Brit-Am Anthropology and DNA Update
(18 June, 2019, 15 Sivan, 5779)
Contents:
1. Research Breakthrough. DNA Archaeological Clocks are Virtually Useless!
Brought to our attention by Mark Williams
2. Blue eyed people in Ancient Northern Israel
3. Radical Findings Show Mitochondrial DNA Can Be Inherited From Dads by Peter Dockrill
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1. Research Breakthrough. DNA Archaeological Clocks are Virtually Useless!
Brought to our attention by Mark Williams
From:
Mark Williams
tl;dr... Y-STRs and molecular clocks may be useless for estimating the
age of any particular ydna lineage.
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August 24, 2011
Back to the drawing board for R-M269 (Busby et al. 2011)
https://dienekes.blogspot.com/2011/08/back-to-drawing-board-for-r-m269-busby.html
Extracts:
I will probably update this entry when I read the actual paper carefully.
Nonetheless, it seems to confirm that the marker set influence on TMRCA [The Most Recent Common Ancestor] estimates that Tim Janzen reported and I highlighted is a nuissance even for a relatively young haplogroup. It is also probably consistent with the idea that Y-STR based estimates are suspect because of deviations from the linear model.
UPDATE I (An epitaph for Y-STRs)
The paper could just as easily have been titled "An epitaph for Y-STRs". Of course, Y-STRs do carry information related to antiquity; and there are so many datasets collected from both academics and genealogist enthusiasts. Thus, they will continue to be used and analyzed for at least a few years more.
Nonetheless, the conclusion is inescepable that a very specific use of Y-STRs on modern populations, with the goal of discovering tight links with archaeological/historical events is all but dead.
The reason is simple: as clocks, they suck. A bad clock is not useless: it gives you some information about time. Moreover, you can often use several to iron out the inaccuracy of any single one of them.
Unfortunately, better estimation through averaging of bad estimators works only in one case: when the estimators are unbiased.
An unbiased estimator has an expected value equal to what you are trying to estimate. For example, suppose that the true age of a founder is 100 generations. For various reasons, bad clocks may give you estimates different than 100: some more, some less.
But, if some of them tend to give you an estimate of around 50 generations, and some of them tend to give you estimates around 200 generations, then averaging them out tells you nothing, except what ratio of slow and fast clocks you used.
Use more fast ones, and get a recent estimate; use more slow ones and get a more ancient one.
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Proc. R. Soc. B doi: 10.1098/rspb.2011.1044
The peopling of Europe and the cautionary tale of Y chromosome lineage R-M269
https://royalsocietypublishing.org/doi/full/10.1098/rspb.2011.1044
George B. J. Busby et al.
Recently, the debate on the origins of the major European Y chromosome haplogroup R1b1b2-M269 has reignited, and opinion has moved away from Palaeolithic origins to the notion of a younger Neolithic spread of these chromosomes from the Near East. Here, we address this debate by investigating frequency patterns and diversity in the largest collection of R1b1b2-M269 chromosomes yet assembled. Our analysis reveals no geographical trends in diversity, in contradiction to expectation under the Neolithic hypothesis, and suggests an alternative explanation for the apparent cline in diversity recently described. We further investigate the young, STR-based time to the most recent common ancestor estimates proposed so far for R-M269-related lineages and find evidence for an appreciable effect of microsatellite choice on age estimates. As a consequence, the existing data and tools are insufficient to make credible estimates for the age of this haplogroup, and conclusions about the timing of its origin and dispersal should be viewed with a large degree of caution.
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2. Blue eyed people in Ancient Northern Israel
Blue-Eyed Immigrants Transformed Ancient Israel 6,500 Years Ago
By Mindy Weisberger,
https://www.livescience.com/63396-ancient-israel-immigration-turkey-iran.html
Extracts:
Thousands of years ago in what is now northern Israel, waves of migrating people from the north and east, present-day Iran and Turkey, arrived in the region. And this influx of newcomers had a profound effect, transforming the emerging culture.
Archaeologists recently discovered this historic population shift by analyzing DNA from skeletons preserved in an Israeli cave. The site, in the north of the tiny country, contains dozens of burials and more than 600 bodies dating to approximately 6,500 years ago, the scientists reported.
DNA analysis showed that skeletons preserved in the cave were genetically distinct from people who historically lived in that region. And some of the genetic differences matched those of people who lived in neighboring Anatolia and the Zagros Mountains, which are now part of Turkey and Iran, the study found.
The southern Levant experienced a significant cultural shift during the Late Chalcolithic period, around 4500 B.C.E. to 3800 B.C.E, with denser settlements, more rituals performed in public and a growing use of ossuaries in funerary preparations, the researchers reported.
Though some experts had previously proposed that cultural transformation was driven by people who were native to the southern Levant, the authors of the new study suspected that waves of human migration explained the changes. To find answers, the scientists turned to a burial site in Israel's Peqi'in Cave, in what would have been Upper Galilee 6,500 years ago.
...... the allele (one of two or more alternative forms of a gene) that is responsible for blue eyeswas associated with 49 percent of the sampled remains, suggesting that blue eyes had become common in people living in Upper Galilee. Another allele hinted that fair skin may have been widespread in the local population as well, the study authors wrote.
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3. Radical Findings Show Mitochondrial DNA Can Be Inherited From Dads
https://www.sciencealert.com/radical-findings-shows-mitochondrial-dna-can-be-inherited-from-dads-after-all
Peter Dockrill
Extracts:
Not all DNA is the same, and science has long held that not all kinds of DNA are passed down from both your mother and your father. But it looks like the time has come to rewrite the textbooks.
While most of our DNA resides within the nucleus of the cell, some of our genetic code is stored inside mitochondria, the so-called 'powerhouse of the cell'. The conventional view is this mitochondrial DNA (or mtDNA) is only inherited from mothers, but new evidence suggests that's not the case at all.
A new study led by geneticist Taosheng Huang from the Cincinnati Children's Hospital Medical Centre shows human mitochondrial DNA can be paternally inherited, in a landmark case that started with the treatment of a sick four-year-old boy.
.... "Our results suggest that, although the central dogma of maternal inheritance of mtDNA remains valid, there are some exceptional cases where paternal mtDNA could be passed to the offspring," the authors explain in their paper.
But while these cases might be exceptional, they're not necessarily as rare as scientists might have thought.