Can similar shifts be seen in finger sizes?
Did we just keep the little ones (fingers) for digging bugs and various substances out of bodily orifices?
Why not just have bigger toes to retain heat during the ice ages, whereas smaller toes with less unit volume per unit of surface area would be more prone to freezing?
After the climate mediated, big, hairy toes would sweat more and smell bad, where delicate toes would be less prone to getting funky and driving Og-ette out of the cave.
Thus, a shift in mating habits brought about by foot odor....
Feet without shoes don't get that funky foot smell.