We’re trying to explain why humans spent almost no time grooming each other. Grooming one’s self is a different kind of grooming, and there’s no indication self-grooming serves the purpose of social cohesion.

This shows early humans had a replacement for social grooming. Because they had languages, they didn’t need to groom as much for the purpose of social cohesion.

The main purpose of social grooming was social cohesion. So, even if humans didn’t need to clean each other as much due to having less hair, we’d still expect significant social grooming for the purpose of social cohesion.

This still tells us early humans lived in large groups. So, we’d still expect a lot of social grooming for the purpose of social cohesion.

If other primates, like humans have large neocortex regions, and engage in lots of social grooming, we’d expect humans to do the same.