The Evolution of Human Skin Color

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

The Evolution of Human Skin Color by Annie Prud’homme-Généreux Life Sciences Quest University, Canada

Part I Skin Cancer
“Stop it!” called Tatiana, playfully. Her boyfriend, Zach, was inspecting her skin very carefully. “Look,” he answered her, his voice taking on a more serious tone. “Today a woman walked into the clinic for her annual physical. Everything about her seemed ne. She leads a balanced lifestyle, she eats well, she exercises: she’s healthy! But as she was about to leave, I noticed a mole on her arm. It had many of the warning signs of skin cancer. So, I removed the mole. is woman now has to wait for the lab results to see if it was cancerous. If it is, maybe we caught it early enough to treat it, and maybe not. Either way, her life is changed. I just want to make sure you don’t have any suspicious moles, okay?” Tatiana relented and allowed Zach to examine her skin. She asked: “Do only white people get skin cancer?” “No, people of all skin tone can get skin cancer, but it does occur more frequently in Caucasians.”

Questions
1. What are the causes of skin cancer? 2. Why are Caucasians more at risk of skin cancer than other populations? 3. At what age does skin cancer typically occur? Is the incidence of skin cancer greater in youth or old age?

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e Evolution of Human Skin Color” by Annie Prud’homme-Généreux

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NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

Part II Skin Pigmentation and UV Light
Why are human populations di erently pigmented? What caused the evolution of an array of di erent skin colors?

Humans Were Initially Lightly Pigmented
About seven million years ago, humans and chimpanzees shared a common ancestor. Since that time, the two species have evolved independently from one another. It is generally assumed that chimpanzees changed less over that time period than humans—because they have remained in their original environment. Chimpanzees are therefore

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