Consistent shoe use results in a more delicate bone structure, because footwear reduces the force on middle toes during walking.
In his latest study, this anatomical evidence allowed Trinkaus to date the origin of shoes to a period long before the oldest known shoe remains.
Elizabeth Semmelhack curates the Bata Shoe Museum in Toronto, Canada. She said given what we know about the effects of shoe-wearing, Trinkaus' approach makes perfect sense.
"The simple act of wearing shoes alters the structure of our feet," Semmelhack said.
"It's interesting that [Trinkaus] is looking at these prehistoric remains and coming to the same conclusions."
Function vs. Fashion
The first forms of protective footwear probably evolved from simple wrappings used to insulate the feet from snow and freezing temperatures, experts say.
The oldest preserved shoe remains, dating to roughly 10,000 years ago from the western United States, are simple sandals woven of plant fibers.
But at some point shoes stopped being mere protection and become a fashion item.
Some anthropologists have suggested that even the earliest shoes may have served a more symbolic than protective function.
Beads found around the ankles and feet of human skeletons dated to 27,000 years ago suggest the presence of decorated footwear, Trinkaus said.
"History is replete with examples of impractical, irrational shoes," noted shoe museum curator Semmelhack.
"The actual first shoes may have been created out of necessity. But elements of irrationality probably crept in very early on," she said.
"Even these ancient people were probably trying to express something."
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