Name _______________________
Period___________
Human Diversity: How different are we?
Objective: SWBAT utilize genetic evidence to determine whether phenotypic differences can be
utilized to categorize individuals by race.
QUESTION: Our eyes tell us that people look different. But is this difference “only skin deep”?
Is race a genetic (and therefore biological) category or a social category?
Geneticists, anthropologists, and biologists are unlocking human variation and the evolution of
our species. Let's see what they're finding out:
FIRST: Test what you know about human diversity. Answer the following questions before
beginning this activity
1. Is the human species old or young as compared to most species?
A. Old
B. Young
2. Does this mean we have A. high or B. low variation as compared to other species?
3. How do natural selection, sexual selection, and selective breeding affect variation?
A. increase
B. decrease C. have no effect
4. What is the “driver” of variation?
a. natural selection b. sexual selection
c. selective breeding d. mutation
5. What in the lifestyle of humans contributes most to the genetic similarity across human
populations?
a. staying within a community b. mutation c. migration c. natural selection
6. What caused differences in skin color?
a. community isolation
c. UV radiation climate change
d. we don’t know
7. What determines whether the sickle-cell trait exists in a population?
a. If the population is African
b. the incidence of malaria c. blood type
8. If we could go back into our ancestry 2000 years (35-45 generations), how many of your
classmates might share at least one common ancestor with you?
a. 5
b. 10
c. 15
d. 20
9. Which continent has the highest genetic diversity?
a. North America
b. South America
c. Africa
d. South America
10. Is genetic diversity larger within a continent or between continents?
a. within continents
b. between continents
11. Are there more genetic differences within races or between races?
a. within races
b. between races
Name _______________________
Period___________
Go to
http://www.pbs.org/race/004_HumanDiversity/004_00-home.htm
Choose : Explore Diversity. Read the intro slide, and then select Our Idea of Race.
1. How did ideas about “distinct” races arise?
2. What is a cline map?
?
Wander through the topics in the Explore Diversity Window
1. What do you learn from the cline map of skin color?
2. What physical characteristics show clinal variation? Why do you think this variation might exist?
(you may want to read the geographic origin section first)
3. Return to the Diversity menu and Choose Geographic Origin. Be sure to read the “READ
MORES” Why do we perceive distinct races when the maps actually show that characteristics
attributed to race (and those that were measured by Germans during the Holocaust as
determinants of “racial categorization (Jews, Blacks, Gypsies) ) are actually clinal (they change
gradually)?
4. Each menu within Geographic Origin provides examples which highlight why humans are
genetically similar. But what is/are the common event (s) that occurred to promote genetic
similarity across the human species?
Name _______________________
Period___________
5. Click the conclusion button. Given what you have learned about traits that are used to describe
“race”, create a pro/con chart about the validity of using physical measurements (such as nose
width, skull width and hair and eye color to “categorize” individuals. They are measures, but
can they be used as measures to categorize?
6. Return to the Diversity Menu and choose Genetic Similarity. How much of our DNA is the same?
Is the amount that is NOT the same (i.e. the variation) primarily due to differences in race?
Explain.
7. Finally, go to the RACE website (American Anthropology Association)
http://www.understandingrace.org/humvar/index.html
View: a. The Human Spectrum (and consider the two questions at the end). Return to the main
menu using the Menu button.
b. Race and Human Variation.
1. There are three different concepts of race. How is the “actual (real)” variation
between the three “race categories” different than the population concept and the essentialist
concept?
2. Explain the animation of the distribution of human genetic diversity over time. (The
time is shown on a “clock” in the bottom left hand corner of the screens. Where is genetic
diversity the highest? How does the diversity change as you move away from this point?
Name _______________________
Period___________
Finally, read the section, Only Skin Deep. Identify selective reasons (environmental and dietary
as to why skin pigmentation varies over the globe, and why dietary factors and the environment
may play a role in the variation.
AS A GROUP (Summary Activity)
8. Create a small poster (bulleted list) summarizing what you have learned (or validated) about
genetic variation and race. Be sure to include information you learned during this activity (use
the starting quiz questions as a guideline). Be quantitative when discussing DNA similarities.
Name _______________________
Period___________
HOMEWORK
Why do Human Race Concepts Persist?
There are several reasons why simple race concepts continue to be used, despite their
poor fit to the actual pattern of genetic variation.
First, the large body of DNA data that reveals the nested structure of genetic variation
among human groups became available only recently. These data are side benefits
from advances in molecular biology and gene mapping. Before this, there were not
enough data to reveal the asymmetrical distribution of genetic variation.
Second, many current studies are focused on the distinctiveness between groups, or
the percent of individuals that can be correctly assigned to their population of origin (1,
42, 48). Classification is the principal concern of these studies. The fact that accurate
classification is possible with a great deal of variation within groups is not a mystery. It is
expected when a large number of traits can be measured and computers perform heavy
computation without effort.
Unfortunately, the results from classifying individuals are equally compatible with
essentialist and population concepts of race. They hide the nested pattern of variation in
DNA that typifies human populations.
Third, many people in both the lay and scientific communities use what I call the implicit
definition of race (12). In this view, races represent a pattern of variation that is difficult
to pinpoint but clear to most people. It is impossible to assess or refute this definition.
Because the implicit concept is so fuzzy, it is easy for its users to unwittingly fall back on
typological race thinking.
Fourth, recognizing genetic differences among groups can be useful
in medicine and public health. Organ transplantation requires careful genetic matching.
Failure to recognize genetic differences among populations can create spurious results
in genetic epidemiology and mapping disease genes. While some investigators argue
that race is a reliable and useful proxy for the pattern of genetic differences (3, 45, 57)
others are quite skeptical (10).
There is a lively discussion ongoing about the utility of race as a variable in health and
medicine (25, 34, 56, 58, 61, 64). Despite the imperfection of race concepts for
describing patterns of genetic variation, a universally accepted alternative does not
exist.
QUESTION: Are there truly “group differences” between races? Why or when is
categorization important?