Anthropology assistant professor uncovers genetic patterns
New questions of human origin could shed light on what makes groups of people more or less prone to certain diseases, an OU researcher has found.
Cecil Lewis, assistant professor of anthropology and director of the OU Molecular Anthropology laboratory, studied genetic diversity among American populations. His research is not only groundbreaking for anthropology but it could also affect future health research.
“I made a number of surprising discoveries, some of which actually applied to the Americas as a whole,” Lewis said.
Lewis’ research, which was recently published in the American Journal of Physical Anthropology, focused on the genetic variations in the Americas. What he found has challenged previous assumptions of the human origins in the country.
The genetic evidence of Lewis’ research in South America suggests the continent was populated first from the east to the west.
Lewis said this goes against the more common idea that North America was populated first in the western coastal regions, with people then migrating to South America and populating the continent from west to east.
“When it comes to genetic data, there is an expectation for what area of the Americas should have the largest genetic diversity,” Lewis said.
This expectation is dependent on what population geneticists call the “founder effect,” he said.
Lewis explained a founder effect occurs when there is a “parent population” that has a lot of genetic diversity. If a small group of the population moves away from the parent population to form a “daughter population” in another area, that population would be expected to only have less genetic diversity present in the parent population.
Lewis’ research about South American genetic diversity challenges those expectations. He said his data shows local populations in the east of the continent, and when pooled together, yield a much greater genetic diversity than in the west.
“Now the real story here is that when we look at the genetic data we have to rethink our original idea for the peopling of South America,” Lewis said. “There’s much more we need to look into before we can make that kind of a strong statement, but it’s certainly true that the genetic data is not fitting the pattern we would expect if the West coast had the initial migration.”
Lewis said the founder effect could be traced back to the theory that humans originated from Southern Africa. He said examination of the genetic diversity of populations in Northern Africa and the Middle East reveal smaller subsets of the genetic diversity found in South Africa. European and Asian populations follow this trend, having subsets of the genetic diversity found in the Middle East. North American populations, in turn, have subsets of diversity found in Asia.
Lewis’ study of founder effects and genetic diversity holds important clues for disease risk and resistance among population groups.
“This history of founder effects helps us determine how well one local population’s genetic risk factors might reflect the risk factors of a larger community,” Lewis said.
He said this research is important because it will help determine whether medical studies should focus on general populations or smaller subsets of the population.
Lewis is currently leading a study to help answer this question. The research involves the study of genes of blacks in Georgia and comparing the results with the same study being done on blacks in Oklahoma.