Three things that we’ve heard before ad nauseam – climate change, human migration, and Africa being the cradle of modern humans. Combining all of them together is a fascinating new study which shows that prehistoric climate change repeatedly affected and caused pockets of human migration into the Arabian Peninsula over the last 400,000 years.
Exploring the Depth of the Study
The research has been carried out by the Max Plank Institute for the Science of Human History in conjunction with the Heritage Commission of the Saudi Ministry of Culture and an international consortium of scientists. The subsequent findings have been published in an open access form in the journal Nature.
The rich prehistory of the largest country in the Saudi peninsula , Saudi Arabia, and the peninsula in general, has not been explored enough. Human history has been particularly neglected in this area, which has had scientific inquiry focused on the coastal and woodland margins and neglecting the vast, mostly desert interior, reports the Max Plank Institute .
This is also because of the paucity of both biological and environmental records from this vast, arid area: “limiting regional-scale insights into changes in hominin demography and behaviour”, they write in the study. To add to this, southwest Asian palaeontological, palaeoenvironmental and archaeological records are severely fragmented.
This has “limited our ability to overcome problematic generalizations regarding the palaeoanthropological record of Southwest Asia and address key questions about the extent to which hominin occupations of the region were continuous, the role of hominin dispersals into and within the region, and how these dispersals and interactions between hominin populations related to changes in biogeography, environment and ecology”, says the study. So what has the fledgling research into the Saudi interior discovered?
A 400,000 year ‘handaxe’ stone tool from Khall Amayshan 4. (Ian Cartwright, Palaeodeserts Project ).
Dr Huw Groucutt, lead author of the study and head of the ‘Extreme Events’ Max Planck Society Research Group in Jena, Germany, based at the Max Planck Institute for Chemical Ecology, describes it as “a breakthrough in Arabian archaeology”, referring in particular to the oldest dated evidence for humans in Arabia from 400,000 years ago – Pleistocene hominins . Remains of stone tools and fossilized animal bones were found in several layers of dried-up lakes in the Nafud Desert , in northwest Saudi.
The Green Windows and the Arabian Wetlands
Extensive research of archaeological and palaeontological records point to drastic cultural and biological shifts, which includes alternating occupations by Homo sapiens and Neanderthals. The current archaeological digs have revealed at least 5 hominin expansions into the peninsula starting at approximately 400,000 years right up until 55,000 years ago, each coinciding with brief ‘green windows’ of reduced aridity and distinct form of material culture.
Archaeological sites were dated using a process called luminescence dating “which records the length of time since tiny grains of sediment were last exposed to sunlight”. This showed the researchers that breaking the arid spell were short bursts of intense rainfall that led to the formation of thousands of lakes, ponds, oases, wetland and rivers, that criss-crossed across the predominantly sandy Arabian Peninsula. Over these were formed migratory routes for both human beings and animals, like the hippo. The Nefud region, for example, was a lush grassland for temporary periods of time, whereas today being one of the least habitable places on earth.
Project leader Prof. Michael Petraglia, from the Max Planck Institute for the Science of Human History says, “It’s remarkable; every time it was wet, people were there. This work puts Arabia on the global map for human prehistory.”
A storm arrives during archaeological excavation of the remains of ancient lake in northern Saudi Arabia, where ancient humans lived alongside animals such as hippos. (Klint Janulis, Palaeodeserts Project )
The Acheulean Culture: From Palaeolithic to Present Day
The primary site explored was called Khal Amishan, where artifacts have been found dating back to 400,000 years ago. They’ve been found on the outskirts of Tabuk and are the oldest archaeological remains on record in the Arabian Peninsula. There is evidence of waves of migration occurring at 300,000 years, 200,000 years and 100,000 years ago, along with the most recent one at 55,000 years ago. The ancient lakes at Khal Amishan, and the Jubbah Oasis (a little further east) have allowed layers of sediment to form over these years, coinciding with rainy periods in the history of the region.
The site of Khall Amayshan 4 in northern Saudi Arabia, where evidence of repeated visits by early humans over the last 400,000 years was found, associated with the remains of ancient lakes. (Michael Petraglia, Palaeodeserts Project )
What particularly astonished scientists was the linear growth in the development of stone crafts, particularly Acheulean stone crafts dating back to 200,000 years . Each phase of human occupation is characterised by a different kind of material culture, documenting the transition from the Lower Palaeolithic Acheulean ‘hand axe’ culture to different kinds of stone flake-based Middle Palaeolithic technologies.
This clearly points to human migration from different areas and zones, that brought distinctive cultural differences and diversity with them. There is evidence of clashes of cultures too, suggesting that Arabia was a kind of a potpourri and interface zone for hominins from different places in Africa and Eurasia, making it a melting pot of sorts. Even animal fossils show a similar geographical diversity!
Dr. Grocutt sums it up very beautifully and succinctly by saying, “Arabia has long been seen as an empty place throughout the past. Our work shows that we still know so little about human evolution in vast areas of the world and highlights the fact that many surprises are still out there.”
Indeed, this study has opened up vast possibilities that fill up the bits in the hominin jigsaw puzzle, that has barely been explored to its full potential.
Top image: The Jubbah Oasis in northern Saudi Arabia, where humans were repeatedly present during periods of increased rainfall over hundreds of thousands of years. Source: Ceri Shipton, Palaeodeserts Project / Nature
By Sahir Pandey