Around 1.1 million years ago, a substantial cooling of the climate in southern Europe led to the extinction of early human populations on the continent, according to a recent study led by researchers from UCL. The findings, published in the journal Science, reveal the existence of previously unknown extreme glacial conditions during that period, driving the climate to levels unsuitable for archaic humans and ultimately causing their disappearance from the continent.
The study challenges the prevailing notion of continuous early human occupation in Europe, suggesting a significant disruption due to the extreme glacial cooling event. Previously, the common belief was that early humans arrived in Europe around 1.4 million years ago and managed to survive through various climate changes, adapting to harsher conditions over time.
The research, conducted by scientists from UCL, the University of Cambridge, and CSIC Barcelona, involved analyzing the chemical composition of marine microorganisms and examining pollen content in a deep-sea sediment core off the coast of Portugal. These analyses unveiled abrupt climate shifts, resulting in a dramatic glacial cooling period. Ocean surface temperatures near Lisbon dropped below 6°C, leading to the expansion of semi-deserts on adjacent land areas.
Lead author Dr. Vasiliki Margari (UCL Geography) explained that the cooling event at 1.1 million years ago was on par with some of the most severe episodes of recent ice ages, indicating a significant climatic challenge for early humans.
Professor Axel Timmermann and his team from the IBS Center for Climate Physics at Pusan National University conducted climate simulations to recreate the extreme conditions during that period. Combining the simulation outcomes with fossil and archaeological evidence from southwest Eurasia, the team developed a human habitat model. This model gauged the suitability of the environment for early human habitation and indicated that the Mediterranean region became too hostile for archaic humans around 1.1 million years ago.
Consequently, paleoclimate data and the human habitat model results jointly suggest that regions such as Iberia and southern Europe experienced a population decline during the Early Pleistocene. The absence of stone tools and human remains over the next 200,000 years further suggests a prolonged gap in European occupation.
Professor Chris Stringer from the Natural History Museum in London posited that more resilient humans who had developed evolutionary or behavioural changes that allowed them to endure the increasingly severe glacial conditions might have recolonized Europe around 900,000 years ago.