I recently changed my Inquiry question to Genetics so I can study the how people evolved from what we were into what we are now. I think genetics is a very cool topic too talk about because it explains why their are different races, eye shape, hair color, and other traits that can be found in humans and in other animals. It can describe why humans do what we do and why we are far more intelligent than them.
skin color is designed to match with the temperature and climate of the area of the natives. if you look around the world most people near the equator are of a darker skin color then people from the north.people with light skin repel heat but also hold it in more. Think of it like an insulated cup with coffee in it if you put in the fridge it will cool a lot faster than a cup with no insulation. People with darker skin absorb heat more easily but also lose it a lot faster. they are like the cup with coffee put in the fridge with no insulation.
Hair color evolved for the same reason, as humans evolved they got sweat glands to cool off their bodies during hunting and other activities during the day. as they got sweat glands they lost hair to help cool off their bodies. darker skin was then developed to deal with the high intensity UV rays coming from the sun in Africa. Curly hair is also beneficial to blocking UV rays so people with curly hair were chosen through natural selection and other hair faded away. As people began to migrate out of Africa their dark skin prevented them from getting vitamin D from the sun. once again natural selection intervened changing skin color light and made hair straight to allow more sunlight in to make vitamin D.
Jablonski (2006) agrees that it was evolutionarily advantageous for pre-humans (Homo erectus to retain the hair on their heads in order to protect the skin there as they walked upright in the intense African (equatorial) UV lightUV light of northern regions was too weak to penetrate the highly pigmented skin of the initial migrants in order to provide enough vitamin D for healthy bone development. Jablonski, (2006).