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Overview:
The Genographic Project, a partnership of the National Geographic Society and IBM, is a five-year study to understand the human journey—where we came from and how humankind came to populate the planet. Led by population geneticist Dr. Spencer Wells and a team of international scientists, this unprecedented effort will map humanity's genetic journey through the ages. The project relies on the identification of genetic markers—occasional mutations to DNA that are passed on through generations. Different populations carry distinct markers. Following them through the generations reveals a genetic tree on which today's many diverse branches may be followed ever backward to their common African root. Scientists are collecting this data from people across the globe, particularly indigenous populations, before modern globalization further erodes the cultural groupings that could provide the geographical and historical context for interpreting the diverse genetic patterns.
This is the second in a set of lessons exploring migration, genetic markers, markers in context, Genographic's legacy, and genographic data. In this lesson, students will review background information about the basics of DNA and chromosomal structure. They will then explore the Genographic Project and the work of lead scientist Dr. Spencer Wells. Using a hands-on simulation activity, they will learn how genetic markers are passed from generation to generation and haplogroups are formed. Finally, they will use the Atlas of the Human Journey to track one genetic marker over time.
Connections to the Curriculum:
Geography, history, social studies, biology
Connections to the National Geography Standards:
Standard 1: "How to use maps and other geographic representations, tools, and technologies to acquire, process, and report information from a spatial perspective"
Standard 3: "How to analyze the spatial organization of people, places, and environments on Earth's surface"
Standard 9: "The characteristics, distribution, and migration of human population on Earth's surface"
Standard 17: "How to apply geography to interpret the past"
Time:
Two to three hours
Materials Required:
Objectives:
Students will
- discuss how genetic information is passed on;
- learn about genetic markers and haplogroups;
- explore the Genographic Project;
- participate in an activity that simulates how genetic information is passed from generation to generation; and
- use the Atlas of the Human Journey to track a genetic marker over time.
Geographic Skills:
Asking Geographic Questions
Acquiring Geographic Information
Organizing Geographic Information
Answering Geographic Questions
Analyzing Geographic Information
S u g g e s t e d P r o c e d u r e
Opening:
Lead the class in a discussion of familial traits (non-personal) that are passed on from generation to generation. Ask students to list some traits that they think are inherited. Write the list on the board or on chart paper. (Examples might include hair color, eye color, height, athletic ability, temperament, etc.) Tell students that genetic information is passed on through genes, and that they will be studying how genetic research is helping scientists unravel the mysteries of human migration over tens of thousands of years.
Development:
Have students explore the Genetics Overview section of the Genographic Project Web site. As students explore the site they should focus on the following questions:
- What is the relationship between chromosomes, DNA, and genes?
- What happens to DNA during reproduction?
- What is the significance of the Y-chromosome and of mitochondrial DNA?
- What are genetic markers? How are these passed on differently through the paternal and maternal lines? Why are they such a reliable means to trace genetic ancestry?
- What is a haplogroup?
After students explore the genetics information, introduce the Genographic Project and the work of Dr. Spencer Wells and his team of international experts. Explain that studying genetic markers gives scientists clues to lineage. That information helps them to understand patterns of human migration over time.
Permanent Markers Activity:
Focus students on the Population Genetics section of the Genographic website. Tell them that they will be participating in an activity that simulates the lineage patterns created as genetic markers are passed on through generations and haplogroups are formed. Explain that the class will work in groups to create a "permanent marker tree."
(Note: This activity models the lineage patterns of genetic markers and is not meant to accurately reflect scale or frequency of mutations in the real world. Students will discuss these differences in the follow-up.)
Divide students into four groups. Give each group one set of colored markers, 50 index cards, and one set of Descendant Randomizer numbers (PDF, Adobe Reader required). Have students cut out the Descendant Randomizer numbers, fold them, and put them into a cup or hat. Explain to the students that the numbers they draw represent the number of "descendants" during a turn.
Have each group do the following:
Round One
- Start the simulation by writing "1" on one side (back) of a blank index card.
- Draw a unique symbol (such as a heart, star, circle, etc.) on the other side (front) of the card.
- Pull a number from the Descendant Randomizer "hat" (if you draw a zero in the first few rounds, draw again. After the first few rounds, a zero means no descendants.)
Round Two
- Take one index card for each descendant. Write a "2" on the back of each card.
- Draw the "inherited" permanent marker symbol from round one on each descendant card. Additionally, if the number you pulled from the descendant randomizer hat was red, draw a new symbol on one of the cards to introduce a new permanent marker into the game.
- Place those cards directly below the card from round one in a hierarchical tree structure, similar to the Genetic Diversity interactive diagram in the Population Genetics section of the Genographic site (the first card should be at the top with its "descendants" directly beneath it, and the descendants of those cards directly beneath those, etc.).
- For each card in round two, pull one number from the descendant randomizer hat.
Round Three
- For each card in round two, take one index card for each descendant and write "3" on the back of each one.
- Draw the symbol or symbols inherited from the corresponding round two cards. If you pulled a red number, add an additional symbol to one card to introduce a new permanent marker into the simulation (be sure that each new symbol introduced is unique and has not been used before).
- Place those cards directly under the corresponding round two cards in the tree structure. (At this point, you should have one card from round one, one to three cards from round two, and one to nine cards from round three).
