Sunday, September 2, 2012

Denisovan Genome Deciphered!

Article at Popular Archaeology:

Archaic Human DNA Reveals its Secrets

Thu, Aug 30, 2012
Recently completed research has revealed the complete sequence of the Denisovan genome, the DNA "blueprint" or strands that describe the makeup of a new species of archaic human, fossils of which were first recovered in March, 2010 in a cave in southern Siberia*.

Although the available evidence for testing was slim -- the Denisovan finds have consisted only of a finger bone fragment and two teeth (the test sample itself was derived from the finger bone fragment) -- the researchers were able to develop a means to "unzip" the DNA such that its two strands could be used to generate new molecules for sequencing, permitting the team to determine a very complete genome sequence much like what can be obtained for a modern human genome. [So, basically, they made it up?] They then compared the genome with genomes of modern humans from around the world.

Among the study results, the researchers found that the Denisovans share more genes with individuals from Papua New Guinea than any other population, and that more Denisovan alleles were common with those of Asian and South American populations than European populations. The study authors suggest that the latter reflects interbreeding between modern humans and the Neandertals, who are also related to Neanderthals, rather than direct gene flow from the Denisovans. [What?] In addition, the study reports several other findings: One, that the Denisovan genome contained alleles that correspond to alleles in present-day humans that are associated with dark skin, brown hair and brown eyes; two, that there were a number of genetic changes in modern humans that occurred after the split from the Denisovans; and three, that Denisovan genetic diversity was extremely low, due, they suggest, to a small initial population that grew quickly, without time for genetic diversity to increase to any substantial degree. Along this vain, the authors suggest that if further research shows that the Neanderthal population size changed over time in a similar way, it could mean that a single population expanding out of Africa gave rise to both the Denisovans and Neandertals.

In conclusion, the study team remarks on the general implications of the research results for future endeavors. Reports M. Meyer, et. al.:
By providing a comprehensive catalog of features that became fixed in modern humans after their separation from their closest archaic relatives, this work will eventually lead to a better understanding of the biological differences that existed between the groups. This should ultimately aid in determining how it was that modern humans came to expand dramatically in population size as well as cultural complexity while archaic humans eventually dwindled in numbers and became physically extinct. [1]
* In March 2010, scientists announced the discovery of a finger bone fragment of a juvenile female that lived about 41,000 years ago, found in the remote Denisova Cave in the Altai mountains in Siberia, a region also inhabited at about the same time by Neanderthals and perhaps modern humans. Two other bone specimens belonging to different members of the same population have since been found.

[1] "A High-Coverage Genome Sequence from an Archaic Denisovan Individual," by M. Meyer; M. Kircher; M.-T. Gansauge; F. Racimo; K. Prüfer; C. de Filippo; Q. Fu; M. Siebauer; U. Stenzel; J. Dabney; A.M. Andrés; J. Kelso; S. Pääbo at Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. For a complete list of authors, please see the manuscript.


VAIN?  Are you kidding me?  Are there no longer people who know the difference between VEIN and VAIN?  Holy Goddess! 

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