Genetic Mugshot: How Scientists Used DNA To Draw 3-D Faces
DNA can predict the color of eyes or the pigment of skin, but until now, it had never predicted the shape of a face.
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On Thursday, a team of scientists unveiled a cascade of 3-D mugshots, the features of which they've painstakingly paired with genetic data. By narrowing down the DNA strands that help determine the shape of a face, the researchers say they have laid the foundation for revolutionary new technologies. "DNA left at crime scenes could be tested and faces predicted in order to help to narrow the pool of potential suspects," the authors write. "Our methods could be used to predict the facial features of descendants, deceased ancestors, and even extinct human species."
For the study, led by Mark Shriver of Penn State University, the team selected 592 people of West African and European descent living in the United States, Brazil, and Cape Verde. Then they made a digital cast of all of their faces. From these images, they created an "average face" — average-sized nose, lips, brow ridges, forehead — from which they could measure variables.
As Shriver and his colleagues explained in their paper, published in the journal PLOS Genetics, eye color and skin pigmentation are fairly simple to predict with genes. But "features such as the strength of the brow ridge, the spacing between the eyes, the width of the nose, and the shape of the philtrum are largely scientifically unexplained." The exact genes that control these subtle shapes are elusive and numerous. Humans have about 24,000 genes, but they all work together to give us our characteristics.
In this experiment, they chose three categories of predictive genes. The first two were sex (whether you look like a man or a woman) and ancestry (whether you look Italian or Ghanaian). They report that differences between European ancestry and African can be found in the lips and nose; differences between the sexes can be found around the eyes, cheeks, and bridge of the nose.
They chose the third category of genes mostly from a pool of diseases known to cause changes in facial features, including Jackson-Weiss syndrome and osteoglophonic dysplasia. From this pool, they came up with 24 difference places in the genome to look for patterns. Using these three kinds of markers, they could accurately map a very rough sketch of what a person might look like.
But don't expect perfect computer-generated portraiture just yet. For one, genes can't predict everything. Previous research has suggested that environmental factors, like climate, can affect, say, the length of a nose. Shriver is the first to admit these are only the first steps for future research, testing even more genes. He writes that they've proven the effectiveness of their method: "We show that facial variation with regard to sex, ancestry, and genes can be systematically studied with our methods, allowing us to lay the foundation for predictive modeling of faces."
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