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Two-Million-Year-Old Teeth Tell Us Something About Ancient Africa’s Climate

Findings from the anthropologists at the University of Toronto shows that southern Africa’s environment 2 million years ago was much wetter – unlike any modern African environment.

The research was conducted in Wonderwerk Cave, a massive excavation site in the Kurmann Hills of the northern Cape Province of South Africa.

The team consists of postdoctoral fellow in the Department of Anthropology at U of T, Michaela Ecker, who is also the lead author of the paper Nature Ecology and Evolution. Director of U of T’s Archeology Center, Michael Chazan, recreated the interior of southern Africa’s environmental climate change over the course of 2 million years.

Using carbon and oxygen isotope analysis on prehistoric, herbivorous teeth from the cave allowed Ecker and her team to evaluate the type of environment the animal was living in. They did this by reconstructing the vegetation from the animal’s teeth.

“Understanding the environment humans evolved in is key to improving our knowledge of our species and its development,” Ecker says, “Our work at Wonderwerk Cave demonstrates how humankind existed in multiple environmental contexts in the past- contexts which are substantially different from the environments today.”

Ecker is referring to the scientific hypothesis that human adaptation evolves in response to environmental instability. Natural selection is not about “survival of the fittest” but who’s most capable of adapting to change.

For example, paleoanthropologists (scientists who study human evolution) strongly believe in the savanna hypothesis. This hypothesis states that upright walking is associated with the spread of grasslands.

Ancient hominins lived in diverse habitats. Modern day people evolved to live in diverse habitats in order to match our earth’s expansive geology.

A 3.18 million-year-old skeleton known as Lucy (Australopithecus) was discovered in Ethiopia in 1974. Her skeleton has a human-like hip and knee joints, long flexible arms, longer fingers than humans and flexible feet. She has a mixture of ape and human features and is believed to be one of our human ancestors.

We know that she is a direct ancestor to modern day people because Lucy walked upright, which is a striking human trait.

In referring to how climate change affects human evolution and adaptation, she said:

“The influence of climatic and environmental change on human evolution is largely understood from East African research. Our research constructed the first extensive paleoenvironmental sequence for the interior of southern Africa using a combination of methods for environmental reconstruction at Wonderwerk Cave.”

East African research shows that there has been an increase in aridity and spread of grasslands that contributes to human development. However, there was a time when the African savanna was much wetter. Humans were once living in environments that were not open, arid grasslands.  

Based on research from South African archaeologist Peter Beaumont, Chazan was able to discover early evidence of fire created by human ancestors and cave-dwelling humans. There is also evidence that humans occupied caves for at least 2 million years.

Africa’s climate changing from wet to dry might have been a driving influence for mass migration out of southern Africa some 60,000 years ago. Early humans fled to places like Eurasia and the Middle East.

“There’s always been a question about whether climate change had any influence on when our species left Africa,” said Jessica Tierney, UA associate professor of geosciences. “Our data suggest that when most of our species left Africa, it was dry and not wet in northeast Africa.”

The University of Toronto’s findings is another piece of information that brings us closer to fully understanding why we, modern humans, are the way that we are; it gives us a better idea of our anatomy’s and world’s future.

You can find Ecker’s team’s full research here.

 

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