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For Educators
Intro Lesson Plan 1 Lesson Plan 2 Lesson Plan 3
  by Ashlinn Quinn
  • Overview
  • Procedures for Teachers

    INTRODUCTORY ACTIVITY

    1) Tell the students that you'd like to know what they know about tracing family histories. Ask them if they can tell you how people usually go about tracing their ancestry. For example, if you wanted to find out who your great-great-great-grandmother was, how would you find out? Who would you talk to, and what kinds of things would you want to look at? (Accept all ideas -- but make sure the students understand that traditional genealogical research is conducted using a combination of oral histories and archival/document-based research.)

    2) Now ask the students: how effective is a search for ancestors likely to be if documents and records prove difficult or impossible to locate? (Answer: Not very effective.) Ask the students if they can think of any circumstances that might result in the unavailability of relevant historical documents. A list might include:

    • Records have been lost due to fire, theft, or damage

    • Important records never existed (for example, older relatives or those from other countries may not have had birth certificates)

    • Identity of biological parents is not known (for example, due to adoption)

    • Family members emigrated from one country to another, resulting in loss of records

    • War, famine, natural disasters or other catastrophes resulted in separation or deaths of family members

    • Etc.

    3) Explain that the students will see a video clip about one group of Americans who might have a hard time reconstructing their ancestry. CUE the videotape of AFRICAN AMERICAN LIVES, Episode Four past the opening sequence to the scene where Henry Louis Gates, Jr. is standing on a beach. He will begin by stating "The West Coast of Africa..." Provide the students with a FOCUS FOR MEDIA INTERACTION: Ask them: "Why will the people shown in the video have a hard time tracing their ancestry?" PAUSE the video after Whoopi Goldberg finishes speaking and the narrator says "But all that is about to change." Ask the students to consider the African American case. Why might African Americans have a hard time tracing their family histories? (The ancestors of many contemporary African Americans were brought to this country against their will during the period of slavery. The forced emigration resulted in the loss of contact with family members in Africa, so family histories, names, and languages were lost.) Ask students if they can think of other groups of people who might have a hard time tracing their ancestry for similar reasons (Student answers may vary, but examples might include refugees from various war zones: Jews who fled Europe during World War II, Southeast Asians who fled their home countries during the Vietnam War, etc.)

    4) Ask students if they have any idea how new technologies might be able to help African Americans and other groups trace their ancestry (Student answers will vary). Ask the students what they know about DNA testing -- what can it be used for? (The students have probably heard of forensic DNA tests that identify criminals using traces of hair, saliva, etc. that are left at the scene of a crime; and may also have heard of paternity testing, which can determine the identity of the father of a child.) Explain that new technologies using DNA testing can also help people identify certain aspects of their ancestry. The tests that are used for the purposes of tracing ancestry must trace our DNA through many generations, covering a much longer time span than the DNA tests commonly featured on television shows like "CSI." When combined with other evidence, these tests can shed light on the geographic areas and ethnic groups from which our ancestors may have originated. This kind of DNA testing can be interesting even to people who think they have a pretty good idea of their family history, as oral histories and documents may not tell the whole story of our ancestry. Often, surprises turn up that may challenge what we think we know about ourselves and our family histories.

    5) FAST FORWARD the videotape to the scene showing a busy freeway. The narrator will state: "The attempt to answer those questions will take me, and the eight guests whose family trees I've been tracing, on the last leg of our epic journey back into history." Provide the students with a FOCUS FOR MEDIA INTERACTION: How do you think scientists will use DNA to help African Americans trace their genetic roots back to Africa? PAUSE the video after the three scientists are introduced and the screen shows Henry Louis Gates, Jr. driving in a car. Ask the students what thoughts they had in response to the focus question. (Students will have to extrapolate from the brief overview in the video, so answers may vary. The basic idea is that scientists have been collecting DNA samples from tens of thousands of people in Africa. They have made a database of this information. By comparing a sample of African American DNA to the database, commonalities between the samples can indicate that the African American person shares ancestry with a particular group of people in Africa).

