In the early chapters of our history, there’s a pivotal figure who helped us transition from quadrupedal movement to walking upright. Recently, scientists believe they’ve found the best candidate for this crucial moment: an ape-like ancestor from Africa, known as Sahelanthropus tchadensis, which lived approximately 7 million years ago.
Research has shown that while Sahelanthropus had features similar to an ape, its bones suggest it was adapted for walking on two legs. According to Dr. Scott Williams from New York University, this ancestor resembled a bipedal ape, akin to today’s chimpanzees or bonobos, but it likely spent more time standing than modern chimps, who mostly walk on their knuckles.
The history of Sahelanthropus began in 2001 when fossils were discovered in Chad’s Djurab desert. The lead researcher, Prof. Michel Brunet, initially suggested that this species walked upright based on how it held its head. He boldly claimed it as the “ancestor of all humankind.” However, other scientists were skeptical, noting that without more complete fossils, especially from the legs, it was hard to determine how it moved.
In the latest study, researchers revisited old fossils with advanced techniques. They paid particular attention to a feature on the thigh bone, known as the femoral tubercle, which is crucial for supporting bipedal movement. Dr. Williams pointed out that this bump anchors a major ligament that helps maintain balance while walking—a trait unique to upright walkers.
As they examined the bones, they found additional signs of an upright gait. These included specific twists in the thigh bone and muscle attachments that suggest it could have walked or stood upright. This research was published in Science Advances.
Dr. Williams believes that Sahelanthropus adapted to walking on the ground but still relied on trees for safety and food. However, not all experts agree. Dr. Marine Cazenave from the Max Planck Institute considers the evidence weak and believes the traits observed could also link Sahelanthropus to modern great apes. She questions whether those adaptations were exclusive to ground walking.
Similarly, Dr. Rhianna Drummond-Clarke acknowledges some arguments but emphasizes that more research is needed to clarify how this species moved. The discussion continues, as some believe Sahelanthropus could have been an early form of chimpanzee that became less upright over time.
Despite the debate, experts agree that more fossil discoveries are necessary. Dr. Guillaume Daver and Dr. Franck Guy from the University of Poitiers have long supported the idea of Sahelanthropus being a bipedal walker and are hopeful for new findings from their upcoming trips to Chad.
In the end, this mystery of our origins remains open, with many questions still to explore. As new evidence emerges, the narrative of how we became who we are today will continue to evolve.
For further details, you can read more on The Guardian.