- For each card in round three, pull one number from the descendant randomizer hat.
Rounds Four to Ten
- Repeat steps eight to eleven (noting the corresponding round number on the back of each descendant card) until you have approximately 15 to 20 cards in your final round.
Remind students that as they work they should be arranging their index cards into a tree structure. When each group has finished their simulation, have them draw their "permanent marker tree" on a piece of paper. This chart will be used in the next part of the activity. Then, have students swap sets of index cards with another group.
Using their understanding of how genetic markers are passed on, have students attempt to arrange their classmates' set of cards into a permanent marker tree without looking at the round number on the back. Students will find some parts of this task easier than others, but allow them first to work through as much as they can before addressing these challenges. Then, discuss the task with students and have them identify what they can and cannot determine with the information they have. Students will find that they can identify the various sets of symbols and can organize these into a lineage by following the patterns of change as cards branched out and accumulated different sets of symbols. However, they will also struggle with the duplicate cards. They can determine the branch of the lineage tree to which a card relates, but they cannot necessarily determine precisely in which round those descendants occurred. Tell students to draw a diagram of what they can tell about the lineage from the information they have. (Note: they should end up with lineage trees, illustrating the branches of each permanent marker symbol combination, rather than complete family trees, which show the number of individuals per generation that make up those branches.)
Now have students take the original diagram made by their classmates and compare its tree with their own. In what ways are they similar and in what ways are they different? Students should note that the original trees detailed the relationships between individuals, while their trees highlight the relationships between groups.
Next, have students consider time as a factor in the simulation. Allow them to turn over the cards to find out the earliest round in which each new marker symbol first occurred. Have students recreate their lineage trees by adding a time line showing the number of total turns and plotting the tree according to the first occurrence of each new branch. What does the dimension of time illuminate about the lineage pattern? Does it impact how they view the relationship between the branches?
Reconvene as a class and ask the students:
- How was this simulation similar to and different from population genetics on the scale and complexity of Genographic? In what ways were the permanent marker lines of lineage similar to haplogroups? How are permanent markers like or unlike genetic markers?
- Do all descendants of a particular individual receive their genetic markers?
- How might this help scientists understand how people from different time periods are related? How might this help them understand how people from different places are related?
As explored in depth in the lesson Genographic: Mapping the Human Journey, the Genographic Project traces the migration of our human ancestors across time and geographic location. To do this, the project uses the occurrence of genetic markers as "signposts." Have students consider what this means based on their experience in the simulation. You may also use the Atlas of the Human Journey for reference. The following questions may assist the discussion:
- How does time factor into retracing the lineage pattern? How might this information give scientists clues about migration?
- What might it mean if the same genetic markers were found in populations in Russia, Alaska, and California?
- How might a scientist use genetic markers to determine where an isolated South Pacific island population originated?
- In what ways is the diagram created in the second part of the activity, showing marker branches, similar to the lineages traced on the Atlas? In what ways is it different? How does the scale compare? How does time compare?
Closing:
Have students use the Atlas of the Human Journey to "track" one of the identified haplogroups over time. Students should begin by examining the most recent period of the atlas to choose a group of interest to them. They can then trace its journey back through the time periods to learn more. Students should write a brief history of their chosen group covering where and when it first appeared and how it is related to the original African haplogroups (Y-chromosome African haplogroups represented by the mutational markers: M168, M91, and M60; and L1, L2, and L3, if they chose to follow a mitochondrial line). Students should note which other groups it is related to, including modern-day descendants. They should also describe the group's migration pattern through time, considering possible causes—natural, cultural, and anthropogenic—of migration (in the atlas, the Genetic Marker descriptions [viewed by clicking on the migratory path of the haplogroup], Journey Highlights icons, and Era Overviews may provide some information).
Suggested Student Assessment:
Ask students to design a poster presentation about the Genographic Project for younger students (such as 6th graders). The posters should use text and images to explain to a younger audience about DNA and genetic markers and how genetic information is passed on. Include the example of the group they tracked over time during the closing activity above. Students should do research to see how a variety of science education organizations explain complex topics to younger groups. Some suggested sites include:
Posters should demonstrate student understanding of the topics. Extending the Lesson:
- Educators, learn more about your ancient ancestors by participating in the Genographic Project. Have students help you track your results over time.
- (Highly recommended) Have students see the film Journey of Man, highlighting Dr. Wells's earlier work on tracing the human family tree, which led to the Genographic Project. (Note: this film is included in the Genographic Project Participation Kit DVD). Students might also read all or excerpts of Spencer Wells's book The Journey of Man: A Genetic Odyssey.
- Have students explore the science of genetics in-depth by accessing the Morgan Genetics Tutorial (named in honor of pioneering geneticist Thomas Hunt Morgan).
- Have students visit the Canadian Wildlife Service's page on Wildlife Conservation Genetics to learn how genetic markers can be used to help conserve wildlife.
- Get involved. See "Migration: The Human Journey" at Geography Action!, National Geographic's annual conservation and awareness program.
- Visit EdNet, National Geographic's Teacher Community, to access peer-suggested resources and ideas related to human migration. Post your own ideas, resource suggestions, and class projects to share best practices with other educators.
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