Between 2 and 19% (on average 11%) of the genetic pool of sub-Saharan populations evolved separately from the rest of humanity for up to 1.02 million years. It is estimated that 4 million years ago, there was a common ancestor of chimpanzees and the homo line – over a million years is half that time (other studies suggest that the separation of the lines may have occurred as long as 1.5 million years ago). Introgression into West African populations came from a highly diverse, large population (approximately 25,000 individuals) that separated from the human lineage almost a million years ago, and gene flow occurred relatively recently, between 6,000 and 124,000 years ago, contributing 2% to 19% to the genetic pool of these populations. The archaic hominid population separated from the ancestor of Neanderthals and modern humans between 360,000 years ago (ka) and 1.02 million years ago (Ma) (on average 625,000 years ago) – much earlier than all other hominids identified so far, whose traces of introgression have been recorded among non-sub-Saharan modern humans. The genetic fraction of modern Africans derived from this archaic population is significant. The average posterion estimate (for YRI - Yoruba) is 11%, with a confidence interval (95% HPD, for YRI) ranging from 0.045 (4.5%) to 0.19 (19%). Total range (for all West African populations): It is estimated that the archaic population contributed 2 to 19% to their gene pool. Time when introgression (gene flow) from this archaic population to the ancestors of modern Africans occurred: Average posterior estimate (for YRI): 43,000 years ago (B.P.). Confidence interval (95% HPD, for YRI): 6,000 to 124,000 years ago. Total range (for all West African populations): Introgression occurred between 0 and 124,000 years ago (ka B.P.). There is uncertainty about the exact time of introgression. One interpretation suggests that archaic forms survived in Africa relatively recently (admin's note: under the tag “evolution” you will find links to studies on the skeleton from the Iwo Eleru cave – a hominid dated to 12,000 BC). Another possibility is that introgression occurred earlier into another population of modern humans, which later interbred with the ancestors of the populations analyzed. A joint CSFS (conditional allele frequency spectrum) analysis of the CEU (European) and YRI populations suggests that at least some of the archaic lineages in YRI are also shared with CEU, indicating that the lower limit of introgression is even older than the simulated split of CEU and YRI. The effective population size for the introgressive lineage of the archaic population is also significant, with a mean post-reduction estimate (for YRI) of 25,000. The researchers caution that the large effective population size of the introgressive lineage may indicate additional structure within this archaic population. The following genes have been identified that show evidence of adaptive introgression from archaic hominins (ghost population), as archaic segments are present at high frequency in both the YRI and MSL populations (percentages for YRI and MSL, respectively): NF1 Tumor suppressor gene (Protein coding) 83% and 85%, MTFR2 Associated with mitochondrial oxygen respiration in the nucleus (Protein coding) 67% and 78%, HSD17B2 Associated with hormone regulation (Protein coding) 74% and 68%, KCNIP4 Associated with potassium channels (Protein coding) 73% and 69%, TRPS1 Associated with trichorhinophalangeal syndrome (Protein coding) 71% and 75%. Sources also mention other loci that have achieved high archaic frequency (some of them are included in the Top 10 segments by frequency in YRI or MSL): RP11-286M16.1 (lincRNA): 84% in YRI, 81% in MSL. MIR125B2 (MicroRNA): 76% in YRI, 64% in MSL, RP11-125N22.2 (Pseudogene): 12% in YRI, but 88% in MSL, KRT18P61 (Pseudogene): 84% in YRI, 36% in MSL. Such a high frequency of archaic segments in West African populations reveals a significant contribution of archaic origins to the gene pool of modern West Africans. For nearly 1.02 million years, sub-Saharan genes were never transmitted to populations outside sub-Saharan Africa – until the fall of the Roman Empire. After the 8th century CE, due to the slave trade, the gene spread among Arab populations (currently about 10% of Arab genes come from sub-Saharan Africans), and through them, it later found its way into the genomes of the inhabitants of southern Europe (Sicilians, Spaniards 2-4% of the genome) . Note: In the case of Arabs, Sicilians, and southern Spaniards, the values given refer to genes originating from a diluted sub-Saharan gene pool, and not directly from the hominid in question, as in the case of Africans (i.e., Arab 10% sub-Saharan genes should give 0.2% - 1.9% hominid genes - the exact amount depends on the degree of dilution of the hominid genome among the Blacks “absorbed” into the population). For more on the process of Arabs interbreeding with sub-Saharan populations, see the studies tagged Arabs and Evolution. Apart from the populations mentioned above, the genes do not occur at all, so genetically native Poles, Swedes, Germans, and Chinese continue to evolve separately from a significant fragment of the genome of every black person 1.02 million years ago. At the same time, sub-Saharan populations have ceased to evolve separately from non-sub-Saharan populations as a result of the introgression discussed above. To put it simply, genes from Eurasia recently flowed into the sub-Saharan population, creating a hybrid of humans and hominids, which, from the perspective of their DNA, interrupted separate evolution, but did not change anything from the perspective of the DNA of non-sub-Saharan populations because there was no reverse flow. The genes of this hominid and other similarly archaic ones are native and common among black people.