Posted on 05/24/2011 1:06:30 PM PDT by decimon
More than just a tool for predicting health, modern genetics is upending long-held assumptions about who we are. A new study by Harvard researchers casts new light on the intermingling and migration of European, Middle Eastern and African and populations since ancient times.
In a paper titled "The History of African Gene Flow into Southern Europeans, Levantines and Jews," published in PLoS Genetics, HMS Associate Professor of Genetics David Reich and his colleagues investigated the proportion of sub-Saharan African ancestry present in various populations in West Eurasia, defined as the geographic area spanning modern Europe and the Middle East. While previous studies have established that such shared ancestry exists, they have not indicated to what degree or how far back the mixing of populations can be traced.
Analyzing publicly available genetic data from 40 populations comprising North Africans, Middle Easterners and Central Asians were doctoral student Priya Moorjani and Alkes Price, an assistant professor in the Program in Molecular and Genetic Epidemiology within the Department of Epidemiology at the Harvard School of Public Health.
Moorjani traced genetic ancestry using a method called rolloff. This platform, developed in the Reich lab, compares the size and composition of stretches of DNA between two human populations as a means of estimating when they mixed. The smaller and more broken up the DNA segments, the older the date of mixture.
Moorjani used the technique to examine the genomes of modern West Eurasian populations to find signatures of Sub-Saharan African ancestry. She did this by looking for chromosomal segments in West Eurasian DNA that closely matched those of Sub-Saharan Africans. By plotting the distribution of these segments and estimating their rate of genetic decay, Reich's lab was able to determine the proportion of African genetic ancestry still present, and to infer approximately when the West Eurasian and Sub-Saharan African populations mixed.
"The genetic decay happens very slowly," Moorjani explained, "so today, thousands of years later, there is enough evidence for us to estimate the date of population mixture."
While the researchers detected no African genetic signatures in Northern European populations, they found a distinct presence of African ancestry in Southern European, Middle Eastern and Jewish populations. Modern southern European groups can attribute about 1 to 3 percent of their genetic signature to African ancestry, with the intermingling of populations dating back 55 generations, on average—that is, to roughly 1,600 years ago. Middle Eastern groups have inherited about 4 to 15 percent, with the mixing of populations dating back roughly 32 generations. A diverse array of Jewish populations can date their Sub-Saharan African ancestry back roughly 72 generations, on average, accounting for 3 to 5 percent of their genetic makeup today.
According to Reich, these findings address a long-standing debate over African multicultural influences in Europe. The dates of population mixtures are consistent with documented historical events. For example, the mixing of African and southern European populations coincides with events during the Roman Empire and Arab migrations that followed. The older-mixture dates among African and Jewish populations are consistent with events in biblical times, such as the Jewish diaspora that occurred in 8th to 6th century BC.
"Our study doesn't prove that the African ancestry is associated with migrations associated with events in the Bible documented by archeologists," Reich says, "but it's interesting to speculate."
Reich was surprised to see any level of shared ancestry between the Ashkenazi and non-Ashkenazi Jewish groups. "I've never been convinced they were actually related to each other," Reich says, but he now concludes that his lab's findings have significant cultural and genetic implications. "Population boundaries that many people think are impermeable are, in fact, not that way."
Rolloff ping.
The same pattern is seen among all primates, all felines, all canids, all ursine, etc, etc.
2011 - 1600 years is the time period of 400 to 500 AD. That would make it during the transition period from Romand Emprie to Tolosa, Italia, and Eastern Roma. It is also the time of the Vandals
In 429 Vandals cross out of the Iberaian pensula to Roman North Africa
In 439 Carthage (North Africa) falls to the Vandal who in the next year, capture Sicily
In 455 the Vandals enter Rome itself and plunder the city for two weeks.
Since raping and pillaging were considered part of the “spoils of war”, it is very logical that the Vandals were responsible for this genitic migration.
“Modern southern European groups can attribute about 1 to 3 percent of their genetic signature to African ancestry, “
About the same as most Europeans have of Neanderthal genes.
The Vandals were originally from southern Scandinavia like the Goths, but by way of Central Europe, Italy, Iberia and lastly North Africa where Belisarius ended their career.
Before the Sahara became as dry as it is now, there were people living there--possibly some of the connections date back to a time when there was continuous human habitation from West Africa to North Africa and the chance for shared DNA traits to be found on both sides of what is now a desert.
About a thousand genes are shared by every organism, however simple or complicated. Although their common ancestor must haved lived more than a billion years ago, their shared structure can still be glimpsed. It shows how the grand plan of life has been modified through the course of evolution.
Does all this mean that Obama IS related to Ted Kennedy after all?
Language (etymology) is the best indicator of permanent ‘influence’ on a civilization. Genes simply identify which women were confiscated as the ‘spoils of war’.
Obama is Irish. Kennedy is Scotch (and Gin)
Human populations are all very closely related, with the differences largely superficial. We are one people. But, we are not one culture. The cultural differences are vast and stark. Moreover, contrary to what the multiculturalists would have us believe, cultures can be clearly distinguished one from the other and can easily be classified into successful and dysfunctional buckets.
Don;t agree that language gauges anything. Anyone can learn any language. You can’t change your genes though. Languages mark who was in charge at the time.
"About a thousand genes are shared by every organism, however simple or complicated. Although their common ancestor must haved lived more than a billion years ago, their shared structure can still be glimpsed. It shows how the grand plan of life has been modified through the course of evolution."
All it really shows is that the fallacies of 'begging the question' and 'affirming the consequent' have dominated the discipline formerly known as science.
It is obvious that what is now several independent languages (or populations) were once one language (or population).
When isolated, small changes accumulated (in language or DNA) until there was a noticeable difference between regions - and eventually the different groups could no longer communicate (or reproduce fertile offspring) together.
There was no point where Latin suddenly became Italian. And no Latin speaker had to give birth to an Italian speaker in one generation - or two born to the same Latin populations so that they would have someone to communicate (reproduce) with.
A continuum of small accumulating changes in what was once one thing - and now you have several distinct things that are obviously not the same.
“Language (etymology) is the best indicator of permanent ‘influence’ on a civilization.”
Not “best” but rather just one of several.
I agree, but with a quibble — genes don’t even do that much. Genes and chromosomes are accidental survivors. Looking at the modern samples can, at best, reveal what genes are around today. That’s it. Ethnic groups have an (accidentally selected) ancestral pool that’s smaller, which means the chromosomes passed down are themselves pooled. Just because some oddball now-rare snippet of DNA is found in someone with no known connection to a group where it’s not rare doesn’t mean that the ethnic group is somehow among ones ancestors. Where the genetic evidence matches the paper trail, then yes. Otherwise, no, probably not.
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ping
Yeah, other than contain the proper elements to create an open reading frame to produce a functional mRNA in the proper cellular contexts - DNA doesn't do much.
And that mRNA doesn't do much - other than have all the information needed on how to make a functional protein.
And that functional protein - it doesn't do much. Usually just one or two small biochemical functions.
But together...... DNA -> RNA -> Protein.
That is what is going on in the cell. It does EVERYTHING.
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