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[The following is an exact transcript of this podcast.]
Neandertals were our closest relatives. And now we know a lot more about them. Because researchers have for the first time sequenced a complete Neandertal genome—that of their mitochondrial DNA. The study appears in the August 8th issue of the journal Cell.
The new info shows that a disproportionate number of Neandertal sequence differences change the amino acid sequences in proteins. One explanation would be that Neandertals had a smaller population size. Which would give natural selection fewer options to choose from. So, did Neandertals mix with our direct ancestors? The sequence finds no evidence for such mixing. But we’ll have to wait for a full nuclear genome sequence to be sure.
—Steve Mirsky
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7 Comments
Add CommentDepending on your presuppositions, this data can be interpreted in a number of different ways. If one presupposes that we evolved from "neanderthals" such a long time ago, it would be a logical conclusion to view this data as a link between modern day man and neanderthal.
Reply | Report Abuse | Link to thisHowever, presupposing that we were "created" a much shorter time ago, one might arrive at the conclusion that these findings describe either a very old man or another kind of creature all together (an old type of ape extinct ape maybe). Therefore we must be careful about using this data as a support for evolution as it has been used in this article--showing similarity in DNA for what some scientists have already presupposed to be "Neanderthal Man--(a link between man and ape)" does not prove that we came from apes. These are conclusions that people render feasible when they choose that believing in a Creator is too mystical and non-scientific. On the other hand, I find it more mystical and non-scientific to believe that billions of years ago it rained on the Earth's mud and created something as complex as the DNA they are sequencing! The evidene is right in front of their faces. As they study these complex structures that take countless hours of research, they fail to see the unutterable complexity within them. These did not happen by accident--they were created.
Oh Jesus Christ. And I mean that as facetiously as possible. Keep your creationist mumbo jumbo away from here. Evolution doesn't say that we "descended from apes", but that we share a common ancestor with them. And the primordial soup theory is a LITTLE more complex than "it rained on the Earth's mud". Way to diminish it to lend credence to your own idea instead of being objective. Some "educatorman" you are. Also, recognize the difference between evolution - FACT - and natural selection - THEORY. Now mind you, I do not exclude the possibility of a creator's intervention in the evolutionary process, but you only do your own fellow ideologues a disservice by posting such nonsense.
Reply | Report Abuse | Link to thisI visited this temple of science, Journal Cell (indeed Cell online). It is specialized and very interesting. References of others publications in the texts of Scientific American function like suggestion for more scientific information; I think so. I am very fond of scientific matters for the revealing of the real world. Religion theme is enticing for me too, like a fable is. Science and religion are compounds of our cultural soup, and we have to cohabit with both for the times ahead. But, like is said, each ape in your branch. Reality is reality; fiction is fiction. I think so!
Reply | Report Abuse | Link to thisFinding skulls in Europe in the early 19th century that displayed a marked difference in morphology from modern humans (Neandertal), was our earliest clue that a 'distant human cousin' inhabited Europe before the arrival of what we have termed 'modern humans' of the time (not to be confused with modern humans of today).
Reply | Report Abuse | Link to thisSince then, speculation on whether or not such modern humans interbred with neandertal has weighed heavily on the side of the "No they didn't/couldn't have, wouldn't have, etc..." argument, as opposed to the "They most likely did at one time or another or perhaps frequently." argument.
The former argument often appeared to be based upon reasoning such as "To the modern human of circa 40,000 years ago, neandertal would have appeared as 'lower animals' -- like apes appear to us now." -- and -- "MH had a markedly different physical appearance and a higher social organization than N." and so forth.
Some of the historic arguments against an interbreeding of the two hominid sub-species seem to be unreasonably adamant that no such thing occurred -- perhaps possessing even racial overtones.
