Category: Genetics

Stonehenge DNA

Stonehenge DNA

by Justin Durand

Our world is shifting. Once upon a time we thought humans spread from Africa, eventually reached and spread through Europe, then settled down to several millennia of farming — punctuated by invasions and population movements in historic times that are more or less known. 

Well, we didn’t exactly think that, but if you didn’t take time to make a study of it you could be forgiven if that’s more or less the idea you had about human history. 

DNA testing is changing everything. One of the things that has changed is the idea of continuity in Britain from the Mesolithic to the present. It turns out there’s a break with the invasion of farming people in the Neolithic.

“Although Britain was inhabited by groups of “western hunter-gatherers” when the farmers arrived in about 4,000BC, DNA shows that the two groups did not mix very much at all.

“The British hunter-gatherers were almost completely replaced by the Neolithic farmers, apart from one group in western Scotland, where the Neolithic inhabitants had elevated local ancestry. This could have come down to the farmer groups simply having greater numbers.

“‘We don’t find any detectable evidence at all for the local British western hunter-gatherer ancestry in the Neolithic farmers after they arrive,’ said co-author Dr Tom Booth, a specialist in ancient DNA from the Natural History Museum in London.“

An Ancient Plague

An Ancient Plague

by Justin Durand

Something happened to Europe’s Neolithic farmers. These people had largely displaced the old hunter gatherer population in many places. Then, 5 or 6 thousand years ago they began to decline themselves. Some people have suggested they were displaced by invaders from the steppe. That has been my preferred theory. Other people think they just moved away because of stress from climate change. That would be interesting. There’s no evidence either way, or at least there’s not enough evidence to convince a majority of experts. 

Now, here we go. A new theory. Maybe it was the plague.

“Between 5,000 and 6,000 years ago, many Neolithic societies declined throughout western Eurasia due to a combination of factors that are still largely debated. Here, we report the discovery and genome reconstruction of Yersinia pestis, the etiological agent of plague, in Neolithic farmers in Sweden, pre-dating and basal to all modern and ancient known strains of this pathogen. We investigated the history of this strain by combining phylogenetic and molecular clock analyses of the bacterial genome, detailed archaeological information, and genomic analyses from infected individuals and hundreds of ancient human samples across Eurasia. These analyses revealed that multiple and independent lineages of Y. pestis branched and expanded across Eurasia during the Neolithic decline, spreading most likely through early trade networks rather than massive human migrations. Our results are consistent with the existence of a prehistoric plague pandemic that likely contributed to the decay of Neolithic populations in Europe.” (Davidski, quoting Rascovan et al., emphasis added by Davidski)

Y. pestis. Oh, very nice. This seems like good answer. It’s certainly an interesting answer.

Haplogroup Nations

Haplogroup Nations

by Justin Durand

My old haplogroup posts are so out of date I ought to hunt them down and delete them. I don’t do it because I (still) like the idea of coming across them them now and then and being reminded what the world was like.

This map is not the most rigorous replacement I could find for those old posts, but it shows something much more interesting than mere detail. It shows the approximate boundaries of the male mega lineages of Europe. Or more strictly, where each of those lineages is the majority. Like nations but not. Or tribes but not.

I’m drawn to this map for the simple reason that this (in a way) is the most common question newbies have.

Everyone wants to know what their haplogroup tells them about their family history. That’s not an easy question to answer. For one thing, your haplogroup is not who you are. Everyone in Europe and in the European Diaspora is descended from men who belonged to all the different haplogroups. That’s just the way it works.

On top of that, no matter what your haplogroup, it is almost certainly spread throughout Europe by links that are tens of thousands of years old. Knowing where it originated or where it’s been for the past few thousand years tells you almost nothing meaningful about your personal history.

That doesn’t mean the big picture is meaningless. That’s what I like about this map. It gives the big picture. If you look at it, and remember what you see here, you’ll be able to get your bearings whenever anyone starts talking about haplogroups.

I encourage you to go read the original post If European Borders Were Drawn By DNA Instead Of Ethnicity at BrilliantMaps.com (June 25, 2017). There’s a short and very nifty piece about each of the haplogroups shown here. Then if you’re in love with the data, go explore the DNA pages at Eupedia.com, starting with Distribution of European Y-chromosome DNA (Y-DNA) haplogroups by country in percentage. Or, if you’re looking for something not quite as hardcore, European Prehistory, Anthropology & Genetics.

