Human evolution: 325,000 year old environmental changes (Introduction)

by David Turell , Wednesday, October 21, 2020, 20:35 (1492 days ago) @ David Turell

New studies in Ethiopia from deep earthen core samples:

https://phys.org/news/2020-10-turbulent-era-human-behavior-years.html

" For hundreds of thousands of years, early humans in the East African Rift Valley could expect certain things of their environment. Freshwater lakes in the region ensured a reliable source of water, and large grazing herbivores roamed the grasslands. Then, around 400,000 years ago, things changed. The environment became less predictable, and human ancestors faced new sources of instability and uncertainty that challenged their previous long-standing way of life.

" The first analysis of a new sedimentary drill core representing 1 million years of environmental history in the East African Rift Valley shows that at the same time early humans were abandoning old tools in favor of more sophisticated technology and broadening their trade networks, their landscape was experiencing frequent fluctuations in vegetation and water supply that made resources less reliably available. The findings suggest that instability in their surrounding climate, land and ecosystem was a key driver in the development of new traits and behaviors underpinning human adaptability.

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"...early humans at Olorgesailie relied on the same tools, stone handaxes, for 700,000 years. Their way of life during this period was remarkably stable, with no major changes in their behaviors and strategies for survival. Then, beginning around 320,000 years ago, people living there entered the Middle Stone Age, crafting smaller, more sophisticated weapons, including projectiles. At the same time, they began to trade resources with distant groups and to use coloring materials, suggesting symbolic communication. All these changes were a significant departure from their previous lifestyle, likely helping early humans cope with their newly variable landscape, Potts said.

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While some scientists have proposed that climate fluctuations alone may have driven humans to evolve this remarkable quality of adaptability, the new study indicates the picture is more complicated than that. Instead, the team's analysis shows that climate variability is but one of several intertwined environmental factors that drove the cultural shift they described in 2018. The new analysis reveals how a changing climate along with new land faults introduced by tectonic activity and ecological disruptions in the vegetation and fauna all came together to drive disruptions that made technological innovation, trading resources and symbolic communication¬—three key factors in adaptability—beneficial for early humans in this region.

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"They found that after a long period of stability, the environment in this part of Africa became more variable around 400,000 years ago, when tectonic activity fragmented the landscape. By integrating information from the drill core with knowledge gleaned from fossils and archeological artifacts, they determined that the entire ecosystem evolved in response.

"The team's analysis suggests that as parts of the grassy plains in the region were fragmented along fault lines due to tectonic activity, small basins formed. These areas were more sensitive to changes in rainfall than the larger lake basins that had been there before. Elevated terrain also allowed water runoff from high ground to contribute to the formation and drying out of lakes. These changes occurred during a period when precipitation had become more variable, leading to frequent and dramatic fluctuations in water supply.

"With the fluctuations, a broader set of ecological changes also took place. The team found that vegetation in the region also changed repeatedly, shifting between grassy plains and wooded areas. Meanwhile, large grazing herbivores, which no longer had large tracts of grass to feed on, began to die out and were replaced by smaller mammals with more diverse diets.

"'There was a massive change in the animal fauna during the time period when we see early human behavior changing," Potts said. "The animals also influenced the landscape through the kinds of plants that they ate. Then with humans in the mix, and some of their innovations like projectile weapons, they also may have affected the fauna. It's a whole ecosystem changing, with humans as part of it.'"

Comment: With big-brained H. sapiens dated at 315,000 years ago in Morocco the ability to adapt had to be improved. Darwinists, like the authors, assume it is all adaptability changes, but the appearance of the big brain was undoubtedly was the main factor in human response and inventiveness.