Convergent evolution is a widespread phenomenon that sometimes produces amazing results. I have always been amazed by how closely some Australian and South American marsupials resembled their eutherian (placental) counterparts – dog-like and and cat-like marsupials evolved which bore striking resemblance to “real” members of the dog and cat families. So it really didn’t surprise me when I came across a BBC story yesterday which reported that at least some Neandertals were red-haired and pale-skinned, like many modern Europeans. At higher latitudes pale skin and hair is an advantage. Since these traits evolved fairly quickly among modern Europeans (whose ancestors left Africa just a few tens of thousands of years ago), you’d expect that their was fairly strong selection for the trait. Neandertals lived in Europe far longer than modern humans have done. Presumably they would have been subject to similar selectional pressures.
In this week’s Science, Elizabeth Culotta reports on an upcoming article by Carles Lalueza-Fox and coauthors* which describes the discovery of a melanocortin 1 receptor (MC1R) allele that suggests the existence of red-haired, fair-skinned Neandertals.
Recovering DNA from Neandertal remains is a fairly new endeavour. Within the last few years, DNA sequencing has suggested that modern humans did not interbreed with Neandertals. A recent study found that Neandertals had one of the key genes associated with speech. Now another gene has been sequenced. In the case of the speech-related gene, there was concern about contamination with human DNA. In this case, however, the Neandertal allele does not appear to be present in humans. In order to test the activity of the allele, the team inserted it into a human melanocyte. This allowed them to look at the activity of the gene.
I find this discovery terribly interesting on quite a number of levels. The simple feat of extracting DNA – nuclear DNA, at that – from 40-50,000-year-old bones is amazing. It’s nice to know more about what Neandertals may have looked like – after all, they are some of our closest relatives. But I find the convergence to be especially interesting. I like the idea that the same “solution” can be obtained through different mutations – I like the idea that evolution can provide multiple solutions to the same challenge, at that closely-related species can, in fact, use different mutations to the same end. Obviously this isn’t news, but it’s nice to see it in this story.
- Lalueza-Fox, C. et al. 2007. A Melanocortin 1 Receptor Allele Suggests Varying Pigmentation Among Neanderthals. Published Online October 25, 2007
Science DOI: 10.1126/science.1147417