Khvorykh et al. 2020:
Global Picture of Genetic Relatedness and the Evolution of Humankind
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7696950/
Erittäin laaja maailmanlaajuinen IBD-fragmenttien vertailu, jossa on mukana myös ihmisen arkaaisia alalajeja:
"The genomes of all three studied Neanderthals (Altai Neandertal (Denisova5, Alt_XXX), Chagirskaya (Cha_XXX), and Vindija (Vin_XXX)) have strikingly similar patterns of relatedness to modern populations, despite these prehistoric people having lived ~30,000 years apart from each other in the area from southern Europe to Western Eurasia and Altai (see bottom of Supplementary Table S4). Supplementary Table S4 demonstrates that Neanderthal genomes have the highest percentage of relatedness (around 50%) with people from Oceania, followed by South Asia (~15%). Meanwhile, American and Arctic populations have the lowest Neanderthal relatedness (~0.5% and ~2% respectively).
Similar to the Neanderthal genome, the Denisovan genome (Den_XXX) also had the highest level of admixture with the Oceania populations. However, Den_XXX contains much higher levels of relatedness to African genomes (see Figure 3). In fact, around 30% of the Denisovan genome relatedness to modern humans comes from Eastern and Western Africa. Drastically lower percentages of Denisovan relatedness to Hindustan and Middle East populations is another notable difference between Denisovans and Neanderthals."
Eurooppalaisissa on enemmän metsästäjäperimää, Lähi-idässä maanviljelijäperimää:
"Analysis of ancient humans from Europe who lived 7000–9000 years ago demonstrated a higher impact of the Luxemburg’s Loschbour genome (Los_XXX) on modern Europeans than the Stuttgart (Lbk_XXX) genome (~74% and ~60% relatedness respectively, see bottom of the Supplementary Table S4). In contrast, the relatedness to modern Middle Eastern (~27% vs. ~16%) and East African (~4% vs. ~0.3%) genomes was found to be higher in the Stuttgart ancient human than in the Loschbour human. Such differences in genomic impact between Loschbour and Stuttgart ancient humans on modern populations are consistent with their affiliation to two distinct human cultures: Western hunter–gatherers and the first European farmers, respectively."
Käytetty menetelmä ei kuitenkaan tunnista kaikkein lyhimpiä IBD-jaksoja:
"We acknowledge that our approach is likely to miss a considerable portion of the very short (<10 Kb) IBD segments. This is because there is only about one very rare SNP allele per 10 Kb in the human genome. We decided not to loosen our stringent criteria for characterization of IBDs (which is at least 5 very rare SNPs) because false positive results with these conditions are negligible (see our computer modeling with Rnd_XXX in the Section 2). Therefore, our approach yields a cleaner background but likely creates a bias by missing many of the shortest IBD fragments. Altering this constraint (for example, changing our lower limit to a cluster of three very rare SNP alleles instead of five) would very likely help in detecting the shortest IBDs, but would also greatly increase the false positive IBD detection."
Menetelmä tuottaa erilaisia tuloksia kuin esim. yleisesti käytetty Admixture-analyysi:
"Regarding Europeans, the strongest genetic distinction in their population occurs along the North-South axis. All European Mediterranean countries (Spain, Italy, Greece, Albania, Croatia) have around the same level of relatedness to the Middle East and North Europe (around a 1:1 ratio at 40%, see Supplementary Table S4). In contrast, the Middle East component of relatedness in Scandinavians and other people from Northern Europe is lower than 10%."
Admixture-analyyseissä jopa saamelaisissa on noin 20 % maanviljelijäperimää ja skandinaaveissa vielä selvästi enemmän. IBD-menetelmä näyttää kuitenkin löytävän hyvin väestöjen juuria, esimerkkinä Euroopan romanien eteläaasialainen perimäosuus on peräti 44 %, mutta toisaalta he saapuivatkin vasta noin 500 vuotta sitten:
"Among 47 studied European populations, only one (Roma, Bosnia-Herzegovina) stands out from the others by its unique pattern of genetic relatedness. Specifically, the Roma population has the highest genetic relatedness (44%) to the SAS natives, which is, on average, eight times higher than in other Europeans. The Roma people came to Europe from India, and astonishingly, they have almost fully preserved their genetic identity despite producing dozens of generations since their separation from their original founder population."