8 billion people: how different the world would look if Neanderthals had prevailed

[Random Boomer]

7. You're conflating two different kinds of aggression

There's reactive aggression in which an individual gets angry at another person and lashes out, versus premeditated aggression where an attack is planned in order to gain something (land, resources, prestige).

Compared to other apes (including bonobos), humans have significantly less reactive aggression. This is a reflection of domestication, and it results in unusually high levels of cooperation within a group. Conversely, humans have much higher rates of premeditated aggression between groups (tribes, countries) under certain circumstances (perceived advantages in the outcome).

That combination makes us extremely competitive with Neanderthals. More effective group cohesion with other humans, and greater likelihood of attacking Neanderthals if there is a perceived advantage for doing so.

Again, I highly recommend the book I cited on how human aggression developed as our species forked from other apes.