🔎 Monkey Faces As anyone who’s been scolded to “fix your face” knows, facial expressions are voluntary in most humans. But the running assumption for other expressive primates, like monkeys, was that their facial expressions aren’t so—until now. In a recent study, scientists recorded neural activity as rhesus macaque monkeys interacted with one another in a lab. They found that both the medial cortex, which controls spontaneous emotional expressions, and the lateral cortex, which controls voluntary actions, were active as the monkeys made faces at each other.     Why this is interesting: These two parts of the brain’s frontal lobe were long thought to operate independently. But the study showed that they can work together, further entangling brain regions’ function in the production of facial expressions. This was true for both friendly facial expressions and threatening faces in the primates. The regions, however, did run at different speeds—activity in the lateral cortex changed qu...