Scientists have long been fascinated by the evolution of human bipedalism, but a new study sheds light on the crucial molecular steps that led to our ancestors walking upright. Researchers analyzed embryonic tissue from humans, mice, and primates, revealing that the development of the ilium bone – which is essential for daily life and childbirth – was more complex than previously thought.
The study’s lead author, Gayani Senevirathne, created 3D models of human fetal tissue and analyzed the genes that regulate the formation of the ilium. She found that in humans, the bone develops from a rod of cartilage parallel to the spine, whereas in mice, it develops from two tiny rods of cartilage that grow and fuse to the spine.
This unexpected twist has significant implications for our understanding of human evolution. The researchers argue that this “flip” allowed early human ancestors to grow a new kind of pelvis that supported muscles strong enough for walking upright. However, they also discovered that the ilium underwent a second major change millions of years later, when humans evolved big brains.
The study suggests that this shift was driven by natural selection favoring curves on the ilium that made deliveries easier. The researchers hope to continue their research to better understand the history of the pelvis and its evolution in humans.
Despite the promising findings, the team’s funding has been terminated due to budget cuts, leaving them uncertain about the future of their project.
Source: https://www.nytimes.com/2025/08/27/science/human-evolution-ilium-bipedal.html