More room for brains
5.3-2.4 million years ago
Compared to other apes, humans can’t bite very hard because we have flimsy jaw muscles. This seems to be largely down to a mutation in the MYH16 gene, which controls the production of muscle. This happened between 5.3 and 2.4 million years ago. The smaller jaws could have freed up space for our brains to grow.
See other: What Makes Humans Human?