Basal Eurasian

Basal Eurasian is a hypothetical lineage,[1] which exists in greatest amount among ancient Near East individuals.[2] Basal Eurasians may have been present in the Near East, as anatomically modern humans resided in the Levant approximately 100,000 years ago and African-related tools in Arabia were likely developed by modern humans;[3] hence, they may have settled in the Levant or Arabia.[4] The areas of the Near East where Basal Eurasians resided may have been areas where contact with Neanderthals, who were known to have lived in West Eurasia, were not made.[5]

Basal Eurasians are the sibling group that diverged from the main lineage of all other non-African groups[6] (e.g., Australian Aborigines, New Guineans,[7] Europeans, East Asians[8]), prior to their divergence from one another.[6] The admixture of the main lineage of all other non-Africans with Neanderthals likely occurred 50,000-60,000 years ago, after it diverged from Basal Eurasians.[9]

The scenario of a non-Neanderthal-admixed modern human population, which is basal to other Eurasians, and resided in Africa, is plausible.[9] In particular, North Africa is a strong candidate as a location for the emergence of Basal Eurasians as it shares notable connection with Eurasia.[10] Natufians, who share craniometric affinity with North Africans and were of the Y-chromosomal haplogroup E, are of Basal Eurasian ancestry.[9] Basal Eurasians had little to possibly no Neanderthal admixture.[9] However, Natufians do not share a greater amount of alleles with Sub-Saharan Africans than other ancient Eurasians, and the Basal Eurasian ancestry in Natufians is consistent with originating from the same population as Neolithic Iranians and Mesolithic Iranians.[9] Mesolithic Iranians (66±13%), Neolithic Iranians (48±6%), and Epipaleolithic Natufians (44±8% or 63%[11]) share Basal Eurasian ancestry.[12] Another estimate given for Holocene-era Near Easterners (e.g., Mesolithic Caucasian Hunter Gatherers, Mesolithic Iranians, Neolithic Iranians, Natufians) is that they possess up to 50% Basal Eurasian ancestry.[10] Additionally, while the Taforalt individuals were considered likely direct descendants of Basal Eurasians, they were shown to not be genetically closer to Basal Eurasians than Holocene-era Iranians.[10]

High levels of Basal Eurasian ancestry were found in ancient Middle Eastern genomes, which negatively correlated with Neanderthal ancestry.[1] Basal Eurasians may have less Neanderthal ancestry than other ancestral Eurasian lineages, and the extent to which Basal Eurasian ancestry is present may explain the extent to which Neanderthal ancestry is present in Middle Eastern genomes.[1] For example, a high level of Basal Eurasian or Sub-Saharan African ancestry could be the underlying reason for the low level of Neanderthal ancestry in Qatari Bedouin in comparison to Europeans or other Middle Eastern populations.[1] The most parsimonious explanations for similar or less Neanderthal introgression in Middle Eastern populations, compared to other Eurasian populations, are the presence of Sub-Saharan African ancestry as well as the presence of Basal Eurasian ancestry, which has little to no signatures of Neanderthal introgression.[1] Bedouin, who have the greatest amount of autochthonous Arab genetic ancestry, may be the direct descendants of Basal Eurasians.[13]

Early European Farmers (EEFs), who had some Western European Hunter-Gatherer-related ancestry and originated in the Near East, also derive approximately 44% of their ancestry from Basal Eurasians.[4]

Ust’-Ishim is an approximately 45,000 year old Eurasian without Basal Eurasian ancestry.[8] The later Villabruna Cluster of Western Hunter Gatherers do not have high levels of Basal Eurasian ancestry.[8]

References
  1. Taskent, Recep (2017). "Variation and Functional Impact of Neanderthal Ancestry in Western Asia". Genome Biology and Evolution. 9 (12): 3516–3524. doi:10.1093/gbe/evx216. PMC 5751057. PMID 29040546.
  2. Yang, Melinda A.; Fu, Qiaomei (2018). "Interactive Questions" (PDF). Trends in Genetics. 34 (3): 184–196. doi:10.1016/j.tig.2017.11.008. PMID 29395378.
  3. Lazaridis, Iosif (2014). "Ancient human genomes suggest three ancestral populations for present-day Europeans". Nature. 513 (7518): 409–413. arXiv:1312.6639. Bibcode:2014Natur.513..409L. doi:10.1038/nature13673. PMC 4170574. PMID 25230663.
  4. Lazaridis, Iosif (2014). "Ancient human genomes suggest three ancestral populations for present-day Europeans". Nature. 513 (7518): 409–413. Bibcode:2014Natur.513..409L. doi:10.1038/nature13673. PMC 4170574. PMID 25230663.
  5. Harvard Medical School. "DNA analyses reveal genetic identities of world's first farmers". EurekAlert!. American Association for the Advancement of Science (AAAS).
  6. Lazaridis, Iosif (2018). "The evolutionary history of human populations in Europe". arXiv:1805.01579 [q-bio.PE].
  7. Powell, Alvin (2014-09-17). "A mark on modern Europe". Havard Gazette. Havard Gazette.
  8. Fu, Qiaomei (2016). "The genetic history of Ice Age Europe". Nature. 534 (7606): 200–205. Bibcode:2016Natur.534..200F. doi:10.1038/nature17993. hdl:10211.3/198594. PMC 4943878. PMID 27135931.
  9. Lazaridis, I (2016). "Genomic insights into the origin of farming in the ancient Near East" (PDF). Nature. 536 (7617): 419–424. Bibcode:2016Natur.536..419L. doi:10.1038/nature19310. PMC 5003663. PMID 27459054.
  10. Van de Loosdrecht, Marieke. "Supplementary Materials for Pleistocene North African genomes link Near Eastern and sub-Saharan African human populations" (PDF). Science. Science.
  11. Reviewer, Anonymous (2018). "Pleistocene North African genomes link Near Eastern and sub-Saharan African human populations". Science. 360 (6388): 548–552. Bibcode:2018Sci...360..548V. doi:10.1126/science.aar8380. PMID 29545507.
  12. Lazaridis, Iosif (2016). "Genomic insights into the origin of farming in the ancient Near East". Nature. 536 (7617): 419–424. Bibcode:2016Natur.536..419L. doi:10.1038/nature19310. PMC 5003663. PMID 27459054.
  13. Rodriguez-Flores, Juan (2016). "Indigenous Arabs are descendants of the earliest split from ancient Eurasian populations". Genome Research. 26 (2): 151–162. doi:10.1101/gr.191478.115. PMC 4728368. PMID 26728717.
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