On Feb. 13, the College hosted Dr. Christopher Scholz of Syracuse University as he discussed Climate Change and Human Origins: New discoveries through drilling in East Africa. The lecture took place from 4 to 5 p.m. in the New Science Building and was based on his research and that of his colleagues.
According to Scholz, human origins can be traced back to a region of Africa that doubles as home to the most active rift system on the continent. The area’s climate and plate tectonics sculpted the landscape, facilitating the fragmentary beginnings of the human race. Scholz and his team conducted research through drilling in Lake Malawi.
Lake Malawi, the southernmost lake in the East African Rift System, is nestled between Malawi, Mozambique and Tanzania. At 700 m deep and 550 km long, it is the second deepest and third largest lake in Africa. It is also the presumed home to more species of fish than any other body of freshwater.
Scholz and his team sampled lake sediments, extending over 15,000 feet below the lake’s bottom, and graphed their observations.
“What we are trying to do are to sample lake sediments to understand things like wind and pressure,” Scholz explained, “We are trying to understand climate change in the tropics.”
The team drilled from a boat they built on site; there were no connecting rivers from which they could import an existing boat. They drilled to a depth containing sediments dating back 1.2 million years ago, noting, “Layers of organic sediment grow more frequent as we go deeper into the earth.” These layers provided evidence for cyclic sedimentation due to climate change.
Scholz states that according to geneticists, “Our ancestors are thought to have originated around 150,000 years ago, based upon not only fossil evidence, but also DNA evidence.” Scholz’s data supports this theory, explaining that our ancestors’ initial exodus occurred about 150,000 years ago, with a final exodus taking place a mere 50,000 years ago. This final exodus indicates a population bottleneck in which tropical climate variability stabilizes.
Scholz said, “We think that perhaps this change in the variability may not quite be a coincidence,” but instead suggests that the climate chance coincides with the final African exodus.