The evolutionary psychologist explains that attractive people tend to have girls, a trend that is making women far more attractive on average than men.

Question: Why do attractive people tend to have daughters? 

Satoshi Kanazawa: According to the two studies I conducted it is true. The basic contention of the theory is that whenever parents have any trait that they can transmit to their children that are better for boys than for girls then they have more boys. Conversely, whenever parents have some traits that they can transmit to their children that are better for girls than for boys then they tend to have more girls. Being attractive, being physically attractive, is good both for boys and girls, but it’s even better for girls to be attractive than boys–and therefore physically attractive parents, knowing that they can transmit that trait to their children, tend to bias their offspring sex toward girls. 

Question: Does this mean that women are becoming more attractive? 

Satoshi Kanazawa: That is the logical conclusion if more attractive people are more likely to have daughters than sons and if physical attractiveness is heritable then it follows that over time more and more women will be attractive compared to men and that’s the trend that we’re seeing.