The earliest ancestor of humans walked on two legs 7 million years ago.

According to ТСН: Scientists have made an important step in studying the origins of humanity by examining the remains of the creature Sahelanthropus tchadensis. The new study of bones confirms that this species could walk on two legs as early as 7 million years ago.

Researchers believe they have pinpointed the time when human ancestors made a significant evolutionary transition from four-legged to bipedal movement. It turns out that the human relative that lived in Africa about 7 million years ago is the most compelling candidate for the title of the oldest ancestor of humanity, as its skeletal structure was adapted for moving on two legs.

The remains of Sahelanthropus tchadensis were discovered over two decades ago in the Chad desert, in north-central Africa. Analysis of the skull showed that it likely was positioned above the spine, which was an important clue on the road to bipedalism. Research on the limbs confirmed that this species could indeed move on two legs, as the bones showed signs characteristic only of bipedal creatures.

The humanoid creature resembled modern chimpanzees and bonobos

"Our analysis of these fossils provides direct evidence that Sahelanthropus could walk on two legs, demonstrating that bipedality emerged very early in our evolutionary line and originates from an ancestor that externally resembled modern chimpanzees and bonobos,"

Researchers recorded in the fossil remains a so-called femoral neck – an anatomical feature important for bipedalism. This area is where the iliopsoas muscle attaches, ensuring body stability during standing and walking.

The study also revealed a "natural twist" in the femur that helps properly direct the legs forward. Three-dimensional analysis showed the presence of gluteal muscles similar to those possessed by our early ancestors, which are necessary for pelvic stability during physical activity.

This ancient species had the ability to walk upright

Scientists believe that new data supports the ability of Sahelanthropus to walk upright.

"Sahelanthropus was essentially a bipedal ape with a brain size approximately that of a chimpanzee and likely spent a significant amount of time in the trees searching for food and safety. Despite its superficial resemblance to monkeys, Sahelanthropus was adapted for a bipedal posture and movement on the ground,"

This discovery gives grounds to consider Sahelanthropus the oldest known representative of human evolution after its divergence from chimpanzees. After all, humans and monkeys diverged evolutionarily about 8-19 million years ago, suggesting a rapid adaptation to bipedalism in early ancestors.

The research team compared the discovered remains with bones of other early hominins and modern apes, finding that Sahelanthropus had a long femur compared to its forelimbs, which indicates its ability for bipedal movement.

Bipedality – "a key adaptation"

In an article published in the journal Science Advances, scientists emphasized that bipedality is a "key adaptation" that distinguishes hominins from modern and fossil apes.

"Sahelanthropus is interpreted here as an early African hominin of the ape type that demonstrates some of the earliest adaptations to bipedality,"

Scientists believe that the emergence of upright walking was a "process, not an event," highlighting the possibility of simultaneous movement on two legs and climbing trees.

Scientists' doubts about Sahelanthropus

However, some scientists have expressed doubts about whether Sahelanthropus is a direct ancestor of humans. Professor of anthropology at the University of Michigan Milford Wolpoff noted that

"Sahelanthropus does not belong to the direct evolutionary line leading to humans."

The evolution of humanity is a complex process involving various species of hominins. Among them, Homo sapiens remains the only survivor. Research on Ardipithecus ramidus, Homo georgicus, and new findings from China confirm that the path to modern humans was not direct – debates about early forms of ancestors continue.