True. And for a long time, marriages were arranged by the fathers. It was a business transaction. Hence dowries, family names, who inherit what, etc that we see through history.

While nobles and kings illustrate this well, that also happened with peasants, who have the right to cultivate certain lands and, sometimes, it made sense to marry the neighbour so two small pieces of land became one larger. Not to mention the horrific ways slaves were treated and forced to breed.

Nothing there was about natural selection. But there was a lot of man-made selection.