The interior of Central Asia has been identified as a key route for some of the earliest hominin migrations across Asia in new research co-led by Griffith University.

Professor Michael Petraglia, Director of Griffith’s Australian Research Centre for Human Evolution, is a senior author of the PLOS ONE study, co-led by Dr Emma Finestone from the Cleveland Museum of Natural History and the Max Planck Institute for the Science of Human History.

The team compiled and analysed paleoclimatic and archaeological data from Pleistocene (2.58 million years ago to 11,700 years ago) Central Asia, including examination of a new stalagmite from a cave in Uzbekistan that grew at the end of the Marine Isotope Stage 11 (a warm period between glacials MIS 12 and MIS 10) around 400,000 years ago.

The findings indicated that the steppe, semi-arid, and desert zones of Central Asia may have served as key areas for early hominin dispersals into Eurasia.

“Central Asia is positioned at a crossroads linking several zones important to hominin dispersal during the Middle Pleistocene,” Professor Petraglia said.

“However, the scarcity of stratified and dated archaeological material and paleoclimate records makes it difficult to understand dispersal and occupation dynamics during this time period, especially in arid zones.

“We argue that arid Central Asia would have been intermittently habitable during the Middle Pleistocene when long warm interglacial phases coincided with periods when the Caspian Sea was experiencing consistently high water levels, resulting in greater moisture availability and more temperate conditions in otherwise arid regions.”

During periodic intervals in the Middle Pleistocene, the local environment of arid Central Asia was a favourable habitat for paleolithic hominins and was frequented by Lower Paleolithic (the earliest subdivision of the Paleolithic) toolmakers producing stone tools that have been worked on both sides, known as bifaces.

Dr Farhod Maksudov from the Uzbekistan Academy of the Sciences said relatively little was understood about the region’s earliest toolmakers because the majority of Lower Paleolithic occurrences in Central Asia lacked reliable context for dating and environmental reconstruction.

“Despite the importance of Central Asia to early dispersals, our knowledge of hominin activity in this vast and diverse landscape is disproportionately limited when compared with other regions,” he said.

The interdisciplinary team of scholars from institutions that spanned four continents assembled to address this problem. Their approach combined building a dataset of Paleolithic finds with a new high-resolution climate record from a stalagmite in southern Uzbekistan.

“In this study, we compiled data on Paleolithic findings from across Central Asia, creating a dataset of 132 Paleolithic sites — the largest dataset of its kind,” Professor Petraglia said.

“This allowed us to consider the distribution of these sites in the context of a new high-resolution stalagmite-based multi-proxy record of hydrological changes in southern Uzbekistan from the Middle Pleistocene.”

“Cave deposits are incredible archives of environmental conditions at the time of their growth. Using geochemical data from stalagmites we gain insights into seasonal to millennial-scale changes in moisture availability and the climatic dynamics that governed rain- and snowfall,” said Professor Breitenbach from Northumbria University, who lead the stalagmite-based analysis.

“Our work suggests that the lowland desert region of Central Asia was a favourable habitat for some Paleolithic toolmakers during warmer and wetter intervals and that local and regional conditions did not follow simple long-term trends but were quite variable.”

“Interdisciplinary work that bridges archaeology with paleoclimate models are becoming increasingly necessary for understanding human origins,” Dr Finestone said.

“In the future, the databases generated from this study will continue to allow us to ask questions about the context of hominin dispersals.”

The research ‘Paleolithic occupation of arid Central Asia in the Middle Pleistocene’ has been published in PLOS ONE.