tag:blogger.com,1999:blog-7785493.post5423674770109072778..comments2024-01-04T04:11:55.717+02:00Comments on Dienekes’ Anthropology Blog: Human-chimp divergence date pushed back in timeDienekeshttp://www.blogger.com/profile/02082684850093948970noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-7785493.post-69692640976776933152012-08-28T07:46:10.966+03:002012-08-28T07:46:10.966+03:00These results are inconsistent with research recen...These results are inconsistent with research recently reported on by Science Daily (http://www.sciencedaily.com/releases/2012/08/120824103020.htm) <br /><br />"The study, based on the DNA of around 85,000 Icelanders, also calculates the rate of human mutation at high resolution, providing estimates of when human ancestors diverged from nonhuman primates. It is one of two papers published this week by the journal Nature Genetics as well as one published at Nature that shed dramatic new light on human evolution.<br /><br />"Most mutations come from dad," said David Reich, professor of genetics at Harvard Medical School and a co-leader of the study. In addition to finding 3.3 paternal germline mutations for each maternal mutation, the study also found that the mutation rate in fathers doubles from age 20 to 58 but that there is no association with age in mothers -- a finding that may shed light on conditions, such as autism, that correlate with the father's age.<br /><br />The study's first author is James Sun, a graduate student in Reich's lab who worked with researchers from deCODE Genetics, a biopharma company based in Reykjavik, Iceland, to analyze about 2,500 short sequences of DNA taken from 85,289 Icelanders in 24,832 father-mother-child trios. The sequences, called microsatellites, vary in the number of times that they repeat, and are known to mutate at a higher rate than average places in the genome.<br /><br />Reich's team identified 2,058 mutational changes, yielding a rate of mutation that suggests human and chimpanzee ancestral populations diverged between 3.7 million and 6.6 million years ago.<br /><br />A second team, also based at deCODE Genetics (but not involving HMS researchers), published a paper this week in Nature on a large-scale direct estimate of the rate of single nucleotide substitutions in human genomes (a different type of mutation process), and came to largely consistent findings."DAEhttps://www.blogger.com/profile/06950818774209434657noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-85660096236960322872012-08-16T22:22:48.958+03:002012-08-16T22:22:48.958+03:00Really great to see an actual independent test of ...Really great to see an actual independent test of divergence dates. And it fits the fossil record better than the calibrated ones! Extremely cool.Mike Keeseyhttps://www.blogger.com/profile/00147156174467903264noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-14183205549503764722012-08-14T14:50:03.060+03:002012-08-14T14:50:03.060+03:00So, are we back to the original paleotological bon...So, are we back to the original paleotological bone-based estimate?sykes.1https://www.blogger.com/profile/10954672321945289871noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-9998158171611542732012-08-14T07:58:46.065+03:002012-08-14T07:58:46.065+03:00A very reasonable estimate - and Maju will be plea...A very reasonable estimate - and Maju will be pleased, ;)eurologisthttps://www.blogger.com/profile/03440019181278830033noreply@blogger.comtag:blogger.com,1999:blog-7785493.post-66148530168537688842012-08-14T06:52:22.821+03:002012-08-14T06:52:22.821+03:00"We date the human–chimpanzee split to at lea..."We date the human–chimpanzee split to at least 7–8 million years" <br /><br />That will please Maju. I've always been agnostic as to the dating of the split but this date makes sense. Places Sahelanthropus tchadensis right at the base, possibly ancestral to both species. A place where I have long though the fossil belongs: <br /><br />http://en.wikipedia.org/wiki/Sahelanthropus<br /><br />Quote: <br /><br />"Sahelanthropus tchadensis is an extinct hominid species that is dated to about 7 million years ago. Whether it can be regarded as part of the Hominina tree is unclear; there are arguments both supporting and rejecting it. Another complication in its classification is that it is older than the human–chimpanzee divergence (estimated to 6.3 to 5.4 million years ago) seen in genetic data" <br /><br />Bang goes that last argument. Although the article later says: <br /><br />"Sahelanthropus may represent a common ancestor of humans and chimpanzees; no consensus has been reached yet by the scientific community". terrythttps://www.blogger.com/profile/17327062321100035888noreply@blogger.com