Biology & Life Sciences Chapter 8 Homework Deficiency Estimated The World Health Organization

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LABORATORY MANUAL AND WORKBOOK FOR BIOLOGICAL

ANTHROPOLOGY INSTRUCTOR’S MANUAL

Lab 8: Modern Human Variation

ANSWERS TO LAB 8 CONCEPT REVIEW QUESTIONS

Northern Europe, or Eastern North America).

shape, or elongated shape).

(not South America, Australia, or Southern Africa).

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8. B. Populations that have a history of raising dairy animals will more commonly have

lactose tolerance; lactose tolerance is not common among people that live near the

GUIDE & ANSWERS TO LAB 8 EXERCISES

Exercise 1: Clinal Distributions (10 minutes)

We learned in this lab that skin color has a clinal distribution. This is true for many of our other

traits as well.

1. Identify one human trait, other than those discussed in this lab, that you think has a clinal

distribution.

2. Why do you think this trait varies in different individuals and populations? (Does it

provide advantages in certain environments, or might it improve reproductive success?)

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3. How would you study this hypothesis? What data would you collect about the trait?

4. What data would you collect about the evolutionary context (such as the environment or

reproductive rates)?

Exercise 2: Skin Color Variation (10 minutes)

Recent research has identified a gene (SLC45A2) that codes for a protein that affects melanin

production in humans and other animals. A mutation in this gene has given rise to two variant

alleles. The L374 allele correlates with darker pigmentation, and the F374 allele correlates with

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lighter pigmentation. Researchers collected DNA samples from people in 14 European, Asian,

and African populations and identified the frequency of the F374 allele in these groups. Review

the data in the chart and answer the questions that follow.

1. In what populations do we see the highest frequencies of the F374 allele for lighter

pigmentation?

2. In what populations do we see the lowest frequencies of the F374 allele for lighter

pigmentation?

3. The map shows the ancestral locations of the populations studied, superimposed on Figure

8.2, a map of regional skin color variation. Are these results what you would expect based on

the skin color information in the map? Why or why not?

For the most part, yes. The European and Turkish populations have lighter skin

4. Why might some light-skinned populations, such as the Japanese, be missing the F374

allele for lighter pigmentation? (Hint: Consider the various forces of evolution that may be at

play.)

Many factors could be considered. First, pigmentation is a complex polygenic

Exercise 3: Altitude Adaptation (10 minutes)

You and your fellow classmates have decided to take a vacation to the Andes in South America.

You plan to spend 2 weeks hiking, camping, and exploring the area.

1. While you are there, you can expect to undergo some acclimatization to this higher

altitude environment. Describe one of these possible acclimatizations.

2. Why would your body undergo such a change? What benefit or benefits does this

acclimatization afford while you are vacationing at high altitude?

3. Several weeks after you have returned home from your vacation, can you expect to still

have this acclimatization? Why or why not?

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4. While you are in the Andes, you notice that local people seem to be better adapted to the

high-altitude conditions than you are. Describe one of their possible adaptations.

5. If someone with this adaptation were to come visit you in a lower altitude, would they

lose their adaptation? Why or why not?

Exercise 4: Climate Adaptation (10 minutes)

PART A: Examine the images provided by your instructor (or the image in the Lab 8 Exercise

Image Library).

1. Is this person adapted for a cold climate or a hot climate?

2. Describe one trait that helped you make this determination.

3. Is this trait related to Bergmann’s rule or Allen’s rule?

PART B: Examine the material provided by your instructor (or the image in the lab Image

Library).

1. Is this person adapted for a cold climate or a hot climate?

2. Describe one trait that helped you make this determination.

3. Is this trait related to Bergmann’s rule or Allen’s rule?

Exercise 5: ABO Blood Group (10 minutes)

Review Figure 8.6 (on p. 235). Use this information, as well as your understanding of the forces

of evolution, to answer the following questions.

1. Many populations throughout central Eurasia share high frequencies of the B allele. What

does this pattern suggest about the evolutionary history of these populations? Describe

the evolutionary force that probably caused this trait distribution.

2. The O allele is unusually frequent in the Americas. What does this pattern suggest about

the evolutionary history of these populations? Describe the evolutionary force that

probably caused this trait distribution.

Exercise 6: Overlap of Multiple Traits (10 minutes)

You are conducting a survey about human variation at the bus station. While conducting your

survey, you meet a very large tour group of adult college students. The tour group has a high

number of people who are carriers of the sickle-cell trait and a high number of people who are

lactose tolerant.

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1. Why would a population have a higher number of people who are carriers of the sickle-

cell trait? (Consider factors such as economic practices, location in the world, and

history.)

2. Why would a population have a high number of adults who are lactose tolerant?

(Consider factors such as economic practices, location in the world, and history.)

3. Based on these adaptations, what can you suggest about the group’s geographic or

cultural background? (Be as specific as possible.)

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4. If you had data about only one of these traits (sickle-cell or lactose tolerance), how might

your answer to Question 3 above be different?

