Posted on 05/16/2006 3:33:16 PM PDT by blam
Neanderthal yields nuclear DNA
Neanderthals died out about 29,000 years ago
The first sequences of nuclear DNA to be taken from a Neanderthal have been reported at a US science meeting. Geneticist Svante Paabo and his team say they isolated the long segments of genetic material from a 45,000-year-old Neanderthal fossil from Croatia.
The work should reveal how closely related the Neanderthal species was to modern humans, Homo sapiens.
Details were presented at a conference at New York's Cold Spring Harbor Laboratory and reported by News@Nature.
It is a significant advance on previous research that has extracted mitochondrial DNA (mtDNA) from Neanderthal (Homo neanderthalensis) specimens.
This genetic material is contained in structures that power cells; and although the information it holds is very useful, it is more limited in scope than the DNA bundled up at the cell's centre.
This nuclear DNA is what really drives an organism's biochemistry.
Divergent code
So far, Paabo and colleagues have managed to sequence around a million base-pairs, which comprises 0.03% of the Neanderthal's entire DNA "catalogue", or genome. Base-pairs are the simplest bonded chemical units which hold together the DNA double helix.
The genetic material comes from a 45,000-year-old male Neanderthal specimen found in Vindija Cave outside Zagreb, the News@Nature website reports.
DNA IN HUMAN CELLS
* The double-stranded DNA molecule is held together by chemical components called bases
* Adenine (A) bonds with thymine (T); cytosine (C) bonds with guanine (G)
* These "letters" form the "code of life". There are estimated to be about 2.9 billion base-pairs in the human genome wound into 24 distinct bundles, or chromosomes
* Written in the DNA are 20-25,000 genes, which human cells use as starting templates to make proteins. These sophisticated molecules build and maintain our bodies
* Preliminary analysis shows the bundle of DNA responsible for maleness in the Neanderthal - its Y chromosome - is very different from modern human and chimpanzee Y chromosomes; more so than for the other chromosomes in the genome.
This might suggest that little interbreeding occurred between our own species and the Neanderthals.
Usually, DNA must be cloned in bacteria to produce large enough amounts to study. But Professor Paabo, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his team have used a novel sequencing method to decode the genetic material. This involves using tiny wells to directly sequence DNA fragments in an emulsion.
However, the researcher is also working to extract and read Neanderthal DNA by the traditional method. About 75,000 base-pairs have been sequenced this way so far. They show that Neanderthals diverged from the evolutionary line that led to modern humans about 315,000 years ago.
Neanderthals lived across Europe and parts of west and central Asia from approximately 230,000 to 29,000 years ago. It is unclear what factors led to their demise, but climate change and competition from modern humans may have played a role.
Far as I'm concerned, all of those things were glorified apes. That's basically an ape's skull. Most likely gorillas and chimps survived and neanderthals and other hominids didn't because the gorillas and chimps were better adapted.
Archive
Visions of 'Clan of the Cave Bear' dance in my head.
Mitochondrial recombination hasn't held up to investigation. Adam Eyre-Walker seems to have already studied this. It is a interesting idea that didn't pan out.
"If recombination occurs, there needs to be a route by which genetic material can incorporate itself into mitochondrial lineages. We review the evidence for possible routes and then review the current state of the population genetic evidence for recombination. We conclude that there is no firmly established route by which recombination can occur, and that while some of the population genetic evidence is suggestive of recombination, it is far from conclusive" (Eyre-Walker A, Awadalla P (2001) Does human mtDNA recombine? Journal of Molecular Evolution)
Yesss!!! Finally, like the answer or not, we approach an answer to the Neanderthal question. I get tired of explaining the limitations of matrilineal mtDNA.
Our paths haven't passed in a while. Where have you been?
Clueless.
Look at the size of the brain case.
while some of the population genetic evidence is suggestive of recombination, it is far from conclusive...because I just wanna believe all these mtDNA studies which pay all my bills. Waaaah!
I wonder if anyone has ever done a geographic mobility study on Neanderthals using isotope analysis from teeth...
Good idea.
"Abstract: The carbon and nitrogen isotopic abundances of the collagen extracted from the Saint-Césaire I Neanderthal have been used to infer the dietary behaviour of this specimen. A review of previously published Neanderthal collagen isotopic signatures with the addition of 3 new collagen isotopic signatures from specimens from Les Pradelles allows us to compare the dietary habits of 5 Neanderthal specimens from OIS 3 and one specimen from OIS 5c. This comparison points to a trophic position as top predator in an open environment, with little variation through time and space. In addition, a comparison of the Saint-Césaire I Neanderthal with contemporaneous hyaenas has been performed using a multi-source mixing model, modified from Phillips and Gregg (2003, Oecologia 127, 171). It appears that the isotopic differences between the Neanderthal specimen and hyaenas can be accounted for by much lower amounts of reindeer and much higher amounts of woolly rhinoceros and woolly mammoth in the dietary input of the Neanderthal specimen than in that of hyaenas, with relatively similar contributions of bovinae, large deer and horse for both predators, a conclusion consistent with the zooarchaeological data. The high proportion of very large herbivores, such as woolly rhinoceros and woolly mammoth, in Neanderthal's diet compare to that of the scavenging hyaenas suggests that Neanderthals could not acquire these prey through scavenging. They probably had to hunt for proboscideans and rhinoceros. Such a prey selection could result from a long lasting dietary tradition in Europe."
"Isotopic evidence for diet and subsistence pattern of the Saint-Césaire I Neanderthal: review and use of a multi-source mixing model"
Hervé Bocherensa, Dorothée G. Drucker, Daniel Billiou, Marylène Patou-Mathis, and Bernard Vandermeersch
http://dx.doi.org/10.1016/j.jhevol.2005.03.003
At 45,000 ya, this individual is probably just inside the far range of human contact. To find evidence of interbreeding I would think they need to find a specimen closer to the 29,000 ya mark.
Neanderthals diverged from the evolutionary line that led to modern humans about 315,000 years ago. Neanderthals lived across Europe and parts of west and central Asia from approximately 230,000 to 29,000 years ago
315,000 years ago is a lot more recent than the 700,000ya figure I recall from previous research but still well before Neanderthals show up in Eurasia. It fits the picture of our small group of human ancestors living on the outer banks of Southey Africa 200,000ya and suggests that Neanderthals are/were our closest separate branch moving out.
That was supposed to be southeast Africa. Spell checker does funny things...
Meat eating precedes genus Homo. I remember reading something about meat eating among australopithecines and perhaps it's why there are so few vegetarian species (one maybe?) in the genus. It's something I always mention when putting steaks on the grill.
Widespread recombination in published animal mtDNA sequencesMitochondrial DNA (mtDNA) recombination has been observed in several animal species, but there are doubts as to whether it is common or only occurs under special circumstances. Animal mtDNA sequences retrieved from public databases were unambiguously aligned and rigorously tested for evidence of recombination. At least 30 recombination events were detected among 186 alignments examined. Recombinant sequences were found in invertebrates and vertebrates, including primates. It appears that mtDNA recombination may occur regularly in the animal cell but rarely produces new haplotypes because of homoplasmy. Common animal mtDNA recombination would necessitate a reexamination of phylogenetic and biohistorical inference based on the assumption of clonal mtDNA transmission. Recombination may also have an important role in producing and purging mtDNA mutations and thus in mtDNA-based diseases and senescence.
Tsaousis AD, Martin DP, Ladoukakis ED, Posada D, Zouros E.
Jan 12 2005
Mol Biol Evol.
2005 Apr;
22(4):925-33.
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