According to a twin study, face recognition is heritable, and it is inherited separately from general intelligence or IQ.
This finding, by researchers at MIT and in Beijing, plays into a long-standing debate on the nature of mind and intelligence. The prevailing generalist theory, upon which the concept of IQ is based, holds that if people are smart in one area they tend to be smart in other areas.
IQ is strongly influenced by heredity, suggesting the existence of "generalist genes" for cognition. Yet some cognitive abilities seem distinct from overall IQ, as happens when a person who is brilliant with numbers or music is tone-deaf socially or linguistically.
Also, many specialized cognitive skills, including recognizing faces, appear to be localized to specialized brain regions. Such evidence supports a modularity hypothesis, in which the mind is like a Swiss Army knife - a general-purpose tool with special-purpose devices.
"Our study provides the first evidence supporting the modularity hypothesis from a genetic perspective. That is, some cognitive abilities, like face recognition, are shaped by specialist genes rather than generalist genes," said lead author Jia Liu, Professor of Cognitive Neuroscience at Beijing Normal University in China.
For the study, Liu and his colleagues recruited 102 pairs of identical twins and 71 pairs of fraternal twins aged 7 to 19 from Beijing schools.
Because identical twins have 100 percent of their genes in common while fraternal twins have just 50 percent, traits that are strongly hereditary are more similar between identical twins than between fraternal twins.
Participants were shown black-and-white images of 20 different faces on a computer screen for one second per image. They were then shown 10 of the original faces mixed with 20 new faces and asked which ones they had seen before.
The scores were more closely matched between identical twins than fraternal twins, and Liu attributed 39 percent of the variance between individuals to genetic effects.
Further tests confirmed that these differences were specific to face recognition, and did not reflect differences in sharpness of vision, general object recognition abilities, memory or other cognitive processes.
In an independent sample of 321 students, the researchers found that face recognition ability was not correlated with IQ, indicating that the genes that affect face recognition ability are distinct from those that affect IQ.
The study has been published in the Jan. 7 issue of Current Biology.