Drilling for clues to our ancestors' extinction

2013-11-09T00:00:00Z Drilling for clues to our ancestors' extinctionBy Drew Mccullough Arizona Daily Star Arizona Daily Star
November 09, 2013 12:00 am  • 

A UA professor recently began a lakebed drilling project in the African Rift Valley to determine what role climate change may have played in the evolution of humans and, maybe, how it will affect us in the future.

Andy Cohen, the principal investigator of the Hominin Sites and Paleolakes Drilling Project and a UA professor of geosciences, began drilling with his team last summer in Kenya at a site in the Tugen Hills.

The team of more than 50 scientists from nine countries has received multiple grants to fund the project, including a recent $4.78 million grant from the National Science Foundation.

The team is targeting core samples of lakebed deposits that show certain time intervals, Cohen said. Three of the team’s five drilling sites are in areas that have existing Hominin records, he said.

Hominins are the group of animals that includes humans and our near relatives. All but humans are extinct, Cohen said.

For the first drilling site, the team targeted samples that date back 2.5 million to 3.5 million years, which is a “very interesting time in that particular area,” he said.

“We have the earliest (evolutionary) evidence of our own relative, genus Homo,” he said. “People want to understand if there’s a climate angle to that (evolutionary) process.”

The team has also collected samples at a site in West Turkana, Kenya, that date back 1.5 million to 2 million years.

For that site, the team is working to “tie the climate records into some of the evolution of one particular species of our own genus — Homo erectus,” Cohen said. There’s also a major change in stone tools and in the types of antelopes and other mammals in that area, which people believe may be tied to climate change, he said.

“So (we’re) trying to understand the context of those events,” he said.

The team has three more sites scheduled for drilling, beginning later this year. The sites will be at Chew Bahir Lake and the Northern Awash River Valley in Ethiopia, and Lake Magadi in Kenya.

Once the team has collected its samples from the drilling sites, scientists will begin to analyze the samples.

Their ultimate goal is to understand the connection between human evolution and climate change, Cohen said. The team will conduct computer simulations to show how human populations would respond to changes in landscape or climate conditions, he said.

“This gives us insight about how our near relatives have coped with (these changes), and in some cases gone extinct in the past,” he said.

Cohen has enlisted the help of anthropologists such as Andrew Hill, a professor of anthropology at Yale, to analyze the samples.

Hill, who is one of the co-principal investigators for the Tugen Hills site, said the analysis of the samples “will contribute to knowledge of climate in the recent past of 3.5 millions years.

“Normally, people assume that evolution takes place because of changes in climate and temperature,” Hill said. This project “opens up different ways to think about different theories.”

The results from the samples could also be used as a learning tool for society, Cohen said.

“All those other species from the past are gone for some reason or another,” Cohen said. “Not to say that all those are a consequence of climatic changes, but we certainly want to understand what they are because we’re facing significant climate change right now at a very threatening rate.

“From trying to understand the relationship between human evolutionary changes and climate changes, we can understand the pace at which these things occur and also how fast they might occur in the future,” he said.

The team is also working to determine what kinds of implications these changes might have for humans today. “These species are related to us, so let’s learn from them,” Cohen said.

Cohen and his team have also partnered with the Earth Images Foundation, a nonprofit company that films earth-sciences documentaries. The company is filming a 3-D documentary about the project and plans to show it at science museums including the Smithsonian National Museum of Natural History in Washington, D.C.

Copyright 2014 Arizona Daily Star. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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