In an effort to find the remaining genes that govern myosin --the major contractile protein that makes up muscle tissue-- researchers at the University of Pennsylvania School of Medicine have made a discovery that may be central to answering key questions about human evolution.

Researchers have found one small mutation that undermines an entire myosin gene. Their estimated dating for the appearance of this mutation places it at about 2.5 million years ago, just prior to a period of major evolutionary changes in the hominid fossil record. These include the beginning of larger brain size, so important in making us human. While the characterization of this mutation may better help understand such genetic diseases as muscular dystrophy, this finding has potentially wider implications for re-interpreting long-held notions about the appearance and early evolution of the genus Homo.

Anthropologists have long debated how humans evolved from ancestors with larger jaw muscles and smaller brains. This newly discovered mutation seems responsible for the development of smaller jaw muscles in humans as compared to non-human primates. These converging lines of evidence suggest the question: Did this genetic mutation lift an evolutionary constraint on brain growth in early humans?

In a classic case of scientific sleuthing, researchers took their discovery of a mutation that prevents the expression of a variety of myosin -- designated MYH16 on chromosome 7 -- to its ultimate context: what makes humans different from other primates." >from *Myosin mutant points to human origins. First protein difference between humans and primates that correlates to anatomical changes in early hominid fossil record. march 24, 2004

related context
> metacognition: some animals know their cognitive limits. december 10, 2003
> challenges to evolution education. november 14, 2003
> chimps must be grouped in the human genus: place of humans in evolution. june 2, 2003
> the evolutionary change of our species. september 14, 2002
> technology and evolution. paleolithic technology and human evolution. march 13, 2001

imago
> from australopithecus africanus to homo ...