Steviepinhead
Posts: 532
Joined: Jan. 2006
|
Quote from article:
| Quote | Almost all Dutch people and 99 percent of Swedes are lactose-tolerant, but the mutation becomes progressively less common in Europeans who live at increasing distance from the ancient Funnel Beaker region.
Geneticists wondered if the lactose tolerance mutation in Europeans, first identified in 2002, had arisen among pastoral peoples elsewhere. But it seemed to be largely absent from Africa, even though pastoral peoples there generally have some degree of tolerance.
A research team led by Sarah Tishkoff of the University of Maryland has now resolved much of the puzzle. After testing for lactose tolerance and genetic makeup among 43 ethnic groups of East Africa, she and her colleagues have found three new mutations, all independent of each other and of the European mutation, which keep the lactase gene permanently switched on.
|
Skeptic:
| Quote | | Are they tying the mutations of the dutch and swedes to these groups and if so how does that affect the current migration theory, if at all? Or is this a case of convergent evolution in not only the European and African groups but also among the Eastern African groups or is there any way to tell at this time? |
Skeptic, unless I'm misunderstanding your question, all the answers are in the NYT article. Follow the link. Read.
Three new mutations, independent of each other and of the European one (Dutch, Swedes). So, yes, they're "convergent," in the sense that different mutations have arisen in at least four populations to take advantage of the availability of milk from domesticated animals throughout life.
Since all these domestication events have occurred within the last few thousand years--and since the mutations are independent = not the same mutation, then this research has no impact on theories regarding migrations of modern humans out of Africa (if that's what you're talking about). None of the mutations is a result of one population migrating to somewhere else (because they're different, independent mutations) and, in any event, all the domestication events were more recent than the posited out-migration and, obviously, all the mutations were even more recent.
|
