Genetic diseases and genetically mixed populations can help researchers understand human diversity and human origins according to a Penn State physical anthropologist.
"We wanted to get to a strategy to predict what a face will look like," said Mark D. Shriver, associate professor of biological anthropology. "We want to understand the path of evolution that leads to that part of the selection process."
To pinpoint genes that influence the shape of the human face and head, Shriver began with an online database of genes linked to disease -- Online Mendelian Inheritance of Man. If the symptoms of the disease involved the face or skull the gene implicated in the disease became a candidate for those facial traits.
This approach works because although Shriver looked at genes implicated in disease, those same genes in a healthy person may also influence the same physical trait -- length, width, shape, size -- but within the range normal for healthy individuals. Facial traits vary among humans, but do tend to group by population. For example, in general, West Africans have wider faces than Europeans and Europeans have longer faces than West Africans.
"There is a strong relationship between genetic ancestry and facial traits," said Shriver. "Using individuals of combined ancestry, European and African, we can see how the target genes alter facial traits," he told attendees at the 2009 Annual Meeting of the American Association for the Advancement of Science.
The researchers looked at a combined sample of African Americans with West African and European ancestry whose genetic makeup was known through DNA testing. To make it simpler, anyone with Native American ancestry was eliminated so that only two genetic pools were represented -- West African and European. The researchers reported on a sample of 254 individuals using three-dimensional imaging and measured the distances between specific portions of the face. Each individual had provided a
|Contact: A'ndrea Elyse Messer|