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What would you do for another thirty years of life?

Public health advocates, when asked what single intervention would most dramatically prolong human life, tend to be unanimous:

“Stop Smoking

While some anti-smoking campaigs suggest a 30 year old could live as much as 25 additional years by not smoking, other estimates suggest a typical smoker could live an extra ten years by quitting.

A paper in this week’s edition of Current Biology reminds us that there is another practice, long-established in some cultures, that more dramatically prolongs lifespan in people eligible to undergo it:

Castration.

Unfortunately it isn’t an especially practical intervention to prolong lifespan.

As long ago as 1969, a study of patients in US mental hospitals showed that castrated patients lived an average of 13.6 years longer than intact patients. The mere fact that an appreciable number were castrated hints at the barbaric treatment of inmates in these institutions. Fair to say this was not a particularly representative population of castrated men, if such a population exists.

The new development involves the analysis of data from the Yang-Se-Gye-Bo — an 1805 genealogy of Korean eunuchs. As Kyung-Jin Min, Cheoi-Koo Lee and Han-Nam Park explain in their paper:

The Imperial court of the Korean Chosun Dynasty (1392–1910)… had eunuchs …[who]… lived with privileges: Korean eunuchs were conferred with official ranks and were legally allowed to marry, a practice that was officially banned in the Chinese Empire. In addition, married couples were also entitled to have children by adopting castrated boys or normal girls. The boys lost their reproductive organs in accidents, or they underwent deliberate castration to gain access to the palace before becoming a teenager.

The average lifespan of the 81 eunuchs for whom the authors could extract reliable data was 70 years. By comparison, contemporary non-eunuchs from families of similar social status lived an average of between 51 years (the shortest lived family) and 56 years (the longest-lived family).

Interestingly, out of the 81 eunuchs, three were centenarians. The current incidence of centenarians is one per 3,500 in modern Japan (the country with the highest survival to 100). Thus, the incidence of centenarians among Korean eunuchs was at least 130 times higher than in the most centenarian-rich modern society.

Eunuch longevity is also probably not due to cushy palace living. Kings and male royal family members only lived to averages of 47 and 45 years old, respectively.

This effect is never going to be subject to randomized controlled experiment on a representative population. A near-infinite number of aspects of the lives of eunuchs would have differed from the lives of other men.

But that is also the point. Extended longevity isn’t simply due to the magical effects of lower testosterone on otherwise-identical bodies. Sex hormones change everything about our lives because they mediate the investments we make in reproduction. And for men that includes the jostling for status, the respect of other men and the attention of potential mates. And these all lead to stress, risk-taking, violence, and even homicide.

And while they are typically different, the costs of reproduction paid by women may be even more dramatic than those paid by men. For example, reducing fertility is associated with longer lives and lower rates of obesity in women.

The real value of stopping to consider the lives of Korean Eunuchs who lived hundreds of years ago is to consider the toll that investments in reproduction take on the lives women and men lead today.

Are there less dramatic and more humane ways in which we can moderate the effects of sexual competition and reproduction on lifespans, ageing and quality of life?

Join the conversation

9 Comments sorted by

  1. Peter Ormonde
    Peter Ormonde is a Friend of The Conversation.

    Farmer

    Excellent!

    Another thinly veiled attempt to nobble your reproductive rivals with science!!!!

    I have visions of little collection bins on the approaches to Canberra. Please leave your jewels at the door.

    I remember (vaguely) some study on the longevity of nuns which came to similar conclusions, that the whole sex and reproduction business was a nasty nasty habit and nowhere near as satisfying as smoking. I have no idea if recruitment rates responded enthusiastically. Let's hope so.

    When will we ever learn?

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  2. Dale Bloom

    Analyst

    Hands up evolutionary ecologists to be volunteers in a series of experiments to increase life expectancy.

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    1. Dale Bloom

      Analyst

      In reply to Dale Bloom

      As I predicted, no evolutionary ecologist put their hands up or volunteered.

      Maybe they want members of the public to try out their theory first.

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  3. Chris Booker

    Research scientist

    I saw this study covered in almost every major news channel the other day and so decided to read the actual article - and seriously, sometimes I just sit in bemusement wondering how it is that some research attracts headline coverage while other important findings go completely under the radar. I know this has been an issue on the Conversation as regards media coverage of climate and science issues as opposed to celebrities, sports stars, etc., but there's also something going on with media coverage…

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    1. Rob Brooks
      Rob Brooks is a Friend of The Conversation.

      Professor of Evolutionary Ecology; Director, Evolution & Ecology Research Centre at UNSW Australia

      In reply to Chris Booker

      Chris,
      Of course you are right - that paper isn't the best piece of science, and it doesn't advance the questions nearly as well as a hundred other, better studies. But the historic angle, the exoticism of eunuchs at the Korean court etc etc also make it a compelling story. I'm pragmatic about the value of good stories in making sure that science (or scienciness, as Colbert might say) makes it into the popular consciousness - for a moment supplanting the fascinating lives of the sisters Kardashian etc.

      I do appreciate you sending those references. I will be sure to use them in both my science and my longer-form writing on the subject.

      Rob

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    2. Chris Booker

      Research scientist

      In reply to Rob Brooks

      I had to laugh at your mention of 'scienciness' - if I've interpreted Colbert right when he was talking about 'truthiness' it wasn't so much that it was true, but that it sounded like it could be - seems like that is the approach to science journalism a lot of the time - not really science, but sounds like it could be!

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  4. Margo Saunders

    Public Health Policy Researcher

    The sub-text here provides a good example of something that concerns me: if the question being put to public health advocates is, 'what single intervention would most dramatically prolong human life?', then it's probably the wrong question and indicates the gap between mainstream health and those on the receiving end of health-related initiatives. Qualitative research with real people ('lay epidemiology') suggests that it is not so much longer life that people value, but happiness and quality of life -- hence the common decisions to engage in practices which are understood to increase the risk of premature death but which, in the individual's personal cost-benefit analysis, are given a higher value than living longer but being miserable. Has significant implications for understanding decision-making about less dramatic health issues than castration.

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    1. Chris O'Neill

      Retired Way Before 70

      In reply to Margo Saunders

      "Qualitative research with real people ('lay epidemiology') suggests that it is not so much longer life that people value, but happiness and quality of life"

      Urologists put a very low value on the latter when Prostate Cancer is involved.

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  5. Julia Abbott

    logged in via email @gmail.com

    Putting a proposal for an RCT for this through an ethics committee would be a hoot!

    Rob, how does this work with neutered pets - do you know if they have a longer life span than pets that have not been de-sexed?

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