Oh dearie me. A slight confusion of cause and effect here.
Psychologists believe that traits such as selflessness and altruism have become part of our genetic make-up because they were attractive to mates.
“The expansion of the human brain would have greatly increased the cost of raising children so it would have been important for our ancestors to choose mates both willing and able to be good, long-term parents,” said Dr Tim Phillips and colleagues from the University of Nottingham and Institute of Psychiatry, King’s College, London.
“Displays of altruism could well have provided accurate clues to this and so led to a link between human altruism and sexual selection.”
Sorta, but that’s not the way we normally ought to think of such things.
Statistical analysis of their responses suggested that, in our evolutionary past, those with a stronger mate preference towards altruistic behaviour mated more frequently with more altruistic people.
That means that altruistic genes would be more prevalent than selfish genes.
Dr Phillips said: “These results are consistent with a link between human altruism towards non-relatives and sexual selection and throws an exciting new light on the puzzle of altruistic behaviour – which appears, at first sight, to be at odds with evolutionary theory.”
The results were published in the British Journal of Psychology.
Somebody really ought to send the psychologists down the hall to have a chat with their colleagues, the biologists.
Yes, OK, increasing brain size (and more importantly, increased neoteny as a result of trying to get that increased brain size through the pelvis) did raise the cost of raising children and yes, altruism (ie, sticking around and giving a hand) would be a good thing.
But we don’t generally then go on to say that sexual selection was the mechanism by which this happened. Rather, the sexual selection carried on as normal (Woo! nice tits!) and those couples where there was more altruism (ie, the man stuck around) had greater success in raising children who went on to have their own children.
Thus, whether it was genetic or learned behaviour, altruism spread.
In short, it’s not that people chose such mates, it’s that those which did were more successful.