quote: Despite broad agreement that Homo sapiens originated in Africa, considerable uncertainty surrounds specific models of divergence and migration across the continent. Progress is hampered by a shortage of fossil and genomic data, as well as variability in previous estimates of divergence times1. Here we seek to discriminate among such models by considering linkage disequilibrium and diversity-based statistics, optimized for rapid, complex demographic inference. We infer detailed demographic models for populations across Africa, including eastern and western representatives, and newly sequenced whole genomes from 44 Nama (Khoe-San) individuals from southern Africa. We infer a reticulated African population history in which present-day population structure dates back to Marine Isotope Stage 5. The earliest population divergence among contemporary populations occurred 120,000 to 135,000 years ago and was preceded by links between two or more weakly differentiated ancestral Homo populations connected by gene flow over hundreds of thousands of years. Such weakly structured stem models explain patterns of polymorphism that had previously been attributed to contributions from archaic hominins in Africa2,3,4,5,6,7. In contrast to models with archaic introgression, we predict that fossil remains from coexisting ancestral populations should be genetically and morphologically similar, and that only an inferred 1–4% of genetic differentiation among contemporary human populations can be attributed to genetic drift between stem populations. We show that model misspecification explains the variation in previous estimates of divergence times, and argue that studying a range of models is key to making robust inferences about deep history.
(video lecture also added to top of OP, also article link is now updated to complete article)
Posts: 42940 | From: , | Registered: Jan 2010
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This is exactly why I don't place too much faith in what the so-called experts say in regards to their interpretations of genetic data especially those of autosomal markers in regards to relationships between Africans populations, let alone between Africans and alleged "Eurasians".
They can't even figure out the ancestral population structure of modern Africans let alone prehistoric ones and many of these alleged "Eurasian" date to those prehistoric periods. Remember that ANA was originally mistaken to be "Eurasian" until it was clarified to be African in origin. Then we had the discovery of Basal Eurasian and after that the Mota debacle. As I said, it's only going to be a matter of time before the Natufian-Levantine Neolithic marker will be realized as African as well.
quote:Originally posted by Djehuti: This is exactly why I don't place too much faith in what the so-called experts say in regards to their interpretations of genetic data
Couldn't agree more with this statement. As I always say raw data is raw data but it's the interpretation of that data which can be subject to manipulation.
quote:Originally posted by Djehuti: Remember that ANA was originally mistaken to be "Eurasian" until it was clarified to be African in origin.
Sorry to go a little off topic Dhejuti but which study or geneticist(s) thought of ANA to be originally Eurasian and which one(s) clarified it to be African?
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^ The only geneticist I could think of is Brenna Henn et al. (2012), though there were other similar papers which took ANA as evidence of back-migration. I don't blame them at all since they are still in the process of refining the relationships of all these genetic elements.
We now know that ANA is present in a wide assortment of African peoples including Sub-Saharans as well as Western Eurasians which suggest that such ancestry may represent the relation between Africans and Basal Eurasian. Again, I'm not holding my breath either way since I've never denied any "back-migrations" into Africa but only question how many and at what time periods.
-------------------- Mahirap gisingin ang nagtutulog-tulugan. Posts: 26293 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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It's not quite the same thing as the OP topic, but I know Swenet has mentioned Neanderthal genomes having uniparental haplogroups of AMH origin. It looks like more evidence of AMH ancestry in Neanderthals has been unearthed:
quote: Comparisons of Neanderthal genomes to anatomically modern human (AMH) genomes show a history of Neanderthal-to-AMH introgression stemming from interbreeding after the migration of AMHs from Africa to Eurasia. All non-sub-Saharan African AMHs have genomic regions genetically similar to Neanderthals that descend from this introgression. Regions of the genome with Neanderthal similarities have also been identified in sub-Saharan African populations, but their origins have been unclear. To better understand how these regions are distributed across sub-Saharan Africa, the source of their origin, and what their distribution within the genome tells us about early AMH and Neanderthal evolution, we analyzed a dataset of high-coverage, whole-genome sequences from 180 individuals from 12 diverse sub-Saharan African populations. In sub-Saharan African populations with non-sub-Saharan African ancestry, as much as 1% of their genomes can be attributed to Neanderthal sequence introduced by recent migration, and subsequent admixture, of AMH populations originating from the Levant and North Africa. However, most Neanderthal homologous regions in sub-Saharan African populations originate from migration of AMH populations from Africa to Eurasia ∼250 kya, and subsequent admixture with Neanderthals, resulting in ∼6% AMH ancestry in Neanderthals. These results indicate that there have been multiple migration events of AMHs out of Africa and that Neanderthal and AMH gene flow has been bi-directional. Observing that genomic regions where AMHs show a depletion of Neanderthal introgression are also regions where Neanderthal genomes show a depletion of AMH introgression points to deleterious interactions between introgressed variants and background genomes in both groups—a hallmark of incipient speciation.
