research Council, the Swedish Cancer Society, the National Institute on Aging.</span></em></p><p class="fine-print"><em><span>Jonathan Ka Long Mak does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Why we should all try to be biologically younger.Jonathan Ka Long Mak, PhD Candidate, Karolinska InstitutetSara Hägg, Associate Professor, Molecular Epidemiology, Karolinska InstitutetLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2110612023-08-15T15:35:26Z2023-08-15T15:35:26ZYour body can be younger than you are – here’s how to understand (and improve) your ‘biological age’<figure><img src="https://images.theconversation.com/files/542812/original/file-20230815-17-dwl420.jpg?ixlib=rb-1.1.0&rect=17%2C0%2C5906%2C3641&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Your chronological age and biological age may not be the same.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/old-young-sportsmen-running-on-road-1266665947">Realstock/ Shutterstock</a></span></figcaption></figure><p>The saying goes that money can’t buy you love. But can it buy you time? This is what <a href="https://www.standard.co.uk/tech/bryan-johnson-tech-millionaire-reverse-ageing-b1083695.html">US billionaire Bryan Johnson</a> is hoping to find out. </p>
<p>The 45-year-old reportedly spends millions each year in an attempt to reverse ageing and regain his 18-year-old body (presumably sans acne). To achieve this, Johnson sticks to a rigid diet and exercise regime, takes multiple supplements, and has frequent tests to analyse the function of his organs. He’s also tried some <a href="https://pubmed.ncbi.nlm.nih.gov/37500974/">novel procedures</a> to rejuvenate his body, such as injecting himself with his 17-year-old son’s <a href="https://www.thetimes.co.uk/article/tech-millionaire-injected-with-sons-blood-in-quest-for-youth-z8bbtm9f8?utm_medium=Social&utm_source=Twitter#Echobox=1684906320">blood plasma</a>.</p>
<p>Not only has Johnson’s quest garnered a lot of attention online, it has also left many wondering to what extent his ultimate goal is achievable – can your body really be younger than your calendar age?</p>
<p>There are two interconnected ways of measuring your age. The first is chronological age, which is the easiest to understand. It’s really nothing more than how long you’ve been alive. The most accurate estimate of that is the date and time on your birth certificate.</p>
<p>But, in circumstances where documentary evidence is lacking (typically, archaeological excavations or forensics), there are several techniques available to estimate chronological age. Arguably, the best method is by looking at teeth – specifically, their annual “<a href="https://pubmed.ncbi.nlm.nih.gov/35088895/">cemental lines</a>”, which are much like growth rings in trees, alongside changes in the dentine (which sits beneath the enamel and supports tooth structure).</p>
<h2>How to measure your ‘true’ age</h2>
<p>Biological age, on the other hand, reflects the exponential increase in an organism’s chances of becoming sick or dying with the passage of time. Basically, this translates to the rate at which your body is losing function. </p>
<p>While <a href="https://pubmed.ncbi.nlm.nih.gov/31449890/">most species age</a>, there are some rare creatures on the planet that are truly non-ageing – such as the <a href="https://genomics.senescence.info/species/entry.php?species=Arctica_islandica">ocean quahog</a>. These have such a low chance of dying that some alive today are old enough that <a href="https://pubmed.ncbi.nlm.nih.gov/24347613/">Henry VIII could have eaten them</a> in a bowl of chowder.</p>
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<a href="https://theconversation.com/is-there-a-natural-limit-to-how-long-humans-can-live-66460">Is there a natural limit to how long humans can live?</a>
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<p>Yet, while we all grow older, we don’t all lose functional capacity at identical rates – and the organ systems in our body <a href="https://pubmed.ncbi.nlm.nih.gov/6967883">decline at different speeds</a>. This means that some people’s biological age may be younger or older than the average for their chronological age.</p>
<p>Take the example of the <a href="https://www.runnersworld.com/news/a25593341/70-year-old-marathon-record/">70-year-old US marathon runner</a> who set a world record for his age group in 2018, and contrast it with many of his peers who are in delicate health or long-term care. This shows how biological age can be uncoupled from chronological age. </p>
<p>There are several ways to estimate biological age. Surprisingly, one of the best is incredibly simple: use your eyes. Research shows that age estimates made by <a href="https://pubmed.ncbi.nlm.nih.gov/35650301">looking at someone</a> are just as good as some more complicated techniques of gauging biological age.</p>
<p>Another study found that smokers, people who were obese, and those in poor health were all perceived as <a href="https://pubmed.ncbi.nlm.nih.gov/7100970/">being older</a> than their chronological age by their peers. Given <a href="https://pubmed.ncbi.nlm.nih.gov/19485966/">these factors</a> do indeed <a href="https://pubmed.ncbi.nlm.nih.gov/3226152/">increase biological age</a>, this shows how accurate just looking at someone can be. </p>
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<img alt="A photo of a woman at three different stages in life." src="https://images.theconversation.com/files/542814/original/file-20230815-27-b6u290.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542814/original/file-20230815-27-b6u290.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542814/original/file-20230815-27-b6u290.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542814/original/file-20230815-27-b6u290.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542814/original/file-20230815-27-b6u290.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=453&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542814/original/file-20230815-27-b6u290.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=453&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542814/original/file-20230815-27-b6u290.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=453&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Our eyes may be one of the best methods for determining biological age.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/aging-process-rejuvenation-antiaging-skin-procedures-436064953">Leszek Glasner/ Shutterstock</a></span>
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<p>Another simple but powerful predictor of biological age is measuring a person’s <a href="https://pubmed.ncbi.nlm.nih.gov/36215867">grip strength</a>, which tends to decrease with age as they lose muscle mass. <a href="https://theconversation.com/how-strong-your-grip-is-says-a-lot-about-your-health-145861">Other factors</a> – such as illness, obesity, and lack of fitness – can also affect this. Low grip strength is one sign that your biological age is probably higher than your calendar age.</p>
<p>Other, more complicated methods of estimating biological age include testing multiple <a href="https://academic.oup.com/biomedgerontology/article/68/6/667/873700">organ function</a> and looking at <a href="https://pubmed.ncbi.nlm.nih.gov/32554926/">sterile inflammation</a>, which measures how many inflammatory molecules are circulating in the body (a high level is not good news). You could also look at <a href="https://pubmed.ncbi.nlm.nih.gov/36206857/">epigentic changes to DNA</a>, the length of <a href="https://theconversation.com/end-of-ageing-and-cancer-scientists-unveil-structure-of-the-immortality-enzyme-telomerase-95591">chromosomal ends</a>, or the <a href="https://www.frontiersin.org/articles/10.3389/fragi.2021.686382/full">number of senescent cells</a> a person has to measure their biological age. However, the latter two methods typically only provide a <a href="https://pubmed.ncbi.nlm.nih.gov/33552142/">rough estimate</a>.</p>
<h2>Staying young</h2>
<p>If you’re hoping to turn back the clock and “reverse ageing”, the best place to start is by focusing on your lifestyle.</p>
<p>Regular exercise, quitting smoking, drinking in moderation, watching your weight and eating plenty of fruit and veg are all simple things that make a huge difference to your biological age. There’s a roughly <a href="https://www.epic-norfolk.org.uk/study-findings">15-year difference</a> in life expectancy between a person who does four of these five things and someone who does none of them. </p>
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Read more:
<a href="https://theconversation.com/life-extension-the-five-most-promising-methods-so-far-169881">Life extension: the five most promising methods – so far</a>
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<p>There are also treatments in development that could rapidly and significantly reverse ageing, if they translate effectively from rodents to humans. </p>
<p>For example, researchers have demonstrated that the accumulation of senescent cells in tissue is a primary cause of ageing in mice. <a href="https://pubmed.ncbi.nlm.nih.gov/22048312/">Removing them</a> has shown improvements in both their <a href="https://pubmed.ncbi.nlm.nih.gov/26840489/">health and lifespan</a>.</p>
<p>These studies have also compared the effects of removing senescent cells throughout the animal’s life with letting them accumulate, then removing them when the mouse is old. Both interventions improve the health and lifespan of mice – and the latter could justly be described as “reversing ageing”. </p>
<p>Many attempts are ongoing to <a href="https://pubmed.ncbi.nlm.nih.gov/36857968/">duplicate these effects in humans</a>, while a range of <a href="https://www.ukanet.org.uk/">other techniques</a> to improve late-life health are also being studied. Success with any of these could <a href="https://pubmed.ncbi.nlm.nih.gov/37117804/">dramatically reduce healthcare costs</a> and revolutionise how we <a href="https://www.theactuarymagazine.org/breaking-the-dam">spend our later years</a>. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/the-secret-to-staying-young-scientists-boost-lifespan-of-mice-by-deleting-defective-cells-54068">The secret to staying young? Scientists boost lifespan of mice by deleting defective cells</a>
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<p>In my view, Johnson’s attempts to reverse ageing are something of a mixed bag of the practical and the hopeful. However, achieving his long-term goal of reaching the age of 200 might be a tad optimistic.</p><img src="https://counter.theconversation.com/content/211061/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Faragher is co-Director of the BLAST Healthy Ageing Network and a co-ordinator of the UK Ageing Research Networks (UKAN). He receives funding from the Biotechnology and Biological Sciences Research Council and the Medical Research Council. He serves on the Scientific Advisory Board of the Longevity Vision Fund and is a member of the Board of Directors of the American Federation for Aging Research. </span></em></p>Many factors such as smoking, how much your exercise and what foods you eat, can affect your biological age.Richard Faragher, Professor of Biogerontology, University of BrightonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2020962023-07-06T12:27:34Z2023-07-06T12:27:34ZAging is complicated – a biologist explains why no two people or cells age the same way, and what this means for anti-aging interventions<figure><img src="https://images.theconversation.com/files/535886/original/file-20230705-16248-djnyz1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2121%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">While some people may be older in chronological age, their biological age might be much younger.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-older-chinese-womans-eye-royalty-free-image/1082691656">FangXiaNuo/E+ via Getty Images</a></span></figcaption></figure><p>You likely know someone who seems to <a href="https://theconversation.com/are-you-a-rapid-ager-biological-age-is-a-better-health-indicator-than-the-number-of-years-youve-lived-but-its-tricky-to-measure-198849">age slowly</a>, appearing years younger than their birth date suggests. And you likely have seen the opposite – someone whose body and mind seem much more ravaged by time than others. Why do some people seem to glide though their golden years and others physiologically struggle in midlife? </p>
<p>I have <a href="https://scholar.google.com/citations?user=DDc-okgAAAAJ&hl=en">worked in the field of aging</a> for all of my scientific career, and I teach the cellular and molecular biology of aging at the University of Michigan. Aging research doesn’t tend to be about finding the one cure that fixes all that may ail you in old age. Instead, the last decade or two of work points to aging as a multi-factoral process – and no single intervention can stop it all.</p>