Exercise 7: The Sickle-Cell Trait and G6PD Deficiency (10 minutes)

Glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency) is an inherited disorder

where either the body has less of the G6PD enzyme than normal or the available G6PD is not

functioning correctly. This deficiency affects red blood cell function and may result in anemia

(the destruction of red blood cells) when people with the condition have infections, are taking

certain medications, or eat certain foods. People with G6PD deficiency may have some

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protection from malaria because their abnormal red blood cells interfere with the reproduction of

the malaria parasite in their bodies.

1. Consider the prevalence of G6PD deficiency estimated by the World Health Organization

(WHO) as shown in the map. Compare the distribution of G6PD deficiency with the

distributions of the sickle-cell trait and malaria shown in Figure 8.9 (on p. 238). What

similarities between these distributions do you notice? What differences do you notice?

Similarities: G6PD deficiency and sickle-cell trait are high in Africa, particularly

2. Why might these similarities and differences exist? Be sure to consider the evolutionary

context (including the natural environment, cultural practices, and interbreeding).

Sickle-cell and G6PD deficiency may both afford some protection from malaria, so

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Exercise 8: Variation in the ADH1B Gene (10 minutes)

The ADH1B gene is one of the genes that codes for alcohol dehydrogenase (ADH)—an enzyme

that helps in the digestion of alcohol. A variant of this gene, called the ADH1B*47His allele,

helps metabolize alcohol faster than other variants of the gene, thus reducing the amount of

alcohol that saturates the bloodstream. It also causes a negative side effect, where a person’s face

flushes red when he or she consumes alcohol. This allele is rarely found in African or European

populations, but it is very frequent in East Asian populations, where it is often found in more

than 50% of the population and may even be found in almost 100% of people in certain

populations. These East Asian populations also have a long history of growing rice and making

fermented rice beverages that extends as far back as 12,000 years before the present (BP). The

map shows the frequency of the ADH1B*47His allele in East Asia. Sites where evidence of rice

cultivation has been found are superimposed on the map.

1. Given what you know about the evolutionary forces behind human variations, how would

you explain the distribution of the ADH1B*47His allele? Why do you think this allele is

common in East Asian populations? Do you see a relationship between rice cultivation

and allele frequency? Hint: Consider the benefits and drawbacks of consuming alcoholic

beverages and how this might factor into the evolution of the ADH1B*47His allele.

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Exercise 9: Body Mass Index (10 minutes if using known measurements; allow extra time if

students are taking height and weight measurements in class)

One way to measure obesity and other weight categories is called body mass index (BMI).

Calculate your own body mass index using this formula:

[Weight in pounds / (height in inches × height in inches)] × 703 = BMI

For example, if you are 5 feet 6 inches tall and weigh 120 pounds, your BMI is

[120 / (66 × 66)] × 703 = 19.4

STEP 1: Calculate your BMI. Using the formula above, calculate your own body mass index

(BMI). If you have access to a scale and measuring tools, take current measurements of your

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STEP 2: Make comparisons. To answer the following questions, use the BMI database compiled

by the World Health Organization at

http://gamapserver.who.int/gho/interactive_charts/ncd/risk_factors/bmi/atlas.html. This site

shows mean (average) BMI data for adults around the world. If you scroll over or click on a

country in the map, it highlights the country’s data on each chart.

1. How does your BMI compare to the mean (average) for adults in the United States?

2. A person is considered overweight if their BMI is ≥ 25. How does the mean (average)

for adults in the United States compare to this standard?

3. Looking at the worldwide map for mean (average) adult BMI, what trends do you

notice?

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4. Why might there be regional differences in BMI?

5. What are the implications of these trends for worldwide health now and in the future?

ANSWERS TO LAB 8 CRITICAL THINKING QUESTIONS

1. Student survey data will vary. In general, they should document that not everyone agrees

on what traits to use. Some people will use only physical traits (such as body type), while

others will also include cultural traits (such as language). Some traits (such as skin color)

will be more common, while other traits (such as eye color, nose shape, or hair texture)

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2. The peopling of the Americas is a classic example of a founder effect. The Americas

were settled recently (within the last 15,000 years or so) by subsets of populations from

3. Answers regarding high-altitude adaptations will vary, depending on the students’

research, but they are likely to mention such characteristics as the Tibetan circulatory

system, which allows for greater blood flow and oxygen movement (although this does

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4. Lepus americanus is adapted for a cold climate, and Lepus californicus is adapted for a

hot climate. L. americanus has a short, stocky build (with a large body size relative to

surface area and relatively equiaxed form with shorter limbs and ears). L. californicus has

5. Lactose tolerance: Humans began concentrating on the dairy products produced by their

herds, not just the animals’ meat or labor potential. This is a shift in cultural practices.

This shift, however, creates an environmental context where adult lactose tolerance is

selectively favored as protection from malaria. Again, humans impacted the

6. Answers will vary greatly, but students should recognize that lighter skin color indicates

nonequatorial areas, darker skin color indicates equatorial areas, lactose tolerance

indicates European areas, lactose intolerance indicates non-European areas, short and