The Primate Family Tree: A classroom activity in evolution, adaptable for all ages

Feel free to email me to request the document (with all this text and all these figures) which is easier to work with. holly_dunsworth@uri.edu

In this activity, students will…

• Observe and describe the similarities and differences between primates and other familiar mammals, and also the similarities and differences among primates.

• Classify primate species into groups (superfamily and above). 

• Transform Linnaean classification into evolutionary theory by merely changing the question from How do primates look similar and different from one another? to Why do primates look similar and different from one another?

• Build a primate “family” tree by turning Linnaean classification into phylogeny (or evolutionary tree-thinking) to describe how common ancestry and change over time explain both similarities and differences among primates.

How old are the students? 

5-105* 

*Prior to about age 8, teachers will need to riff quite creatively off track from this (for one, because reading the Primate Taxonomy Table may be very difficult for younger students), but I include those earlier ages because I believe that teachers of those age groups can find a way to use this lesson if they’d like to. It's possible that just knowing how to read is enough to do a stripped down version of this activity, which includes children even younger than 5. I have used this activity successfully with students aged 8-25. For upper-level anthropology courses I've used it as an ice-breaker to kick off the semester (with students who have a background in evolutionary thinking already).

How long will it take? 

30 minutes minimum (much more depending on detail you wish to cover)

What materials?

• Color pictures of a diverse array of primates - approximately 3-5 times as many pictures as students. Too many is better than too few. Rip them out of old textbooks and laminate for durability. Print them off the Internet (arkive.org is one of the best sources) and laminate for durability. Make sure to have at least two different pictures of the same species for many of the species you include. Label most of them with the common names under “examples” on the chart for Part 2 (e.g. “baboon”). But a fraction may be only labeled with geographic region, scientific name, or nothing at all.  Explanation is in the instructions below. Specific sources of primate photos for printing are listed in Appendix A.

• Pencil – 1 per student

• Note cards -  1 per student (for them to draw a self-portrait or a symbol to represent themselves)

• Poster paper, or large sheets of paper – 6, one for each superfamily on the Primate Taxonomy Table (below)

• Tacky gum, reusable tape, or some other ingenious sticky tool that can both hold primate pictures to the posters and also be removed and moved to different posters when students change their minds. 

• Handout for students (see options below; must at minimum include Part 2: Primate Taxonomy Table)

 

Teacher Instructions

Part 1. (3 MINUTES minimum) DISCUSS CLASSIFICATION

Using the resources under Part 1 of the materials below, hold a discussion about classification. Don’t talk about relatedness or common ancestry! And especially don’t talk about evolution! (Next, in Part 2, the taxonomic terminology they will use, like “family,” will encourage them to think evolutionarily, hopefully, and this will come into play later in the activity.)  They will already be familiar with how like is grouped with like—I often use sock and underwear drawer analogy, grocery store organization works too. Stick to primates if you’d like, but if you go broader, make sure to end your discussion with primates, including humans. Make sure to explain how (Linnaean) taxonomy/classification works. That is, simply/broadly (or complicated/specifically if you’d like) describe the methods—the use of comparative anatomy and homology and also the binomial species name for the smallest, most exclusive group within ever-more inclusive groups going up to the Kingdom level.

Part 2. (10 MINUTES minimum) CLASSIFY THE PRIMATES INTO SUPERFAMILIES

Hang a poster for each superfamily along the wall in no particular order, lay out a pile of the photos in no particular order. Students get up out of their chairs, and using the Primate Taxonomy Table (below) they stick each primate picture to a poster labeled with the superfamily to which they think it belongs. They are able to do this without any knowledge of primates because you have labeled most of the pictures with “baboon”, for example. They can go to the table on the handout and see that baboons belong in the superfamily “cercopithecoidea” and stick the photo to that poster. Unlabeled baboons should look similar to labeled ones and they should also be sticking those to the cercopithecoidea poster if they are carefully observing and are engaged in the activity. Make sure they stick their own “human” cards to a poster too.  Hopefully they will respectfully work together and move others’ around if they think they have a better case for a different classification of a particular primate.  

Primate Taxonomy Table (handout).
Email me for a file you can work with more easily (holly_dunsworth@uri.edu)

Part 3. (5 MINUTES minimum) STUDENTS SHARE THEIR REASONING FOR THEIR CLASSIFICATION

Lead the students through a tour of the features that unite the primates into each of the superfamilies. First ask them to describe the similarities among all the primate superfamilies (a quick review of Part 1). Then ask them to describe the differences they can see between the superfamilies: what makes hominoids separate from cercopithecoids, etc?  It’s not imperative, but I recommend starting with the primates that share the most with humans (hominoidea) then going to the cercopithecoidea, and so on. This may appear to be difficult because they may observe overall (super) family resemblance but not be able to describe any more detail than that, which is fine! Using the resources under Part 3 below, you can provide details of the differences between the superfamilies, both that are visible in the pictures and that are not. 

Part 4. (2 MINUTES minimum) CHANGE THE QUESTION FROM HOW DO PRIMATES VARY? TO WHY DO PRIMATES VARY? 

Challenge students to explain the patterns of similarities that make all these creatures primates and that, for example, unite the hominoids, the cercopithecoids, etc..., while also explaining the differences that make each species unique and each superfamily unique.  Hopefully, with very little help from you, they will arrive at the idea that relatedness explains it. Family history, on a larger scale than our own families, but the same kind of thing. Common ancestry and change over time since common ancestors. Evolution plain and simple.  

Part 5. (10 MINUTES minimum) BUILD A PRIMATE TREE and DISCUSS ITS MEANING. 

There are many ways to do this and showing more than one way would be great, but one way is to put the known phylogenetic structure, the branches of the tree for the superfamilies (see resources below) on the wall or board and have them deduce where the superfamilies go and stick the posters to those branches. Another way, for older students, is to have them figure out the relatedness of superfamilies first, starting with humans and hominoids and hypothesizing which are more and more distantly related based on increasing differences. Another is to merely show them how to walk through the table for Part 2, and change it into a hypothesis for phylogenetic/evolutionary history, with lineages diverging where each level of taxonomy divides things further into more exclusive groups. So show them how to draw time and descent lines around that evolution-free taxonomy (classification table for Part 2) that they already have and they’ll arrive at.. dun-dun-DUN evolution! I prefer to draw the students’ hypothesized tree like a big oak tree (with a streps/haplorhine split in the trunk deep down near the bottom) on the wall, and to stick the posters at the ends of the branches. But it’s obviously up to teachers and whether they have a big wall to draw on! I cover my wall in paper first so that I can draw the big tree. 

Teacher Resources and Optional Handout Materials

Teachers: Pick and choose what you’d like to include in your handout, depending on what you will cover with your particular students (depending on age, time, goals, etc…). Be careful not to share any handouts too soon and spoil the opportunity for students to think first, if that’s what you have time for and are going for. 

Part 1

• Where do humans fit in the classification of life on Earth? (link)
• How do we make these categories? We ask, ‘What’s similar” of the anatomy, when comparing different species.  That is we look to homologous structures.  A great example is the tetrapod forelimb. (link)

• What makes a primate a primate? (link)

Part 2

Lemuroidea

Nose: wet (hence the name strepsirrhine)

Geographic region: Madagascar

Tail present: yes

Activity: Some nocturnal, some diurnal

Teeth: Many more than we have, some shaped like comb for grooming fur

Body size: Small but variable from the smallest primate alive (<< 1 lb.) to ones as big as big pet cats (20 lbs.)

Lorisoidea

Nose: wet (hence the name strepsirrhine)

Geographic region: Sub-Saharan Africa and Southeast Asia

Tail present: yes and no

Activity: nocturnal

Teeth: Many more than we have

Body size: small

Tarsioidea

Nose: dry (hence the name haplorhine) 

Geographic region: Southeast Asia

Tail present: yes

Activity: nocturnal

Teeth: Many more than we have

Body size: small

Ceboidea

Nose: dry (hence the name haplorhine) 

Nostrils: flat and facing out to the side (hence the name platyrrhine)

Geographic region: Central and South America

Tail present: yes (and some are even prehensile!)

Activity: Most diurnal, some nocturnal

Teeth: four more than humans (one extra premolar/bicuspid in each quadrant of mouth compared to us)

Body size: Variable, with some small (like pygmy marmosets) but the largest, the spider monkey, is 25 lbs.

Cercopithecoidea

Nose: dry (hence the name haplorhine) 

Nostrils: facing down (hence the name catarrhine)

Geographic region: Asia, Southeast Asia, and Africa (all sub-Saharan except the Barbary macaque of Morocco and Gibraltar)

Tail present: yes (but 2-3 species are no or have very small stubs)

Activity: diurnal

Teeth: same number as humans

Body size: Many, including most macaques and baboons, weigh more than any ceboids. Some mandrills weigh over 100 lbs.!

