Wednesday, October 26, 2022

A Neanderthal Family Tree: A Beginning

Environmental & Science Education, STEM, Biodiversity, Evolutionary Biology, Anthropology, History of Science, Nature of Science.

Ed Hessler

A report published in the October 19, 2022 British journal Nature has received considerable media coverage. The short title provides the reason, "Genetic Insights into the Social Organization of Neanderthals."

It is the subject of a briefing of the study by Ewen Callaway for a less technical audience in Nature News.

Southern Siberia is becoming a treasure trove for learning more about our early ancestors: humans, Neanderthals, Denisovians, and even a Neanderthal - Denisovan hybrid "all who lived (there) intermittently over some 300,000 years."

Callaway describes what the research revealed "when DNA was extracted, including 17 other ancient human remains from Chagryska" as well as Okladnilkova Cave (nearby). These remains included what turned out to be a surprising finding. Two closely related Neanderthals - a father, teen-aged daughter and two other, more distant relationships, plus seven others and two from the nearby cave. And this opens new research territory providing insights into kinship and social structure.

The scientific paper, one with few illustrations, includes a map showing the locations of the caves. The research was led by paleogeneticist Laurents (Laurits) Skov and population geneticist Benjamin Peters of the Max Planck Institute for Evolutionary Anthropology. This opens a new research territory, promising the ability to gain insights into kinship and social structure.

Callaway continues, "With this trove, the researchers confirmed that Chagyrskaya’s residents were more closely related to Neanderthals living in Europe around the same time than to those who occupied Denisova Cave tens of thousands of years earlier.

"The glut of Neanderthal genomes — which nearly doubles the number now available — has allowed researchers to look at other aspects of Neanderthal life. The genomes of the Chagyrskaya Neanderthals all had low diversity between maternal and paternal copies, a sign that the interconnected population of breeding adults was low. Researchers have uncovered similar patterns in mountain gorillas, which typically live in communities of fewer than 20 individuals, and other threatened species."

Skov said “'It makes you wonder what the familial relationship between these individuals were and how they were interacting with each other. It is a little glimpse into a Neanderthal family.'” By the way it is not known how the father and daughter died - no evidence.
Callaway includes two quotes that tell us a lot about science and which reminded me of physicist Sean Carroll's definition of science. "1. We have ideas. 2. They could be right. 3. Or they could be wrong. 4. But sometimes we fall in love with them anyway. 5. How do we guard against that?" Here is the quote.
"“I think we can say this social structure was present in most Neanderthals,' stated palaeogeneticist Carles Lalueza-Fox, director of the Natural Sciences Museum of Barcelona, Spain. A decade ago, his team analysed 12 Neanderthals buried in a Spanish cave and found diverse mitochondrial DNA in women, but not in men, which they interpreted as evidence that females had left their communities. This makes Lalueza-Fox wonder whether it was mobile Neanderthal women who encountered — and mated with — Homo sapiens in other parts of Eurasia." 
However, "other scientists caution that Neanderthal groups living elsewhere or at other times might have adopted different social customs. 'Until you get more (data) points on the board, you can’t tell,'” says Krishna Veeramah, a population geneticist at Stony Brook University in New York. More research --  evidence (multiple lines even better), data is how you guard against the first idea.

Callaway points out that it is hoped that the cave will yield more information since only one-third of it has been fully excavated and less than one-quarter of the remains have been examined.
A feature of Chagyrskaya Cave that plays into the research writes Callaway is that it "is also chock full of bison and horse remains, and Skov and his colleagues think that the site served as a hunting camp of sorts during these animals’ seasonal migrations. These hunts could have created opportunities for disparate Neanderthal communities to meet and mix," according to "Rebecca Wragg Sykes, an archeologist at the University of Liverpool.  “'I don’t think Neanderthals were planning to meet up with each other, but it offers that opportunity.'”

I urge you to read Calloway's full report for additional information and also to scan the original paper for details on the techniques, background and the discussion. The original research report includes a table with full information on the Neanderthals from both caves included in the study. In addition, as you will notice the paper included a slew of authors and you may find their affiliations of interest *.

* One of the co-authors is Svante Paabo who was awarded the 2022 Nobel Prize in Medicine of Physiology. He "succeeded in sequencing the genome of the Neanderthal. He also discovered the previously unknown hominin, Denisova" as well as for his research "on gene transfer and flow to present-day humans."

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