Archaeology: Early human migrations into Arabia associated with hydro-climatic variability

Early humans ventured into Arabia as part of at least five migratory phases over the past 400,000 years according to a study published in Nature. A collection of stone tools and animal fossils discovered in the Arabian desert has provided evidence for these movements, each of which was associated with a brief interval of reduced aridity.

As the only land bridge connecting Africa and Eurasia, the vast arid zone of the Arabian Peninsula has been a focus for research into the evolution of hominins — Homo sapiens and our extinct relatives — as they migrated out of, and back into, Africa. Despite this significance, cultural, biological and environmental records from this region are limited, which restricts our understanding of hominin demography and behaviour.

The discovery of a collection of stone tools and animal fossils associated with the deposits of what were once ancient lakes located in the Nefud Desert in northern Saudi Arabia are reported by Huw Groucutt, Michael Petraglia and colleagues, working in a collaboration with the Heritage Commission of the Saudi Ministry of Culture. These discoveries — which included artefacts associated with the oldest known dated hominin occupation in Arabia — reveal that there were at least five phases of early hominin dispersal into Arabia during the Pleistocene epoch (spanning from around 2.6 million to 11,700 years ago). Each of these migrations coincided with more favourable environmental conditions, namely brief intervals of reduced aridity at approximately 400,000, 300,000, 200,000, 130,000–75,000 and 55,000 years ago. These migratory phases could also be categorized according to differences in material culture, with two phases containing Acheulean technology — generally associated with earlier hominin species such as Homo erectus — and three with distinct forms of Middle Palaeolithic technology, including hand-axes and cleavers. These findings suggest colonization of Arabia by diverse hominin populations, potentially even composed of different species.

The authors conclude that these discoveries not only corroborate the importance of this region for enhancing our understanding of hominin migrations at the nexus of Africa and Eurasia, but also, more specifically, reveal how interactions between early human populations can be linked to periods of extensive environmental and ecological change.