One of the things that separate us from chimps is our big brain. How did we develop such big brains while the chimp's stayed relatively smaller? To answer this question we have to find the DNA mutations that gave us bigger brains.
Some researchers now think that they may have found one of these mutations, in the MYH16 gene. Humans all have this mutation but other primates including the chimp don't. As explained above, this is only one of the many differences predicted between human and chimp. What tells us that this particular change was important for human evolution?
The mutation in the MYH16 gene probably gave humans weaker jaw muscles. So how do weaker jaw muscles lead to a bigger brain? Studies have shown that when muscles change, the bones attached to them can change too. It is possible that smaller jaw muscles allowed for the reshaping of the skull and at some point for the enlargement of the brain
Another piece of supporting evidence is that the mutation appears to be about 2.4 million years old. This is about 400,000 years before humans developed smaller jaw muscles and our brains started to enlarge. The mutation may have been necessary for the morphological change.
The idea that a mutation in a gene that shapes muscles may have contributed to the evolution of the human skull is very interesting. Researchers now have to do more experiments to strengthen their theory.