1. Black and White: an adaptation
Why are people different colors?

2. The short answer is: different amounts of melanin
The short answer is: different amounts of melanin. Melanin is a pigment that absorbs UV light

3. 4.5 – 2 million years ago people lived in the savanna.
The savanna is hot … and sunny

4. Advantages of being black or: natural selection pressures for black skin
Dark skin blocks more UV radiation
Too much sunlight decreases the amount of vitamin B (folate) in the body. In pregnant women, low vitamin B can cause infants to be born without a full brain or a spinal cord.

5. When people started to move to less sunny areas
When people started to move to less sunny areas... Evolutionary pressures changed

6. Advantages of being brown or: natural selection pressures for lighter skin
Lighter skin absorbs more UV radiation.
The body needs sunlight to produce vitamin D. Without vitamin D, the body cannot store calcium in the bones and people develop rickets.

7. But skin too light may mean too much UV radiation, excess vitamin D and excessive calcium build up... calcification of soft tissues

8. So: Where are white people
So: Where are white people? Skin color of indigenous people around the world

9. White are de-pigmented (with no melanin) people that originated in Scandinavian countries.

10. Typology: pre-scientific idea that there are different “types” of people.