The climbing is for the forest, and the walk is for the savannah. It is the basic premise behind one of the greatest theories of human evolution, which maintains that our ancient ancestors went from climbing in trees to walking on the ground when climate change has transformed their environment from a forest to savannah.
But a new study in Boundaries in ecology and evolution suggests that things were perhaps not so simple, because many first hominins maintained their arboreal adaptations once they have developed their terrestrial emissions.
Looking at the chimpanzees in the Issa valley in Tanzania, the study confirms that the chimpanzees are climbing trees to find food in the savannas – a behavior that can explain why many first hominins were climbers as well as walkers. The study also suggests that chimpanzees must make the most of the trees they climb in savannas (since the trees are rare), encouraging a movement method that may have encouraged the two-way of our ancients.
“For decades, we assumed that the biped was born because we got off the trees and we needed to cross an open savannah,” said Rhianna Drummond-Clarke, study author and researcher at the Max Planck Institute of Evolutionary Anthropology, according to a press release. “Here, we show that navigation safely and effectively in the canopy can remain very important for a large semi-arboricultural monkey, even in open habitat. Adaptations to arboreal life, rather than terrestrial, may have been the key to shaping the early evolution of the human line. ”
Find out more: Chimpanzees could answer the reason why humans have evolved to walk up
Chimpanzee indices on the locomotion of hominines
Of course, why the first hominines stopped climbing trees and started walking on the ground is difficult to explain. But modern chimpanzees in the Issa valley in Tanzania can help. During the dry seasons, these chimpanzees live in a savannah mosaic which resembles the environment in which our ancient ancestors probably lived, which means that their life can help us understand our own evolutionary past.
So, to find out more about the movement of the first hominines, Drummond-Clarke and his colleagues watched the chimpanzees of Issa Valley, measuring where and how they found their food. The results confirmed their results of previous studiesThis has shown that chimpanzees spent a lot of time feeding in the trees.
In addition, the results revealed that chimpanzees tended to feed in larger and richer trees – those with an abundance of food. They also revealed that the chimpanzees had adapted their movements to travel on the thin branches of these trees safely, allowing them to eat the fruits, leaves and flowers of the trees. Indeed, to access these foods, the chimpanzees did not climb. Instead, they dragged or stood over the branches, holding other branches to support.
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Right in trees
Although these types of vertical movements are also observed in the forests, they could have been particularly beneficial in a savannah, where the trees are rare. “Savannah-Mosaics is characterized by more little distributed trees,” said Drummond-Clarke in the press release, “we therefore hypothesized that the adaptation of behavior to feed effectively in a tree would be particularly beneficial when the next tree is further.”
According to the team, if a similar type of vertical movement was developed by the first hominines when they passed through the Savannahs, this may have helped them to develop their two -way.
“We suggest that our bipedal approach continued to evolve in the trees even after the transition to an open habitat,” Drummond-Clarke said in the press release. “The observation studies of the big apes demonstrate that they can walk in the field for a few steps, but most often use the two -way in the trees. It is logical that our first hominine parents also engaged in this type of two -way, where they can keep branches for an additional balance. ”
Drummond-Clarke adds that more research is necessary to test this idea, both of a paleontological and observation perspective.
“It is also only one community of chimpanzees,” she said in the statement. “Future studies of other chimpanzees living in such dry and open habitats will be essential to see if these models are really a Savannah-Mosaic or unique in Issa signal.”
Find out more: The interior ears of the old monkey can keep the key to the evolution of walking on two feet
Sources of articles
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Sam Walters is a journalist covering archeology, paleontology, ecology and the evolution of Discover, as well as an assortment of other subjects. Before joining the Discover team as a deputy editor in 2022, Sam studied journalism at the Northwestern University in Evanston, Illinois.
