Economics and Evolution

There are a lot of economics in evolution: competition and cooperation among cells, costs and benefits of acquiring/shedding genes, strategic behaviors between sexes, etc. This experiment illustrates this point beautifully, and it makes so much sense if you think it from evolutionary perspective.

Evolution is all about passing down genes by reproduction, at least this is true for multi-cellular eukaryotes like human. Since reproduction is very energy intensive, nature has evolved a way to determine when to engage in reproduction. When food is abundant, you reproduce; when food is scarce, they hang on a bit longer hoping things will turn around so you can reproduce later. So women actually become semi-fertile when there is not enough food. I used to think that it would have the similar impact on men's fertility. It turns out to be just the opposite -- intermittent fasting instead increase men's fertility, at least this is what this research is saying.

Puzzling, isn't it? But again if you think about it carefully it actually makes sense: there is very little energy requirement for men to be reproductive: sperm is tiny and does not cost a lot to produce them, and once they are out, that's it. Women, on the other hand, need to consume a lot of energy to be reproductively ready and even more energy during pregnancy and child rearing. And keep in mind men and women would face the same deprivation when food is short supply; in order to compensate the deceased fertility of women during harsh times, men has to kick up a notch to ensure the reproduction successful, that's why men has higher testosterone level while fasting.