By Claire Asher, on 17 April 2015
Unconditional generosity is a characteristic of humans on which we pride ourselves, and billions of dollars is donated to hundreds of thousands of charitable organisations every year. But look at it from an evolutionary perspective, and this trait seems difficult to explain. In some situations, giving may have evolved to advertise positive characteristics of the giver in the aim of attracting a mate. Recent research from GEE suggests this may explain the charitable behaviour of men donating to female fundraisers online. Data from over 2500 fundraising campaigns showed that men donate £10 more on average if previous male donors have been particularly generous.
Helping others at random, with no promise of reciprocity in the future, should not be favoured by natural selection as it will tend to disadvantage the altruist. Yet we see people doing just that every day. One theory that may explain selfless, unconditional generosity in humans (and other animals) is the ‘competitive helping’ hypothesis, which suggests generosity may sometimes be used to advertise positive characteristics to potential mates. The hypothesis suggests that people will compete to be the most generous, particularly when they are in the presence of attractive potential mates. If generosity is costly, and competition for mates is tough, then competitive generosity could be favoured by natural selection as a mechanism to honestly communicate quality. Only the best quality males could afford to be so generous, making them more attractive to on looking females.
To test this hypothesis, GEE researcher Dr Nichola Raihani and Professor Sarah Smith from the University of Bristol reviewed 2561 online fundraising pages, and selected 668 that had public donations and an image of the fundraiser. They then calculated the average donation running up to a large donation of £50 or more. They compared these donations with those made after the large donation, according to the gender of the donors and the gender and attractiveness of the fundraiser. They found men tended to give larger amounts after other men had made large donations. Men were also more generous when the fundraiser was an attractive female, giving four times more to female fundraisers following a large donation from another male. Attractive female fundraisers received £28 more during these bidding wars than less attractive females and males!
Interestingly, while this pattern is clear in donations by men, the same is not true for women donating money online. This suggests that male charitable behaviour represents a competitive helping display, favoured by sexual selection as an honest signal of male quality.
“It’s fascinating that evolutionary biology can offer insights into human behaviour even in the modern world. People are really generous and their reasons for giving to charity are generally not self-serving but it doesn’t preclude their motives from having evolved to benefit them in some way. Take eating for example, our primary drive is to dispel the feeling of hunger, which is pleasurable, but the evolutionary purpose is to make sure we don’t starve and die. Generous behaviours can be seen in a similar way – the motivation for performing them doesn’t have to be the same as the evolutionary function.” – Dr Nichola Raihani