Grey horse gene found, according to EurekAlert 20 July 2008 and ScienceNOW, 21 July 2008.
Grey horses are born with black, brown or chestnut coloured coats but begin to lose their colour early in life, and are often completely white by the age of eight. Although their hair turns white, the skin remains pigmented, in the same way that human hair goes grey but the skin remains pigmented.
A team of Swedish scientists compared DNA from a segment of chromosome 25 from 727 grey horses with the same segment in 131 non-grey horses. They found a duplication of a 4,600 base pair region in a gene named STX17 in the greys that was not present in any of the non-greys. The duplication was the same in all the greys, indicating that all the horses tested had a common ancestor. Although grey horses are highly valued because of their colour, they have a tendency to develop melanomas. By age 15 between 70 and 80 percent of greys have a benign form of this skin cancer, and some go on to develop a malignant form. Lief Anderson, a geneticist at University of Uppsala, explained the researchers proposed “the Grey mutation stimulates growth of melanocytes and that this leads to a premature loss of the melanocyte stem cells needed for hair pigmentation whereas the mutation promotes an expansion of some of the melanocytes causing skin pigmentation.”
According to EurekAlert, “Domestic animals constitute extraordinary models for evolution of biological diversity as already recognized by Charles Darwin.”
Editorial Comment: Charles Darwin did use diversity in domestic animals as evidence for his theory but he simply documented the enormous variation that is possible within the same kind of living organism. This is no help to a theory that claims horses evolved from some other kind of animal. It is not really much help to explain how natural selection works.
As the study described above shows, some of the variation in domestic animals is actually the result of degenerative changes to genes that would not survive for many generations without the deliberate un-natural selection by intelligent human beings who are prepared to care for domestic animals.
Evidence News 24 Sept 2008
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