An interdisciplinary study in southern Ethiopia has permitted the decoding of eastern Africa's climatic heartbeat and demonstrated how crucial stages of climate change affected human development, dispersion, and creativity.
Key stages in human evolution correspond to climatic fluctuations in eastern Africa
An examination of environmental proxies from a lake sediment record indicated three different stages of climatic variability in eastern Africa over the last 620,000 years, coinciding with variations in human development and migration, as per ScienceDaily.
The project investigated the most recent chapter in human development by employing scientific deep drilling to examine lacustrine strata near paleo-anthropological important sites in eastern Africa.
Dr. Verena Foerster of the University of Cologne's Institute of Geography Education headed the study team of more than 22 academics from 19 institutions in six nations.
Nature Geoscience has published the paper "Pleistocene climatic variability in eastern Africa altered hominid development."
Despite more than a half-century of hominin fossil finds in eastern Africa, the regional environmental backdrop of modern humans and their predecessors' development and migration remains unknown.
There are no continuous high-resolution paleo-environmental data for the African continent, particularly for the Pleistocene (or Ice Age) period between 2,580,000 and 11,700 years ago.
Two continuous 280-meter sediment cores were collected from the Chew Bahir Basin in southern Ethiopia, where early humans lived and flourished during the Pleistocene epoch.
Chew Bahir is located in a deep tectonic basement near the Turkana region and the Omo-Kibish, both of which are important paleo-anthropological and archaeological sites.
The cores provided the most complete record for such a long period ever retrieved in the area, illustrating how varied climates affected the biological and cultural transformations of the region's inhabitants.
An interdisciplinary team of geoscientists, sedimentologists, micro-paleontologists, geologists, geographers, geochemists, archaeologists, chronologists, and climate modelers worked together to recover the two continuous sediment cores, from which proxies (such as microfossils or elemental variations) were used to glean data to reconstruct the region's climate history.
Archaeologists, evolutionary biologists, and evolutionary anthropologists then identified periods of climatic duress as well as more favorable conditions and interpreted how these elements influenced human biological and cultural evolution as well as dispersal.
The scientists discovered that multiple anatomically distinct hominin groups inhabited the area from roughly 620,000 to 275,000 years ago during a period of long-lasting and reasonably constant humid weather.
Several briefs, sudden, and intense dry pulses, however, disrupted this lengthy, largely steady, and moist epoch.
This most likely resulted in habitat fragmentation, population dynamics alterations, and perhaps extinctions of local populations.
As a result, small, reproductively, and culturally isolated populations were forced to adapt to dramatically altered local environments, most likely stimulating the emergence of numerous geographically and anatomically distinct hominin groups and the separation of our modern human ancestors from archaic groups.
From around 275,000 to 60,000 years ago, substantial temperature swings resulted in routinely altered ecosystems in the region, resulting in environmental transitions from lush vegetation with deep freshwater lakes to very dry landscapes with huge lakes reduced to little salty puddles.
During this period, population groups steadily progressed from Acheulean technologies (oval stone hand axes linked with Homo ergaster/erectus) to more advanced Middle Stone Age technologies.
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East Africa's contribution to the evolution of a human variety
This critical period also included the appearance of Homo sapiens in eastern Africa, as well as key human social, technological, and cultural innovations that may have protected early Homo sapiens from the effects of severe environmental changes.
The period from around 60,000 to 10,000 years ago had the most dramatic climatic swings, but also the driest period in the whole record, which might have worked as a driving force for continual indigenous cultural transformation.
The scientists believed that the brief alignment of humid pulses in eastern Africa with wet phases in north-eastern Africa and the Mediterranean was critical in opening favorable migration routes out of Africa on a roughly north-south axis along the East African Rift System (EARS) and into the Levant, allowing Homo sapiens to spread globally.
Since the discovery of the first hominid fossils, East Africa has been the focus of palaeo-anthropological research due to its putative significance as a cradle of mankind and a route out of Africa.
With the advent of the genomic age, an increasing quantity of data has begun to supplement this idea and position the region within a larger, Pan-African context, as per ScienceDirect.
Researchers looked at the most recent genetic and fossil data that recapitulate the previous hundreds of thousands of years of human history in the area, and pointed to a number of unexplored routes that may supplement the developing picture in the next years.
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