Sharp leaps in the development of human ancestors followed global climate changes, as evidenced by the climatic "chronicles" imprinted in the deposits of dust and sand in marine sedimentary rocks on the coast of Africa, German and British paleoclimatologists write in an article published in the journal Proceedings of the National Academy of Sciences
“We have always believed that climate has made a significant contribution to the history of human development, but so far this has not been proven statistically. For the first time, we were able to prove that the coincidences between abrupt changes in climate and leaps in human evolution were not at all accidental,”explained the head of the research group Jonathan Donges of the Potsdam Institute for Climate Impact Studies (Germany).
Doungs and his colleagues tried to neutralize the most important flaw in all paleontological and paleoclimatic research - the fragmentary and non-linear evidence of the evolution of the animal world and the planet's climate - using a recurrent statistical network. The essence of this method is to search for repeating patterns in periodic climatic variations and their changes on a long-term scale using complex computational algorithms.
The authors of the article used this algorithm to analyze samples from compressed grains of sand and dust, extracted by other teams of scientists from the bottom of the Mediterranean Sea, Atlantic and Indian oceans off the northern and eastern coasts of Africa.
The wind constantly carries dust and other small particles of matter from the mainland to the coastal regions of the ocean, where they settle and accumulate on the bottom in the form of marine sedimentary rocks. Analysis of the mineral and chemical composition of these deposits and the study of organic particles that accidentally got into these rocks helps scientists understand what climate prevailed in Africa in past eras.
Researchers have compared the periodic climate variations in eastern and northern Africa over the past 5 million years.
Scientists have identified three eras in this segment, which they associate with global or major regional climate changes.
Thus, the latest epoch of climatic changes - from 1.1 to 0.7 million years ago - is associated with the transition from 40 thousand-year fluctuations in the retreat and advance of glaciers to longer 100 thousand-year intervals between the peaks of glaciation.
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The second - from 2.25 to 1.6 million years ago - is associated with changes in the global atmospheric circulation system - a spatial shift and acceleration of air circulation cycles over the equatorial waters of the Pacific Ocean.
Scientists consider the last period as an echo of the cooling period, which "wedged in" in the era of the mild climate of the Middle Pleistocene.
According to paleoclimatologists, two events could have caused this. The first reason could be the separation of New Guinea from Australia and a decrease in the intensity of the equatorial water circulation. The second hypothesis includes periodic openings and closings of the Panama Passage with similar climate implications.
Scientists have noticed that the periods of climate change surprisingly coincide with the emergence of new species of ancient people. They believe that these coincidences are difficult to consider as an accident, since they go beyond statistical errors. For example, paleoclimatologists associate the cooling in the Middle Pliocene with the appearance of the first Australopithecus and the development of bipedal locomotion by their descendants.
“As a highly gifted animal, humans were more likely to survive and thrive during climate fluctuations than other, more specialized creatures,” concludes Doungs.