<h2>What is aging?</h2>
<p>There are many different definitions of aging, but scientists generally agree upon <a href="https://doi.org/10.1007/978-3-319-69892-2_29-1">some common features</a>: Aging is a time-dependent process that results in increased vulnerability to disease, injury and death. This process is both intrinsic, when your own body causes new problems, and extrinsic, when environmental insults damage your tissues.</p>
<p>Your body is comprised of <a href="https://medlineplus.gov/genetics/understanding/basics/cell/">trillions of cells</a>, and each one is not only responsible for one or more functions specific to the tissue it resides in, but must also do all the work of keeping itself alive. This includes metabolizing nutrients, getting rid of waste, exchanging signals with other cells and adapting to stress.</p>
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<figcaption><span class="caption">Aging results from a number of physiological factors.</span></figcaption>
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<p>The trouble is that every single process and component in each of your cells <a href="https://doi.org/10.1016/j.cell.2022.11.001">can be interrupted or damaged</a>. So your cells spend a lot of energy each day preventing, recognizing and fixing those problems. </p>
<p>Aging can be thought of as a gradual loss of the ability to <a href="https://doi.org/10.1113/JP275072">maintain homeostasis</a> – a state of balance among body systems – either by not being able to prevent or recognize damage and poor function, or by not adequately or rapidly fixing problems as they occur. Aging results from a combination of these issues. Decades of research has shown that nearly every cellular process becomes more impaired with age.</p>
<h2>Repairing DNA and recycling proteins</h2>
<p>Most research on cellular aging focuses on studying how DNA and proteins change with age. Scientists are also beginning to address the potential roles many other important biomolecules in the cell play in aging as well.</p>
<p>One of the cell’s chief jobs is to maintain its DNA – the instruction manual a cell’s machinery reads to produce specific proteins. DNA maintenance involves protecting against, and accurately repairing, damage to genetic material and the molecules binding to it. </p>
<p>Proteins are the workers of the cell. They perform chemical reactions, provide structural support, send and receive messages, hold and release energy, and much more. If the protein is damaged, the cell uses <a href="https://doi.org/10.1093/jnci/92.19.1564">mechanisms involving</a> <a href="https://theconversation.com/research-that-shines-light-on-how-cells-recover-from-threats-may-lead-to-new-insights-into-alzheimers-and-als-163210">special proteins</a> that either attempt to fix the broken protein or send it off for recycling. Similar mechanisms tuck proteins out of the way or destroy them when they are no longer needed. That way, its components can be used later to build a new protein.</p>
<h2>Aging disrupts a delicate biological network</h2>
<p>The cross-talk between the components inside cells, cells as a whole, organs and the environment is a complex and ever-changing network of information. </p>
<p>When all processes involved in creating and maintaining DNA and protein function are working normally, the different compartments within a cell serving specialized roles – <a href="https://www.genome.gov/genetics-glossary/Organelle">called organelles</a> – can maintain the cell’s health and function. For an organ to work well, the majority of the cells that make it up need to function well. And for a whole organism to survive and thrive, all of the organs in its body need to work well. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/535889/original/file-20230705-19007-k74rlb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of cross-section of an animal cell and its organelles" src="https://images.theconversation.com/files/535889/original/file-20230705-19007-k74rlb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/535889/original/file-20230705-19007-k74rlb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535889/original/file-20230705-19007-k74rlb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535889/original/file-20230705-19007-k74rlb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535889/original/file-20230705-19007-k74rlb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535889/original/file-20230705-19007-k74rlb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535889/original/file-20230705-19007-k74rlb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Each organelle within a cell carries out specific functions.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/internal-structure-of-an-animal-cell-3d-rendering-royalty-free-image/1306045773">Jian Fan/iStock via Getty Images Plus</a></span>
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<p>Aging can lead to dysfunction at any of these levels, from the sub-cellular to the organismal. Maybe a <a href="https://doi.org/10.1016/j.arr.2020.101154">gene encoding an important protein for DNA repair</a> has become damaged, and now all of the other genes in the cell are more likely to be repaired incorrectly. Or perhaps the cell’s <a href="https://theconversation.com/cells-routinely-self-cannibalize-to-take-out-their-trash-aiding-in-survival-and-disease-prevention-199148">recycling systems</a> are unable to degrade dysfunctional components anymore. Even the <a href="https://doi.org/10.1016%2FS2213-8587(18)30026-3">communication systems</a> between cells, tissues and organs can become compromised, leaving the organism less able to respond to changes within the body. </p>
<p>Random chance can lead to a growing burden of molecular and cellular damage that is progressively less well-repaired over time. As this damage accumulates, the systems that are meant to fix it are accruing damage as well. This leads to a <a href="https://doi.org/10.1038%2Fs43587-021-00150-3">cycle of increasing wear and tear</a> as cells age.</p>
<h2>Anti-aging interventions</h2>
<p>The interdependence of life’s cellular processes is a double-edged sword: Sufficiently damage one process, and all the other processes that interact with or depend on it become impaired. However, this interconnection also means that bolstering one highly interconnected process could improve related functions as well. In fact, this is how the most successful anti-aging interventions work. </p>
<p>There is no silver bullet to stop aging, but certain interventions do seem to slow aging in the laboratory. While there are ongoing clinical trials investigating different approaches in people, most existing data comes from animals like nematodes, flies, mice and nonhuman primates. </p>
<p>One of the best studied interventions is <a href="https://doi.org/10.1126/science.abe7365">caloric restriction</a>, which involves reducing the amount of calories an animal would normally eat without depriving them of necessary nutrients. An FDA-approved drug used in organ transplantation and some cancer treatments <a href="https://doi.org/10.1007/s11357-020-00274-1">called rapamycin</a> seems to work by using at least a <a href="https://doi.org/10.1016/j.arr.2020.101240">subset of the same pathways</a> that calorie restriction activates in the cell. Both affect signaling hubs that direct the cell to preserve the biomolecules it has rather than growing and building new biomolecules. Over time, this cellular version of “reduce, reuse, recycle” removes damaged components and leaves behind a higher proportion of functional components.</p>
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<figcaption><span class="caption">The effects of calorie restriction on aging are still under study.</span></figcaption>
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<p>Other interventions include changing the <a href="https://theconversation.com/can-this-new-anti-ageing-supplement-turn-back-the-clock-126795">levels of certain metabolites</a>, selectively <a href="https://doi.org/10.1111%2Fjoim.13141">destroying senescent cells</a> that have stopped dividing, changing the <a href="https://theconversation.com/hangry-bacteria-in-your-gut-microbiome-are-linked-to-chronic-disease-feeding-them-what-they-need-could-lead-to-happier-cells-and-a-healthier-body-199486">gut microbiome</a> and <a href="https://doi.org/10.1111%2Facel.12338">behavioral modifications</a>.</p>
<p>What all of these interventions have in common is that they affect core processes that are critical for cellular homeostasis, often become dysregulated or dysfunctional with age and are connected to other cellular maintenance systems. Often, these processes are the central drivers for mechanisms that protect DNA and proteins in the body. </p>
<p>There is no single cause of aging. No two people age the same way, and indeed, neither do any two cells. There are countless ways for your basic biology to go wrong over time, and these add up to create a unique network of aging-related factors for each person that make finding a <a href="https://theconversation.com/despite-research-breakthroughs-an-anti-aging-pill-is-still-a-long-way-off-44949">one-size-fits-all anti-aging treatment</a> extremely challenging.</p>
<p>However, researching interventions that target multiple important cellular processes simultaneously could help improve and maintain health for a greater portion of life. These advances could help people live longer lives in the process.</p><img src="https://counter.theconversation.com/content/202096/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ellen Quarles does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Aging is a culmination of factors spanning from your cells to your environment. A number of interconnected processes determine how quickly your body is able to repair and recover from damage.Ellen Quarles, Assistant Professor in Molecular, Cellular, and Developmental Biology, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1988492023-03-15T12:21:15Z2023-03-15T12:21:15ZAre you a rapid ager? Biological age is a better health indicator than the number of years you’ve lived, but it’s tricky to measure<figure><img src="https://images.theconversation.com/files/514749/original/file-20230310-2079-5uhxpf.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2122%2C1410&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Healthspan measures incorporate quality of life in ways that lifespan does not.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/female-babyboomer-jumping-into-lake-royalty-free-image/92930493">Ira T. Nicolai/The Image Bank via Getty Images</a></span></figcaption></figure><p>Do you ever wake up some days and think, “When I was younger, I could survive on just four hours of sleep, but now it seems like I need 10”? Or have you ever walked out of the gym and “felt” your knees?</p>
<p>Almost everyone experiences these kinds of signs of aging. But there are some people who seem to defy their age. The late U.S. Supreme Court Justice <a href="https://www.cbsnews.com/news/remembering-rbg-justice-ruth-bader-ginsburg-a-woman-who-lived-a-life-defying-expectations/">Ruth Bader Ginsberg</a> stayed on the bench until her death at age 87. The “Great British Bake Off” judge <a href="https://www.bbc.com/news/entertainment-arts-58982697">Mary Berry</a>, now in her 80s, continues to inspire people all over the world to bake and enjoy life. And actor <a href="https://www.washingtonpost.com/arts-entertainment/2021/11/10/paul-rudd-sexiest-man-alive-people/">Paul Rudd</a> was named People magazine’s “Sexiest Man Alive” in 2021 at age 52 while still looking like he’s in his 30s. Is age just a number then? </p>
<p>Researchers have focused a lot of attention on understanding the causes and risk factors of age-related diseases like Alzheimer’s, dementia, osteoporosis and cancer. But many ignore the major risk factor for all of these diseases: aging itself. More than any individual risk factor such as smoking or lack of exercise, the number of years you’ve lived predicts onset of disease. Indeed, aging increases the risk of multiple chronic diseases <a href="https://doi.org/10.1016/j.cub.2012.07.024">by up to a thousandfold</a>. </p>
<p>However, <a href="https://doi.org/10.1038/s41586-018-0457-8">no two people age the same</a>. Although age is the principal risk factor for several chronic diseases, it is an unreliable indicator of how quickly your body will decline or how susceptible you are to age-related disease. This is because there is a difference between your chronological age, or the number of years you’ve been alive, and your biological age – your physical and functional ability.</p>
