Past climates and environments experienced by the Saharo-Arabian desert belt are of prime importance for palaeoclimatic and palaeoanthropological research. On orbital timescales transformations of the desert into a grassland landscape in response to higher precipitation provided “windows of opportunity” for hominin dispersal from Africa into Eurasia. On long timescales, palaeoenvironmental reconstructions for the region are predominantly derived from marine sediments and available terrestrial records from the Arabian Peninsula are limited to 450 ka before present (BP). Here, we present a new stalagmite-based palaeoclimate record from Mukalla Cave in Yemen which extends back to ∼1.1 million years BP or Marine Isotope Stage (MIS) 31, as determined by Uranium-lead dating. Stalagmite Y99 grew only during peak interglacial periods and warm substages back to ∼1.1 Ma. Stalagmite calcite oxygen isotope (δ18O) values show that every past interglacial humid period was wetter than the Holocene, a period in which large lakes formed in the now arid areas of southern Arabia. Carbon isotope (δ13C) values indicate habitable grassland environments developed during these pluvial periods. A total of 21 pluvial periods with precipitation of more than 300 mm yr−1 occurred since ∼1.1 Ma and thus numerous opportunities for hominin dispersals occurred throughout the Pleistocene. New determinations of hydrogen (δDFI) and oxygen (δ18OFI) isotopes in stalagmite fluid inclusion water demonstrates that enhanced precipitation in Southern Arabia was brought by the African and Indian Summer Monsoons. When combined with sub-annual calcite analysis of δ18O and δ13C, these data reveal a distinct wet (summer) and dry (winter) seasonality.
Bibliographical noteFunding Information:
This work was supported by the AHRC South, West and Wales Doctoral Training Partnership (Grant AH/L503939/1) the Swiss National Science Foundation (Grant PP002-110554/1 to DF and Grant CRSI22-132646/1 to DF and ML), U.S. National Science Foundation (Grant 1702816 to RLE and HC) and the National Natural Science Foundation of China (Grant NSFC 41888101 ). DF acknowledges support from NERC Isotope Geosciences Facilities Steering Committee (Grant IP-1376-051 ). We would like to thank the editor and three anonymous reviewers for their constructive comments and suggestions.
- Human dispersal
- Middle east
- Uranium-series dating