MYH16 gene

About 2.4 million years ago an ape was born with a genetic defect: the MYH16 gene was disabled by a mutation. Consequently, its jaw muscles did not develop properly (the temporalis and masseter muscles). However, the ape somehow survived and bred. Because of the lack of musculature which covered the skull of this ape's descendants, it is thought that it became possible for these early humans to develop larger brains. This gene is jokingly referred to as the rft mutation, (room for thought).

Research regarding the MYH16 gene was done by a team at the University of Pennsylvania led by Hansell H. Stedman. A report of the research is published in the March 25th issue of Nature. Their research established that the MYH16 gene is disabled in all humans but active in all other great apes. Other chance mutations establish the date of the mutation as about 2.4 million years ago.