Visitors to the Boston Museum of Science helped researchers uncover the ‘floppy-foot’ syndrome.
The study’s findings, published in the American Journal of Physical Anthropology, show differences in the foot’s bone structure that are similar to those seen in fossils with a human lineage that dates back more than two million years.
A team of scientists observed the feet of close to 400 museum visitors using a mechanised carpet. Participants were asked to walk barefoot while the carpet analysed several components of the structure of the feet as they moved.
While most of us have rigid feet, thanks to the stiff ligaments that hold bones of the foot together and help us with stability, primates tend to display floppy feet. When they lift their heels off the ground the middle part of their foot, known as the midtarsal break, bends to allow them to propel off on to their next step.
This function allows apes and chimpanzees, which spend much of their time in trees, the flexibility to grip onto branches and move fluidly.
Interestingly, the Boston research team was able to identify a similar function in some of their barefoot participants. Most who displayed the foot trait where unaware that they had this flexibility – with no noticable difference in the speed of their stride.
Dr Jeremy DeSilva , lead researcher of the Boston University team, told reporters that there was a way to determine whether you are one of the one in thirteen who display the foot trait:
“The best way to see this is if you’re walking on the beach and leaving footprints, the middle portion of your footprint would have a big ridge that might show your foot is actually folding in that area.”
Another way, Dr DeSilva said, was to observe the trait is to record yourself walking on a video camera and play back the video and observe the bones responsible for the folding motion.
Those with the flexible fold in their feet also roll to the inside of their foot as they walk, he added.
Scientists also hope the variation in feet will help them understand the evolution of these features, after closer examination of the bone structure of a two-million-year-old fossil human relative, Australopithecus sediba, suggested it also had this mobility.