The MYH16 gene encodes a protein called myosin heavy chain 16 which is a muscle protein in mammals. At least in primates, it is a specialized muscle protein found only in the temporalis and masseter muscles of the jaw. Myosin heavy chain proteins are important in muscle contraction, and if they are missing, the muscles will be smaller. In non-human primates, MYH16 is functional and the animals have powerful jaw muscles. In humans, the MYH16 gene has a mutation which causes the protein not to function. Although the exact importance of this change in accounting for differences between humans and other apes is not yet clear, such a change may be related to increased brain size and finer control of the jaw which facilitates speech. It is not clear how the MYH16 mutation relates to other changes to the jaw and skull in early human evolution (for example, whether the MYH16 mutation happened first and led to other changes, or whether the MYH16 mutation happened after other changes made the MYH16 protein no longer necessary).
The initial discovery of the human MYH16 mutation was published in 2004 by a team at the University of Pennsylvania led by Hansell H. Stedman. The date of the mutation has variously been estimated at about 2.4 million years ago or 5.3 million years ago.
- Carroll, Sean B. (2005). Endless forms most beautiful: the new science of evo-devo and the making of the animal kingdom. New York: Norton. pp. 272–274. ISBN 0-393-32779-5.
- Stedman, H.H.; Kozyak, B.W.; Nelson, A.; Thesier, D.M.; Su, L.T.; Low, D.W.; Bridges, C.R.; Shrager, J.B.; Purvis, N.M. & Mitchell, M.A. (25 March 2004). "Myosin gene mutation correlates with anatomical changes in the human lineage". Nature 428 (6981): 415–8. doi:10.1038/nature02358. PMID 15042088.
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- Perry, G.H.; Verrelli, B.C. & Stone, A.C. (2005). "Comparative analyses reveal a complex history of molecular evolution for human MYH16". Mol Biol Evol 22 (3): 379–382. doi:10.1093/molbev/msi004. PMID 15470226.
- Jingchun Zhu1, J. Zachary Sanborn, Mark Diekhans, Craig B. Lowe, Tom H. Pringle, David Haussler (December 2007). "Comparative Genomics Search for Losses of Long-Established Genes on the Human Lineage". PLoS Comput Biol. 3 (12): e247. doi:10.1371/journal.pcbi.0030247. PMC 2134963. PMID 18085818.
- Story from Science Scoop
- Hopkin M (25 March 2004). "Jaw-dropping theory of human evolution". Nature News. doi:10.1038/news040322-9.
- MYH16 from the HUGO Gene Nomenclature Committee database