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.[3][4] Myosin heavy chain proteins are important in
muscle contraction, and if they are missing, the muscles will be smaller.[3] In non-human primates, MYH16 is functional and the animals have powerful jaw muscles. In humans, the MYH16 gene has a
mutation that causes the protein not to function.[5] 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.[3] 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).[3]
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.[4] The date of the mutation has variously been estimated at 2.4 million years ago[4] or 5.3 million years ago.[6]
The MYH16 gene is present in
dogs,[6] but does not appear to be present in
mice.[7]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^
abcdCarroll, 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.
ISBN0-393-32779-5.
^
abcStedman HH, Kozyak BW, Nelson A, Thesier DM, Su LT, Low DW, Bridges CR, Shrager JB, Minugh-Purvis N, Mitchell MA (March 2004). "Myosin gene mutation correlates with anatomical changes in the human lineage". Nature. 428 (6981): 415–8.
Bibcode:
2004Natur.428..415S.
doi:
10.1038/nature02358.
PMID15042088.
S2CID4304466.