Recognizing faces is an important social skill, but not all of us are equally good at it.

Some people are unable to recognize even their closest friends (a condition called prosopagnosia), while others have a near-photographic memory for large numbers of faces.

This finding 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, so if you are good in math you are also more likely to be good at literature and history. 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," said lead author Jia Liu, Professor of Cognitive Neuroscience at Beijing Normal University in China of the study published in the Jan. 7 issue of Current Biology. "That is, some cognitive abilities, like face recognition, are shaped by specialist genes rather than generalist genes."

"Our finding may help explain why we see such disparities of cognitive abilities within the same person in certain heritable disorders," added co-author Nancy Kanwisher of the McGovern Institute for Brain Research at MIT, where Liu studied before moving to Beijing. In dyslexia, for example, a person with normal IQ has deficits in reading, while in Williams Syndrome, people have low IQ but excellent language skills.

Source: Massachusetts Institute of Technology