ANTH 103 Lecture Notes - Lecture 4: Lactose Intolerance, Lactase, Lactase Persistence
Document Summary
The only mutations that are heritable occur during meiosis (the formation of gametes) The original source of variation in a population is mutation. Changes in frequencies of certain traits in populations between generations due to differences in reproductive success between individuals. Added hats and cultural haircuts, etc. to distinguish instead of looking at strictly biological factors. Skin color is an adaptation for different environmental contexts. Color is due to amount of melanin and melanosomes produced in melanocytes. Human skin color shades vary with intensity of uv radiation. Too much uv radiation can damage skin cells not protected by melanin/melanosomes. Some uv exposure is necessary to catalyze vitamin d production in the skin. Vitamin d deficiency can lead to rickets, a disorder in which bones are poorly mineralized. Variation is the result of two competing selective pressures. 1) uv radiation protection in the tropics. 2) adequate uv exposure for vitamin d synthesis.
