An increase in the amount of ultraviolet light entering the atmosphere through holes in the ozone layer will most likely

cause an increase in the rate of certain mutations

Hands have a larger range of dexterity compared to feet. Longer tendins and stronger grip strength, they are made for more intrucite tasks such as making and using tools. Feet have a larger surface area, made for holding large amount of weight, shorter bones and tendins allow for easy acceleration and no extra flesh to get in the way. Other more primitive species will not have the  feet we have due to evolution. They simply do not have the evolved sense of brain pwer hians haev in order to make tools. So they have more need for speed, grip exc. in feet to escape pradators and live day to day. Where on the other hand humans do not.

Explanation: