NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE CASE TEACHING NOTES for “When Wilma Met Fred: A Human Evolution Case” by Bruno Borsari, Biology Department, Winona State University INTRODUCTION / BACKGROUND Objectives This case is a modified version of “The Dating Game: A Case Study in Human Evolution” by Shoshana Tobias and Clyde Freeman Herreid, published as part of the National Center for Case Study Teaching in Science’s case collection in 1999. It is organized primarily as a case, but also as a game that is played by all of the students in class. For the game, students anonymously take on the role of a specific hominin and need to select the appropriate mate in the diverse populations of the genus Homo that lived during the Pleistocene (1.6 million years ago to 10,000 years ago) by paying attention to clues given by the instructor. The case is a “clicker case.” It is presented in class using a series of PowerPoint slides that are punctuated by questions (aka “clicker questions”) posed by the instructor that the students must answer. Through the PowerPoint slide, students are introduced to the Pleistocene epoch and then to Pleistocene hominins. The Pleistocene is a geological epoch of great interest for human evolution because during this time-frame our ancestors evolved all of the characteristics that make us distinctively humans. The focus of the case is on the physical and cultural differences among this group of hominins. This information prepares students for the game that is played in class, which requires that they understand and can differentiate among the traits of early humans of the genus Homo. The case is designed to be taught at the end of an evolution unit of the curriculum. Though not essential for this exercise, it would be useful if students were familiar with concepts such as genetic drift, mutation, gene flow, and nonrandom mating, and have basic knowledge of evolution. With this background, the instructor could pursue issues such as what forces might have driven the evolution of specific traits in early humans. Developed for a non-majors’ introductory biology course, the case is also suitable for courses in evolution, natural history, biological anthropology, and general biology for majors with modifications. Through this case study, students will practice the following skills: • Understand the environment—both physical and social—in which early humans and their recent ancestors evolved and how this has led to what we think of as uniquely human characteristics. • Learn the physical and cultural differences among early hominins of the genus Homo. Case Teaching Notes for “When Wilma Met Fred” by Bruno Borsari Misconceptions • The extinction of early hominins was necessary to allow the evolution of modern humans. CLASSROOM MANAGEMENT This case was written for an introductory biology class (non-majors) with 180 students and access to a student response system (“clickers”). It can be completed in a single 50-minute class period. Students in my class normally work in permanent groups, but the case can be used with or without such groups. The case consists of a PowerPoint presentation (~1.3MB) that is shown in class. In addition, there are several handouts associated with the case. One of these handouts students complete as homework, while the others explain the game and assign students a species role to play. There is also a handout that is used by the instructor when the game is played. The handouts are included at the end of these teaching notes. The PowerPoint slides tell the fictitious story of a group of students who have traveled abroad with their instructor, who is a paleontologist, to Tanzania to learn more about the origin of humans. The case concludes with a classroom game that mimics modern TV shows where people look for an “ideal soul mate.” Students prepare for the game in advance, but the game is played in class. To prepare for the game, students are assigned a species beforehand, which they do not disclose to anyone else in the class. Their homework assignment (see pre- Page 1 NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE class assignment handout at end of notes) is to research that species. In class, the game challenges students to identify in the audience mates of the same species through a set of characteristics/clues that are disclosed by the instructor in a “quiz” show format. The game is entertaining at the same time it is educational, and facilitates student learning of the often challenging topic of human evolution. It assesses their knowledge after they have researched the main traits of one species on their own and after being challenged by the clicker and openended questions proposed by the case up to this point. At the beginning of class the instructor will distribute the handout to each student making sure that the information given to one is not disclosed to other students. ancient Lake Turkana but in Ethiopia) have been found that put the origin of Homo sapiens back to 195,000 years ago (http://www.eurekalert.org/pub_ releases/2005-02/uou-toh021105.php). Optional Video Recommendation The following links to a short video clip of less than 5 minutes long from the History Channel about the Neanderthals: http://www.youtube.com/watch?v=WgV6OzauVmE& feature=related This is an excellent documentary that I recommend showing to students to complement this topic, perhaps at the beginning of the class