If you have thick heel and feet calluses, you should consider yourself lucky instead of fighting them vehemently. Calluses protect the foot like a shoe sole and maintain the sensitivity of the feet. With them, nature is ahead of our shoes' purpose.
A direct comparison between the callus and the shoe sole suggests that the callus also forms a protective layer on the foot sole, but unlike the sole of the shoe, it does not restrict tactile perception when walking or running. The so-called "foot feeling", on the other hand, is noticeably reduced by thick and well-cushioned footwear.
Calluses on the feet have probably existed since the beginning of the upright gait. The shoe then tried to replace the protective function of the cornea on the foot about 40,000 years ago. And indeed, a shoe, especially with a comfortably designed footbed, protects the foot much better than nature could do with the callus. However, shoes also make our feet less sensitive to the small bumps in our everyday movements. This, in turn, has an influence on gait and gait safety.
A recent study also showed that barefoot runners generally form thicker calluses on the soles of the feet, but that even thick layers of callus do not limit the sensitivity of the soles of the feet. However, this is completely different with well-cushioned footwear with thick soles, which additionally changes the stress on the ankles compared to barefoot walking, so that they are even subjected to greater stress in the shoe.
In the future, the researchers want to investigate more closely whether shoes with hard soles could do more justice to the natural state of the foot. In fact, there are indications that shoes with hard soles are less restrictive of the foot feeling and, for example, that older people in particular benefit from a lower propensity to fall.
Nature 2019; doi: 10.1038/s41586-019-1345-6