To protect them from ultraviolet rays from the sun.
Genetic Drift Defined. Populations of organisms are constantly changing and adapting to their environment. Drastic changes in environmental conditions can sometimes cause drastic changes to the gene pool of the population. Genetic drift is when chance events cause changes in frequencies of alleles in a population.
The sun gives off light energy to plants. Light is required for plants to perform photosynthesis. And the plant provides nutrients for organisms such as humans. Some of those other organisms the plant provides nutrients for, we humans consume.