Basal Eurasians are considered a “ghost” population believed to have significantly influenced ancient populations in the Middle East and North Africa during the Upper Paleolithic to Mesolithic periods. The earliest sequenced sample with Basal Eurasian ancestry (~24%), known as NEO283, dates back to the Upper Paleolithic era (26,000 BP) from Kotias Cave in Georgia, with the remaining ancestry attributed to West Eurasian Upper Paleolithic hunter-gatherers. (Allentoft et al., 2024)

Between the Upper Paleolithic and Mesolithic periods, there is an observed increase in Basal Eurasian ancestry in the Caucasus and Iran, coupled with an Ancient North Eurasian (ANE)-related admixture. This results in approximately 35% Basal Eurasian + ANE and 65% Basal Eurasian + ANE admixture in Mesolithic Caucasus Hunter Gatherers (CHG) and Mesolithic Iran (HotuIIIb) samples, respectively. However, the Basal Eurasian admixture decreases to less than 50% in Neolithic Iran (Lazaridis et al., 2016).

In contrast to the Caucasus and Iran, Basal Eurasian ancestry in Anatolian and Natufian Hunter Gatherers in the Levant is accompanied by Western Hunter-Gatherer (WHG)-like admixture. Anatolian Hunter Gatherers and their direct descendants, Anatolian Neolithic Farmers, are estimated to have approximately 25% Basal Eurasian + WHG ancestry (Feldman et al., 2019)  while Natufian Hunter Gatherers exhibit around 45% Basal Eurasian + WHG-like ancestry. It remains unclear whether this WHG-like ancestry later migrated from South Europe to the Middle East or was already present in the region (Lazaridis et al., 2016, supplementary information).

Ferreira et al. (2021) proposed that Basal Eurasians and the ancestors of East and West Eurasians were genetically close, with Basal Eurasians likely descending from the same group that left Africa but split earlier, either in southwest Asia or in Africa before the Out-of-Africa (OoA) event. In the latter scenario, they followed the ‘southern route’ in the Arabian Peninsula and took refuge somewhere in the Persian gulf while the sister group followed ‘northern route’ mixed with the Neanderthals in northern Arabian Peninsula before moving further into Europe and Asia.  Ferreira’s estimations also suggest that Iberomaurissians from the Tarofalt Culture (15,000 – 13,000 BP) in Morocco carry approximately 60% Basal Eurasian ancestry. Additionally, in contrast to Lazaridis et al. (2016), Natufians are estimated to have above 20% Basal Eurasian ancestry, while CHGs have approximately 40%.