>BuzzFeed

Think of it this way: A fertile male is capable of conceiving children at any time more or less from puberty until death. What's more, a male can father children with multiple mates simultaneously without any immediate physical detriment. Therefore, males that attempt to father as many children as possible will be more prevalent in the gene pool. By contrast, a female can only conceive offspring with an ultimately limited supply of ova, which can only be fertilized within a specific time frame. If the ova is fertilized, the female can't conceive until giving birth several months later and the process of birth itself especially dangerous for humans, meaning that the "investment" that a female makes when reproducing is considerably higher than that of a male. This means that females have fewer potential chances to produce offspring with survivable genes, and therefore females that are more selective of mates are more likely to be prevalent in the gene pool. The investment disparity shouldn't be as much of a factor in post birth-control society, but a few decades isn't enough to nullify millions of years of natural selection.