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Have scientists found birthplace of modern humans? + New science of social genomics

#1
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The homeland of modern humans (intro): A study has concluded that the earliest ancestors of anatomically modern humans (Homo sapiens sapiens) emerged in a southern African 'homeland' and thrived there for 70 thousand years. The breakthrough findings are published in the prestigious journal Nature ... The authors propose that changes in Africa's climate triggered the first human explorations, which initiated the development of humans' genetic, ethnic and cultural diversity.

This study provides a window into the first 100 thousand years of modern humans' history. "It has been clear for some time that anatomically modern humans appeared in Africa roughly 200 thousand years ago. What has been long debated is the exact location of this emergence and subsequent dispersal of our earliest ancestors," says study lead Professor Vanessa Hayes from the Garvan Institute of Medical Research and University of Sydney, and Extraordinary Professor at the University of Pretoria. "Mitochondrial DNA acts like a time capsule of our ancestral mothers, accumulating changes slowly over generations. Comparing the complete DNA code, or mitogenome, from different individuals provides information on how closely they are related." (MORE)

Scientists claim to have found birthplace of modern humans (excerpt): : . . . She followed the trail of mitochondrial DNA ... That led her first to the Kalahari Desert, and then to the Khoesan (pronounced koh sahn) people, a group identified through their use of a clicking language. “They represent a lineage that never left the homeland,” Professor Hayes says. ... Their oral histories record them living in the area forever. “They know they have always been there,” says Professor Hayes[/url].

[...] Today the Kalahari is dry. But hundreds of thousands of years ago, according to climate modelling, the region was lush, humid, and dominated by Lake Makgadikgadi, a giant lake twice the size of Africa's Lake Victoria. As modern humans started to emerge, Makgadikgadi was breaking up into a series of smaller wetlands which would have teemed with life; “a perfect oasis for modern humans to live”, says Professor Hayes.

Around the wetland, Africa was dry. But 130,000 years ago changes in the Earth’s climate would have brought warmth and rain to a corridor that ran from the wetland north-east towards the coast. That would have provided food and water for some members of the group to migrate. These were the people who would learn to traverse water and later sail to conquer the rest of the world.

It is a neat and comprehensive origin story. But Professor David Lambert ... fears the evidence is not strong enough to back up the claims. “The authors themselves are slightly cautious about it. Nature is very good at selling what they have got,” he says.

In a press release put out with the study, Nature claims the research pinpoints the ancestral homeland of all humans. But the last paragraph of the paper notes the evidence cannot rule out the possibility modern humans evolved at similar times in different spots across Africa before interbreeding. That would mean the Kalahari is only one of several homelands. “That is a very debatable issue, and that one worries me a bit,” says Professor Lambert. “I really dislike this paper. I just find it very, very difficult.” (MORE)



The promise and peril of the new science of social genomics
https://www.nature.com/articles/d41586-019-03171-6

EXCERPT: . . . Geneticist Abdel Abdellaoui has never been to Kellingley or any of the United Kingdom’s other former coal-mining regions. But he has found something surprising about the towns and their inhabitants. His research shows that the DNA in these districts is flecked with disadvantage, just as the coal seams once threaded through the ground. By looking at the genomes of people living in former coal-mining areas, he has found genetic signatures associated with spending fewer years at school compared with people outside those areas, and — at weaker significance levels — variants that correlate with lower socio-economic status. Some genetic variants even correlate with political persuasion and whether or not communities voted to leave the European Union in the 2016 Brexit referendum. Abdellaoui ... acknowledges that he is venturing onto politically charged ground. “I try to understand human genetic variation and this is what I run into,” he says.

The study — published this week in Nature Human Behaviour — is a high-profile example of an emerging trend: using huge amounts of data and computing power to uncover genetic contributions to complex social traits. Studies published in the past decade have examined genetic variants linked to aggression, same-sex sexual behaviour, well-being and antisocial behaviours, as well as the tendency to drink and smoke. In doing such science, geneticists are heading for controversial territory. They have even been accused of “opening a new door to eugenics”, according to the title of a 2018 MIT Technology Review article by science historian Nathaniel Comfort.

To the geneticists and social scientists doing this work, the results offer a useful and important guide to the relative contributions of nature and nurture to specific behavioural traits — just as genetic analysis can already highlight people who have an increased risk of cancer or heart disease. The approach could, for example, improve understanding of how the environment affects complex traits, and so offer a way to intervene to improve areas such as public education. “It is super-exciting,” says Philipp Koellinger, a genoeconomist at Vrije University Amsterdam in the Netherlands. “It gives us better and more-precise ways for scientists to answer questions they have been interested in for a long time.”

Caveats abound. The genetic contribution to any behavioural trait is relatively small and easily swamped by the influence of the environment. The studies can reveal only whether someone is likely to have a certain trait, and cannot predict the qualities of any one individual. Most scientists are quick to point out why they do this work — to establish what role, if any, genetics has in behaviour — and to lay out its limitations.

But not everyone is listening: already, some companies see a market in reading DNA like a fortune-teller reads tea leaves. “That stuff totally gives me the shivers. But it’s happening,” Koellinger says. Critics charge that the ethical and societal risks of acting on such information are too great. “One of the main concerns is not so much the study of genomics, but how are we going to use it,” says Maya Sabatello, a bioethicist at Columbia University in New York City. “Who’s going to benefit? Who’s not going to benefit? We live in a very unequal society and this is a major challenge...” (MORE - details)
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#2
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(UPDATE) Scientists Say New Research Tracing the Origin of Modern Humans to Botswana Is Deeply Flawed
https://gizmodo.com/scientists-say-new-r...1839498847

EXCERPT: A new paper claiming that modern humans originated in northern Botswana some 200,000 years ago is being criticized by experts [...] Alarmingly, the paper is also being criticized for its colonial undertones. The elusive search for the proverbial Garden of Eden has led an international team of scientists to northern Botswana, specifically an area just south of the Zambezi River. It was in this exact part of Africa, according to the team’s findings, where anatomically modern humans, Homo sapiens, first appeared hundreds of thousands of years ago, a conclusion derived from genetic, geological, linguistic, and climate data.

The new paper ... is unique in that it pinpoints the exact place and time of our species’ emergence. The paper received a tremendous amount of press coverage ... but given the controversy that now surrounds this research, it’s a wonder the paper, published ... managed to pass peer review—at least according to the many experts we spoke to. The complaints we received from scientists were almost too many to mention, the most serious being a weak and inconclusive genetic analysis, the failure to cite and address competing archaeological evidence, sweeping assumptions about one particular group of indigenous southern Africans, and an outdated “colonial” approach to the subject matter.

“I think it’s a terrible piece of scholarship that has taken us back in time to around 2004 and completely undermined science in the public eye,” archaeologist Eleanor Scerri of the Max Planck Institute for the Science of Human History said in an email to Gizmodo. “The work is incredibly arrogant in how it ignores archaeology and physical anthropology. It’s really staggering how they try to speak with authority about a subject area they clearly know nothing about.”

[...] Research from 2017 showed that Homo sapiens, sometimes referred to as anatomically modern humans, have been around for at least 300,000 years—and possibly even longer—as evidenced by fossils found in northern Africa, specifically the Jebel Irhoud site in Morocco. Scerri said the new paper ignores a “swath of fossil and archaeological evidence” favoring an older inception date for our species, and that paleoanthropologists don’t appear to have contributed to the research. Scerri suspects this archaeological evidence was omitted because the data didn’t “fit with the narrative.” (MORE - details)
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