Hominoidea

Nose: dry (hence the name haplorhine) 

Nostrils: facing down (hence the name catarrhine)

Geographic region: Southeast Asia (gibbons, siamangs, orangutans); Sub-Saharan Africa (gorillas, chimpanzees, bonobos); Worldwide (humans)

Tail present:  no

Activity: diurnal

Teeth: same number as humans

Body size: Although gibbons and siamangs are the smallest of the group, this group is the largest in body size and weight of all primate superfamilies and includes gorillas, the largest of all primates which can weigh 400 lbs.!

Part 4

Evolution and phylogenetic thinking is just family history writ large.

Part 5. The Primate Family Tree

Here is an example (one hypothesis, if you will) of a primate phylogeny or phylogenetic tree or evolutionary tree. 

Here's guidance on how to turn Part 2’s table into a phylogeny with students.

Then here it is, stripped down and rotated...

Appendix A.

Sources for primate pictures

Lemuroidea

Dwarf lemurs: http://www.arkive.org/explore/images?q=Dwarf%20lemurs

Mouse lemurs: http://www.arkive.org/explore/images?q=Mouse%20lemurs

Aye-ayes: http://www.arkive.org/explore/images?q=Aye-ayes

Indris: http://www.arkive.org/explore/images?q=Indris

Sifakas: http://www.arkive.org/explore/images?q=Sifakas

Lemurs: http://www.arkive.org/explore/images?q=Lemurs

Sportive lemurs: http://www.arkive.org/explore/images?q=Sportive%20lemurs

Lorisoidea

Galagos: http://www.arkive.org/explore/images?q=Galagos

Lorises: http://www.arkive.org/explore/images?q=Lorises

Pottos: http://www.arkive.org/explore/images?q=Pottos

Tarsioidea

Tarsiers: http://www.arkive.org/explore/species?q=tarsier

Ceboidea

Howler monkeys: http://www.arkive.org/explore/images?q=Howler%20monkeys

Spider monkeys: http://www.arkive.org/explore/images?q=spider%20monkey

Owl monkeys (night monkeys): http://www.arkive.org/explore/images?q=Owl%20monkeys%20night

Marmosets: http://www.arkive.org/explore/images?q=Marmosets

Tamarins: http://www.arkive.org/explore/images?q=Tamarins

Capuchins: http://www.arkive.org/explore/images?q=Capuchins

Squirrel monkeys: http://www.arkive.org/explore/images?q=Squirrel%20monkeys

Titi monkeys: http://www.arkive.org/explore/images?q=Titi%20monkeys

Sakis: http://www.arkive.org/explore/images?q=Sakis

Uakaris: http://www.arkive.org/explore/images?q=Uakaris

Cercopithecoidea

Baboons: http://www.arkive.org/explore/images?q=Baboons

Macaques: http://www.arkive.org/explore/images?q=Macaques

Vervets: http://www.arkive.org/explore/images?q=Vervets

Guenons: http://www.arkive.org/explore/images?q=Guenon

Colobus: http://www.arkive.org/explore/images?q=Colobus

Langurs: http://www.arkive.org/explore/images?q=Langurs

Proboscis: http://www.arkive.org/explore/images?q=proboscis%20monkey

Drills and mandrills: http://www.arkive.org/explore/images?q=drill%20mandrill

Hominoidea

Gibbons: http://www.arkive.org/explore/images?q=Gibbons

Siamangs: http://www.arkive.org/explore/images?q=Siamangs

Orangutans: http://www.arkive.org/explore/images?q=Orangutans

Humans: students draw a personal sign, symbol, or self-portrait

Chimpanzees: http://www.arkive.org/explore/images?q=Chimpanzees

Bonobos: http://www.arkive.org/explore/images?q=bonobo

Gorillas: http://www.arkive.org/explore/images?q=Gorillas

Luck of the draw: Evolving flipbooks mimic non-selective processes (a classroom activity)

First the lesson plan, then a look at the peer-review process that provided feedback.

A common ancestor (center) and its descendants.

Introduction and scope

Even if evolution is accepted and natural selection is understood, learners of all ages may mistakenly explain all variation with this single mechanism. That there are myriad resources for, and examples of, natural selection and because it is so powerful, it is not surprising that the concept is dominant even though selection is not the only means by which evolution occurs. Here I suggest that there should be better coverage of non-selective processes at the introductory level of learning evolution. Towards that goal, I offer an engaging activity involving the drawing of flipbooks, which not only marries art and science but symbolically demonstrates evolutionary mechanisms other than selection.

Leads into—biology, genetics, evolution, the art of animating with flipbooks.