    6) Explain that the tests that can link African Americans to specific groups in Africa will be explored further in depth a little later. First, the students will learn about a genetic test that is broader in scope. This test is used to break down the percentage of one's genetic heritage that can be traced to different continents of the globe. Genetic ancestry can be traced to the following groups: Sub-Saharan African, European, East Asian, and Native American. Because many people's genetic history includes a mixture of these groups, the test is called an "admixture test." Provide the students with a FOCUS FOR MEDIA INTERACTION: Ask "why was Dr. Mark Shriver surprised by the results of his admixture test?" PLAY the video from the previous stopping point. STOP the video when Dr. Shriver says "She told me to quit talking to the media about it." Ask the students why Dr. Shriver was surprised (Dr. Mark Shriver, a white man, was surprised to learn that his ancestry included 11% African heritage, the equivalent of one great-grandparent being African. He had not known this fact about his heritage). Check for student comprehension -- ask the students if the admixture test determines "race?" (NO -- the origin of our ancestors does not necessarily correlate with the visible features we associate with "race," which is a social construct used to categorize people by the way they look.) You may need to REWIND and REPLAY the last clip to ensure the students understand that admixture testing is NOT a test of "race" -- it merely determines what percentage of our ancestry originates from different continents -- often with surprising results!


    LEARNING ACTIVITY

    1) Tell the students that they will now look more in depth at the admixture tests they have just seen. Distribute the Genealogy Organizer to each student. Explain that the diagram on this organizer is a hypothetical genealogy. It tracks the genetic ancestors of the individual represented at the bottom of the diagram. Point out that this genealogy is NOT a complete family tree. It differs from a family tree in that only information that pertains to genetic heredity is shown. Therefore, the only people shown in the diagram are those that directly contribute to an individual's genetic heritage: his or her parents, grandparents, etc. Have the students follow along as you demonstrate who is included on the chart -- the individual at the bottom has two parents, who each have two parents, who each have two parents, etc. This information does NOT necessarily correlate to a "family," which is much more complicated and might include siblings, aunts and uncles, adopted relatives, marriages that did not result in children, et cetera.

    2) The symbols on the chart are in common usage by anthropologists and other researchers who are interested in studying ancestry. Review the symbols with the students, using the key on the chart. Have the students fill in the information to the right of the chart, working from the bottom of the chart to the top -- the first two levels have been completed already. (Answers: Relationship = parents: 2 ancestors at this level. Relationship = grandparents: 4 ancestors at this level. Relationship = great-grandparents: 8 ancestors. Relationship = great-great-grandparents, 16 ancestors. Relationship = great-great-great-grandparents, 32 ancestors.)

    3) Tell the students that they are going to learn what the admixture results they just saw in African American Lives might indicate about the two scientists' ancestry. REWIND the tape to the point before Dr. Shriver reveals Dr. Rick Kittles' admixture test (he will be pointing at a screen showing a diagram). Provide the students with a FOCUS FOR MEDIA INTERACTION: Ask them to use the back of the Genealogy Organizer to write down the percentages revealed in the admixture tests for both Dr. Rick Kittles and Dr. Mark Shriver. STOP the video after Henry Louis Gates, Jr. asks Dr. Shriver if his results mean that about one in ten of his ancestors were African and Dr. Shriver responds "Yeah. About one great-grandparent." Review the admixture results with the students (Dr. Rick Kittles' admixture test reveals that his heritage is 88% West African and 12% European. Dr. Mark Shriver's admixture test reveals that his heritage is 86% European, 11% West African, and 3% Native American.)

    4) Distribute a calculator and an Admixture Calculation Organizer to each student. This organizer breaks down a genealogy into segments so that students can learn to calculate the percentage of genetic heritage that various ancestors pass on to their descendants. Ask the students to imagine that they are the individual represented at the bottom of each diagram (the "question mark"). In each case, the students will calculate the percentage of their genetic heritage that has been transmitted to them from their various ancestors.

    5) Go through the first example, "one parent," with the students. Ask the students how many ancestors they have at the "parent" level? (Two.) Since the individual at the bottom of the diagram is descended from two ancestors at this level, what fraction of the individual's heritage is inherited from ONE parent? (One out of two, or 1/2: one half). What PERCENTAGE of one's heritage does this one parent represent? (50%. If needed, show the students how to calculate this percentage from the fraction: 1 ÷ 2 X 100% = 50%).

    6) Have the students work alone or in small groups to complete the rest of the organizer. (Answers: One grandparent: 4 ancestors at this level, fraction of heritage = 1/4, percentage of heritage = 25%. One great-grandparent: 8 ancestors at this level, fraction of heritage = 1/8, percentage of heritage = 12.5%. One great-great-grandparent: 16 ancestors at this level, fraction of heritage = 1/16, percentage of heritage = approx. 6%).

