Science Figures Interpreted and Analyzed by RealClearScience
Estimating another person's age in a social setting can be exceedingly awkward, especially if you overestimate by a few years. So, unless you can enlist the aid of a facial recognition software, it's probably best not to hazard a guess.
However, certain individuals may be more skilled at guessing ages than others and the reason behind their competence my rest within the brain.
In a study just published in PLoS ONE, European neuroscientists sought to determine the specific pathways in the brain that transmit age-relevant information about faces. They recruited 24 subjects (12 males, 12 females), and -- while the subjects were in an fMRI scanner -- presented them with 201 beardless, neutral faces (age range 2 to 81) in a random order. Subjects were asked to estimate the faces' ages.
The top twenty percent of performers (5 individuals) were accurate to within 5.7 years on average, the middle 60% of performers (14 individuals) were accurate to within 7.1 years, and the bottom 20% (5 individuals) were accurate to within 9.1 years. When the neuroscientists compared the brain scans of the high performers to that of the average performers, they discovered fMRI response magnitudes almost five times higher in the posterior angular gyrus area of the brain, a region associated with number processing and spatial cognition (see figure below).
According to the researchers, the findings "correspond to a known importance of the left angular gyrus for abstract number representations... numerical comparisons and operations, as well as high mental calculation abilities." But, it's unclear what facial features the brain uses to decipher age, or what other brain regions are involved in the estimation. It's only apparent that the input data seems to assemble within the posterior angular gyrus.
Age estimations are incredibly important to human social interactions, since a person's age often determines how we act around them. Moreover, we most frequently associate with people from age demographics close to our own.
The researchers' findings contribute to the growing body of knowledge about the human "social brain."
Source: Homola GA, Jbabdi S, Beckmann CF, Bartsch AJ (2012) A Brain Network Processing the Age of Faces. PLoS ONE 7(11): e49451. doi:10.1371/journal.pone.0049451