Extreme climate changes in prehistory may have driven early humans to technical and social innovations. This is the conclusion of a study that examined climate change in Africa. The global spread of Homo sapiens could also be related to this.
Phases of sometimes dramatic climate fluctuations in East Africa could have had a decisive influence on the development of modern humans. This is the conclusion of a study by an international research team that was published in the journal “Nature Geoscience”. The determined climate data come from lake sediments in southern Ethiopia. According to the authors, the extreme climate changes that can be seen in it went hand in hand with technological development spurts from early humans.
The study identifies three key phases. The first, from about 620,000 to 275,000 years ago, featured a period of prolonged and relatively stable wet conditions. However, this was interrupted by a series of short, abrupt and extreme drought episodes. The habitats of the hominids of that time were split up as a result, the population dynamics shifted and some local groups may even have become extinct, the researchers suspect. Small, isolated populations have had to adapt to dramatically changed environments, which may have led to the divergence of our modern human ancestors.
Between 275,000 and 60,000 years ago, this was followed by a phase of considerable climate fluctuations, which repeatedly led to changes in the habitats in this area. During this phase, populations gradually transitioned from Acheulean technology – oval stone hand axes used by ancestors such as Homo erectus – to more advanced technologies. Homo sapiens also evolved in East Africa during this crucial phase, the study says. Technical and social innovations have made modern humans “enormously adaptable to the repeatedly changed living space,” said lead author Verena Förster from the University of Cologne, according to a statement.
According to the researchers, the most extreme climate fluctuations, including the driest phase on record, occurred in the third phase from around 60,000 to 10,000 years ago. This phase may have accelerated the continuous cultural change of the population. The research team theorizes that wet periods opened up favorable migration routes out of Africa, which may have enabled the global spread of Homo sapiens.
The new findings were made possible by an international deep drilling project in the Chew Bahir Basin in southern Ethiopia. Researchers from the universities of Cologne, Potsdam, Aberystwyth and Addis Ababa were involved – in total there were more than 22 researchers from 19 institutions in six countries. Scientists from the fields of archaeology, evolutionary biology and evolutionary anthropology identified phases of climate stress and phases with more favorable conditions in the sediment cores. The sediments studied are from the immediate vicinity of a region of important paleoanthropological and archaeological sites.
The research is part of the Hominin Sites and Paleolakes Drilling Project (HSPDP), which investigates and assesses the impact of different timescales and magnitudes of climate change on early human living conditions. “Given the current threats posed by climate change and the overexploitation of natural resources for human living space, it is more important than ever to understand the relationship between climate and human development,” says lead author Förster.
(This article was first published on Tuesday, September 27, 2022.)