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<figcaption><span class="caption">As the author notes in her TED Talk, aging is not just a number.</span></figcaption>
</figure>
<p>I am a <a href="https://scholar.google.com/citations?user=tqI8C_UAAAAJ&hl=en">scientist interested in redefining “age.”</a> Instead of benchmarking chronological age, my lab is invested in <a href="http://agresearchlab.com">measuring biological age</a>. Biological age is a <a href="https://doi.org/10.1016/j.jacc.2019.11.062">more accurate measure of healthspan</a>, or years lived in good health, than chronological age, and doesn’t directly correlate with wrinkles and gray hairs. Rapid agers experience a faster rate of functional deterioration relative to their chronological age. </p>
<p>My grandmother, who lived to be 83 but was bedridden and could not remember who I was for the last few years of her life, was a rapid ager. My grandfather, on the other hand, also lived until he was 83, but he was active, functional and even did my homework with me until he passed away – he was a healthy ager.</p>
<p>With the unprecedented <a href="https://www.who.int/news-room/fact-sheets/detail/ageing-and-health">growth of the world’s aging population</a>, I believe that figuring out ways to measure biological age and how to maintain or delay its advance is critical not only for individual health, but also for the social, political and economic health of our society. Detecting rapid agers early on presents an opportunity to delay, change or even reverse the trajectory of biological aging. </p>
<h2>Genetics and biological age</h2>
<p>Biological aging is multifaceted. It arises from a complex mix of genetic traits and is <a href="https://doi.org/10.1016/j.jacc.2019.11.062">influenced by factors</a> like microbiome composition, environment, lifestyle, stress, diet and exercise.</p>
<p>Genetics were once thought to have no influence on aging or longevity. However, in the early 1990s, researchers reported the first studies identifying <a href="https://doi.org/10.1098/rstb.2010.0276">genes that were able to extend the lifespan</a> of a small roundworm. Since then, multiple observations support the influence of genetics on aging.</p>
<p>For example, children of long-lived parents and even those with long-lived siblings <a href="https://doi.org/10.1038/ejhg.2011.40">tend to live longer</a>. Researchers have also <a href="https://doi.org/10.1038/s41576-019-0183-6">identified multiple genes</a> that influence longevity and play a role in resilience and protection from stress. These include genes that repair DNA, protect cells from free radicals and regulate fat levels.</p>
<p>However, it is clear from studies in identical twins – who share the same genes but not the same exact lifespans – that genes are not the only factor that influences aging. In fact, genes probably account for only <a href="https://www.scientificamerican.com/article/genetic-factors-associated-with-increased-longevity-identified/">20% to 30% of biological age</a>. This suggests that other parameters can strongly influence biological aging.</p>
<h2>Environmental and lifestyle effects</h2>
<p>Researchers have found that environmental and lifestyle factors heavily influence biological age, including social connectedness, <a href="https://doi.org/10.1001/jamanetworkopen.2021.24387">sleeping habits</a>, <a href="https://www.cnn.com/2023/01/02/health/hydration-disease-aging-death-risk-study-wellness/index.html">water consumption</a>, exercise and diet. </p>
<p><a href="https://doi.org/10.1016/j.alcr.2019.02.002">Social connectedness</a> is essential for well-being throughout life. But social connections can be challenging to maintain over time due to loss of family and friends, depression, chronic illness or other factors. Several studies have reported a <a href="https://doi.org/10.1073/pnas.1219686110">strong link</a> between social isolation and increased stress, morbidity and mortality.</p>
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<a href="https://images.theconversation.com/files/514754/original/file-20230310-449-nugrkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Three women dancing together in a park" src="https://images.theconversation.com/files/514754/original/file-20230310-449-nugrkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514754/original/file-20230310-449-nugrkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514754/original/file-20230310-449-nugrkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514754/original/file-20230310-449-nugrkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514754/original/file-20230310-449-nugrkx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514754/original/file-20230310-449-nugrkx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514754/original/file-20230310-449-nugrkx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Social connectedness and physical activity are linked to well-being throughout life.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/three-ladies-listening-to-music-and-dancing-royalty-free-image/1152656857">Filippo Bacci/E+ via Getty Images</a></span>
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<p>Similarly, diet and exercise are strong influencers of biological age. <a href="https://doi.org/10.1177/1559827616637066">Blue zones</a>, which are areas around the world where people live long lives, attribute their successful aging to diet, exercise and social connectedness. Mostly plant-based meals and spurts of activity throughout the day are well-known “secrets” of healthspan and longevity. Although newer studies on the effects of diet interventions such as intermittent fasting and time-restricted feeding on longevity have not been rigorously tested, they do show multiple health benefits, including <a href="https://doi.org/10.1007/s00125-022-05752-z">better glucose</a> and <a href="https://doi.org/10.1186/s12986-021-00613-9">insulin regulation</a> </p>
<p>While genetics is difficult to control, diet and exercise can be modified to delay biological aging.</p>
<h2>How to measure biological age</h2>
<p>Currently, there is no effective test to predict an individual’s health trajectory early enough in life in order to intervene and improve quality of life with age. Scientists are interested in identifying a molecule that is sensitive and specific enough to serve as a <a href="https://doi.org/10.1038/s41576-022-00511-7">unique fingerprint for biological age</a>. </p>
<p>Considering the health and resilience of the individual instead of focusing solely on disease state is important in discussions on biological age. Resilience is the state of <a href="https://doi.org/10.1093%2Fgeroni%2Figab046.621">adapting and bouncing back</a> from a health challenge and is often more predictive of functional health. A molecular aging fingerprint may provide a tool to help identify people who are less resilient and require more aggressive monitoring and early intervention to preserve their health and help <a href="https://doi.org/10.1038%2Fs43587-021-00044-4">reduce gender, racial and ethnic health disparities</a>.</p>
<p>There are several promising molecular markers that may serve as biological age fingerprints.</p>
<p>One of these markers are epigenetic clocks. <a href="https://www.cdc.gov/genomics/disease/epigenetics.htm">Epigenetics</a> are chemical modifications of DNA that control gene function. Several scientists have found that DNA can get “marked” by methyl groups in a pattern that changes with age and could potentially act as a <a href="https://theconversation.com/epigenetic-and-social-factors-both-predict-aging-and-health-but-new-research-suggests-one-might-be-stronger-200153">readout for aging</a>.</p>
<p>It is important to note, however, that while epigenetic clocks have been valuable in predicting chronological age, they do not equate to biological age. In addition, it is unclear how these epigenetic marks work or how they contribute to aging.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/514752/original/file-20230310-140-5j83gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Older adult holding gold balloons of the number 70 in a backyard" src="https://images.theconversation.com/files/514752/original/file-20230310-140-5j83gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514752/original/file-20230310-140-5j83gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514752/original/file-20230310-140-5j83gz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514752/original/file-20230310-140-5j83gz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514752/original/file-20230310-140-5j83gz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514752/original/file-20230310-140-5j83gz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514752/original/file-20230310-140-5j83gz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Age is so much more than a number.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/happy-man-with-number-70-helium-balloons-in-royalty-free-image/1187298370">Klaus Vedfelt/DigitalVision via Getty Images</a></span>
</figcaption>
</figure>
<p>Another well-regarded marker of biological age is the build-up of dysfunctional cells called senescent or <a href="https://theconversation.com/cells-become-zombies-when-the-ends-of-their-chromosomes-are-damaged-a-tactic-both-helpful-and-harmful-for-health-186445">zombie cells</a>. Cells become senescent when they experience multiple types of stress and become so damaged that they cannot divide anymore, releasing molecules that cause chronic low-grade inflammation and disease.</p>
<p><a href="https://doi.org/10.1111/acel.12344">Animal studies</a> have shown that getting rid of these cells can improve healthspan. However, what clearly defines senescent cells in humans is still unknown, making them challenging to track as a measure of biological age.</p>
<p>Lastly, the body <a href="https://doi.org/10.1126/sciadv.add6155">releases unique metabolites</a>, or chemical fingerprints, as byproducts of normal metabolism. These metabolites play a dynamic and direct role in physiological regulation and can inform functional health. My lab and others are figuring out the exact makeup of these chemicals in order to figure out which can best measure biological age. A lot of work still remains on not only identifying these metabolites, but also understanding how they affect biological age.</p>
<p>People have long sought a fountain of youth. Whether such an elixir exists is still unknown. <a href="https://doi.org/10.1038/s43587-022-00278-w">But research</a> <a href="https://doi.org/10.1038/ncomms3192">is starting</a> <a href="https://doi.org/10.1073/pnas.2107621118">to show</a> that delaying biological age may be one way to live healthier, fuller lives.</p><img src="https://counter.theconversation.com/content/198849/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aditi Gurkar receives funding from National Institute on Health, Richard King Mellon Foundation, AFAR/Hevolution. </span></em></p>Aging is a major risk factor for many chronic diseases. Figuring out what influences longevity and how to identify rapid agers could lead to healthier and longer lives for more people.Aditi Gurkar, Assistant Professor of Geriatric Medicine, University of PittsburghLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1290682020-01-15T19:08:18Z2020-01-15T19:08:18ZDon’t die wondering: apps may soon be able to predict your life expectancy, but do you want to know?<figure><img src="https://images.theconversation.com/files/310160/original/file-20200115-151844-1ole8rh.jpg?ixlib=rb-1.1.0&rect=46%2C23%2C3833%2C2681&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Monaco and Japan have some of the highest life expectancies in the world. But calculating an individual's life expectancy will require taking data analysis several steps further.</span> <span class="attribution"><span class="source">SHUTTERSTOCK</span></span></figcaption></figure><p><em>When will I die?</em></p>
<p>This question has endured across cultures and civilisations. It has given rise to a plethora of religions and spiritual paths over thousands of years, and more recently, <a href="https://apps.apple.com/us/app/when-will-i-die/id1236569653">some highly amusing apps</a>. </p>
<p>But this question now prompts a different response, as technology slowly brings us closer to accurately predicting the answer. </p>
<p>Predicting the lifespan of people, or their “Personal Life Expectancy” (PLE) would greatly alter our lives. </p>
<p>On one hand, it may have benefits for policy making, and help optimise an individual’s health, or the services they receive. </p>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/were-not-just-living-for-longer-were-staying-healthier-for-longer-too-118588">We're not just living for longer – we're staying healthier for longer, too</a>
