Interbreeding between archaic and modern humans

Map of western Eurasia showing areas and estimated dates of possible Neanderthal–modern human hybridization (in red) based on fossil samples from indicated sites.[1]

Interbreeding between archaic and modern humans occurred during the Middle Paleolithic and early Upper Paleolithic. The interbreeding happened in several independent events that included Neanderthals and Denisovans, as well as several unidentified hominins.[2]

In Europe, Asia and North Africa, interbreeding between Neanderthals and Denisovans with modern humans took place several times. The introgression events into modern humans are estimated to have happened about 47,000–65,000 years ago with Neanderthals and about 44,000–54,000 years ago with Denisovans.

Neanderthal-derived DNA has been found in the genomes of most or possibly all contemporary populations, varying noticeably by region. It accounts for 1–4% of modern genomes for people outside Sub-Saharan Africa, although estimates vary, and either none or up to 0.3% for those in Sub-Saharan Africa.[3] Cushitic and Semitic speaking populations from the Horn of Africa (such as Ethiopians), who derive a large portion of their ancestry from West Eurasians, have ~1% Neanderthal-derived DNA.[4]

Neanderthal-derived DNA is highest in East Asians, intermediate in Europeans, and lower in Southeast Asians.[5] According to some research, it is also lower in Melanesians and Polynesians compared to both East Asians and Europeans.[5] However, other research finds higher Neanderthal admixture in Melanesians, as well as in Native Americans, than in Europeans (though not higher than in East Asians).[6]

Denisovan-derived ancestry is largely absent from modern populations in Africa, Western Asia and Europe. The highest rates, by far, of Denisovan admixture have been found in Oceanian and some Southeast Asian populations. An estimated 4–6% of the genome of modern Melanesians is derived from Denisovans, but the highest amounts detected thus far are found in the Negrito populations of the Philippines. While some Southeast Asian Negrito populations carry Denisovan admixture, others, such as the Andamanese, have none. In addition, low traces of Denisovan-derived ancestry have been found in mainland Asia, with an elevated Denisovan ancestry in South Asian populations compared to other mainland populations.[7]

In Africa, archaic alleles consistent with several independent admixture events in the subcontinent have been found. It is currently unknown who these archaic African hominins were.[5] A 2020 paper found that "despite their very low levels or absence of archaic ancestry, African populations share many Neanderthal and Denisovan variants that are absent from Eurasia, reflecting how a larger proportion of the ancestral human variation has been maintained in Africa."[8]

A 2016 paper in the journal Evolutionary Biology argued that introgression of DNA from other lineages enabled humanity to migrate to, and succeed in, numerous new environments, with the resulting hybridization being an essential force in the emergence of modern humans.[9]

In December 2023, scientists reported that genes inherited by modern humans from Neanderthals and Denisovans may biologically influence the daily routine of modern humans.[10]

  1. ^ Churchill, Steven E.; Keys, Kamryn; Ross, Ann H. (August 2022). "Midfacial Morphology and Neandertal–Modern Human Interbreeding". Biology. 11 (8): 1163. doi:10.3390/biology11081163. ISSN 2079-7737. PMC 9404802. PMID 36009790.
  2. ^ Woodward, Aylin (5 January 2020). "A handful of recent discoveries have shattered anthropologists' picture of where humans came from, and when". Business Insider. Archived from the original on 25 April 2022. Retrieved 6 January 2020.
  3. ^ Cite error: The named reference pr-atcn was invoked but never defined (see the help page).
  4. ^ Haber, Marc; et al. (2016). "Chad Genetic Diversity Reveals an African History Marked by Multiple Holocene Eurasian Migrations". Am J Hum Genet. 99 (6): 1316–1324. doi:10.1016/j.ajhg.2016.10.012. hdl:11577/3455530. PMC 5142112. PMID 27889059. Eurasian ancestry in Ethiopians ranges from 11%–12% in the Gumuz to 53%–57% in the Amhara. [...] Neanderthal ancestry proportion in Africans is correlated with gene flow from Eurasians. For example, knowing that today Eurasians carry ~2% of Neanderthal ancestry, we observed that East Africans (Ethiopians) had ~1% Neanderthal ancestry and ~50% Eurasian ancestry.
  5. ^ a b c Wolf, A. B.; Akey, J. M. (2018). "Outstanding questions in the study of archaic hominin admixture". PLOS Genetics. 14 (5): e1007349. doi:10.1371/journal.pgen.1007349. PMC 5978786. PMID 29852022.
  6. ^ Sankararaman, Sriram; Mallick, Swapan; Patterson, Nick; Reich, David (2016). "The Combined Landscape of Denisovan and Neanderthal Ancestry in Present-Day Humans". Current Biology. 26 (9): 1241–1247. Bibcode:2016CBio...26.1241S. doi:10.1016/j.cub.2016.03.037. PMC 4864120. PMID 27032491.
  7. ^ "Ancient human relative interbred with ancestors of modern humans as recently as 50,000 years ago". UCLA. Archived from the original on 21 November 2022. Retrieved 21 November 2022.
  8. ^ Cite error: The named reference Bergstrom2020a was invoked but never defined (see the help page).
  9. ^ Rogers Ackermann, Rebecca; Mackay, Alex; Arnold, Michael L. (2016). "The Hybrid Origin of "Modern" Humans". Evolutionary Biology. 43 (1): 1–11. Bibcode:2016EvBio..43....1A. doi:10.1007/s11692-015-9348-1. S2CID 14329491.
  10. ^ Zimmer, Carl (14 December 2023). "Morning Person? You Might Have Neanderthal Genes to Thank. - Hundreds of genetic variants carried by Neanderthals and Denisovans are shared by people who like to get up early". The New York Times. Archived from the original on 14 December 2023. Retrieved 14 December 2023.