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 1-4

• 15 bullets

How We Get Our Skin Color 11m31s-18m07s

5

https://www.youtube.com/watch?v=hFw8mMzH5YA

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 youobserve.

• 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 befound in those areas)?

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

18

19

Classwork

• Read Science Line: The Skin We’re In

• Read Dark Skin May Have Evolved to Protect Against Skin Cancer

NO HIGHLIGTHING- CLASS SET20

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 activity22

Log-In How To

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 1234567890– pgeor7890@rowlandschools.org

• Password: Full student ID (10 digit) – e.g. 1234567890