period following this case to reinforce learning about the physical and cultural characteristics of this early human species. Some Considerations for the Instructor Teaching the Case There are two current hypotheses for the evolution of humans: the multiregional hypothesis and the “Out-ofAfrica” hypothesis, which are covered in most introductory biology textbooks (see also http://anthropology.si.edu/ humanorigins/faq/Encarta/diversity.htm). The second hypothesis (which this case supports) is the one usually favored now because the genetic as well as fossil evidence supports it better. It is also important to point out that all four hominin species considered in this case never lived together. However, Homo habilis and Homo ergaster/ erectus probably overlapped in Africa, and Homo neanderthalensis and Homo sapiens definitely overlapped in Europe, while Homo erectus and Homo sapiens probably overlapped in East Asia. In addition, it is important to make a clear distinction between “early hominids” and “humans” or “modern humans”: • “Hominidae” are now considered to be extinct and extant humans, chimps, gorillas, and orangutans, although it used to mean only extinct and extant humans (which are now the sub-tribe Hominina along with chimpanzees). • “Human” refers to Homo sapiens, a convention used by many, though not all, researchers in this field. There used to be a distinction between “modern humans” and archaic humans. The instructor should be referring to archaic humans when telling students that the first humans appeared about 160,000 years ago (Slide 11) as opposed to saying modern humans evolved 100,000 years ago. However, now archaic humans are considered to be Homo heidelbergensis and new fossils (not along The class before the case, students are given an assignment (see pre-class assignment handout at the end of these notes) to select one of the four species considered in the case (H. habilis, H. erectus, H. neanderthalensis, or H. sapiens ) and to research and retrieve information (individually) about that species with particular emphasis to the following traits: origin, height/weight, build (body type), climate/habitat in which the species was mostly established, time range, diet, use of fire, ability to make tools, brain size, communication skills, and any other distinguishing feature. At the beginning of the next class, the instructor distributes a handout (either Table 1 or Table 2, depending on the student’s gender) to each student, making sure that the information given to one is not disclosed to any other students. With Table 1, given to male students, a checkmark on one of the four columns of the handout indicates the species of the genus Homo each male student is going to be, without disclosing this information to anyone else. Similarly, all of the female students are given a handout (Table 2), which contains a list of 10 important traits each woman is going to select for the choice of her mate. This information also is not disclosed, so that nobody knows which species of Homo each student is. Case Teaching Notes for “When Wilma Met Fred” by Bruno Borsari Characteristics of the Pleistocene Slide 2 presents the first clicker question (CQ#1), which is intended to verify whether or not students know that Charles Darwin and other scientists also considered the origin of humans. Slide 3 recounts how students taking a field course in Tanzania appear to have discovered some hominin Page 2 NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE remains. This slide can be read out loud by a student selected at random. Slide 4 presents the second clicker question (CQ#2), which is aimed at assessing whether students know where Tanzania is and why the class described in the case story traveled there. Slide 5 presents the third clicker question (CQ#3), which further engages students in the case by asking whether they know what the Pleistocene was. Slides 6–10 present the main characteristics of the Pleistocene. This information can be read by the instructor and expanded upon, if desired (3–5 minutes). More specifically, Slide 6 describes when the Pleistocene occurred within the earth’s natural history. Slides 7–9 provide more information about the Pleistocene epoch. This is where the instructor should point out that the most recent glaciation is the last of four major glaciations that occurred over the past 425,000 years of the Pleistocene. This event began about 100,000 years ago and ended about 10,000 years ago. It was characterized by several mild spells that allowed early human migration and habitation at higher latitudes for thousands of years (especially in North America). Human Evolution Slide 11 presents the “Out-of-Africa” theory. Africa is considered by most scientists to be the cradle of human origins and for decades it has been a primary center for studies about human evolution. Slide 12 presents the fourth clicker question of the case (CQ#4), which evaluates the students’ knowledge of fossilization. Slide 13 continues the story. A student can be selected at random to read the slide out loud. Slide 14 invites students to join the other students who have been studying the same species of hominin and share their collected information about it. Allow students to discuss their findings in groups for 5 to 7 minutes. In the meantime, write the name of the species being considered on the board and invite group leaders to come and report (write) the