Sex and the single worm | Richard P Grant

Research into genetically encoded sex differences could tell us not just about sexuality, but also about how we learn things

It is said - often as if it's a bad thing - that a man thinks about sex every 7 seconds. Even if the reality is slightly less fantastical, it's not too difficult, from an evolutionary standpoint, to understand why this might be. The most successful organisms are those that are able to reproduce most prolifically in their given ecological niche. The plants and animals you seen around you today exist because they are the ones whose genomes were able to survive better than their competitors in the fight for limited resources.

It's not a major stretch to think that if an animal invests a significant chunk of its daily routine into seeking out opportunities to reproduce - to have sex - it's more likely to succeed in that aim, and therefore be more evolutionarily successful. And an animal with even a rudimentary neural system would therefore be expected to use a substantial proportion of its processing ability to find a sexual partner - up to a point of course. Some neurons are presumably always going to be necessary for obtaining food, avoiding predators, checking iPhones, etc. (What plants think is still a mystery of course - I guess nobody's yet asked a cabbage about sex).