Behavioral modernity happened over 40,000 years ago, and probably over 50,000 years ago. We can see Chauvet cave paintings, Venus figurines and other evidence

Behavioral modernity happened over 40,000 years ago, and probably over 50,000 years ago. We can see Chauvet cave paintings, Venus figurines and other evidence of behavioral modernity. The whole world of art-creating humans lived in non-hierarchical hunter gather bands until 10,000 years ago. Deep in the Amazon some still live like this, although a few centuries back many in North America and much of the world lived like this. Even a few hundred kilometers north of Stockholm. The initial hierarchical structures 10,000 years ago only covered a limited area. If hierarchy and class division is an innate biological thing, why did humans not live like this through most of biological modernity?