Human Walking Evolution Linked to Wearing Shoes

Wearing shoes is linked to slight structural changes in the spongy bone of our ankles, a discovery that challenges our understanding of human walking evolution.

This finding has significant implications for paleontologists who study fossilized bones and footprints of ancient humans. Fossils have often been compared to modern ankle bones, but this comparison may not be entirely accurate. The structure of the ankle bone can change over time due to repeated strain from wearing shoes.

Studying populations that do not wear shoes regularly offers a unique perspective on how our extinct human relatives moved. Zewdi Tsegai at the University of Chicago notes that modern humans who don't wear shoes can provide valuable insights into the past, effectively serving as a "window into the past".

The trabecular bone in our ankles is particularly responsive to external forces and remodels throughout an individual's life. This characteristic makes it a useful tool for studying how ancient humans used their feet and legs.

The researchers used high-resolution CT scans to create 3D maps of the trabecular bone in the talus, an ankle bone that connects the lower leg to the foot, in a group of modern humans.

This study involved 56 individuals, with the majority being shoe wearers who had passed away since 2000. The team also included a smaller group of barefoot individuals from different parts of the world.

The barefoot group consisted of skeletons from the mid-19th century, housed at the Natural History Museum in London. This collection included 13 Andaman Islanders, two Khoisan people from southern Africa, and one Aka hunter-gatherer from Central Africa.

The team's analysis revealed distinct differences between the trabecular bone structure of shoe wearers and barefoot individuals.

The researchers' findings suggest that shoe wearers have a distinct trabecular bone structure at their ankles compared to those who go barefoot. This could be due to the way shoes distribute weight and position the foot during walking or standing.

Shoe wearers tend to have more consistently oriented struts and plates in their ankle bones, indicating that footwear restricts ankle movement and channels forces through a narrower range of paths. This is likely a result of shoes holding the foot in an extended position, especially when heels are present.

The study's results highlight the importance of considering habitual footwear habits when studying the evolution of the human foot or conducting research on foot anatomy. Further studies will be necessary to tease out any compounding effects of lifestyle factors and body size on bone architecture.