    7) Now have the students return to the percentages that they recorded for Dr. Rick Kittles and Dr. Mark Shriver. Start with Dr. Rick Kittles, who has 88% African heritage and 12% European heritage. Tell the students that the admixture test cannot determine which of Dr. Kittles' ancestors contributed his European heritage. Nonetheless, the percentages revealed by the admixture test provide us with information that can be used to make educated guesses about our genetic relatives. Ask the students what this admixture might mean in terms of Rick Kittles' ancestry? (Student answers may vary, but the simplest explanation would be if one of Rick Kittles' great-grandparents was European and all the rest were of African origin: with this ancestry, he would end up with approximately 12% European heritage. The same percentage could be gained in other ways, for example, two unrelated great-great-grandparents who were European would each contribute 6% to Rick Kittles' genetic heritage, adding up to 12%).

    8) Proceed to Dr. Mark Shriver's results. Ask the students how the 3% Native American heritage in his admixture results could have been passed on through the generations? (Student answers may vary, but this number could result from one of Dr. Shriver's great-great-great grandparents being 100% Native American in origin). Dr. Shriver's results also indicate 11% African heritage. As he says in the film, this number could be the result of approximately one of his great-grandparents being of African origin. Ask the students what percentage they would expect Dr. Shriver's results to indicate if this great-grandparent were 100% of African origin? (One great-grandparent contributes 1/8, or 12.5%, of Dr. Shriver's heritage). Since the African component of Dr. Shriver's results is slightly less than 12.5%, it indicates that Dr. Shriver's ancestry is a little more complicated than the above scenario implies -- for example, such a result might indicate that his great-grandparent was not 100% of African origin.


    CULMINATING ACTIVITY/ASSESSMENT

    1) FAST FORWARD the video until a scene showing a laboratory comes to the screen and the narrator states "Today, however, we don't have to guess about our African origins" (this will be after a scene showing Chris Tucker sitting with his father). Provide the students with a FOCUS FOR MEDIA INTERACTION: Ask them to list the two DNA tests that are discussed in the clip. STOP the video after haplotypes are discussed and the narrator states "A match means that we've found someone with whom we share a common ancestor." Review the clip with the students: what were the two tests discussed? (Answers: the first is a test of mitochondrial DNA, passed on through the mother; and the second is a test of Y-chromosome DNA, passed on through the father.)

    2) Remind the students that they have learned about three types of DNA testing by watching the video clips. Ask them to name all three (Answers: admixture testing, mitochondrial DNA testing, and y-chromosome testing). Tell the students that they will learn more about these three types of DNA testing by consulting the companion Web site to African American Lives. Divide the students into groups of three or four students each, and assign each group ONE test (either admixture, y-chromosome, or mitochondrial DNA) to investigate. Provide the students with a FOCUS FOR MEDIA INTERACTION: tell them to research their assigned DNA test and be prepared to explain it to the class. Provide scratch paper for the students to take notes on their assigned DNA test. Direct the students to the "Lineage and Admixture: Testing for Ancestors" Web feature, at: http://www.pbs.org/aalives/science_tests.html. Allow the students ten to fifteen minutes to conduct their research.

    3) Once the class has finished investigating the tests, have the students researching each test explain their assigned test to the class. Ask them questions to assess their understanding of each test: Where is this kind of DNA located? How is this DNA transmitted from generation to generation? Can both men and women use this test? Which ancestor (or ancestors) does it trace? 4) Pass out the What does it Test? organizer to each student. This organizer provides charts that can be used to trace how different kinds of DNA are passed through the generations. Have the students follow the directions to shade in the ancestors who contribute the DNA traced in each test.

    5) Review the organizer with the students (an answer key is provided). Point out the following facts about the tests:

    • The y-chromosome test traces genes on the y chromosome, so only males can use this test. It traces the "patriline" -- from an individual's father to his father's father, to his father's father's father, etc.

    • The mitochondrial DNA test uses DNA that is passed through the mother to all of her children, male and female. It traces back through one's mother to one's mother's mother, etc -- this is called the "matriline."

    • As the students should be able to see from the diagrams, the y-chromosome and the mitochondrial DNA tests each trace the genetic information passed through only a tiny portion of one's ancestors. A lot of ancestors are left out in these tests. The reason these tests are important is that they can trace the patriline and the matriline back for many, many generations, giving us traceable information from our very distant past.

    • The admixture test is more general, and all of one's ancestors are included in the data it reveals. While this may seem to be a superior test for this reason, it reveals less specific information than either of the other two tests. Also, the admixture test is best at clarifying information about our recent ancestors, not those in our distant past.

