DNA Tweaks May Have Helped Ancestors Walk Upright

Researchers say two small changes in human DNA may have played a crucial role in helping our ancestors stand upright and walk on two legs. The study found that these genetic tweaks changed how a key hip bone developed, allowing for the transformation of a structure once used for climbing into one built for upright walking. The changes were essential for creating and shifting muscles that helped humans stay upright as they walked.

Key Takeaways:

• The study found that two small changes in human DNA, one causing the ilium to rotate 90 degrees and the other slowing down its hardening into bone, were essential for creating and shifting muscles that helped humans walk upright.
• Researchers examined samples of developing pelvic tissue from humans, chimpanzees, and mice, pairing microscopic samples with CT imaging to identify the differences in pelvic development.
• The changes in gene regulation, which controlled how and when certain genes were active, led to horizontal growth of cartilage and a slower hardening process of bone, allowing for the formation of a wider pelvis.
• These adaptations may have also made the human hip more prone to osteoarthritis, according to the researchers.
• The wider hips may have also created a roomier birth canal, making it easier for humans to give birth to larger-brained babies as evolution progressed.
• The study, published in the journal Nature, suggests that these changes appeared early in human evolution, after our lineage split from chimpanzees.
• The research was funded by the National Institutes of Health and originally aimed to understand how the pelvis forms to improve treatments for hip disorders.

Statistics:

• 90 degrees: The rotation of the ilium bone caused by one of the genetic changes.
• 2: The number of genetic changes identified in the study that may have helped ancestors walk upright.
• 3: The number of species studied in the research, including humans, chimpanzees, and mice.
• 1: The target population for the study, aimed at understanding how the pelvis forms to improve treatments for hip disorders.

Sources:

• Science News, Oct. 28, 2025