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</em>
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<p>But the potential misuse of this information by the government or private sector poses major risks to our rights and privacy.</p>
<p>Although generating an accurate life expectancy is currently difficult, due to the complexity of factors underpinning lifespan, emerging technologies could make this a reality in the future.</p>
<h2>How do you calculate life expectancy?</h2>
<p>Predicting life expectancy is not a new concept. <a href="http://www.bbc.com/travel/story/20170807-living-in-places-where-people-live-the-longest">Experts do this</a> at a population level by classifying people into groups, often based on region or ethnicity. </p>
<p>Also, tools such as <a href="https://www.nature.com/articles/s41598-018-23534-9">deep learning</a> and <a href="https://mipt.ru/english/news/scientists_use_ai_to_predict_biological_age_based_on_smartphone_and_wearables_data">artificial intelligence</a> can be used to consider complex variables, such as biomedical data, to predict someone’s biological age. </p>
<p>Biological age refers to how “old” their body is, rather than when they were born. A 30-year-old who smokes heavily may have a biological age closer to 40.</p>
<p><a href="https://www.mdpi.com/2227-7080/6/3/74/htm">Calculating a life expectancy reliably</a> would require a sophisticated system that considers a breadth of environmental, geographic, genetic and lifestyle factors – <a href="https://www1.health.gov.au/internet/publications/publishing.nsf/Content/oatsih-hpf-2012-toc%7Etier1%7Elife-exp-wellb%7E119">all of which have influence</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/310166/original/file-20200115-151848-pc2cam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/310166/original/file-20200115-151848-pc2cam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/310166/original/file-20200115-151848-pc2cam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/310166/original/file-20200115-151848-pc2cam.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/310166/original/file-20200115-151848-pc2cam.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/310166/original/file-20200115-151848-pc2cam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/310166/original/file-20200115-151848-pc2cam.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/310166/original/file-20200115-151848-pc2cam.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The use of devices such as fitness trackers will become crucial in predicting personal life expectancy in the future.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/healthy-lady-run-away-angel-death-329261456">Shutterstock</a></span>
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<p>With <a href="https://builtin.com/artificial-intelligence/machine-learning-healthcare">machine learning</a> and artificial intelligence, it’s becoming feasible to analyse larger quantities of data. The use of deep learning and cognitive computing, such as with <a href="https://www.ibm.com/watson-health">IBM Watson</a>, helps doctors make more accurate diagnoses than using human judgement alone. </p>
<p>This, coupled with <a href="https://www.cio.com/article/3273114/what-is-predictive-analytics-transforming-data-into-future-insights.html">predictive analytics</a> and increasing computational power, means we may soon have systems, or even apps, that can calculate life expectancy.</p>
<h2>There’s an app for that</h2>
<p>Much like <a href="https://www.mdanderson.org/for-physicians/clinical-tools-resources/clinical-calculators.html">existing tools</a> that predict cancer survival rates, in the coming years we may see apps attempting to analyse data to predict life expectancy.</p>
<p>However, they will not be able to provide a “death date”, or even a year of death.</p>
<p>Human behaviour and activities are so unpredictable, it’s almost impossible to measure, classify and predict lifespan. A personal life expectancy, even a carefully calculated one, would only provide a “natural life expectancy” based on generic data optimised with personal data.</p>
<p>The key to accuracy would be the quality and quantity of data available. Much of this would be taken directly from the user, including gender, age, weight, height and ethnicity.</p>
<p>Access to real-time sensor data through fitness trackers and smart watches could also monitor activity levels, heart rate and blood pressure. This could then be coupled with lifestyle information such as occupation, socioeconomic status, exercise, diet and family medical history. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/your-local-train-station-can-predict-health-and-death-54946">Your local train station can predict health and death</a>
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</em>
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<p>All of the above could be used to classify an individual into a generic group to calculate life expectancy. This result would then be refined over time through the analysis of personal data, updating a user’s life expectancy and letting them monitor it.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/308303/original/file-20191230-11891-nswi58.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308303/original/file-20191230-11891-nswi58.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=176&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308303/original/file-20191230-11891-nswi58.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=176&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308303/original/file-20191230-11891-nswi58.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=176&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308303/original/file-20191230-11891-nswi58.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=221&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308303/original/file-20191230-11891-nswi58.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=221&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308303/original/file-20191230-11891-nswi58.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=221&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This figure shows how an individual’s life expectancy might change between two points in time (F and H) following a lifestyle improvement, such as weight loss.</span>
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</figure>
<h2>Two sides of a coin</h2>
<p>Life expectancy predictions have the potential to be beneficial to individuals, health service providers and governments.</p>
<p>For instance, they would make people more aware of their general health, and its improvement or deterioration over time. This may motivate them to make healthier lifestyle choices.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/faster-more-accurate-diagnoses-healthcare-applications-of-ai-research-114000">Faster, more accurate diagnoses: Healthcare applications of AI research</a>
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</em>
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<p>They could also be used by insurance companies to provide individualised services, such as how some car insurance companies use <a href="https://www.theguardian.com/money/2017/dec/16/motoring-myths-black-boxes-telematics-insurance">black-box technology</a> to reduce premiums for more cautious drivers.</p>
<p>Governments may be able to use predictions to more efficiently allocate limited resources, such as social welfare assistance and health care funding, to individuals and areas of greater need.</p>
<p>That said, there’s a likely downside. </p>
<p>People <a href="https://www.theatlantic.com/health/archive/2017/11/the-existential-slap/544790/">may become distressed</a> if their life expectancy is unexpectedly low, or at the thought of having one at all. This raises concerns about how such predictions could impact those who experience or are at risk of mental health problems. </p>
<p>Having people’s detailed health data could also let insurance companies more accurately profile applicants, <a href="https://www.abc.net.au/news/2019-07-08/fitness-tracker-used-to-set-health-insurance-premiums/11287126">leading to discrimination against groups or individuals</a>. </p>
<p>Also, pharmaceutical companies could coordinate targeted medical campaigns based on people’s life expectancy. And governments could choose to tax individuals differently, or restrict services for certain people.</p>
<h2>When will it happen?</h2>
<p>Scientists have been working on ways to <a href="https://towardsdatascience.com/what-really-drives-higher-life-expectancy-e1c1ec22f6e1">predict human life expectancy</a> for many years. </p>
<p>The solution would require input from specialists including demographers, health scientists, data scientists, IT specialists, programmers, medical professionals and statisticians.</p>
<p>While the collection of enough data will be challenging, we can likely expect to see advances in this area in the coming years.</p>
<p>If so, issues related to data compliance, as well and collaboration with government and state agencies will need to be carefully managed. Any system predicting life expectancy would handle highly sensitive data, raising ethical and privacy concerns.</p>
<p>It would also attract cybercriminals, and various other security threats.</p>
<p>Moving forward, the words of Jurassic Park’s Dr Ian Malcolm spring to mind:</p>
<blockquote>
<p>Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.</p>
</blockquote><img src="https://counter.theconversation.com/content/129068/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Predicting life expectancy remains in the realm of science fiction, but it may soon be possible. Are we prepared for such information? And who else would benefit from this knowledge?James Jin Kang, Lecturer, Edith Cowan UniversityPaul Haskell-Dowland, Associate Dean (Computing and Security), Edith Cowan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1276552019-11-28T14:50:58Z2019-11-28T14:50:58ZAre ‘dog years’ for real? An explanation of calculating canine age<figure><img src="https://images.theconversation.com/files/304244/original/file-20191128-178107-9wucox.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-brown-cute-happy-labrador-retriever-587936159">Shutterstock/Blanscape</a></span></figcaption></figure><p>If your dog has been alive and kicking its paws about for a decade, the widely held belief is that it has aged as much as a human would have done by the grand old age of 70. This conversion factor – each year of a dog’s life accounting for seven human years – comes from dividing human life expectancy of around 77 by the canine life expectancy of around 11.</p>
<p>The underlying assumption is that each calendar year a dog lives though is equivalent to seven human years at any stage of a dog’s life. But <a href="https://www.biorxiv.org/content/10.1101/829192v1?ct=">new research</a> suggests that things aren’t so simple. And if we look at some basic developmental milestones, it’s clear why. </p>
<p>For example, most dog breeds <a href="https://www.akc.org/expert-advice/health/sexual-maturity-in-puppies-what-to-expect/">reach sexual maturity</a> between the ages of six and 12 months – the upper end of that range corresponding, by the traditional conversion, to a human age of seven. And at the other end of the spectrum, although unusual, some dogs have been known to live for over 20 years. Under the “factor-of-seven” conversion rule, this would equate to an unfathomable 140 human-equivalent years.</p>
<p>To make matters more complicated, dogs’ life expectancy depends significantly on the breed. Smaller dogs <a href="https://www.akc.org/expert-advice/health/why-do-small-dogs-live-longer/">tend to live significantly longer</a>, suggesting that they age more slowly than bigger dogs. </p>
<p>All of this raises the question of what exactly we mean by age. The most obvious way to describe it is simply the length of time that has passed since birth. This is known as the chronological definition of age. </p>
<p>However, there are other descriptions. “Biological age”, for example, is a more subjective definition, which relies on assessing physiological indicators to identify an indivdual’s development. These include measures like the “<a href="https://bmcgeriatr.biomedcentral.com/articles/10.1186/1471-2318-8-24">frailty index</a>” – surveys which take into account an individual’s disease status, cognitive impairments and levels of activity.</p>