A recent 'documentary' produced by the Discovery Channel depicted a meeting between a modern human and a neandertal, in which the neandertal was small, naked, covered with fur and grunted through a huge set of nostrils set in an ape-like face with a mouthful of fangs, whereas the modern human 'hunter' was tall, white, fur-less and semi-clothed, had a shaven head, wore face-paint and a shell-bead necklace, and mumbled to his compatriots in a sophisticated dialect. Archaeological evidence suggests this depiction is a highly fanciful departure from reality, with the actual disparity between the two species at the time being not so dramatic.
It's as if we are to imagine that 'modern homo sapiens sapiens' were too sophisticated and too socially centric to have mated with a "lower species" (whether neandertal was indeed a 'lower species' comparatively is yet to be proven). But most anthropological evidence suggests modern humans of the time were successful in large part due to our predisposition to consistently and rapidly conquer and assimilate other groups/tribes.
I imagine a hunting party of MH stumbling upon a healthy young N female and, regardless of her smaller stature and facial morphology, simply having their way with her -- perhaps after which they carried her back to their camp to place with the rest of the women.
In my mind these modern humans would not have been so socially advanced that small differences in anatomy would have lead them to discard or shun an otherwise healthy female. Reproductive impulses would often overrule any such high thoughts, since successful reproduction and enlargement of family/tribe was of paramount importance to survival -- and there is evidence to suggest that MH and N were entirely capable of successful interbreeding.
The discoveries of Trinkaus of a 25,000-year-old skeleton in Portugal appears to share a mix of neandertal and modern characteristics. The Pestera cu Oase finds, he adds, "are also fully compatible with the blending of modern human and Neandertal populations."
The analysis of early human behavior and social organization, along with other similar findings suggest that, with MH and N living at the same time period in the same relative geographical locale, some interbreeding must have occurred -- at one point if not regularly -- and that N was simply 'bred out' of existence (one plausible explanation for what many consider their 'sudden disappearance').
We know, for instance, that neandertal had a sophisticated use of both tools and art-symbology, and most likely a rudimentary language. They were quite well adapted to the relatively cold, sparse climate of the time and, though it appears they tended to live in small, family groups with no higher level of social organization, they were successful, self-sustaining and productive. We have no archaeological evidence that they were in decline as a species -- neither do we have any evidence they were slaughtered by mobs of racist modern humans in some eugenically-inspired fit of genocidal purification.
Today, our closest living genetic relative is the Chimpanzee, with which we cannot interbreed. They still exist successfully in the wild and, barring deforestation and general destruction of their habitat, will continue to do so. No other species currently exists with which we can interbreed and has not done so for approximately 10,000 years. Why?
Obviously when the full genome is sequenced, we will have a definitive picture of the relationships of MH and N, but I am betting we will find evidence that the humans of today do indeed share a recent genetic legacy.
I don't have access to the journal, and I'm not likely to. But I'm curious to learn where/how someone gets their hands on a useful supply of neanderthal mitochondrial DNA.
Reply | Report Abuse | Link to thisFrom the Cell article:
Reply | Report Abuse | Link to thisA complete mitochondrial (mt) genome sequence was reconstructed from a 38,000 year-old Neandertal individual with 8341 mtDNA sequences identified among 4.8 Gb of DNA generated from ∼0.3 g of bone. Analysis of the assembled sequence unequivocally establishes that the Neandertal mtDNA falls outside the variation of extant human mtDNAs, and allows an estimate of the divergence date between the two mtDNA lineages of 660,000 ± 140,000 years. Of the 13 proteins encoded in the mtDNA, subunit 2 of cytochrome c oxidase of the mitochondrial electron transport chain has experienced the largest number of amino acid substitutions in human ancestors since the separation from Neandertals. There is evidence that purifying selection in the Neandertal mtDNA was reduced compared with other primate lineages, suggesting that the effective population size of Neandertals was small.
http://www.cell.com/content/article/abstract?uid=PIIS0092867408007733
I wonder if anyone cares to recall the laws against "bestiality"? If that behavior was not even thinkable, why have a law against it? Some humans will try to mate with anything that comes along, on two or four legs. It may be that MH and N would have produced the hominid version of a mule, a sterile offspring, which could explain the absence of N genes in modern humans. None survived to reproduce.
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