Ancient hominids may have left the trees, but we never abandoned them

If you ’re quickly trying to define what sets human apart from other order Primates , you might first point to our greater intelligence and our capacity for complex spoken communication . The next big difference is that we walk on two feet and stay out of the tree … except , as this video explains , it ’s not quite that simple .

Part of the reason why the 1974 uncovering of the remains of the hominid Lucy was such a big deal — beyond the fact that you do n’t find a 40 % thoroughgoing skeletal frame of a 3.2 - million - twelvemonth - old Australopithecus afarensis underframe just any day — was that it rewrote a key part of our evolutionary tarradiddle . Before the discovery of Lucy , anthropologists and paleontologists assumed the expansion of brain sizing was the first cardinal evolutionary leap that moved the evolutionary ancestors of homo away from the other primates . But Lucy was relatively small - brain , and yet she was biped , intend the shift out of the tree precede the growing in news .

Since then , bipedalism has been recognized as one of the most all important milestone in our phylogenesis , and with it the abandonment of an arboreal sprightliness for an existence spent firmly on the ground . But as a squad of researchers at the University of Dartmouth reason , the theme that a bipedal existence automatically puts trees out of compass of humans and our antecedent is n’t necessarily true . As carbon monoxide - author Nathaniel Dominy excuse in the television up top , plenty of humans still pass lots of time in the tree today , even if we ’re ostensibly no longer properly adapted for climbing tree diagram .

Specifically , he and his two co - author Vivek Venkataraman and Thomas Kraft compare set of modern hunter - gatherers and farmers both in Uganda and in the Philippines . The Twa of Uganda and the Agta of the Philippines are hunter - gatherers that climb trees regularly to get honey , which forms a key part of their diet , a behavior that pose them aside from their respective agricultural vis-a-vis , the Bakiga and the Manobo .

Dartmouth Now explainsjust how the Twa and Agta climb trees :

They rise in a style that has been described as “ walk ” up small - diam trees . The mounter utilize the soles of their feet directly to the tree trunk and “ walk ” upward , with their arms and legs get along alternately . Among the climbers , Dominy and his squad document extreme dorsiflexion - crouch the foot upwards toward the tibia to an extraordinary degree- beyond the range of a function of forward-looking “ industrialized ” humanity . Assuming their leg off-white and ankle roast were normal , “ we hypothesized that a soft - tissue paper chemical mechanism might enable such extreme dorsiflexion , ” the author spell .

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The researchers subsequently recover out that the Twa and Agta had much longer muscle fibre in their calves , uncover how they were able-bodied to keep mount tree diagram so easy even when the balance of their frame was no longer well - suited for it . This , according to the researchers , is a good monitor that there are few absolute in our evolution , and indeed Lucy and her Australopithecus afarensis coeval could have possess likewise expand sura musculus so that they could keep up some of their species ’s old arboreal habits even after the shift to bipedalism .

For more , check out the television up top , in which Dominy tender a good overview of the determination . Also , the complete paper is currently available atPNAS .

Photo of Twa man climbing by Nathaniel Dominy .

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