<p>Then there are the more objective <a href="https://academic.oup.com/biomedgerontology/article/56/4/B180/619965">ageing biomarkers</a>, such as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639797/">levels of gene expression</a> (genes produce proteins at differing rates at different stages of life) or <a href="https://academic.oup.com/biomedgerontology/article/56/4/B180/619965">numbers of immune cells</a>. The rate at which biological age increases depends on <a href="https://www.biorxiv.org/content/10.1101/578245v1.full">genetically inherited factors, mental health and lifestyle</a>. </p>
<p>For example, if you’ve spent a lot of time eating junk food and smoking cigarettes instead of taking exercise and eating healthily, the chances are your biological age will exceed your chronological age. Or, you might be a 60-year-old with the body of a 40-year-old if you’ve looked after yourself well. </p>
<h2>A new look at a dog’s life</h2>
<p>When it comes to comparing animal ages across species, the biological definitions of age are far more useful than their chronological counterparts. Knowing a hamster is six weeks old doesn’t give you a good picture of that animal’s life stage even if you know the life expectancy of a hamster is only three years. Learning that a hamster has reached an age at which it can reproduce gives a much better picture of its level of maturity. </p>
<p>The authors of the <a href="https://www.biorxiv.org/content/10.1101/829192v1?ct=">new ageing study</a> suggest that a sensible way to measure biological age is though so-called “epigenetic clocks” – changes to the packaging of our DNA that accumulate over time in all mammals. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/304245/original/file-20191128-178062-1b3uptc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304245/original/file-20191128-178062-1b3uptc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304245/original/file-20191128-178062-1b3uptc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304245/original/file-20191128-178062-1b3uptc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304245/original/file-20191128-178062-1b3uptc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304245/original/file-20191128-178062-1b3uptc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304245/original/file-20191128-178062-1b3uptc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">New tricks? No chance.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/old-lazy-mixed-breed-dog-prepares-8021299?src=c8957236-c3fe-4b09-a428-f14ae9f9c00a-1-48">Shutterstock/Greg Henry</a></span>
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<p>In particular, “methylation” – the addition of methyl groups (a carbon atom bonded to three hydrogen atoms) to DNA – seems to be a good indicator of age. Many prominent physiological markers, such as the development of teeth, seem to occur at the same levels of methylation across different species. So by matching the levels of methylation in Labrador retrievers and humans, the researchers derived a formula to map dog age to its human equivalent.</p>
<p>That formula is: human equivalent age = 16 x ln(dog’s chronological age) + 31.</p>
<p>Here “ln” represents a <a href="https://www.rapidtables.com/calc/math/Ln_Calc.html">mathematical function</a> known as the <a href="https://www.britannica.com/science/logarithm#ref795970">natural logarithm</a>. The logarithm function is well-known in the non-linear scales for energy released during earthquakes (Richter) or for measuring sound (decibels). It comes in useful for measuring quantities whose sizes vary over many orders of magnitude. It’s even possible, as I explore in my new book <a href="https://amzn.to/2MkmdcM">The Maths of Life and Death</a>, that a logarithmic experience of the passing of time might explain why we perceive <a href="https://theconversation.com/why-time-seems-to-go-by-more-quickly-as-we-get-older-63354">time speeding up as we get older</a>. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-time-seems-to-go-by-more-quickly-as-we-get-older-63354">Why time seems to go by more quickly as we get older</a>
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<p>In the graph below, you can see how the natural logarithm works to convert the years a dog has lived (dog age) into the equivalent human age in the red dashed curve. The curve suggests that dogs mature extremely rapidly at first, but that their ageing then slows down, meaning that most of their lives are experienced as a form of protracted middle age.</p>
<p>A handy short cut is to remember that the first dog year counts for 31 human years. Then, every time the dog’s chronological age doubles after that, the number of equivalent human years increases by 11. So eight calendar years represents three “doublings” (from one to two, two to four and then four to eight) giving a dog age equivalent of 64 (that’s 31 + 3x11). </p>
<p>This useful approximation is plotted as the black curve on the conversion figure below. The green line represents the discredited factor-of-seven rule that suggests unrealistic ages at the higher end of the dog age spectrum.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/304278/original/file-20191128-178114-11gk665.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/304278/original/file-20191128-178114-11gk665.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304278/original/file-20191128-178114-11gk665.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304278/original/file-20191128-178114-11gk665.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304278/original/file-20191128-178114-11gk665.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304278/original/file-20191128-178114-11gk665.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304278/original/file-20191128-178114-11gk665.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304278/original/file-20191128-178114-11gk665.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The different ways of converting a dog’s age to the equivalent progression through a human life.</span>
<span class="attribution"><span class="source">Kit Yates</span></span>
</figcaption>
</figure>
<p>Most dog lovers will already have suspected that the human-to-dog age relationship is non-linear, having noticed that, initially, their pets mature much more quickly than the linear factor-of-seven rule suggests. </p>
<p>A <a href="https://www.telegraph.co.uk/pets/news-features/calculate-dogs-age-human-years/">more sophisticated refinement</a> to the factor-of-seven rules has suggested that each of the dog’s first two years correspond to 12 human years while all subsequent years count for four human equivalents. The blue curve in the above figure, which represents this ad hoc rule, shows better agreement with the new logarithmic law. </p>
<p>In practice the new molecular insights into human-to-dog age conversion encapsulated by the logarithmic law suggest that dogs move into middle age even more rapidly than most dog-owners would have suspected. It’s worth bearing in mind, when you find that Rex is reluctant to chase the ball like he once did, that he’s probably got more miles on the clock than you’ve been giving him credit for.</p><img src="https://counter.theconversation.com/content/127655/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christian Yates does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Your pup may be older than you think. Another reason to let sleeping dogs lie.Christian Yates, Senior Lecturer in Mathematical Biology, University of BathLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1067942018-11-12T14:22:04Z2018-11-12T14:22:04ZFeel younger than you are? Here’s why you’re on to something good<p>Emile Ratelband made <a href="https://www.telegraph.co.uk/news/2018/11/07/dutch-man-69-identifies-20-years-younger-launches-legal-battle/">international headlines</a> when he launched a controversial legal battle to change his official date of birth from March 1949 to March 1969, reflecting the fact that he feels 20 years younger. The story probably made some of us laugh, but who can blame him for wanting to share his year of birth with the likes of <a href="https://en.wikipedia.org/wiki/Jennifer_Aniston">Jennifer Aniston</a>, <a href="https://en.wikipedia.org/wiki/Jay-Z">Jay-Z</a>, <a href="https://en.wikipedia.org/wiki/Steffi_Graf">Steffi Graf</a> or even my good self? </p>
<p>The legal bid may be a first, but it is actually common to feel younger than we are. A 2018 study with 33,751 respondents showed that once people pass the pivotal age of 25, they typically <a href="http://www.projectimplicit.net/nlindner/articles/LN.2008.SPSP.pdf">rate their subjective age as younger</a> than their chronological age. And this discrepancy grows as we get older – for every decade that passes, people tend to feel that have only gained five or six years. This is the equivalent to living Martian years as opposed to Earth years. </p>
<p>It turns out that this phenomenon may have rather important implications. A recent surge in research in this area has revealed that the extent to which people feel younger than they are is strongly associated with a whole range of health outcomes. People with a younger subjective age are less likely to suffer from <a href="https://www.ncbi.nlm.nih.gov/pubmed/17986588">diabetes, hypertension</a>, <a href="https://academic.oup.com/psychsocgerontology/advance-article-abstract/doi/10.1093/geronb/gby006/4838941?redirectedFrom=PDF">depression</a>, <a href="https://academic.oup.com/psychsocgerontology/article/72/6/966/2632084">cognitive impairment and dementia</a>. These people also tend to report <a href="https://www.tandfonline.com/doi/abs/10.1080/08870446.2017.1324971?casa_token=ZYpj_9MtK1kAAAAA:xcjyTUafoVgf0oO8cF-0Lw4lCbPbeUfpy-iqNnwtV5i7DwaBWN8tR01zveWGj7KN_IqIi7ydxbmRAw">better sleep</a>, <a href="https://academic.oup.com/psychsocgerontology/article/71/4/675/2604974">stronger memory function</a> and more <a href="https://www.tandfonline.com/doi/abs/10.1080/00224499.2017.1293603">fulfilling sex lives</a>. </p>
<p>People with a younger subjective age also view their future selves in a more positive light and are more likely to <a href="https://link.springer.com/article/10.1007/s11357-015-9830-9">walk faster</a>. One group of researchers even found that people with a lower subjective age have a <a href="https://www.frontiersin.org/articles/10.3389/fnagi.2018.00168/full">younger looking brain</a>. Brain scans showed that they had more grey matter overall, with particular resilience in areas called the prefrontal cortex (involved in planning and complex cognitive behaviour) and superior temporal gyrus (responsible for processing sounds and emotions). </p>
<p>These findings are not trivial – new research shows that people who think of themselves as 13 years older <a href="https://journals.lww.com/psychosomaticmedicine/Citation/2018/09000/Subjective_Age_and_Mortality_in_Three_Longitudinal.9.aspx">are 25% more likely to die</a>, even when education, race and marital status are taken into account. This study, by a team at the University of Grenoble, pooled together data from three large longitudinal studies, where 17,000 participants were assessed over a number of time points. </p>
<p>Overall, people reported feeling on average 16-17 years younger than they really were – not far off the difference described by Ratelband. But importantly, this research showed that the risk of mortality was almost twice as high in those people who felt older than their age compared to those who felt younger. This effect appeared for both shorter time intervals (three years) and for longer ones (20 years). </p>
<h2>Cause and effect</h2>
<p>So it seems that to some extent, we really are as young as we feel. But how do we know which is the chicken and the egg? Are people who feel younger simply healthier to start with or are they so keen on being young that they actually take better care of themselves and therefore live longer?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/245047/original/file-20181112-83576-1hk4245.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/245047/original/file-20181112-83576-1hk4245.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/245047/original/file-20181112-83576-1hk4245.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/245047/original/file-20181112-83576-1hk4245.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/245047/original/file-20181112-83576-1hk4245.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/245047/original/file-20181112-83576-1hk4245.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/245047/original/file-20181112-83576-1hk4245.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Being young at heart can help prevent depression.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/happy-senior-african-american-woman-dancing-119165200?src=YCmprOGQR3Mbf02CGrqdMg-1-3">Spotmatik Ltd/Shuttestock</a></span>
</figcaption>
</figure>
