The previous paragraph was written by me and so of course it's not necessarily completely accurate. This PBS website has a better explanation for the evolution of skin color.
The Biology of Skin Color: Black and White
Humans have spent most of their history moving around. To do that, they've had to adapt their tools, clothes, housing, and eating habits to each new climate and landscape. But Jablonski's work indicates that our adaptations go much further. People in the tropics have developed dark skin to block out the sun and protect their body's folate reserves. People far from the equator have developed fair skin to drink in the sun and produce adequate amounts of vitamin D during the long winter months.
How did early humans adapt to different climates and diets as they split off from other primates and spread across the globe? And what does that mean for humans living today?
A panel of scholars from the fields of genetics and anthropology will present their findings on Sunday February 20th at the AAAS meeting in Washington, DC, as part of a session titled "Humans Without Borders: Evolutionary Processes at Work In Humans and Their Relatives."
The speakers in this session will plumb human and nonhuman primate DNA for clues to our evolutionary past, and what this means for our present. What do we know about our ancestors' movements in and out of Africa, what challenges they met while on the move, and how those challenges leave their mark on us today? Find out answers to these and other questions during the following presentations:
Building bigger brains
Duke University biologist Gregory Wray will talk about some of the genetic and dietary factors underlying brain size differences between humans and our closest living relatives, the chimpanzees.
Penn State anthropologist Nina Jablonski will talk about how the range of human skin colors came to be. Find out how our skin adapted to changing light conditions as our ancestors migrated from the equator to northern reaches of the globe.
University of Pennsylvania geneticist Sarah Tishkoff will talk about how in the past 10,000 yrs, several different populations - all raising cattle or camels in Northern Europe, East Africa and the Middle East - gained the ability to digest milk past infancy into adulthood.
The panel, organized by the National Evolutionary Synthesis Center (NESCent), will take place Sunday, February 20th, from 8:00 AM-9:30 AM (EST) in room 207A of the Washington Convention Center, 801 Mount Vernon Place NW, Washington, DC.
NESCent Director Allen Rodrigo will moderate the symposium. Science journalist Carl Zimmer will serve as the discussant.
Humans Without Borders: Evolutionary Processes at Work In Humans and Their Relatives
Sunday, 20 February 8:00AM-9:30AM
Greg Wray, Duke University
Genetic Links Between Human Diet and Brain Evolution, 8:00 AM
Nina Jablonski, Pennsylvania State University
Human Skin Pigmentation as an Example of the Action of Natural Selection, 8:30 AM
Sarah Tishkoff, University of Pennsylvania
Evolution of Lactose Tolerance in Human Populations in Africa, 9:00 AM
Provided by National Evolutionary Synthesis Center (NESCent)