In a revelation that could change Charles Darwin’s theory of evolution, the BBC reports on a new study that may have solved the mystery of how human hands became dexterous enough to make and manipulate tools. Darwin believed walking upright simply freed up our hands for more intellectual pursuits. But a team of scientists from the University of Calgary in Canada recently showed that walking on two feet is more closely linked to the emergence of stone tool technology. 

Dr. Campbell Rolian led the study that simulated the change from an ape-like hand to a human-like hand. The researchers took measurements from the hands and feet of humans and of chimpanzees, our closest genetic relatives. According to Dr. Rolian, this new research showed a strong correlation between similar parts of the hand and foot. Dr. Rolian and his team adjusted the shape of the hands or the feet, recreating single, small evolutionary changes to see what effect they had. They found that changes in the feet caused parallel changes in the hands, especially in the relative proportions of the fingers and toes.

In turn, these parallel changes may have been the key to allowing our ancestors to develop the dexterity to use stone tool technology. "One reason fingers and toes may be so strongly correlated is that they share a similar genetic and developmental 'blueprint'," Dr. Rolian told the BBC, "and small changes to this blueprint can affect the hand and foot in parallel."

Not all of the scientific community is in agreement with these new findings. Robin Crompton is professor of anatomy at the United Kingdom's Liverpool University. Crompton points out to the BBC that there was a lot more to the functional shape and biomechanics of the human foot than its proportions. Further, he says the lowland gorilla may be a more accurate testing subject than the chimpanzee.

Nonetheless, evolutionary researchers are excited. As one put it, “the results are quite exciting and will doubtless spur further testing and additional work."

For further reading: Feet Hold the Key to Human Evolution

Hands and feet of humans evolved simultaneously
New study tweaks Darwin's theory that walking upright contributed to hand development.