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Unformatted text preview: o Adaption- something that enhances the survival and reproductive success of an organism
in a particular environment.
o Skin color not adaptive
▪ Adaptations to protect against skin cancer happen later in life, after reproduction,
will not pass on to children
▪ Skin color is a side effect for selecting for something else, result of sexual
o Skin color is adaptive
▪ Melanin pigmentation varies by latitude, darker skin protects against UVR, light
skin absorbs more UVR
▪ Darker skin protects against the deleterious effects of UVR (e.g.,sunburn,
damage to sweat glands, skin cancer)
o Skin color measured by skin reflectance, higher reflectiveness lighter
o Skin color from Melanin (natural sunscreen)
▪ Carotene (orange)
▪ Hemoglobin (red)
o The history of skin color in the human lineage can be understood by looking at skin color
in our close relatives.
o MC1R gene
● “Melanocortin 1 receptor makes a protein that affects the color of skin and hair. At this locus,
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- Spring '08
- The American