Christopher Scholz, associate professor of earth sciences at Syracuse University, was the lead investigator on the Lake Malawi Drilling Project, which recently discovered that major African climate changes may have significantly affected human evolution.
The paper, published online last week in the journal Proceedings of the National Academy of Sciences, found that amid severe droughts, a rainy period 70,000 years ago may have allowed for the "Out of Africa" movement.
Lake Malawi and Lake Tanganyika diagrams cover the walls of Scholz's office. His curiosity about going to the source of evolution, where the continents broke apart and where ocean basins formed, led him to eastern Africa as a graduate student 20 years ago.
He has done research in the past on Africa's Lake Victoria and Lake Tanganyika, as well as the world's deepest lake, Lake Baikal, located in Siberia.
What humans know about Earth's history of climate change during tens of thousands of years comes from the study of deep oceans or ice cores from Antarctica and Greenland, Scholz said. These studies have allowed humans to understand a lot, he added, but "people did not live in the deep ocean or ice sheets."
Humans evolved in the interior of Africa, he said.
The Lake Malawi project, funded by The National Science Foundation, was conducted at the southern end of the African rift valley.
More than 70,000 years ago, there were fluctuations in the human population due to changes in climate, according to the study. At one point, there were only 10,000 individuals in existence.
About 70,000 years ago, a wetter climate may have prompted an increase in population and "subsequent spreading of 'Out of Africa' colonizers," Scholz said.
The migration of the human population and climate changes significantly affected evolution, he said.
The sediment and mud samples collected from Lake Malawi, which is 450 miles long and more than 2,300 feet deep, are records of climate changes where human ancestors evolved, according to the study.
"The prevailing theory about evolution, population growth and the migration of early hominids is that they reacted to climate change resulting from the growth and collapse of high latitude ice sheets," Scholz said. "Our research proves that these climate changes were controlled by changes in the earth's orbit around the sun."
The only way to collect samples of the lake core was to begin drilling. And that is exactly what Scholz and his team did.
The crew spent six weeks on a dynamically positioned drilling vessel on the water. Lake Malawi is landlocked so the drilling vessel is constructed on a fuel barge that was already on the lake.
The crew drilled in two different locations, each based on thorough research. Twenty-six individuals were aboard, including eight international science team members, three cooks, drillers, a captain, two mates and an engineer. The crew spent all of the time on the ship and slept in shipping containers.
The drilling vessel was unable to be anchored, which complicated the research further. Large thruster engines were placed on each corner of the ship to hold it in place.
"This drilling was the first of its kind," Scholz said.
The drilling was not the only novel element in this project. It exposed the first long record of climate change anyone has ever recovered from tropical Africa, Scholz said.
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