BritainsDNA Goes Down

BritainsDNA Goes Down

by Justin Durand

Many of us who delve into DNA for genealogy have the same frustration. The general public seems to have an almost childlike belief in stories. People either believe their DNA tests are telling the absolute, scientific truth, or they’re skeptics who think it’s all bunk.

Comparatively few see the stories for what they are—marketing. Does that seem harsh? Keep reading.

The valuable part of DNA tests is that they can tell you who you’re related to, and working from that you can learn quite a bit about your family history.

What DNA can’t tell you very accurately is where your ancestors came from with any meaningful specificity.

All of the DNA companies walk a narrow line here. They have to put your DNA results into enough context so you understand what your results “mean”. But, they have to avoid leaving the impression the results show more than than they do.

BritainsDNA was far over the line, and everyone knew it. They focused on yDNA and mtDNA, which are only a small part of a person’s DNA, and they spun highly romanticized stories. When called on it, they threatened legal action. Now they’re gone.

There were reports back in 2012 and 2013. I remember reading Exaggerations and errors in the promotion of genetic ancestry testing by Vincent Plagnol, at Genomes Unzipped (Dec. 17, 2012). Can’t believe I missed BritainsDNA – Caveat Emptor by Roberta Estes, at DNA Explained (Dec. 20, 2012). She’s my DNA cousin on the Estes line. I almost always see her stuff even when I miss everything else.

You can read the story here: What we learned about fighting bad science by taking on a genetic ancestry testing company by David Balding and Debbie Kennett, at Cruwys News (Jan. 3, 2019).

I’m betting this isn’t over. I won’t be surprised if BritainsDNA finds a way to come back. People don’t walk away from a lucrative business. I just hope when they come back, they do it with more professional skill.

Jews in the New World, II

Jews in the New World, II

by Justin Durand

We’ve seen this idea, now very common, that many Hispanos in the American Southwest have crypto-Jewish ancestry.

The evidence for this exotic ancestry is weak. The story seems to be a relatively recent phenomenon, and there is some reason to believe it might have its roots in the 19th and 20th century Seventh Day Adventists.

A recent story in The Atlantic seems to go the other direction, offering some new genetic evidence.

“Chacón-Duque and his colleagues pieced together the genetic record by sampling DNA from 6,500 people across Brazil, Chile, Colombia, Mexico, and Peru, which they compared to that of 2,300 people all over the world. Nearly a quarter of the Latin Americans shared 5 percent or more of their ancestry with people living in North Africa and the eastern Mediterranean, including self-identified Sephardic Jews.”

Sarah Zang, “The Genetic Legacy of the Spanish Inquisition” in The Atlantic (Dec. 21, 2018).

But that’s not quite the same thing as saying Latin Americans have crypto-Jewish ancestry. This is about people with Jewish ancestry, not necessarily people who are practicing Judaism secretly. And even then, the article goes on to say, “DNA alone cannot prove that conversos were the source of this ancestry, but it fits with the historical record.”

In fact, because of the history of the Iberian peninsula from Roman times to the discovery of America, there would be quite a bit of mixed ancestry among the New World colonists. Not just from the time of the expulsion of the Jews in 1492 but also from the preceding centuries as well.

After the expulsion of the Jews, the Spanish and Portuguese were deeply suspicious of those who converted to Christianity, and equally suspicious of their descendants. They were haunted, it seems, by the idea these people might be practicing their former religion in secret. They emphasized limpieza de sangre (purity of blood), and went to great lengths to hide mixed marriages in their own ancestries.

Given the stigma of converso ancestry it would be no surprise if the immigrants to America included a number of people with Jewish and Muslim ancestry. And this is all this new study is reporting. The evidence is consistent with widespread and low-level converso ancestry in Latin America. We don’t need to add to the stories about crypto-Judaism.

For the original article, see Juan-Camilo Chacón-Duque et al., “Latin Americans show wide-spread Converso ancestry and imprint of local Native ancestry on physical appearance” in Nature (Dec. 19, 2018).