Two children, Anne and Carla, have worked together to make a cake and they have to split it between them. Anne says that she’s the bigger cake aficionado and deserves the lion’s share. But Carla demands the bigger slice since she did most of the cooking. A nosy third party, Brenda, argues that the only fair call would be for the two girls to split the cake equally. Which is the right path?
There’s no obvious right answer and different people will probably side with different viewpoints. Dilemmas like this have been the subject of much philosophical debate, and they’re a common part of everyday life. How do you allocate pay rises between your staff? How should the UK’s new government split its budget among its various departments?
According to Norwegian scientist Ingvild Almås, our attitudes to such questions change during our childhood and adolescence, as we start changing our opinions on what counts as ‘fair’. Children tend to shun any form of inequality – they’d agree with Brenda. But as they enter the turmoil of adolescence, they become more meritocratic and are happier to divide wealth according to individual achievements, as Carla suggested. As their teens draw to a close, they (like Anne) pay greater heed to efficiency, making choices of maximum benefit to the group.
Some people go out of their way to help their peers, while others are more selfish. Some lend their trust easily, while others are more suspicious and distrustful. Some dive headlong into risky ventures; others shun risk like visiting in-laws. There’s every reason to believe that these differences in behaviour have biological roots, and some studies have suggested that they are influenced by sex hormones, like testosterone and oestrogen.
It’s an intriguing idea, not least because men and women have very different levels of these hormones. Could that explain differences in behaviour between the two sexes? Certainly, several studies have found links between people’s levels of sex hormones and their behaviour in psychological experiments. But to Niklas Zethraeus and colleagues from the Stockholm School of Economics, this evidence merely showed that the two things were connected in some way – they weren’t strong enough to show that sex hormones were directly influencing behaviour.
To get a clearer answer, Zethraeus set up a clinical trial. He recruited 200 women, between 50-65 years of age, and randomly split them into three groups – one took tablets of oestrogen, the second took testosterone tablets and the third took simply sugar pills.
After four weeks of tablets, the women took part in a suite of psychological games, where they had the chance to play for real money. The games were designed to test their selflessness, trust, trustworthiness, fairness and attitudes to risk. If sex hormones truly change these behaviours, the three groups of women would have played the games differently. They didn’t.
Their levels of hormones had changed appropriately. At the end of the four weeks, the group that dosed up on oestrogen had about 8 times more than they did at the start, but normal levels of testosterone. Likewise, the testosterone-takers had 4-6 time more testosterone and free testosterone (the “active” fraction that isn’t attached to any proteins) but normal levels of oestrogen. The sugar-takers weren’t any different. Despite these changes, the women didn’t play the four psychological games any differently.