According to a new study by researchers at Stanford Medicine and KU Leuven, a university in Belgium, the shape of your face and your brain are genetically linked more closely than had been previously thought, according to a news release from Stanford.
Although developmental biologists are used to thinking about the developing face as a receptacle for the embryonic brain – morphing and stretching as the growing brain pushes outward – it turns out that the face is an active participant in biological cross-talk during development that affects the three-dimensional features of both structures.
The reason is that these regions are not the same as those that determine brain structure in ways that affect cognitive function. It’s an important distinction, if only to once again discredit the idea that a person’s intelligence is reflected in their facial features – a belief that’s been used to promote racial and ethnic discrimination.
The study is published in Nature Genetics.
The hills and valleys of the brain’s wrinkled folds help increase the surface area of the cerebral cortex, which is responsible for our cognitive function. Studies of families and twins have shown that brain shape is an inherited trait.
Brain shape can also correlate with neuropsychiatric disorders and cognitive-behavioral traits. Scientists first linked the development of the face and brain in studies of some rare genetic conditions like holoprosencephaly, in which the brain doesn’t divide properly into two hemispheres. Affected people often also have facial malformations that run the gamut from mild to severe. But the true extent of the interaction between face and brain development among healthy people was unknown.
The researchers used information stored in the UK Biobank to study the brain structure – obtained through magnetic resonance imaging – of nearly 20,000 healthy people from the United Kingdom. Previous studies of brain shape have mostly focused on easy-to-measure aspects such as total surface area, but in this study the researchers used a technique to study the three-dimensional structure of faces.
They found 472 regions, or loci, in the genome that affect brain shape. Of these, 76 were previously shown to influence facial structure. The 76 shared genetic regions include genes involved in well-known developmental pathways, as well as others that regulate the expression of other genes.
The face and brain shape are intertwined, not just in cases of malformation, but also in normal variation in healthy people.
Supporting this notion, genetic signals influencing brain shape are enriched in genomic regions regulating gene expression during embryogenesis, specifically in facial progenitor cells.
None of these shared genes, however, are known to be associated with any cognitive behavioral or neuropsychiatric conditions like Alzheimer’s disease.
