24 March 2014
ByAppeared in BioNews 747
The researchers say it may one day be possible for the procedure to be applied to DNA left at crime scenes: faces could be modelled to help police to narrow the pool of potential suspects.
The researchers placed a grid on 3D models of subjects' faces and measured the spatial coordinates of the grid points. Using statistical methods, they were then able to examine the relationship between variation in the faces, and the differing effects of sex, genomic ancestry and genes that affect the shape of the head and face.
To identify genes in that category, the scientists looked at genes that had previously been found to cause facial deformations when mutated. The thinking was that even when not mutated, normal variation within these genes might affect the appearance of the face and the head.
Facial characteristics are likely to be influenced by selection: environmental factors such as rainfall and local temperatures could influence certain physical features. Similarly, sexual selection may play a role in the development of facial features; fostering a preference for a certain look. Both forms of selection result in the concentration of certain variations in geological areas over time.
For this study, the subjects were of mixed West African and European ancestry, allowing them to understand more about the different contributions made by each gene.
'Probably only five percent of genes show a difference between populations', explained Professor Mark Shriver of Penn State University, USA, who was involved in the research. 'We are using different populations because they have had different environments and different social environments'.
The procedure requires much refinement before it can be used in a forensic setting. A major challenge for the future is working out how just many genes are involved in face shape.
'We use DNA to match an individual or identify an individual, but you can get so much more from DNA', said Professor Shriver. 'Currently we can't go from DNA to a face or from a face to DNA, but it should be possible'.
The technique could also have applications outside forensic science. For example, it could be used to predict the facial features of descendants, deceased ancestors, and even extinct human species.
The study was published in PLOS Genetics.