Researchers have identified a small groove that runs deeper along the right side of the human brain than the left. Because other primates lack this feature, it's conceivable that its function is what sets us apart.

The groove within the STS resides immediately below the red band seen in this digital image. (Turken et al.)

It's located within the superior temporal sulcus, the part of our brain that's responsible for handedness, language, and social skills. The function of the new groove, which was discovered by François Leroy of the French National Institute of Health and Medical Research in Saclay, is unknown, but it probably played a role in the evolution of our communication skills. Further study could shed light on its function and how it differentiates the human brain from those of primates.

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STAP is shown in yellow. Sulcal depth shown by color coding of the sulcal mesh (in B and seen from above). (Leroy et al.)

New Scientist reports:

The asymmetrical groove in humans was [already] known, but the new study, in which 177 people and 73 chimps had brain scans, revealed it is almost completely absent in the other primates.

[...] In humans, the deeper groove in the right brain lies in the region that controls voice and face recognition and working out what other people are thinking – our so-called theory of mind. The shallower groove on the left is at the heart of the areas associated with language. The lack of symmetry could signify that tissue layers in the right brain have been reorganised, says Leroy.

"Asymmetrical brain landmarks may be key features to understand what is so specific in our species," says Leroy, since left and right sides of the human brain tend to perform different tasks. "We think that [this asymmetry] is related to either speech or social cognition, which are both abilities for which humans outperform other primates."

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Read more at New Scientist, and check out the scientific study here.