information under each species’ name. Slide 15 presents the fifth clicker question (CQ#5), which asks students to classify the hominin found in the case story. Slide 16 presents the sixth clicker question (CQ#6), which connects the students’ answer to CQ#5 to what they have learned so far about Homo erectus. Slide 17 presents the characteristics of H. erectus. The students’ information transcribed on the board Case Teaching Notes for “When Wilma Met Fred” by Bruno Borsari about H. erectus is compared to the information on the slide. At this point, corrections, comments, and remarks are solicited to make sure that the class has learned some physical and cultural characteristics about this species. Slides 18–20 list the characteristics of the remaining three species of the genus Homo. The instructor continues to facilitate class discussion as the students’ notes written on the board are compared with the information presented in these slides. Slide 21 presents a timeline for when these various hominins were alive. Slide 22 shows the trends in cranial capacity over time and presents the seventh clicker question (CQ#7), which challenges students to analyze the data (and their correlation) presented in the graph. Slide 23 presents the eighth clicker question (CQ#8), which asks students about the leveling off of recent brain sizes. If the instructor wishes to, this slide presents an opportunity to discuss further the difference in brain size between H. neanderthalensis and H. sapiens. The literature suggests that H. neanderthalensis had a larger brain than H. sapiens, although at least one reference says that H. sapiens’ brain was as large as H. neanderthalensis’ when the two species coexisted with one another, but that it is smaller now. The reason given is that our brain became more compact and more efficient so that it used less energy (brains are considered to be energy hogs). This conclusion is inferred from behavior, which is what the instructor should bring out in discussion. Directional selection within each species led to a larger brain—up to a point. What anatomical change could have occurred to allow a smaller brain with more “brain power”? If you have already looked at the nervous system or even the evolution of mammals, the students might be able to come up with increased convolutions of the cerebral cortex in answer to this question, which would provide more surface area despite the volume being the same or smaller than before. Slide 24 proposes three open-ended questions that students are told to discuss with their neighbor/s in small groups. Each group selects a question to discuss within a three-minute time frame. After this time, the instructor solicits answers from the student groups. You may want to select at random students that will report on the outcome of their discussions. Slide 25 shows a phylogenetic tree of our ancestors that can be used by the instructor to summarize and/or reiterate the main information learned to this point, and asks about coexistence of Neanderthals with H. sapiens. Page 3 NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE The “Mating/Dating” Game Slide 26 sets up the game that is played in class. The women (“Wilma”) in class select the “right” mate (a “Fred” of the same species) by paying attention to which males respond to which statement about various species characteristics is being announced by the instructor. How this works is, the instructor reads out loud statements referring to attributes of a certain Homo species as described in the Handout for Instructors (see end of notes) for 35 attributes. When listening to this information, the men to which the statement applies stand up, look around, wave at the audience, and then sit down. In this way, game participants (women in particular), by paying attention to who is standing up and waving at certain points in the proceedings, can hone in on who would be their match-mate. It takes about 25 minutes to do this. At the end, give students half a minute to cross the classroom and reach his/her mate and verify (by disclosing the handout) that both students belong to the same Homo species. You win if you connect with the “right” mate. Extra credit could be rewarded for the first three couples that reach the instructor and show him/her the handout indicating that both partners belong to the same species. Epilogue Slide 27 reviews the common descent theory, while slide 28 reminds students that we are all connected to African ancestors. Slides 29–32 continue the theme of common descent, and cites the remarkable discovery of Ardipithecus ramidus in Ethiopia announced in a series of 11 papers published in the October 2, 2009, issue of the journal Science. ANSWER KEY in Relation to Sex (2 vols). London: John Murray. (Reprinted in 1981 by Princeton University Press) Diamond, J. 1992. The Third Chimpanzee. The Evolution and Future of the Human Animal. New York: HarperCollins. Fleagle, J. G., T.M. Brown, J.D. Obradovitch, and E.L. Simons. 1986. Age of the earliest African anthropoids. Science 234:1247–1249. Finlayson, C. 2005. Biogeography and evolution of the genus Homo. Trends in Ecology & Evolution 20(8):457–463. Hill, K. 1982. Hunting and human evolution. Journal of Human Evolution 11:521–544. Leakey, R.E., and R. Lewin. 