Blonde hair evolved twice, according to articles in Nature News, ScienceNOW, ScienceDaily 3 May 2012, and Science vol. 336 p. 554 DOI: 10.1126/science.1217849 4 May 2012. Most of the people of the Solomon Islands have very dark skin and black hair, but about 10 percent have dark skin and golden blonde hair which has been claimed to be a genetic legacy from European explorers, traders and visitors to the Islands.
An international team of scientists has compared the genes of dark haired and blonde haired Solomon Islanders and found a mutation that causes blonde hair in Solomon Islanders but not in Europeans. The Solomon Island blonde gene comes from a “missence mutation” of a gene named tyrosinase-related protein 1 (TYRP1) and is the result of substituting a C (cytosine) for a T (thymine) in the genetic code. This change decreases the activity of one enzyme involved in pigmentation. The same mutation in mice results in reduced pigmentation in their fur.
The researchers estimated that 25 percent of Solomon Islanders carry the gene, but since it is recessive it only causes blonde hair in those who inherit two copies. The gene carries no visible advantages so researchers suggest it spread rapidly through the population simply because the mutation occurred when the original population was very small. Anthropologist Jonathan Friedlaender of Temple University, Philadelphia explained: “This whole area seems to have been populated by very small groups of people making it across these stepping-stone islands, so you do have very dramatic effects in fluctuations of gene frequency”.
Hair colour is influenced by a number of genes, but blonde hair in Europeans is not related to changes in the TYRP1 gene. The researchers compared the Solomon Islanders’ genes with 941 individuals from 52 other populations around the world, including Europeans, but did not find the altered TYRP1 gene in these. Carlos Bustamante, a geneticist at Stanford University, who participated in the study claimed: “Blonde hair has clearly evolved twice”. Sean Myles of Nova Scotia Agricultural College, Truro, Canada who, was also involved in the study, commented: “It’s a great example of convergent evolution, where the same outcome is brought about by completely different means”.
Editorial Comment: This change in hair colour is not the result of what mutations do – it’s the result of what they don’t! This newly found mutation has caused a loss of function. When such a change causes no survival harm that would remove it from the population, the mutated gene will persist in the population. The move from black to blonde hair is a change but it is not evolution. It is a modification by loss of an already existing characteristic and does not explain how hair colour genes originally got here. Since hair colour is the result of the complex interaction of many genes and proteins, diminishing the function of any of these will result in less pigmentation.
Which also means the fact that Europeans and Solomon Islanders have both ended up with blonde hair by different routes involving mutational loss, is not convergent evolution, but similar degeneration. Overall, the reporting of this finding is an example of the current trend to call all biological changes evolution, and thus convince undiscerning people that evolution must be true. Sadly it also means the blonde is not the epitome of beauty after all. Just another degenerate mutant like the rest of us. (Ref. pigmentation, melanin, genetics)
Evidence News 16 May 2012