<p>Most scientists agree that it is a two-way street. We know that poor health makes people feel older, as indeed can <a href="https://www.tandfonline.com/doi/abs/10.1080/08870446.2015.1061130?casa_token=jAS1ln64TRQAAAAA:BYKaiRq--wx_xdTGk7UsN4LRcng9X1Q6MU9XI3m6n5qdkHw1GjdXP_h4qsNfGEuouLGgRigbTdpcC">stress and low mood</a>. The real question is can we do anything to break this vicious cycle? If we could somehow feel younger – perhaps by ignoring societal and personal expectations about age – might this mean we can live longer, happier and healthier lives? Early indications suggest yes. </p>
<p>In one study researchers enrolled a group of older participants in an exercise regime and found that their performance <a href="https://academic.oup.com/psychsocgerontology/article/68/1/1/611760">improved significantly</a> if they were praised – but specifically if they were favourably compared to other people of the same age. Reducing age stereotyping might also be helpful – another study showed that exposing people to photos and words that are typically associated with old age, such as “grumpy”, “wrinkled”, and “helpless” <a href="https://academic.oup.com/psychsocgerontology/article/67/5/563/658968">made them feel older</a>. Interestingly, this was true even when positive associations like “wise” and “full of life” were used alongside a smiling older face. </p>
<p>Back in 1979, psychologist <a href="https://scholar.harvard.edu/langer/home">Ellen Langer</a> – now the longest serving professor at the University of Harvard – showed that simply turning the clock back 20 years had an age-reversing effect on a group of 75-year-old men. After five days of being immersed in a mocked up 1959 environment and treated as 55-year-olds, <a href="http://news.bbc.co.uk/1/hi/magazine/8498233.stm">these men showed</a> increased physical strength, improved memory and better eyesight. </p>
<p>Rateband’s case centres on his claims that at 69, society does not allow him to do the same things that he could do if he was 49. He does not have the same employment opportunities, cannot buy a new house and does not get replies when he advertises on the dating site Tinder. Only time will tell whether he can win his legal battle, but if nothing else, this case may highlight an opportunity for society to change its attitude to chronological age. </p>
<p>If we can learn to ignore the numbers on a birth certificate and cut down on the relentless societal references to getting old, then maybe we will lead healthier, happier and longer lives.</p><img src="https://counter.theconversation.com/content/106794/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Catherine Loveday does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Research shows that feeling younger than you are could be good for you.Catherine Loveday, Neuropsychologist, University of WestminsterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/967712018-05-31T10:45:00Z2018-05-31T10:45:00ZImmigration agents X-raying migrants to determine age isn’t just illegal, it’s a misuse of science<figure><img src="https://images.theconversation.com/files/221038/original/file-20180530-120518-d8e1xv.jpg?ixlib=rb-1.1.0&rect=3%2C2%2C772%2C542&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Teeth and bones can tell something about age – but not someone's birthday.</span> <span class="attribution"><a class="source" href="https://openi.nlm.nih.gov/detailedresult.php?img=PMC3190433_JFDS-3-14-g005&query=&req=4&npos=-1">Journal of Forensic Dental Sciences</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>A teenager’s father is murdered in Somalia, and the boy travels to the United States seeking asylum. Another teen’s father and brother are murdered by extremist groups in Afghanistan and he too makes his way to the U.S. to seek asylum. Since both are minors, <a href="https://www.gpo.gov/fdsys/pkg/PLAW-107publ296/html/PLAW-107publ296.htm">federal law decrees</a> that they must be held separately from adults under the oversight of the Office of Refugee Resettlement (<a href="https://www.acf.hhs.gov/orr">ORR</a>).</p>
<p>However, <a href="https://www.revealnews.org/blog/heres-how-ice-sent-children-seeking-asylum-to-adult-detention-centers/">in these two cases</a>, and an unknown number of others, these minors were taken in handcuffs by Immigration and Customs Enforcement and held in adult detention facilities. The reason? In the absence of other information that could corroborate the teens’ self-reported ages, analysis of their dental X-rays revealed that both could be adults.</p>
<p>Lawyers for these two teens <a href="https://www.nwirp.org/wp-content/uploads/2016/05/050516-Pechman-Order.pdf">sued on</a> <a href="https://www.documentcloud.org/documents/4451390-H-S-order.html">the grounds</a> that sole reliance on X-rays for age determination is illegal, and several federal judges agreed.</p>
<p>As a forensic anthropologist, I support these judicial decisions. My work can include estimating the ages of deceased persons using X-rays of bones and teeth, and I’m intimately familiar with the limitations of how specific these techniques can be. In my field, we generate an age range alongside several caveats; it’s irresponsible for ICE to rely solely on X-rays to provide a definitive answer in determining if a person is a minor or an adult.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=266&fit=crop&dpr=1 600w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=266&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=266&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=334&fit=crop&dpr=1 754w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=334&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/220866/original/file-20180529-80637-1e77wee.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=334&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">X-ray of a mouth with wisdom teeth emerging on the outside.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.4103/0975-1475.137068">Journal of Forensic Dental Sciences</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<h2>What can bones and teeth tell us?</h2>
<p><a href="https://www.crcpress.com/Forensic-Anthropology-An-Introduction/Langley-Tersigni-Tarrant/p/book/9781439898253">Forensic anthropologists study</a> the hard tissues of the human body, which includes bones and teeth. I’m typically charged with <a href="https://www.elsevier.com/books/research-methods-in-human-skeletal-biology/digangi/978-0-12-385189-5">estimating biological characteristics</a> of deceased persons, including how old a person was when they died.</p>
<p>For children and teenagers, such an analysis can be carried out by examining X-rays. Growth and development are predictable processes, and milestones occur in a particular order. This is the reason that a tooth such as the first adult molar is also known as the “six-year molar,” because it generally erupts in everyone around age 6, give or take.</p>
<p>The analysis proceeds the same way whether we’re examining the X-rays of a living or deceased person. Essentially, we compare the stage of growth shown in the X-ray to <a href="https://www.atlas.dentistry.qmul.ac.uk">existing growth charts</a> from children and teenagers of known ages.</p>
<p>The crucial point is that it’s not possible to make a definitive, single age determination from X-rays or examination of bones or teeth. A variety of factors affect how well chronological age corresponds with biological age; that is, the amount of time since birth doesn’t necessarily correlate to the exact same stage of growth in every child or teenager. </p>
<p><a href="http://admin.cambridge.org/academic/subjects/life-sciences/biological-anthropology-and-primatology/paleodemography-age-distributions-skeletal-samples#jmjs2GKsG24UOjZ3.97">Lots of things</a> can influence how well <a href="https://global.oup.com/academic/product/biological-anthropology-and-aging-9780195068290?lang=en&cc=be">biological and chronological age line up</a>, including nutrition, environmental exposure to disease-causing germs and viruses (and their level of virulence), whether the person has been vaccinated against preventable diseases, body weight, hormones and genetics, among many others.</p>
<p>While these factors differ between individuals, they also differ broadly between populations of people – for instance, as a group, Americans likely develop at a different rate than sub-Saharan Africans. </p>
<p>Many of the studies relied upon to make age estimations are based on populations not representative of the individuals to whom they’re being applied. Therefore, a <a href="https://www.wiley.com/en-us/A+Companion+to+Forensic+Anthropology-p-9781118959794">certain amount of error</a> can be expected in the final age estimation. What’s more, this error is immeasureable. Without scientific studies on growth that are specific to each population, we don’t know if on average, Population A ages six months, one year or two years faster or slower than Population B. And while many methods are bolstered by a statistical likelihood, this is not the same thing as being certain. We can never be 100 percent sure.</p>
<h2>Estimation ranges versus exact ages</h2>
<p>Of course, the amount of time since birth is the legally important age. But because a disparity exists, forensic anthropologists refer to the results of the scientific methods we use as “age estimation.” The estimation will never be a pinpointed exact age, because of the variation that exists between individuals and between populations of people.</p>
<p>Therefore, forensic anthropologists report age estimations as a range. For example, rather than saying someone is 17 years and 8 months old, our estimation may be that she is between 17 and 20 years old.</p>
<p><iframe id="dqTSx" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/dqTSx/4/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Sometimes, the estimated age range might include ages below and above 18. Take the development of the wisdom tooth, something we often look at when estimating age of older teenagers and young adults. But the development of this tooth is extremely variable, ranging from never developing at all to erupting anywhere from the mid-teens to early 20s. In such cases, how would a final decision of adult or minor status be made?</p>
<p><a href="https://www.state.gov/j/tip/laws/113178.htm">Federal law</a> dictates that X-rays in cases where adult age is not obvious be used only in concert with other methods, such as verification of documentation and interviews. This makes sense because X-rays only provide orienting information rather than a definitive answer. </p>
<p>The recent court cases demonstrate that ICE has broken the law by exclusively relying on X-rays for age determination, ruling that the teens be released back into ORR’s custody as minors. Are these cases isolated or illustrative of a bigger problem? <a href="https://www.documentcloud.org/documents/4450510-DHS-OIG-Report-on-ICE.html">A 2008 report</a> by the Office of Homeland Security found that it was not only unclear how often ICE needed to resort to X-rays to assist with age determination, but unknown how common it was for them to rely solely on X-ray results. Without accurate numbers, there is no way to know how widespread the practice is or how to improve the process.</p>
<p>The stakes are high. Children – especially unaccompanied ones – are especially vulnerable. For this reason, the <a href="https://www.aclu.org/sites/default/files/assets/flores_settlement_final_plus_extension_of_settlement011797.pdf">1997 Flores Settlement Agreement</a>, which ICE is bound by, stipulates that migrant minors be kept separate from unrelated adults. </p>
<p>Given recent news that ORR doesn’t know the <a href="https://www.nytimes.com/2018/04/26/us/politics/migrant-children-missing.html">whereabouts of almost 1,500 children</a> it placed, many people have lost confidence in these agencies to do the right or moral thing regarding migrants. If ORR can’t keep track of children under its care, can ICE be trusted to lawfully treat people whose ages are uncertain?</p>