1978. People of the Lake. Mankind and its Beginnings. New York: Doubleday & Co., Inc. Lewin, R. 1986. New fossil upsets human family. Science 233:720–721. Lovejoy, C.O. 1981. The origin of man. Science 211:341–350. Pilbeam, D. 1984. The descent of hominoids and hominids. Scientific American 250:84–96. Rak, Y. 1986. The Neanderthal: A new look at an old face. Journal of Human Evolution 15:151–164. Ranzi, C. 1982. Seventy Million Years of Man. Rizzoli Editore-Milano, Italy. Strickberger, M. W. 1990. Evolution. Boston: Jones & Bartlett Publishers. Stringer, C.B. 2003. Human evolution: Out of Ethiopia. Nature 423, 692–695. doi:10.1038/423692a Stringer, C.B., and P. Andrews. 1988. Genetic and fossil evidence for the origin of modern humans. Science 239:1263–1268. • Answers to the questions posed in the case study are provided in a separate answer key to the case. Those answers are password-protected. To access the answers for this case, go to the key. You will be prompted for a username and password. If you have not yet registered with us, you can see whether you are eligible for an account by reviewing our password policy and then apply online or write to [email protected] Acknowledgements: This material is based upon work supported by the NSF under Grant No. due0618570. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the NSF. I am grateful to the comments of anonymous reviewers that helped tremendously to increase the clarity and quality of this case. REFERENCES Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Originally published January 25, 2011. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work. Arensburg, B., A.M. Tillier, B. Vandermersch, H. Duday, L.A. Schepartz, and Y. Rak. 1989. A middle Paleolithic human hyoid bone. Nature 338:758–760. Darwin, C. 1871. The Descent of Man, And Selection Case Teaching Notes for “When Wilma Met Fred” by Bruno Borsari Page 4 NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE PRE-CLASS ASSIGNMENT for “When Wilma Met Fred: A Human Evolution Case” Your assignment is to independently research one of the four species of the genus Homo that will be considered in this case: H. habilis, H. erectus, H. neanderthalensis, or H. sapiens. Select one and then, working on your own, research and collect information about it with a particular emphasis on the following traits: • Origin • Height/weight • Build (body type) • Climate/habitat in which the species mostly established • Time range • Diet • Use of fire • Ability to make tools • Brain size • Communication skills • Other distinguishing features NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE THE GAME for “When Wilma Met Fred: A Human Evolution Case” The class game described in this handout is an important feature of this case. The women in the class (Wilma) will have to select the “right” mate (a “Fred” of the same species) by following attentively the dynamics of the game and paying attention to who responds to which statements made by the instructor describing attributes of particular species of the genus Homo. The men in the class will each be given a separate handout that will have a checkmark in one of the four columns of a table indicating the species of the genus Homo each male student is going to be. When you get your species role assignment, do not show it to anyone else. Similarly, all of the women in the class will be given a handout that contains a list of 10 important traits each woman is going to select for the choice of her mate. One of the species will be checkmarked. This information as well should not be disclosed so that nobody knows which species of Homo each student is. The instructor will read out loud statements referring to attributes of a certain Homo species. When listening to this information, the men in the class who posses those traits will stand up when the trait is read out, look around, wave at the audience, and then, sit down. In this way, game participants (women in particular, but also men), by paying close attention to who is standing up and waving at particular points in the process, will be able to pick out who is their match. It will take about 25 minutes to accomplish this. At the end, half a minute will be dedicated for each individual to reach his/her mate and verify (by disclosing the handout) that both of you belong to the same Homo species. You win if you connect with the “right” mate. NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE HANDOUT FOR MALE STUDENTS for “When Wilma Met Fred: A Human Evolution Case” Category H. erectus H. habilis H. sapiens (us) H. neanderthalensis Range China, Europe, Africa First found in All over Tanzania; some put Kenyan material into H. rudolfensis Europe, western Asia. Ht/wt 1.6–1.8 m. M: 65 Kg. Less than 1.6 m., very light. Modern – as in European 1.7m., 65–80 Kg. Build Same as human. Lighter than humans Modern Very muscular. Climate/habitat African savannacold Europe. All over, especially warmer regions Cold N. Europewarmer Israel. Time Range 1.5 mya–200,000 ya. 2.0–1.6 mya 160,000 ya–to present 120,000–28,000 ya. Diet Small game, plants, nuts, fruit, some large game. Marrow, scavenging, seasonal vegetation. Hunting, fishing, wild grains, plants, big game. Cooked. Plants, nuts, fruit, big game animals. Use fire? Yes; cooked food. ? Yes; hearths. Yes; cooked food on hearths. Tool making? Hand axes, scrapers. Simple stone tools. Varied material, innovation. Advanced, little variation Brain size 750–1140 cc. 560–700 cc. 1040–1595 cc. 1400–1800 cc. Communication skills ? ? Art, language, ritual, music. Probably; used some rituals. Distinguishing characteristics Heavy brows, strong First evidence of jaws and teeth. stone tools. Innovation, math, complex tools with regional differences and dialects. Agriculture, religion, warfare. Heavy brows, sloping forehead, large nose and lower jaw. Evidence of clothes, burial ceremonies. NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE HANDOUT FOR FEMALE STUDENTS for “When Wilma Met Fred: A Human Evolution Case” ATTRIBUTES LIST OF MY MAN OF CHOICE: H. erectus 1. You are about 1.75 m. tall, modern build, strong face, heavy brows and strong jaws. 2. Your brain size must be between 750 and 1140 cc. 3. You can build hand axes and scrapers. 