    6) Ask the students to summarize their knowledge of the benefits and limitations of mitochondrial DNA, y-chromosome, and admixture testing. Are any of these tests a comprehensive test of ancestry? (Student answers may vary, but they should understand that none of these tests provides complete information about ancestry. Mitochondrial DNA and y-chromosome testing provide fairly specific information about the matriline and the patriline, but many equally important ancestors are ignored in these tests. Admixture takes one's entire genetic heritage into account, but can only estimate the percentage of this heritage that originated in various broad areas.)

    7) Given that they are so limited, ask the students why people might still be interested in using these DNA tests? (Again, student answers may vary -- but when used in conjunction with traditional methods like document research, the genetic tests can provide a fuller picture of family history than could be obtained by document research or oral histories alone. Also, some people might not have a rich pool of documents and family histories to draw from when researching their ancestry, so DNA testing could help them find out more about their heritage.)


    CROSS-CURRICULAR EXTENSIONS

    HISTORY/SOCIOLOGY: RACE AS A SOCIAL CONSTRUCT

    Have the students explore "race" and explore that it is a social, not a biological, fact. The AFRICAN AMERICAN LIVES Web feature "Race, History...and Chemistry" http://www.pbs.org/aalives/science_race.html has an introduction to the issue, while PBS' website for "Race: The Power of an Illusion" at http://www.pbs.org/race/000_General/000_00-Home.htm delves into issues of racial construction in further depth -- particularly appropriate are the "What is Race?" section at http://www.pbs.org/race/001_WhatIsRace/001_00-home.htm and the "Human Diversity" section at http://www.pbs.org/race/004_HumanDiversity/004_00-home.htm. As an extension, have the students research and consider instances where the construction of "racial" distinctions has led to serious social ramifications, for example in South African Apartheid, the Holocaust, etc.

    SCIENCE/ETHICS: PROS AND CONS OF GENETIC TESTING

    The most common usage of genetic testing is for medical purposes. Genetic testing can supply us with important information about diseases to which we may be susceptible. But genetic testing also raises ethical concerns because the information produced through these tests can disrupt lives and families, and could potentially be used to discriminate against people known to carry certain genes. Have the students research the pros and cons of genetic testing, and write an essay outlining several benefits and several risks of this technology.

    Here are some websites to get you started:

    National Health Museum: Understanding Gene Testing: http://www.accessexcellence.org/AE/AEPC/NIH/

    BBC News' Gene Testing: The Pros and Cons: http://news.bbc.co.uk/2/hi/health/3015584.stm

    PBS's DNA website: http://www.pbs.org/wnet/dna/ includes a "Hot Science Ethical Challenge" at http://www.pbs.org/wnet/dna/episode4/index.html

    HISTORY OF SCIENCE: HISTORY OF OUR UNDERSTANDING OF HEREDITY

    Our modern understanding of genetics, DNA, and heredity is based on a series of very recent discoveries. Have the students research how our conception of heredity has changed over the ages.

    NOVA's "Understanding Heredity" website at http://www.pbs.org/wgbh/nova/genome/heredity.html traces major breakthroughs in our understanding of heredity.


    COMMUNITY EXTENSIONS

    • Invite a genetic expert (such as a food scientist, population geneticist, or a medical genetic researcher) to the class to discuss how new technologies involving DNA and the genome are being used in their field. See if a tour of their facility can be arranged for the class.

    • Visit a local museum or science center with an exhibit on DNA or the human genome.

    • Conduct interviews with local residents to see how social perceptions of race have affected people's lives.


    ONLINE RESOURCES

    AFRICAN AMERICAN LIVES: "Lineage and Admixture: Testing for Ancestors"
    http://www.pbs.org/aalives/science_tests.html

    This Web feature explores the three genetic tests (admixture testing, mitochondrial DNA testing, and y-chromosome testing) used in the African American Lives broadcast series. The feature begins with a discussion of the location of DNA in our cells, and proceeds to discuss each test in detail, including graphics that trace how ancestry is passed on in each case.

    Find more teaching aids at PBS TeacherSource.


    ABOUT THE AUTHOR

    Ashlinn Quinn is a lesson plan writer for AFRICAN AMERICAN LIVES. She holds a Master's degree in Anthropology, and has been involved in producing educational content for museums, arts organizations, and educational media since 1997. She joined Thirteen in 2005 as an Outreach Producer in the LAB@Thirteen, the station's Educational and Community Outreach department.


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