{"id":728,"date":"2025-09-18T08:19:11","date_gmt":"2025-09-18T06:19:11","guid":{"rendered":"https:\/\/www.nutrimedia.info\/?post_type=news&p=728"},"modified":"2025-09-08T16:30:47","modified_gmt":"2025-09-08T14:30:47","slug":"primate-thumbs-and-brains-evolution-hand-in-hand","status":"publish","type":"news","link":"https:\/\/www.nutrimedia.info\/en\/news\/pouce-et-cerveau-des-primates-une-evolution-main-dans-la-main\/","title":{"rendered":"What if your thumb told you a lot about the size of your brain?"},"content":{"rendered":"

Primates with longer thumbs have larger brains on average. This is the conclusion of a study published on 26 August 2025 in Communications Biology<\/em>, which provides the first direct evidence of a co-evolution between manual dexterity and cerebral development in the order of primates, of which we are a part.<\/strong>
The hand and the brain, a linked evolution<\/strong><\/p>\n\n\n\n

The hypothesis had been around for a long time: our dexterous fingers and brains<\/a> voluminous would not be the fruit of chance<\/strong>, Two mutually reinforcing traits. The team from the University of Reading, in collaboration with Durham, has just provided quantified proof of this after analysing 95 fossil and living species<\/strong>, covering the full diversity of primates - from lemurs to modern humans.<\/p>\n\n\n\n

Why is this on-the-spot discovery so important?<\/strong><\/h2>\n\n\n\n

The researchers measured the proportions of the thumb (first metacarpal) in relation to the index finger, then correlated this data with brain mass. Result: a significant positive correlation across the entire primate order<\/strong>. And even after removing the human species from the models, proving that the relationship is not a human exception.<\/p>\n\n\n\n

Among hominins, only Australopithecus sediba<\/em> and Australopithecus africanus<\/em> differ slightly from the general model, suggesting particular selective pressures.<\/p>\n\n\n\n

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Surprise: the correlation is with the size of the neocortex<\/strong>, The brain is the seat of cognition and sensory processing, and not the cerebellum, traditionally associated with motor control. This suggests that fine manipulative skills are as much a matter of cognition as motor skills<\/strong>.<\/p>\n<\/blockquote>\n\n\n\n

Another key finding is that tool-using primates do not systematically have longer thumbs than other primates. Anatomy alone is therefore not enough to predict material culture.<\/strong><\/p>\n\n\n\n

Implications for human evolution<\/strong><\/h2>\n\n\n\n

Hand-brain coevolution<\/strong><\/h3>\n\n\n\n

These results confirm a historical co-evolution between dexterity and cognition<\/strong>, This involves high energy and neural costs. As Dr Joanna Baker sums up: \u00abOur big brains and nimble fingers did not evolve separately. When our ancestors became more skilful, their brains had to adapt\u00bb.<\/p>\n\n\n\n

The fact that the proportions of the hominid hand precede the systematic use of tools suggests that the long thumbs<\/strong> were already an evolutionary advantage in themselves, making them easier to handle and extending the range of interactions with the environment.<\/p>\n\n\n\n

The researchers also measured \u2019maximum manipulation space\u00ab (the ability to move a small object between thumb and forefinger). Here again, long thumbs and large brains are excellent predictors of dexterity.<\/strong><\/p>\n\n\n\n

\"The
Communications Biology (Commun Biol) ISSN 2399-3642 (online)\n<\/figcaption><\/figure>\n\n\n\n

A broader look at the evolution of primates<\/strong><\/h2>\n\n\n\n

For the evolutionary sciences, this study opens up a new perspective: the hand and the brain must no longer be studied separately, but as an integrated system.<\/strong> As Professor Robert Barton (Durham) points out: \u00abThis is the first time that we have directly linked two of the most distinctive characteristics of humans: the anatomy of the hand and the size of the brain\u00bb.<\/p>\n\n\n\n

This research sheds new light on human and primate evolution: our thumbs and brains have grown together, paving the way for the cultural and technological complexity that will follow.<\/p>\n\n\n\n

What do you think: did our tools shape our brains, or did our brains pave the way for the tools?<\/strong><\/p>\n\n\n\n

Reference<\/strong><\/h3>\n\n\n\n

Baker J., Barton R. A., Venditti C. (2025). Human dexterity and brains evolved hand in hand<\/em>. Communications Biology<\/em>. https:\/\/doi.org\/10.1038\/s42003-025-08686-5<\/a><\/p>","protected":false},"template":"","meta":{"_acf_changed":true,"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","inline_featured_image":false},"class_list":["post-728","news","type-news","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.nutrimedia.info\/en\/wp-json\/wp\/v2\/news\/728","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.nutrimedia.info\/en\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/www.nutrimedia.info\/en\/wp-json\/wp\/v2\/types\/news"}],"wp:attachment":[{"href":"https:\/\/www.nutrimedia.info\/en\/wp-json\/wp\/v2\/media?parent=728"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}