<p>In this situation, the law is consistent with the science. And as a scientist, I am obligated to ensure my interpretations are not used irresponsibly in a way that could cause harm. Citizens, scientists and government officials alike should ensure that refugees and migrants are treated fairly, with the dignity and respect they deserve, and in a way consistent with how we would expect to be treated. Making age determinations based on X-rays alone is not in line with that goal and can have serious punitive consequences for young migrants.</p><img src="https://counter.theconversation.com/content/96771/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth A. DiGangi is affiliated with the ACLU. </span></em></p>If an undocumented migrant is a minor or an adult can have far-reaching implications. A forensic anthropologist explains why relying solely on dental X-rays to determine age doesn’t work.Elizabeth A. DiGangi, Assistant Professor of Anthropology, Binghamton University, State University of New YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/773422017-05-11T11:52:55Z2017-05-11T11:52:55ZWhat science tells us about successful ageing<figure><img src="https://images.theconversation.com/files/168735/original/file-20170510-28069-shglsq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/373606024?src=QwnaRrxuTclPGMjOtOWMtQ-1-86&size=medium_jpg">Ruslan Guzov/Shutterstock</a></span></figcaption></figure><p>There have been some noteworthy examples of successful human ageing in the press recently. It was announced that Prince Phillip will be <a href="https://theconversation.com/prince-philip-retires-with-a-final-masterclass-in-media-manipulation-77208">retiring from royal duties</a> in the autumn, at the age of 96. A couple of days later we heard the sad news that 85-year-old <a href="http://www.bbc.co.uk/news/world-asia-39829636">Min Bahadur Sharchan died</a> in an attempt to summit Everest (having successfully climbed the mountain at 76 years of age). </p>
<p>Last week, we were <a href="http://www.bbc.com/news/av/uk-politics-39815946/the-105-year-old-still-working-how">also told about</a> Bill Frankland, who, at 105 years of age, still works in immunology research, publishing regularly in scientific journals. What allows some people to be so vital in old age? Are they mere outliers, or can anyone, potentially, reach a ripe old age in good health?</p>
<p>Chronological age reflects how long you’ve been alive, whereas biological age is a measure of how well your body functions compared with your chronological age. Chronological age is both easy to measure and has a high degree of precision. At the time of writing this, I’m 33 years, 2 months and 27 days old (or 12,140 days, including leap years). Biological age is a bit more intangible. We have population averages for blood pressure and heart rate at various ages. We also have good data on how muscle mass and grip strength tends to diminish with age. So if you are better than the population average for your age, you are biologically “younger”. </p>
<p>What separates chronological from biological age? People often think that the two are intrinsically linked; that is, as we age, we become frailer – as our cardiovascular, muscular and neurological capacities decrease. Indeed, it is well understood that these variables, across population groups, tend to decrease with time from about 30 years of age. However, the rate of change in function differs between individuals, as measured by either physical function, cardiovascular function or neurological ability (decision making, reaction time, memory and cognitive function). Also, lower rates of change – that is, better maintenance of function – lead to better health, independence and longevity. In other words: successful ageing.</p>
<h2>Of mole rats and men</h2>
<p>If we look to animal models of successful ageing, biological and chronological ageing don’t always go hand in hand. Lobsters live a very long time and they don’t seem to <a href="http://www.sciencedirect.com/science/article/pii/S001457939801357X">show reductions in function with ageing</a> (nature’s cruellest joke – nearly immortal, yet delicious). One type of jellyfish (<em>Turritopsis nutricula</em>) is biologically immortal. They can <a href="http://www.journals.uchicago.edu/doi/abs/10.2307/1543022">essentially “age backwards”</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/168733/original/file-20170510-28071-cnesi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/168733/original/file-20170510-28071-cnesi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168733/original/file-20170510-28071-cnesi0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168733/original/file-20170510-28071-cnesi0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168733/original/file-20170510-28071-cnesi0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=510&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168733/original/file-20170510-28071-cnesi0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=510&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168733/original/file-20170510-28071-cnesi0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=510&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Subterranean sabre-toothed sausages (aka naked mole rats).</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nationalzoo/6257374009/in/photolist-awZo8C-iMWga-89xh2W-awZo5G-awZnM7-awWERP-awWFhM-awZnJG-cEbYd5-awWEBD-4fN8qX-F377a9-gAiye-awZob1-8DgeJr-awZogq-awZnAu-a8ZyJ8-awWFfg-awWEJr-89xmrA-a5TDdV-9Q5ro4-2ALEp-5dMpAQ-9wNRwg-5VUQzW-aKjjPV-6XLvjV-5VUQt5-cgLrPN-4fKYLv-dsdsrF-qJ2x8Q-a6ybYB-aib5K6-hjyKs-iMVxy-chRs2Q-cEc6Fm-cmtQ3f-awZnDE-5Hvc6k-cgLrKo-7CvF1Z-34NkXD-ab2A8s-8Nx7By-ceaiDY-dy9qqq/">Smithsonian's National Zoo/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>And naked mole rats show reduced ageing. Their chronological age differs from their biological age and their <a href="https://link.springer.com/article/10.1007%2Fs00360-007-0237-5">mortality rates don’t accelerate</a> as they age, like in most mammals. Of course, humans aren’t jellyfish or subterranean sabre-toothed sausages. What evidence do we have of human functionality being preserved with age?</p>
<p>A couple of years ago, Ross Pollock and colleagues at King’s College London <a href="http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2014.282863/abstract">examined</a> a group of 142 successfully ageing people. Participants were cycling enthusiasts, aged 55 and 79 years. To be eligible for the study, men had to be able to cycle 100km in under six-and-a-half hours, and women had to be able to cycle 60km in five-and-a-half hours. Smokers, heavy drinkers and those with high blood pressure or other health conditions were excluded from the study. </p>
<p>The researchers attempted to differentiate between chronological and biological age, and they did indeed tease out some interesting differences. These participants showed remarkable levels of muscular and cardiovascular function, with VO2max (the maximum rate of oxygen consumption as measured during incremental exercise) values more commonly seen in people 30 to 40 years of age. Importantly, the participants’ VO2max values had decreased with age – although not as much as in the general population – suggesting they had delayed, but not prevented, chronological age. Also, there was a wide variation in VO2max – lifelong exercise helped this functional measure but did not totally explain successful ageing. In other words, exercise is good for you but not to the same degree in different people. </p>
<p>Following on from this work, we targeted a group of successfully aged male athletes, with similar criteria as Pollock and colleagues, and compared them with a group of older, inactive people. Both Pollock’s results <a href="http://www.ncbi.nlm.nih.gov/pubmed/24067120">and ours</a> showed a preservation of testosterone levels and physical function in this successfully ageing group of men compared with the inactive group. </p>
<p>We found that getting our inactive group to complete high intensity intermittent training for six weeks <a href="http://www.ncbi.nlm.nih.gov/pubmed/26030347">offset lost physical function</a> differences and increased one form of testosterone to a degree that was closer to that of our successful ageing group. But it’s important to point out that this relatively short six weeks of training didn’t remove all the differences between the groups, nor would it be expected to. Six weeks of training shouldn’t equal a life’s effort. </p>
<p>We’re continuing to conduct research on this model of successful ageing to see if we can establish the effect of genes, environment and training history, and gain insight into cause and effect. Do these individuals maintain high levels of physical activity and thus successfully age better? Or do they successfully age better and thus maintain physical activity for longer? </p>
<p>We do know, however, that it’s never too late to introduce supervised exercise into older people’s lives, no matter their chronological or biological age. But, for the final answer as to how genetics, lifelong activity levels and environment all come together to result in successful ageing, we’ve got more work to do yet to establish the role these all play in making the naked mole rats and Prince Philips of this world.</p><img src="https://counter.theconversation.com/content/77342/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bradley Elliott is a member of, and receives research funding for human ageing from, the Society for Endocrinology, a not-for-profit charity (reg. charity No. 266813), and is also a member of the Society for Cachexia, Sarcopenia and Wasting Disorders.</span></em></p>We may not be able to ‘age backwards’, as some jellyfish do, but research is slowly revealing the secrets of successful ageing for humans.Bradley Elliott, Lecturer in Physiology, University of WestminsterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/669622016-11-14T13:39:21Z2016-11-14T13:39:21ZBiological vs chronological age: how old are you really?<figure><img src="https://images.theconversation.com/files/142677/original/image-20161021-1792-1mkunb8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-103648040/stock-photo-cool-fashion-elder-man-with-electric-guitar.html?src=-9AK697iC8nJTYvBkQqmrQ-1-21">tommaso lizzul/Shutterstock.com</a></span></figcaption></figure><p>Researchers are developing tests to calculate your true biological age. They claim that such tests can measure how well your body is coping with the rigours of life. But how accurate are these tests and could they somehow be used to predict your future health? </p>
<p>Ageing has long been considered an inevitable consequence of life. However, recent scientific advances have revealed that the physical decline associated with growing old is caused by an <a href="https://theconversation.com/why-do-humans-deteriorate-with-age-its-a-biological-puzzle-21824">underlying biological process</a>, influenced by both <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3836174/">genetic and environmental factors</a>. And if ageing is governed by biology then it is <a href="https://theconversation.com/ageing-isnt-fixed-we-can-manipulate-it-to-live-longer-31808">amenable to manipulation</a>. </p>
<p>Being older is a major risk factor for several diseases. As the global population gets <a href="https://www.census.gov/content/dam/Census/library/publications/2016/demo/p95-16-1.pdf">steadily older</a>, this poses serious social, medical and economic costs to society. A better understanding of the mechanisms that cause ageing could lead to interventions to improve age-related health. For these interventions to be successful, clear read-outs of how well our bodies are ageing are first required. </p>
<p><a href="http://www.pnas.org/content/112/30/E4104">Ageing rates between individuals</a> that share the same birth year can vary significantly. As such, the number of years you have been alive – your chronological age – is not necessarily a good predictor of how well you are ageing. Instead, some measurement of biological age that identifies an age-related change in body function or composition could more accurately predict your chances of developing age-related disease. Such biomarkers of ageing could be used to identify people at risk of disease, prompting preventative measures in lifestyle or early treatment. They could also be used to check how effective new anti-ageing therapies are.</p>
<p>But reliable biomarkers for ageing have so far proved elusive. Physical differences clearly exist between old and young, but measuring these differences with any kind of confidence is difficult as <a href="http://www.sciencedirect.com/science/article/pii/S0047637415000317">they can vary hugely</a> from one person to the next. </p>
<h2>Behavioural vs biomedical tests</h2>
<p>Tests that claim to measure biological age usually take one of two forms. The first, including the <a href="http://www.thevitalitygroup.com/whats-your-vitality-age/">Vitality Age test</a>, are based on an assessment of your overall health and behaviour. The online vitality test uses an algorithm that takes into account details such as your weight, your eating habits, the amount of exercise you take, your cholesterol levels and your weekly alcohol consumption. Your answers to such questions are then compared to the average score calculated from a large cohort of relatively healthy people of the same chronological age. Your biological age is calculated as a measure of risk and perhaps not surprisingly, engaging in more risky behaviours such as smoking or eating an unhealthy diet can all dramatically increase your biological age. </p>