quote:Originally posted by BrandonP: It's not quite the same thing as the OP topic, but I know Swenet has mentioned Neanderthal genomes having uniparental haplogroups of AMH origin. It looks like more evidence of AMH ancestry in Neanderthals has been unearthed:
quote: Comparisons of Neanderthal genomes to anatomically modern human (AMH) genomes show a history of Neanderthal-to-AMH introgression stemming from interbreeding after the migration of AMHs from Africa to Eurasia. All non-sub-Saharan African AMHs have genomic regions genetically similar to Neanderthals that descend from this introgression. Regions of the genome with Neanderthal similarities have also been identified in sub-Saharan African populations, but their origins have been unclear. To better understand how these regions are distributed across sub-Saharan Africa, the source of their origin, and what their distribution within the genome tells us about early AMH and Neanderthal evolution, we analyzed a dataset of high-coverage, whole-genome sequences from 180 individuals from 12 diverse sub-Saharan African populations. In sub-Saharan African populations with non-sub-Saharan African ancestry, as much as 1% of their genomes can be attributed to Neanderthal sequence introduced by recent migration, and subsequent admixture, of AMH populations originating from the Levant and North Africa. However, most Neanderthal homologous regions in sub-Saharan African populations originate from migration of AMH populations from Africa to Eurasia ∼250 kya, and subsequent admixture with Neanderthals, resulting in ∼6% AMH ancestry in Neanderthals. These results indicate that there have been multiple migration events of AMHs out of Africa and that Neanderthal and AMH gene flow has been bi-directional. Observing that genomic regions where AMHs show a depletion of Neanderthal introgression are also regions where Neanderthal genomes show a depletion of AMH introgression points to deleterious interactions between introgressed variants and background genomes in both groups—a hallmark of incipient speciation.
Took long enough. Various relationships to he AMH population in question also helps shapes the diversity in post OOA Africans. These two studies are linked. And you will begin to see some more interesting data and results from now on.
Posts: 1782 | From: New York | Registered: Jul 2016
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quote:Originally posted by BrandonP: ] It's not quite the same thing as the OP topic, but I know Swenet has mentioned Neanderthal genomes having uniparental haplogroups of AMH origin. It looks like more evidence of AMH ancestry in Neanderthals has been unearthed:
quote: Comparisons of Neanderthal genomes to anatomically modern human (AMH) genomes show a history of Neanderthal-to-AMH introgression stemming from interbreeding after the migration of AMHs from Africa to Eurasia. All non-sub-Saharan African AMHs have genomic regions genetically similar to Neanderthals that descend from this introgression. Regions of the genome with Neanderthal similarities have also been identified in sub-Saharan African populations, but their origins have been unclear. To better understand how these regions are distributed across sub-Saharan Africa, the source of their origin, and what their distribution within the genome tells us about early AMH and Neanderthal evolution, we analyzed a dataset of high-coverage, whole-genome sequences from 180 individuals from 12 diverse sub-Saharan African populations. In sub-Saharan African populations with non-sub-Saharan African ancestry, as much as 1% of their genomes can be attributed to Neanderthal sequence introduced by recent migration, and subsequent admixture, of AMH populations originating from the Levant and North Africa. However, most Neanderthal homologous regions in sub-Saharan African populations originate from migration of AMH populations from Africa to Eurasia ∼250 kya, and subsequent admixture with Neanderthals, resulting in ∼6% AMH ancestry in Neanderthals. These results indicate that there have been multiple migration events of AMHs out of Africa and that Neanderthal and AMH gene flow has been bi-directional. Observing that genomic regions where AMHs show a depletion of Neanderthal introgression are also regions where Neanderthal genomes show a depletion of AMH introgression points to deleterious interactions between introgressed variants and background genomes in both groups—a hallmark of incipient speciation.
Formal stats testing Neanderthals for shared drift with AMH, with Sima de Los Huesos as an outgroup, is what I'd be interested in seeing. I doubt they would get off that easily (ie with only 6%).
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^ Perhaps this explains the so-called Neanderthal ancestry in Africans like Maasai?
Also, what does anyone make of these g25 results on Mota?
Notice that the first set is closest to Mota especially the Hadza but in the second set comprising both Ethio-Semitic and Cushitic speakers the distance is about equivalent between Neolithic Moroccans and Natufians.
I don't think simple Eurasian admixture alone doesn't explain it when you look at these.
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