Fossils prove that toddlers have climbed trees

More than 3 million years after his death, the fossil of a tiny toddler gives a unique insight into the lives of our human ancestors' children.

His nickname is Selam, which means "peace" in Ethiopian Amharic Language. Selam was a hominin, a precocious human ancestor called Australopithecus afarensis. When she died, she was almost 3 years old.

His nearly complete skeleton was discovered in the Dikika region of Ethiopia in 2002 by Zeresenay Alemseged, paleontologist and professor of biology and organic anatomy at the University of Chicago. But releasing Selam from the ground took years. It was trapped in sediments that were millions of years old and the researchers had to be extremely careful.

One of the most recent elements of his skeleton to study is his foot, which is detailed in a study published on July 4. Science Advances Journal.

"For the first time, we have an incredible window on the walk of a 2½ year old, over 3 million years old," Jeremy DeSilva, lead author of the study and associate professor of anthropology at Dartmouth College, said in a statement. "It's the most complete foot of a former juvenile ever discovered."

It is rare to find juvenile skeletons of human hominid ancestors, especially those that are well preserved.

"The study of younger individuals is important.you see in adults is a result of both their evolution in time and their evolution as they grew up," writes Alemseged, lead author of the study

Lucy And Selam

Prior to this discovery, the oldest and most complete fossilized foot was 1.8 million years old and belonged to a Homo habilis, nicknamed OH 8.

Australopithecus afarensis walked upright. But there are also features similar to those of monkeys about afarensis. Selam would have been similar in size to a chimpanzee who was about the same age – which meant that she also depended on her mother. Selam probably tied her to her mother while she was looking for food or spending time in the trees.

For reference, Lucy, the world's most famous fossil and another example of Australopithecus afarensis who lived 3,18 million years ago. 60 pounds. The analysis of her skeleton and her teeth shows that she has reached maturity, but not very different from chimpanzees, her species has matured young. A 2016 study of what might have caused her death estimates that she was 15 or 16 years old.

Although Lucy and Selam were found in the same area, Selam is not "Lucy's baby." Selam lived more than 200,000 years before Lucy.

Given the size of afarensis, predators such as hyenas, jackals, and saber-toothed cats would have been a threat. Trees provided security, whether to escape a predator or to nest at night. According to data on nesting habits of chimpanzees, researchers estimate that an average of 46 feet above ground reassured them.

"If you lived in Africa 3 million years ago without fire, without structures and without any defense, you'd better be able to get up in a tree when the sun goes down," he said. DeSilva in a statement

Selam and Lucy would have straightened up, feet, knees and hips similar to ours If you saw her walking from a distance, you might think that Lucy was human by her figure. a small head, a brain comparable to that of a chimpanzee, arms and longer hairs covering his body.

Connecting humans and chimpanzees, Lucy had slightly curved fingers and toes, with ankles movable, shoulders that provided more freedom of movement.Even with these abilities, she would have done better to walk than to climb.

Living in the trees

The anatomy of Selam's foot was incredibly well preserved, allow for researchers to study how a small hominin would have worked. At two-and-a-half years, Selam would have walked on two legs

But when the researchers analyzed the structure of Selam's foot skeleton, they noticed that the base of the big toe would have allowed him to be a great climber . Thus, even though toddlers afarensis could walk, they probably spent more time in the trees than on foot, unlike adults. It's a monkey model, the researchers said.

"For me the surprise was" Their findings suggest that Afarensis had traits humans and simians based on their selective advantage, which also shows the "mosaic nature" behind the evolution of the right march and skeletal evolution, says Alemseged.

A 2012 study of Selam's complete shoulder blades also showed that they looked like blackflies because they were adapted to climb trees. The shoulder blades are incredibly rare because they are delicate, almost thin and do not usually fossilize.

A 2017 study of his nearly intact spine, vertebral bones, neck, and ribcage also revealed this part of the human being. Skeletal structure was established millions of years before planned. Like modern humans, Selam had 12 thoracic vertebrae and 12 pairs of ribs – less than most monkeys.

Alemseged believes that all of this combined evidence shows just how crucial and crucial a species was human evolution

climbing was part of the adaptation of a species and in what measure are crucial, "said Alemseged." That tells us a lot about its ecology and the type of selection forces that were acting on it. The new study supports many previous studies that the foot in A. afarensis was adapted for the right walk and was largely human. It also reveals that some features, especially mobility, are a bit different.

Written by Ashley Strickland for CNN

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