<p>Other tests for biological age take a more biomedical approach. They measure some biological parameter that is more prevalent in older individuals or is subject to change as we age. A study led by a team from Kings College London claimed to have determined a <a href="http://genomebiology.biomedcentral.com/articles/10.1186/s13059-015-0750-x">genetic signature of ageing</a> present in individuals that are ageing well. They <a href="https://theconversation.com/revealed-a-new-way-to-test-your-biological-age-47070">measured the expression of 54,000 genes</a> in healthy 25 to 65-year-olds, of which around 150 genes could reliably distinguish between young and old participants in the study. </p>
<p>Importantly, this genetic signature of ageing was different in people with dementia suggesting that it could prove useful in predicting those at risk of developing disease. However, while particular patterns of gene expression were linked to long-term health, they varied widely between individuals. </p>
<p>The <a href="http://www.glycanage.com/">GlycanAge Test</a> claims to be the most accurate method yet to determine your biological age. The test focuses on the structure of Immunoglobulin G (IgG), a protein found in blood serum that is involved in the immune response. The IgG protein is modified by the addition of glycans – sugar molecules that decorate the surface of proteins, influencing the way in which they function. GlycanAge have analysed the structures of IgG glycans in blood samples from over 40,000 people worldwide and claim that the patterns of glycan structures on IgG proteins change with age and reflect the effects of lifestyle choices that impact on ageing such as smoking. By comparing your IgG glycan structures to those studied, GlycanAge says the test can determine how well your body is ageing. </p>
<p>Yet no single measurement is likely to be enough to capture the full biological complexity of ageing. Especially because not all age-related biological changes will affect health to the same extent. The <a href="http://www.sciencedirect.com/science/article/pii/S0047637415000317">MARK-AGE Consortium</a>, an EU funded project comprised of 26 European research partners, proposes a battery of biological tests covering multiple aspects of ageing. It is this kind of an approach that will probably prove more useful in determining overall biological age and predicting age-related health.</p><img src="https://counter.theconversation.com/content/66962/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cathy Slack does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Various tests claim to be able to tell your true age. Here’s how they do it.Cathy Slack, Lecturer, Aston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/649882016-09-09T09:37:12Z2016-09-09T09:37:12ZBio-banding is football’s big idea for developing young talent – and why it might not work<figure><img src="https://images.theconversation.com/files/136739/original/image-20160906-6110-1mxufhi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">'All for one ...'</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-71499067/stock-photo-belgorod-russia-august-21-unidentified-boys-embrace-before-football-game-on-august-21-2010-in-belgorod-russia-the-final-of-chernozemje-superiority-football-kinder-team-of-1996-year.html?src=23e-VYM7xeUqX6YMCZdgEw-1-78">Olga Dmietrieva</a></span></figcaption></figure><p>Now that the summer football transfer window has closed, a new record has been set for spending in England. <a href="http://www.bbc.co.uk/sport/football/37230202">A total</a> outlay of more than £1 billion on Premier League players sounds astronomical when you think that Trevor Francis <a href="http://www.telegraph.co.uk/sport/football/teams/nottingham-forest/4560618/The-day-Trevor-Francis-broke-footballs-1m-mark.html">became</a> the first £1 million player as recently as 1979. Yet despite this spending record, the finances clubs have at their disposal still <a href="http://www.bbc.co.uk/news/business-36412394">appear to be</a> increasing unabated. </p>
<p>In a sport with such huge transfer fees, the youth systems of clubs take on more and more importance. The benefits of academies should be twofold: recruiting players before they become too expensive and then a source of income if they are sold for a profit later in their career. </p>
<p>Predicting which children will be successful in the adult game is difficult, however. You can <a href="http://www.bbc.co.uk/sport/football/35054310">see this</a> from the number of youngsters who are released and signed each year from professional academies. Being signed at 12 years of age is no guarantee of being offered a professional contract.</p>
<p>Clubs have been employing various tactics to tackle this problem, one of which has been to experiment with tournaments that categorise young players based on their biological rather than chronological age. Known as bio-banding, it aims to make competition fairer by assessing technical proficiency rather than physical prowess. Players compete against peers of similar maturity and physicality rather than age.</p>
<p><a href="http://www.afcb.co.uk/news/article/matchday-feature-afc-bournemouth-bio-banding-3022841.aspx">AFC Bournemouth</a>, Southampton and Stoke City <a href="http://www.independent.co.uk/sport/football/news-and-comment/how-bio-banding-aims-to-stop-bigger-children-running-the-show-a6733916.html">are among</a> the Premier League clubs who have been experimenting with youth tournaments that use bio-banding. Some <a href="http://www.bbc.co.uk/sport/football/37054941">clubs in Scotland</a> are doing likewise. So will this approach help clubs select, develop and retain the most promising young players?</p>
<p>The first problem is determining the player’s biological age. It is easy to determine someone’s chronological age – assuming you have a legitimate birth certificate – but biological age poses more of a challenge. The most valid method is to <a href="http://www.aspetar.com/journal/viewarticle.aspx?id=218#.V8_qX1dlmRs">X-ray the wrist</a> to determine skeletal age. Subjecting youngsters to X-rays for something that may or may not benefit them however raises ethical questions – not to mention the associated expense. </p>
<p>Of the various surrogate markers proposed, the <a href="https://www.researchgate.net/profile/Adam_Baxter-Jones/publication/11432300_An_assessment_of_maturity_from_anthropometric_measurements/links/0deec53209707abe0e000000.pdf">most popular is</a> an equation that uses mass, stature and seated stature to predict what is called the maturity offset. Yet like all measures, this calculation has an inherent degree of error and <a href="https://www.researchgate.net/publication/221805238_Interrelationships_among_invasive_and_non-invasive_indicators_of_biological_maturation_in_adolescent_male_soccer_players">may actually</a> be unsuitable for grouping players by maturity. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/136740/original/image-20160906-6110-1e12fx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/136740/original/image-20160906-6110-1e12fx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/136740/original/image-20160906-6110-1e12fx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136740/original/image-20160906-6110-1e12fx3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136740/original/image-20160906-6110-1e12fx3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136740/original/image-20160906-6110-1e12fx3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136740/original/image-20160906-6110-1e12fx3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136740/original/image-20160906-6110-1e12fx3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">“Mon the kids.‘</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-318996482/stock-photo-kids-soccer-team-celebrate-goal-and-victory-defocussed-blur-sport-background-image.html?src=23e-VYM7xeUqX6YMCZdgEw-1-34">Igor Stevanovic</a></span>
</figcaption>
</figure>
<h2>No panacea</h2>
<p>An important philosophical issue around bio-banding is its intended use. <a href="http://www.bbc.co.uk/sport/football/37054941">Some tournaments</a> have used it for players already attached to a club academy as opposed to those on trial. This prompts an important question: is bio-banding better used for identifying talent or for developing it – or neither?</p>
<p>Tournaments that use bio-banding would typically categorise players by recording their vital statistics to calculate biological age before the first game (despite the uncertainty around maturity offset). The trouble is that doing this increases the margin of error and prevents any assessment about how rapidly a player is growing, for example. One may question whether this is any more useful than categorising players by chronological age. </p>
<p>When it comes to developing players that have already been signed, clubs would be in a position to track their growth over time to calculate biological age more accurately. This would give them the necessary information to develop individualised programmes for players who were large or small for their age, negating the need to categorise players through bio-banding. </p>
<p>Players that are mature for their age might for instance be given instructions that limit how much they can use their physicality, such as only allowing them to regain possession by interceptions and not tackling. This should encourage better positioning and less reliance on physical duels. In conjunction, you could give them short spells playing with older players of comparable size. These strategies would allow the coach to differentiate between their physical and technical attributes and devise a training plan that addresses their weaknesses rather than reaffirming their strengths.</p>
<p>For players who are too small and unable to impose themselves in training and matches, clubs could use their biological age to assess how close they are to their growth spurt and how much development is yet to take place. This may prevent players being released before they have realised their physical potential. </p>
<p>Bio-banding also raises the question of why we are so often preoccupied with physical prowess among young players. Perhaps it is because physical attributes can be measured easily. Aspects such as mindset, resilience and ability to learn and take instruction might be equally or even more important – just more difficult to assess. Despite the challenges, there may be a case for young athletes being categorised in future according to their emotional <a href="https://theconversation.com/how-to-win-the-euros-with-a-little-help-from-neuroscience-60679">and cognitive development</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/136741/original/image-20160906-6106-iom061.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/136741/original/image-20160906-6106-iom061.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/136741/original/image-20160906-6106-iom061.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136741/original/image-20160906-6106-iom061.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136741/original/image-20160906-6106-iom061.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136741/original/image-20160906-6106-iom061.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136741/original/image-20160906-6106-iom061.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136741/original/image-20160906-6106-iom061.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">‘Pheep!’</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-61755235/stock-photo-football-or-soccer-ball-at-the-kickoff-of-a-game-outdoors.html?src=tCcsyS3wCLJYYf1CL4WwBw-1-33">Andresr</a></span>
</figcaption>
</figure>
<p>So there are numerous question marks around bio-banding. Using it to identify talent raises issues about accuracy while for developing signed players there are more useful and robust, albeit subjective, ways to assess their ability. That said, clubs may benefit from using biological age to help interpret players’ progress over time, especially when assessing physical attributes such as speed and fitness. </p>
<p>When it comes to spotting and nurturing talent, however, and without discouraging anyone from coming up with something better, there may be no substitute for experienced scouts and coaches seeing past the size and shape of young players and recognising their ability to play the game.</p><img src="https://counter.theconversation.com/content/64988/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Neil Gibson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Bio-banding is all the rage as youth football seeks to make the most of young talent. Here’s why we shouldn’t get carried away.Neil Gibson, Director of Sport, Performance and Health, Heriot-Watt UniversityLicensed as Creative Commons – attribution, no derivatives.