At a biological level, we are attracted to those individuals whose traits suggest to us they are likely to have good genes, hence provide healthy offspring.

A peacock’s tail is a good example: by getting it to grow larger, it signifies its strength and dominion and it makes peahens think it’s got healthy genes.

Across the world, generosity is the trait most commonly rated as attractive, hence suggesting that at a deep biological level, generosity would imply the ability to take care of offspring.

Human beings are social animals, so they do a lot to take care of those close around them. For the vast majority of our history as a species, we lived in tight-knit groups, and we evolved wanting to help those around us. Those with the AVPR-1 gene more likely to ...