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There is a fairly new paper in PLoS on the colonization of the New World. It is the latest in a series of attempts to synthesize biogeography, climate change related paleoenvironmental reconstruction, genetics, and archaeology.
The authors draw these conclusions:
These results support a model for the peopling of the New World in which Amerind ancestors diverged from the Asian gene pool prior to 40,000 years ago and experienced a gradual population expansion as they moved into Beringia. After a long period of little change in population size in greater Beringia, Amerinds rapidly expanded into the Americas ≈15,000 years ago either through an interior ice-free corridor or along the coast. This rapid colonization of the New World was achieved by a founder group with an effective population size of ≈1,000-5,400 individuals. Our model presents a detailed scenario for the timing and scale of the initial migration to the Americas, substantially refines the estimate of New World founders, and provides a unified theory for testing with future datasets and analytic methods.
One of the problems I see in this sort of analysis is placing the evinced genetic splits in populations in space. This paper does a reasonably good job at arguing for an early split in Asia and subsequent population changes happening in the New World. However, if we change the timing of when the Ice Free Corrider was available to facilitate the movement of people, or if we change the rate of DNA mutation that is used to place population events in time, then the model may change fundamentally. I do not have lot of faith in the estimates used for DNA mutation rates.
Nonetheless, this is a good, the best so far, synthesis of the available data with new information added.
Also interesting is the fact that PLoS has a means of commenting on papers published in this Open Access journal. Go visit the paper (link below) and add your opinions!
Here is the link to the paper.
Kitchen, A., Miyamoto, M.M., Mulligan, C.J., Harpending, H. (2008). A Three-Stage Colonization Model for the Peopling of the Americas. PLoS ONE, 3(2), e1596. DOI: 10.1371/journal.pone.0001596
Humanities & Social Science
Comments
Their research offers an interesting possibility, but it is certainly difficult to prove or disprove their hypothesis when most of the archaeological evidence sits under 50 meters of arctic water.
Posted by: Ellery | March 6, 2008 4:31 PM
Ellery: Time to pull out the ol' diving bell blueprints.
Posted by: Greg Laden | March 6, 2008 4:39 PM
Okay, found 'em.
Posted by: Ellery | March 6, 2008 4:56 PM
I LOVE that magazine. But children should never be allowed to see it.
Posted by: Greg Laden | March 6, 2008 4:59 PM
Yes, what I am about to write it off-topic. But it has become a pet peeve of mine with ScienceBlogs.
At the top of your meta tags, this posting is proclaimed to be ISO-8859-1. Yet, the stuff you quoted is clearly Unicode (since, I have to manually switch to Unicode to get the "approximately" characters to display properly).
How about deciding on a standard and sticking to it?
Thanks, and sorry for the mini-rant.
Posted by: Ahcuah | March 6, 2008 6:24 PM
Aheuah,
Thank you for the minirant, no need to apologize. The encoding on this blog is screwy. I understand that this is on the list of things to upgrade/fix/whatever, but I will pass your comment on to the big chief.
Posted by: Greg Laden | March 6, 2008 6:26 PM
Oooh, you used the f-word in relation to mutation rates. (I'm hypersensitive about word-choice when it links religion to science...)
Posted by: Serena | March 6, 2008 8:49 PM
First off, I really liked that paper. I read it a few days ago, and really found it interesting. It is unfortunate that the archaeology is underwater, but there is still hope. Also, to Serena, I do not see why you are against the word "fundamentally". The usage here by no means connects it to religion, it means that it is the basic or base issue. Or, in this case, different DNA mutation rates will change the base meaning of an interpretation.
Posted by: Jason Fox | March 7, 2008 12:14 AM
Oops. I should have been more clear. By the f-word, I meant faith. In my classroom, I am very careful not to say, "I don't have faith in that explanation." As soon as I say faith, students' minds turn to religion. They think about their own faith, and they stop thinking scientifically. Or at least that's what I'm afraid they'll start doing. Even worse, they may raise the point that I used the word faith in my discussion of a topic, so why can't they discuss faith when it comes to evolution?
So that's why I am hypersensitive to the word. I know what Greg meant, but felt compelled to share my concerns about using that word. Perhaps it would be better to say, "I do not have a lot of confidence in the..."
Posted by: Serena | March 7, 2008 10:44 PM