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January 8, 2026<\/p>\n
2 min read<\/p>\n
Add Us On Google<\/span>Add SciAm<\/span><\/span><\/p>\n Do Monkeys Make Faces on Purpose?<\/p>\n A new study suggests that primate facial expressions may not just be reflex<\/p>\n By Cody Cottier edited by Sarah Lewin Frasier<\/span><\/p>\n Macaques\u2019 threatening grins and friendly lip-smacks may be partially intentional.<\/p>\n Christophe Lehenaff\/Getty Images<\/p>\n Facial expressions are central to social life, yet scientists still don\u2019t fully understand how the brain produces them. For decades, one influential theory has held that what appears on your face is largely an emotional reflex\u2014an honest, automatic readout of what you feel inside. But that view struggles to explain the fact that we often tailor our countenance to the moment: we\u2019ve all smiled politely through a dull date or tried not to smile while holding a royal flush.<\/p>\n To find out what\u2019s going on in the brain during facial expressions, researchers turned to rhesus macaques, Old World monkeys with face musculature and neuroanatomy that are similar to that of humans. They recorded neural activity while the animals interacted with one another\u2014as well as with digital avatars and video of other macaques\u2014in the lab. The team\u2019s results, published today in Science, came as a surprise: the monkeys\u2019 expressions, from a threatening face to a friendly \u201clip-smacking\u201d one, were generated by both the medial cortex and lateral cortex.<\/p>\n These brain regions were long thought to operate independently, with the medial dealing with spontaneous emotional expressions and the lateral controlling voluntary actions. \u201cOur study did not show that at all,\u201d says co-lead author Geena Ianni, a neurology resident at the University of Pennsylvania. \u201cIt showed that all regions participated in the production of all kinds of facial expressions.\u201d<\/p>\n If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.<\/p>\n The two regions did, however, run at different speeds. \u201cThe way they encode information has a distinct tempo,\u201d says co\u2013lead author Yuriria V\u00e1zquez, a neuroscientist at the Rockefeller University. Activity in the lateral cortex shifted quickly, over milliseconds, to coordinate the rapid facial movements that make for smooth social interaction. By contrast, things happen at a more leisurely pace in the medial cortex, perhaps allowing it to track slow-changing contextual factors\u2014such as \u201cHas the alpha male stopped threatening me?\u201d\u2014that influence facial expressions. What\u2019s more, both neural patterns show up before facial movements do, suggesting the brain prepares expressions in advance.<\/p>\n This all raises a question: Do macaques intentionally plan the faces they make? That\u2019s the interpretation that Bridget Waller and Jamie Whitehouse, evolutionary psychologists at Nottingham Trent University in England, explore in a commentary on the new study. If facial expressions are partly voluntary, they may be less like emotional mirrors and more like \u201ctools for social influence,\u201d as Waller and Whitehouse put it. At the very least, they seem to arise from complex interactions between emotion and cognition.<\/p>\n Alan Fridlund, a social and evolutionary psychologist at the University of California, Santa Barbara, who was not involved in this study, has no trouble believing macaques wield their faces strategically. But he doubts that staged, lab-bound interactions can capture the full reality of primate communications, or the neural activity underlying it; ideally, future research would take place in the monkeys\u2019 natural environment. Still, Fridlund says, the new study \u201ctells us in infinitely more detail how we can investigate the neurology of facial displays.\u201d<\/p>\n If you enjoyed this article, I\u2019d like to ask for your support. Scientific American<\/span> has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.<\/p>\n I\u2019ve been a Scientific American<\/span> subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm <\/span>always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.<\/p>\n If you subscribe to Scientific American<\/span>, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.<\/p>\n In return, you get essential news, captivating podcasts, brilliant infographics, can’t-miss newsletters, must-watch videos, challenging games, and the science world’s best writing and reporting. You can even gift someone a subscription.<\/p>\n There has never been a more important time for us to stand up and show why science matters. I hope you\u2019ll support us in that mission.<\/p>\n","protected":false},"excerpt":{"rendered":" January 8, 2026 2 min read Add Us On GoogleAdd SciAm Do Monkeys Make Faces on Purpose? A new study suggests that primate facial expressions may not just be reflex By Cody Cottier edited by Sarah Lewin Frasier Macaques\u2019 threatening grins and friendly lip-smacks may be partially intentional. Christophe Lehenaff\/Getty Images Facial expressions are central<\/p>\n","protected":false},"author":1,"featured_media":40962,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[58],"tags":[2395,9996,11470],"class_list":{"0":"post-40961","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-faces","9":"tag-monkeys","10":"tag-purpose"},"_links":{"self":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/40961","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=40961"}],"version-history":[{"count":0,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/40961\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/media\/40962"}],"wp:attachment":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=40961"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=40961"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=40961"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}On supporting science journalism<\/h2>\n
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