One of the central ideas of ancestral health is that if it's a behavior we engaged in back when the primordial soup was still bubbling... it likely stimulates an adaptation in us that is beneficial. So kick off those Nike, Adidas, or... Louis Vuitton, and let's get down to business.
Your feet are a marvel of muscles and sensors (proprioceptors) that not only keep you upright, but provide feedback on the terrain you're moving across. Imagine how it would feel to wear a pair of rubber gloves all day... and not surgical gloves. I'm talking those clunky, yellow dishwashing gloves your grandmother used. You could still function, but it would greatly diminish your dexterity and the quality of your sensual experience. The information from the sensors in your feet trains your gait and foot strike which impacts the ankles, knees, hips, and back. The more that data path is open, the better integrated your movement patterns will be. That translates into less aches and pains.
There's also a more subtle benefit to walking barefoot (earthing). The earth is a ground - a source of negative ions. Being in contact with the earth allows your body to exchange positive ions for negative ones which provides an antioxidant effect. That's right - not all antioxidants come from food. This likely explains why studies have shown earthing to have a positive impact on sleep and lowering stress levels.