Neanderthals, Denisovans, modern humans ‘intermingled’ in Iran, claims research

A new study reveals that Neanderthals, Denisovans, and modern humans could have intermingled in the Caspian region.

Although it is unclear when these prehistoric encounters took place, the presence of old genes in the present human genome indicates that Homo sapiens once interbred with other hominin species like Neanderthals and Denisovans.

The authors of a recent study have retraced the likely dispersal paths used by Neanderthals as they migrated out of Europe in an effort to solve the enigma, and they have identified Persia as a potential meeting point between these three related species, reported IFL Science.

Researchers use computer modeling to determine

Stone tools used by Neanderthals typically belong to one of the two technical cultures known as Micoquian or Mousterian. The geographical distance between these lithic traditions raises the possibility that Neanderthals divided into groups and moved eastward via various routes.

The researchers used computer modeling to determine the two most plausible dispersal pathways taken by Neanderthals as they traveled from Europe to Asia based on the distribution of Mousterian and Micoquian archaeological sites as well as information on topography and temperature.

One of these routes would have required our prehistoric ancestors to go across Siberia, where the harsh climate would have made survival challenging. The other, though, traveled via the warm and inviting Southern Caspian Corridor (SSC).

“Based on the reconstruction of annual precipitation and annual temperature during 57,000-71,000 years ago, we suggest that this area… could serve as a refugium for Neanderthals, as it was for other species,” said researchers.

“The location of SCC between Caucasus and Central Asia, gives rise to the hypothesis of SCC as one of the hot spots for tracking hominin admixture and introgression, as it was the case for some faunal species,” they added.

The authors of the study note that while ancient climate data may suggest that different species may have coexisted in northern Iran, this notion cannot be proven until real hominin remains are found there. Stone tools and other cultural items are the sole indications of past human habitation of the SCC that we now have.

The research was first published in the journal PLOS ONE on February 23.

Study abstract:

The study of the cultural materials associated with the Neanderthal physical remains from the sites in the Caucasus, Central Asia and Siberian Altai and adjacent areas documents two distinct techno-complexes of Micoquian and Mousterian. These findings potentially outline two dispersal routes for the Neanderthals out of Europe. Using data on topography and Palaeoclimate, we generated computer-based least-cost-path modelling for the Neanderthal dispersal routes from Caucasus towards the east. In this regard, two dispersal routes have been identified: A northern route from Greater Caucasus associated with Micoquian techno-complex towards Siberian Altai and a southern route from Lesser Caucasus associated with Mousterian towards Siberian Altai via the Southern Caspian Corridor. Based on archaeological, bio- and physio-geographical data, our model hypothesises that during climatic deterioration phases (e.g. MIS 4) the connection between Greater and Lesser Caucasus was limited. This issue perhaps resulted in the separate development and spread of two cultural groups of Micoquian and Mousterian with an input from two different population sources of Neanderthal influxes: eastern and southern Europe refugia for these two northern and southern dispersal routes respectively. Of these two, we focus on the southern dispersal route, for it comprises a ‘rapid dispersal route’ towards east. The significant location of the Southern Caspian corridor between high mountains of Alborz and the Caspian Sea, provided a special biogeographical zone and a refugium. This exceptional physio-geographic condition brings forward the Southern Caspian corridor as a potential place of admixture of different hominin species including Neanderthals and homo sapiens.