4. You lived between 1.5 million years ago and 200,000 years ago. 5. You do not need to impress me by inventing “new things.” 6. You must be able to use that hand ax to protect me/us from predators and enemies. 7. I do not care whether you can or cannot tell me that you love me. 8. You must be able to build me a fire when I get cold. 9. When you take me out to dinner I want to go eat small/large game, plants, nuts, fruits. 10. …………and I like my food to be cooked. ATTRIBUTES LIST OF MY MAN OF CHOICE: H. habilis 1. You are less than 1.6 m. tall and very light. 2. Your brain size must between 560 and 700 cc. 3. You know how to build simple stone tools. 4. You lived between 2.0 and 1.6 million years ago. 5. You do not need to impress me by inventing “new things.” 6. You must be able to throw rocks to our enemies in order to protect me. 7. I do not care whether you cannot tell me that you love me. 8. Just sleep close to me when I get cold at night. 9. When you take me out for dinner I want to eat small game, plants and soft fruits. 10. …………and I like my food raw. ATTRIBUTES LIST OF MY MAN OF CHOICE: H. neanderthalensis 1. You are about 1.7m. tall, stocky, muscular, heavy brows, strong jaws, large nose. 2. Your brain size is almost 1800 cc. 3. You know how to build wood and stone tools. 4. You lived between 120,000 and 35,000 years ago. 5. You must be able to impress me by inventing new things (jewelry, tools). 6. You are strong enough to protect me but when in danger you call out for help. 7. I do not care whether you can or cannot tell me that you love me. 8. You must be able to build me a fire and give me hides to wear when I am cold. 9. When you take me out for dinner I want to eat mammoth and big game. 10. …………and I like my food to be cooked. ATTRIBUTES LIST OF MY MAN OF CHOICE: H. sapiens 1. You are about 1.55–1.8m.tall. 2. Your brain size between 1095 and 1595 cc. 3. You are the most creative in designing and building tools. 4. You lived between 100,000 years ago and present time. 5. You must be able to impress me by inventing “new things” all the time. You are so creative! 6. Your creative mind is very effective in protecting me from enemies and danger. 7. You are capable of overwhelming me by sweet, loving words. 8. You must be able to build me a comfortable shelter to protect me from the cold. 9. When you take me out for dinner I want to eat meat, fish, wild grains, plants, big game. 10. ………….and I like my food to be cooked. NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE HANDOUT FOR INSTRUCTORS for “When Wilma Met Fred: A Human Evolution Case” 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. I do not care whether you can or cannot tell me that you love me. Your brain size must be between 750 and 1140 cc. You must be able to build me a shelter to protect me from the cold. You lived between 120,000 and 35,000 years ago. When you take me out to dinner I want to eat small or large game, plants, nuts, fruits. You are about 1.55 to 1.8 m. tall. You must be able to impress me by inventing new things (jewelry, tools). You are so creative and capable of inventing new things all the time. You are less than 1.6 m. tall and very light. You lived between 1.5 million years ago and 200,000 years ago. When you take me out for dinner I want to eat mammoth and big game. You must be able to cook my food. You can build me wood and stone tools. You lived between 2.0 and 1.6 million years ago. You are good at throwing rocks at our enemies so that you can protect me. Your brain size is between 1095 and 1595 cc. You must be able to make me a fire and cover me with hides when I am cold. You are about 1.75 m. tall, modern build, strong face, heavy brows and strong jaws. You must be able to build simple stone tools. You are capable of overwhelming me with sweet, loving words. You do not need to impress me by inventing “new things.” Just sleep close to me when it gets cold at night. You lived between 100,000 years ago and the present time. You can build hand axes and scrapers. You do not need to cook my food as I like it raw. Your brain size is almost 1800 cc. When you take me out for dinner I want to eat meat, fish, wild grains, plants, big game. You must be able to use a hand ax to protect me from our enemies. You are about 1.7 m. tall, stocky, muscular, have heavy brows, a strong jaw, and large nose. You must be able to build me a fire when I get cold. You are the most creative in designing and building tools. Your brain size must be between 560 and 700 cc. Your creative mind is very effective in protecting me from enemies and danger. When you take me out for dinner I want to eat small game, plants and soft fruits. You are strong enough to protect me but when in danger you can call out for help.