How do you think that natural selection was involved in the evolution of the hair-like structures?

According to Darwin’s theory:

During human evolution, there was natural selection for the loss of body hair, as it enabled them to better stay cool and to therefore hunt throughout the day.

Early humans went from bodies covered in hair (Ex. Chimpanzee) to having mostly hairless bodies, excluding the heads and other areas.

The last option water because it is slow