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Ancient samples from Shan...
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The Moriopoulos G25 Colle...
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Basal West African?
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Basal West African? |
Posted by: JohnTheodore - 4 hours ago - Forum: Ancient (aDNA)
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Summary: I am wondering if the genetic structure in West Africans is a result of East African-South African-Hunter Gatherer/Taforalt input, or if it is a result of partial Basal West African ancestry. I also want to know if there are more studies that go into depth on the divergence times of East and West Africans, and also if there is more information on the information that more alleles are shared between ancient South Africans and East Africans, versus West Africans.
This study from 2017 (https://www.cell.com/fulltext/S0092-8674(17)31008-5 Reconstructing Prehistoric African Population Structure) posits that the Yoruba and Mende are representative of ancient population structure with either:
A) a genetic input from East-South African Hunter Gatherers into the Yoruba, but not the Mende. Or:
B) a deep basal West African ancestry that contributed in different amounts to the Yoruba and the Mende (9% to Yoruba and 13% to Mende).
They also say "we find that ancient southern Africans, who have none of the eastern African admixture that is ubiquitous today, share significantly more alleles with present-day and ancient eastern Africans (including Dinka, Hadza, and Ethiopia_4500BP) than they do with present-day western Africans"--- they're saying this is because of a deep population divergence which contributed to West Africans. They say that the Basal West African divergence from other humans would have been earlier than the divergence of the ancestors of the San, preceding 200,000-300,000 BP. ((**My own thoughts- this allele sharing of ancient South Africans with ancient East Africans seems to be one of the more potent points supporting the argument of the Basal West Africans contributing to modern West Africans--- are there any other studies exploring this?**))
There is another study which would tangentially support option (A), the Lazaridis study from 2018 (https://www.biorxiv.org/content/10.1101/423079v1) which says there is around 12% Taforalt ancestry in the Yoruba. Taforalt, according to the same study, is 55% West Eurasian and 45% Ancient North African. The presence of minor Neanderthal ancestry in the Yoruba (Chen 2020) also supports some incorporation of Eurasian ancestry, maybe via the Taforalt, into the Yoruba.
Looking at these two studies together, it would indicate it's very likely the Yoruba have amounts of ancestry related to East-South African Hunter Gatherers, and thus an ancestry somewhat related to the Ancient North African portion of the Taforalt.
The only other study that would be supportive of Basal West African ancestry of is this one from 2020: https://pmc.ncbi.nlm.nih.gov/articles/PMC7015685/, which suggests there is an archaic ancestry present in West Africans at around 2% to 19%, but this theory was negated by the 2023 study https://pubmed.ncbi.nlm.nih.gov/37198480/ "A Weakly Structured Stem", which came to the conclusion that archaic ancestry was not necessarily present in West Africans.
Are there any more studies or genetic evidence which would substantiate the presence of a Basal West African lineage? Or is the divergence they are referring to in the 2017 study more likely a product of an ancient East-South African Hunter Gatherer (or Taforalt) in the Yoruba? Maybe some ancestry from Green Saharans migrating southward?
This study (Prendergast 2019: "https://www.science.org/doi/10.1126/science.aaw6275) says the ancestors of West Africans and the East Africans diverged at around 30,000 years ago. Common gene flow after that time period would have taken place during the aftermath of the Green Sahara period and probably migrations across the Sahel. Are there any other newer studies giving different time estimates for this divergence period? Or is there any mtDNA / Y DNA evidence substantiating different divergence periods?
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G25 automatic clusterer |
Posted by: Stefano - Yesterday, 01:54 PM - Forum: Autosomal (auDNA)
- Replies (1)
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Hi, i made this small program which divide a given set of g25 coordinates into a number of clusters of your choice. After opening the program you have to paste the coordinates list in the box by pressing ctrl+v, insert the desired number of clusters and then click the "cluster coordinates" button. it can also display a Pca of them. Let me know if you find some bug or if you have suggestions about features to add.
You can download it here: https://drive.google.com/file/d/1muulQf3...sp=sharing
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How to move a Mosaic - Roman site at the Liberty, London |
Posted by: Rufus191 - Yesterday, 12:08 PM - Forum: History (Ancient)
- No Replies
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Museum of London Archaeology blog
https://www.mola.org.uk/discoveries/news...us-mosaics
Lifting the Liberty’s marvelous mosaics
"In 2022 we discovered the best-preserved Roman mosaics found in London for over 50 years. Uncovered during excavations ahead of the Liberty development, these beautiful mosaics would once have decorated the floor of a large room, possibly a dining room. "
![[Image: discoveries_banner.jpg?itok=sIyCblDl]](https://www.mola.org.uk/sites/default/files/styles/eck_image/public/images/discoveries_banner.jpg?itok=sIyCblDl)
"In this blog, Liz Goodman, our Conservation team leader, takes us through the painstaking process of lifting and storing the mosaics, so they can be returned to their original home for display as part of the Liberty development. "
"Because we wanted to lift each mosaic in one go, we started by creating a solid edge to keep all the tiny tesserae together. To do this, we stuck small squares of a special long-fibered paper over the sides and edges of the mosaic. We also reinforced any areas where tesserae were missing to help strengthen the mosaic when we lifted it. "
" When the Romans made the mosaic, they set the tesserae in thin layer of fine white mortar to keep them together. However, this mortar had broken down over time and was very soft. So, once the edges had been reinforced, we added a layer of netting to the top of the mosaic. We stuck the netting to the tesserae to make sure they stayed in position. "
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