It is common to find that two traders both think their counterparts are idiotically overpaying: that is the beauty of Ricardo’s magic trick. - Matt Ridley

Wherever you look in the historical record, the elites favored sons more than other classes….Lower down the social scale, daughters are preferred even today.

Females choose; their choosiness is inherited; they prefer exaggerated ornaments; exaggerated ornaments are a burden to males. That much is now uncontroversial. Thus far Darwin was right.

But as we shall see, the appearance is misleading. Animal altruism is a myth. Even in the most spectacular cases of selflessness it turns out that animals are serving the selfies interests of their own genes—if sometimes being careless with their bodies.