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Worrying about the future is bad for your survival - have we evolved to prefer optimism? Vassilis Galanos

How we evolved to reject climate science

Is it any wonder so many people turn their back on climate science? Who wants to hear - as the World Bank told us today - we’re heading for a four-degree-warmer world, with more heatwave deaths and life-threatening sea-level rise?

Climate communication is surely the latter day task of Sisyphus. A 2012 Gallup poll found only 52% of Americans accept the earth is warming. Barely more than half of those think it man-made. Warming science is a boulder, and it keeps rolling back down the mountain. And the gravitational force might just be evolution.

The new kid on the climate-change block is the psychology of climate science rejection. Why are so many, faced with so much evidence, so unconvinced?

Confirmation bias is shaping as a strong contender in a wide field. This type of “motivated reasoning” means we favour information that sits well with our values and beliefs, and discount any that contradicts. Cultural leanings, rather than scientific literacy, better predicted climate beliefs in a recent study.

Believing in a world that fits with our values – be it one of wind farms or nuclear power – feels good. Statements that challenge those beliefs – turbines cause illness, nuclear energy is dangerous – disturb the peace. To preserve the pleasant mental state we downgrade the objection.

Everyone is vulnerable to confirmation bias, including scientists - although peer review keeps that mostly in check. But those who reject climate science might just be more prone. Why?

A world of looming environmental catastrophe is, to put it mildly, unpalatable. And so a large hedonic reward is on offer to any who discount it.

The impact of motivated reasoning on climate communication raises a big question. Why are we so disposed to believe in accordance with our feelings, rather than the evidence? The happy news is that it may have conferred evolutionary advantage. Optimism might not only feel good, but be good for you.

The logic runs like this. As brains evolved, so did our capacity for foresight. Faced with an uncertain future, say a season of famine or plenty, big brains were able to muse on either eventuality. But dwelling on the negative was a recipe for ongoing worry, and stress.

And chronic stress is damaging, courtesy of elevated stress hormones like adrenalin and cortisol. The resulting nasties include high blood pressure, heart attack, stroke, diabetes and the modern scourge, depression. A hopeful outlook may well have been protective.

Positive thinking has prolonged life for people with HIV/AIDS. And the bright expectations behind the placebo effect lead to better pain reduction, and stronger responses to immunosuppressants. The glass half full approach also motivates striving and better coping. Pessimism breeds demoralisation and overwhelm.

On each of these counts, daubing one’s psychological canvas with a rosy tint favoured reproductive success. But our penchant for believing what feels best might also be an unhelpful evolutionary spin off.

Emotions are an indispensable tool in the evolutionary survival kit. With them, we parsed the world on two axes. Food, shelter and mates favoured reproduction. They felt good, so we sought them with gusto. Predators threatened survival. Our fear motivated defence and avoidance. Tagging events with feeling enabled rapid decisions and life-saving behaviour.

In a fascinating twist we may also have evolved to tag our beliefs with positive or negative emotion. As Chris Mooney put it recently, “We push threatening information away; we pull friendly information close. We apply fight-or-flight reflexes not only to predators, but to data itself.”

If we accept natural selection, beliefs reinforced with good feeling must have been good for survival. And the beliefs that saved lives were generally true. Ergo, beliefs that felt good were on the money.

Yes, it may have been tempting to think the charging rhino was a mirage. But to succumb to temptation was surely a fatal weakness.

But, as George Ainslie illustrates, there was a compelling downside of felt beliefs. As brains grew larger and forward planning more sophisticated, reward became possible for beliefs about the distant future. Cropfarmer Man could derive pleasure contemplating abundance many seasons hence.

Yet any test of accuracy was so far ahead, that a false belief could be embraced with little impact on survival. Good feeling could reward beliefs whose falsity might never be exposed, nor cause harm to the holder. Positive emotion was no longer an index of truth.

The upshot is that confirmation bias pulls two ways in the rejection of climate science. It may offer a protective shield of optimism, with tangible health benefits. But the shield may also ward off truth.

One solution for communicators is to combine climate facts with an appeal to values. A recent study found progressives were more convinced by warming messages paired with an anti-pollution message. And conservatives were more persuaded by the science when nuclear power was part of the remedy.

Climate communication that acknowledges the listener’s social perspective has a better prospect of instilling beliefs in line with the evidence. And equipping the audience with a concrete means of making a difference will, in all likelihood, see optimism follow.

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