Sponge: Set up Cornell Notes on pg. 51 Topic: 6.5 Skin Color Essential Question: Scientifically, should skin color be used when determining a person’s “race”? 2.1 Atoms, Ions, and Molecules 6.5 Skin Color Scientifically, should skin color be used when determining a person’s race?

p. 51 Skin Color Genetic Factors Environmental Factors Physiological Factors

3 Skin Color Heredity and the environment determine skin color All people have approximately the same # of melanocytes in their skin Only difference is the amount of melanin these cells produce- which is controlled by genes More melanin= darker skin Genetic Factors

50 How we get our Skin Color: Video Notes Evolution of Skin Color: Analysis Questions bullets

How We Get Our Skin Color 11m31s-18m07s 5

6 Albinism: People who inherit mutant melanin genes have non-pigmented skin Can be any “race” Or other species 1 / 110,000 people have albinism

7 Interesting Fact: Hopi People in AZ 1/200 have albinism The men with albinism work with women to avoid sunburn Because they are in more contact with women, their genes are passed on frequently Leading to the disproportionate # of people with albinism

Albinism-Caught Between Dark and Light 6m54s 8

9 Environmental Factors Sunlight and UV rays darken melanin Stimulate melanocytes to produce more pigment and transfer it to nearby epithelial cells Leads to a tan Tan will fade unless sun exposure continues

10 Physiological Factors Blood in dermal vessels adds color in skin: Oxygenated= red Vessels are dilated- more blood enters dermis “blushing” when overheated, embarrassed

11 Physiological Factors Blood in dermal vessels adds color in skin: Non-oxygenated= bluish Circulation issues Vessels are constricted- less blood enters dermis Body temperature drop or frightened= pale

12 Yellow pigment- usually shows the liver is not functioning properly Jaundice Cirrhosis of the liver

Jaundice What is Jaundice 1m34s Neonatal Jaundice 2m39s 13

14 1. Does the amount of UV light reaching the Earth vary in a predictable manner? If so, describe the pattern you observe. 50

15 2. What latitude receives the greatest amount of UV light? The least?

16 3a. Based on this data, WHERE might you expect to find the most lightly pigmented and most darkly pigmented people on the planet? Be as specific as you can. (i.e. Poles/Equator/North/South/Specific countries etc.)

17 3b. Provide a rationale to your answer above (i.e., why did you think that more darkly pigmented people would be found in those areas)?

Global Map of Indigenous skin colors Please get a blank map 18

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Classwork Read Science Line: The Skin We’re In Read Dark Skin May Have Evolved to Protect Against Skin Cancer NO HIGHLIGTHING- CLASS SET 20

Table Talk What was the reason for genus Homo hair loss over time? How does skin color act as “natural sunscreen”? Why did skin get lighter as people moved away from the equator? Why is skin cancer generally not thought to be a driving factor for the evolution of skin color to darker shades?

Skin Color Web Activity Purpose: To explore how the sun’s intensity has contributed to variations in human skin color You will use two websites today: Understandingrace.org PBS.org/race Follow the directions to complete the activity 22

Log-In How To User ID: User ID: First initial, first four letters of the last name and the last 4 digits of student ID –Phil George with a student ID of Password: Full student ID (10 digit) –e.g