The ancestors of the Neanderthals and the Denisovans met Hominin “Superarchaic”, which separated from other humans approximately 2 million years ago. A new study by researchers from the Department of Anthropology at the University of Utah shows that more than 700,000 years ago.
The ancestors of Neanderthals and Denisovans crossed paths with their Eurasian predecessors who were members of a ‘super -chachaic’ population that separated from other humans about 2 million years ago. The first Neanderthals who lived in Sima de los Huesos.
A cave site in the mountains of Atapuerca, Spain. Image by © Kennis & Kennis / Madrid Scientific Films. “We never knew about this episode of miscegenation and we could never estimate the size of the super-population population,” said Professor Alan Rogers of the University of Utah, lead author of the study.
“We are shedding light on an interval in human evolutionary history that was previously completely dark.” Professor Rogers and his colleagues studied the ways in which mutations are shared between modern Africans and Europeans, and the ancient Neanderthals and Denisovans.
The pattern of sharing involved five episodes of miscegenation, including one that was previously unknown.
The newly discovered episode involves miscegenation more than 700,000 years ago between a distantly related “superchachaic” population that separated from all other humans approximately 2 million years ago, and the ancestors of Neanderthals and Denisovans.
The ancestral superchanic and Neanderthal-Denisovan populations were more distantly related than any other pair of human populations previously known to cross. For example, modern humans and Neanderthals had been separated for about 750,000 years when they crossed.
The superchastic and Neanderthal-Denisovan ancestors were separated by more than a million years. “These findings about the time when the crossing in the human lineage occurred are saying something about how long it takes reproductive isolation to evolve,” said Professor Rogers.
The researchers used other clues in the genomes to estimate when ancient human populations separated and their effective population size. They estimated that the superochaicos separated into their own species approximately 2 million years ago.
This is consistent with the human fossil evidence in Eurasia that is 1.85 million years old. An evolutionary tree that includes four proposed episodes of gene flow; The previously unknown event 744,372 years ago (orange) suggests that there was a cross between superochaic and Neanderthal-Denisovan ancestors in Eurasia.
The scientists also proposed that there were three waves of human migration to Eurasia. The first was 2 million years ago when the superochaicos emigrated to Eurasia and expanded to a large population.
Then, 700,000 years ago, Neanderthal-Denisovan ancestors emigrated to Eurasia and quickly crossed paths with the descendants of the superochaic. Finally, modern humans expanded to Eurasia 50,000 years ago, where we know they crossed paths with other ancient humans, including Neanderthals.
“I have been working for the past several years on this different way of analyzing genetic data to learn the history,” said Professor Rogers. “It is gratifying that you come up with a different way of looking at the data and end up discovering things that people have not been able to see with other methods.”
Neanderthal-Denisovan ancestors interfered with a distant hominid. Previous research has shown that modern Eurasians interfere with their Neanderthal and Denisovan predecessors. We show here that hundreds of thousands of years ago, the ancestors of Neanderthals and Denisovans interfered with their Eurasian predecessors, members of a “supercaica” population that separated from other humans 2 million years ago.
The supercarica population was large, with an effective size of between 20 and 50 thousand people. We confirm previous findings that (i) Denisovans also interfered with supercarics, (ii) Neanderthals and Denisovans separated in the early Middle Pleistocene, (iii) their ancestors suffered from population size restriction Y (iv ) the Neanderthal population was higher than before. But then it decreased in size. We provide qualified support for the view that (v) Neanderthals interfere with the ancestors of modern humans.
Over the past decade, we learned about interactions between hominin populations when modern humans expanded to Eurasia (1-3), more than 50,000 years ago. Here, we had to focus on the events that took place a million and a half years ago. In this early period, the ancestors of modern humans separated from Neanderthals and Denisovans.
After a time, Neanderthals and Denisovans broke up. The paleology and archeology of this period register significant changes, since hominids with large brains appear in Europe and Asia, and the tools of Aechalian appear in Europe (4, 5). However, it is not clear how these large-brain homicins relate to other modern or Arctic human populations (6–9).
We studied the period using genetic data from modern Africans and Europeans and from two archaic populations, the Neanderthals and the Denisovans. Configure1 reflects our assumption. The capital letter refers to pop-evection, and combinations such as XY refer to the ancestral population of X and Y. X represents an African (Yoruba) population, Y is a European population, N is Neanderthal, and D is Denisovan.
S is a random population of “supercharch” that is remotely related to other humans. In the lower letters of Fig. -1 label “nucleotide site pattern”. A nucleotide site exhibits an x and n site pattern if the populations of the x, y, and n populations have alleles derived from random nucleotides, but samples from other populations are ancestral.
The site pattern probabilities can be calculated from population history models, and their frequencies can be estimated from the data. Our Legofit (10) software estimates the parameters for these relative frequencies using a fit model. Nucleotide site patterns comprise only part of the information available in the genome sequence data.
This is particularly relevant to the study of the part, however, the history of the deep population. Site pattern frequencies are unaffected by recent population history because they ignore the population component within variance (10). This reduces the number of parameters we must anticipate and allows us to focus on the distant past.
Current data includes two high-coverage Neanderthal genomes: one from the Altai Mountains of Siberia and the other from Vindja.
Cave in Croatia (11). Instead of assigning two Neanderthal fossils to different populations, our model assumes that they inhabited the same population at different times. This implies that our estimate of Neanderthal population size would refer to the Neanderthal metapopulation rather than any individual subset. Altai and Windija appear on the Neanderthal site tag as “A” and “V”.
Therefore, the AV site is the pattern in which the derived allele appears only in the sampled nucleotides of the two Neanderthal genomes. Figure 2 shows the site pattern frequencies studied here. In contrast to our previous analysis (12), the current analysis includes singleton, X, Y, V, A and D site patterns, as recommended by Mphasany and Proofer (13). A simple table, excluding the Vindiza genome, is included as fig. S2.Image graphic characters. Label entry episodes.
We design models by drawing Greek letters to indicate the letters we include. For example, model “” includes only episodes and . Our model does not include Denisovan gene flow in mod-orns, as there is little evidence of such gene flow in Europeans (14, 1415). Two years ago, we studied a model that included only one episode: studied, which refers to the gene flow from Neanderthal to European (12).
The left panel of Fig. 3 shows the residuals of this model using new data. Several are far from zero, suggesting that something is missing from the model (16). The relevant literature suggests some that may be missing. There is evidence of entry into Denisovans of a supercarica population, which was distantly related to other humans (2, 11, –17–19), and also to the entry of early modern people into Neanderthals (19).
These episodes of admission Fig. 1 appear as is and adm. Adding and / or adding to the model improved the fit, however none of the resulting models was satisfactory. For example, the model example implied (presumably) that the superecheatics isolated from other hominids before 7 million years (Ma) understand what may still be missing, consider that we consider the early Middle Pleistocene, you know, about 600 ka ago.
Right now, hominids with large brains appear in Europe with Acheu-lean stone tools (4, .5). They were probably African immigrants, with fossils and similar tools previously found in Africa. According to one hypothesis, these were the first European Neanderthal ancestors (6, 7).
A little earlier, perhaps 750 ka ago [(8), Table S12.2], the “Neandersovans” descendants of the Neanderthal and Denisovan ancestors separated from the ancestry that led to modern humans. The Neandersovans separated from the African population and can then expand to Eurasia.