A toddler was home on the field and in the trees | Smart news

One of the key traits that separates hominids from monkeys is the biped, or walking straight on two legs, releasing arms to throw spears, pick berries, or carry children. This transition from stable quadruped to confident biped took a long time as new members of the human genealogy tree evolved. Now, reports National Geographic a new study shows that toddlers of a famous early bipebe species, Australopithecus afarensis, have retained some foot structures resembling monkeys that probably allowed them to climb trees "Lucy", the first and most famous fossil A. afarensis was discovered in Ethiopia in 1974. More than a quarter of a century later, early [19659004] 2000, researchers discovered the foot of another A. afarensis fossil, a 2.5-year-old girl in the Dikika region of Ethiopia, whom the researchers named Selam. And in a new study, published Wednesday in the journal Science Advances Jeremy DeSilva of Dartmouth and his team analyzed Selam's well-preserved foot bones, the size of a human thumb, and have found that the foot looked like Selam probably had qualities similar to those of baby monkeys

"This foot is very human and indicates that the child Dikika walked on two legs," says DeSilva to George Dvorsky at Gizmodo . "However, the bone at the base of our big toe – called medial cuneiform – has a link to the big toe that is more curved and slightly sloping than what is found in humans today. Such a curved surface would allow the movement of this big toe – which modern monkeys use to grasp.We conclude, and from past studies on the shoulders of the child Dikika, that she could have climbed, and also grabbed her mother during the trip. "

Dvorsky reports, however, that adult foot bones do not seem quite like monkeys. According to the researchers, gripping toes helped young A. afarensis children to extricate themselves from trees to avoid predators, which they probably had to do more often than adults. This may have also helped them catch their mother since they were probably much transported, like baby chimpanzees.

It also turns out that the heel of Selam is different from that of adults A. afarensis. Kimberly Hickok of LiveScience reports that it's much more delicate than the adult heel, which is similar to ours. "So, that suggests [A. afarensis] has grown their heels very differently than we do," says DeSilva to Hickok. "Even though we have the same anatomy, we have had it differently."

As juveniles spent more time in the trees, it is likely that adults also took the branches. In 2012, after 30 years of intense debate over whether Lucy and Selam were strictly bipedal or arboreal, a study of their shoulder blades showed that they could cross the jungle with the best of them. It is likely that they spent the day feeding on foot and climbing trees to sleep. "If you lived in Africa 3 million years ago without fire, without structures, and without any defense, you'd better get up in a tree when the sun goes down," DeSilva said in a statement. Press. 19659010] However, even though the species was sleeping and hiding in the trees, this does not mean that two feet planted on the ground were not important. In fact, Carol Ward, of the University of Missouri, who is currently examining Selam's spine and ribs, tells Hickock that the child's grasping power does not really compare to monkeys. "Even if a baby could have more things between his first and second toe, he would not have had the ability to grasp like a monkey," she says, pointing out that Selam's foot is more suited to the walking only in climbing. "The importance of life on the ground for these animals, and that effective climbing was much less important."

Whatever their lifestyle, they have been very successful.However, the researchers found fossils of 300 A. afarensis individuals – although very few children – and the species lasted more than 900,000 years, three times longer than the ours has traveled the earth.

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