> One is the development of modified tools and fire. Yes I know that’s two things, but they’re both very ancient and probably were enabled by the adaptation that gave us language. It’s possible there were several adaptations there but I suspect they all came from one fundamental advance in cognition. This drove a series of major evolutionary changes that adapted us to a tool and fire using mode of living.

There was a bit going around a number of years ago (not sure where it stands in current scientific thought)... https://www.wired.com/2004/03/docs-drop-jaws-over-gene-mutat...

The theory is that there is a mutation which caused the jaw muscle of the line of hominids that gave rise to humans. If you look at chimpanzees, gorillas, and other hominids you'll find a skull with a crest with the anchor point for the muscle that enables a very powerful jaw. However, that muscle also constricts the size of the cranium which likewise constricts the size of the brain.

The theory goes that by weakening this muscle it allowed for other mutations to increases the size of the cranium and at the same time necessitated the use of fire and tools to help overcome the "we can't kill it by biting it."

That mutation traces back to about 2.4 Mya. Earliest hints of control of fire was about 2.0 Mya. The Oldowan tools date to 2.6 - 1.7 Mya.