Concepts—Mutation, genetic drift, natural selection, common ancestry, diverging lineages, speciation, inheritance, species identification, developmental constraints, complexity, evolutionary progress.

Target age group—All students who are being introduced to the fundamentals of evolution can perform this simple activity and can learn from it. As long as they can trace a line, they can participate. In schools, evolutionary concepts are formally introduced as early as the sixth grade, but basic concepts like change over time, deep time, and common ancestry may be introduced even earlier. Often students are not formally or rigorously introduced to evolution until they reach college or university. Furthermore, many of the more advanced concepts that can be addressed with this activity are only appropriate for secondary and post-secondary courses. It is up to teachers to decide how to integrate this activity into their evolution lessons. I developed this activity, and used it with success, in my introductory biological anthropology course at the University of Rhode Island.

The importance of teaching beyond selection at the introductory level

Natural selection does not explain all of evolution

             Since Darwin’s time we’ve learned that natural selection is just one mechanism of evolution that works in concert with others such as mutation, gene flow, and genetic drift. Mutation, the result of chance, creates the necessary variation for natural selection and drift to take place. Each human inherits an estimated average of 150 mutated nucleotides per person (Ken Weiss, Pennsylvania State University, personal communication[A]). Like mutation, drift is also random, but drift occurs over time as random events accumulate. Because both are due to differential reproduction, the result of drift can look remarkably like that of selection and change away from the ancestral state can occur quickly if the population size is small (1). A classic example of drift occurs in a small culturally isolated population of the Old Order Amish in eastern Pennsylvania; hardly anyone would hypothesize that the relatively high frequency of polydactyly was due to natural selection. For many traits that seem to have no adaptive value, drift is a strong hypothesis. Often drift is considered alongside relaxed selection (2). That is, a trait becomes prevalent through drift in the absence of selective pressures that would otherwise prevent the drift from occurring. The deterioration of human eyesight may be explained this way and so may geographic variation in earwax (3). Many diagnostic characteristics of the Neanderthal face may be explained by drift (4) and so might the fixed loss of tails in our hominoid ancestry.[B]

           

A strict selection perspective creates potential for societal harm

Learning about evolution solely through natural selection is not only inaccurate but may also have negative social consequences.  Wearing adaptation-colored glasses fosters notions that evolution is progressive, that past states were inferior to present ones, and that there is some striving in nature towards perfection (5, 6). From this perspective it is all too easy to assign differential value, worth, or beauty to variation within and between species under the backing assumption that “Mother Nature” has “favored” one trait over another. Judgments like this can lead to human exceptionalism and anti-environmentalism (justifying human superiority over other organisms) or tribal exceptionalism and racism (justifying superiority of some nose shapes or skin colors over others).[C] Presenting a more complete picture of evolution to those in the early phases of learning about it may lower the risk that these dangerous ideological paths will be followed (7).

Flipbooks for teaching evolution

            Seeds, jelly beans, and the like are common stand-ins for alleles or gametes in classroom exercises meant to recreate evolving populations. These exercises demonstrate how new gene pools result from mutation followed by selection or the lack thereof (i.e. drift).  However, these activities are not appropriate for all ages because of the algebra they require for calculating allele frequencies; even at the university level, students can struggle with the math. Furthermore, these engaging hands-on activities do not allow students to witness more than a few generations of evolutionary change. Alternate illustrations of the effects of mutation and genetic drift on evolution are needed. Recently, Gillings (8) provided a pedagogically useful metaphor of these biological processes with language evolution.

Here I offer another sort of instructional device inspired by two films that were recently posted by artist Clement Valla on the Internet. The films show how line drawings, when traced 500 times, can evolve dramatically. And although it is so simple, this is a powerful demonstration of evolution without natural selection.

***

Teacher Resources

Films by Clement Valla (2010)—Inspiration for this flipbook activity

• “A sequence of lines traced by 500 individuals” Also posted here.
• “A sequence of circles traced by 500 individuals” Also posted here.

On-line resources for the art of flipbook animation

• Wired’s How-To “Make a flip book animation”
• National Gallery of Art, Kids. “On the Move”
• “Escape” (flipbook animation)
• “Flip Mania Part 1: Sports” (flipbook animation)
• “Simpsons Fight” (flipbook animation)

On-line resources for teaching and learning about the role of chance in evolution

General evolution:

• NOVA’s “Evolution”
• Berkeley’s “Understanding Evolution for Teachers”

Genetic drift:

• University of Arizona’s “The Biology Project”
• University of Connecticut’s genetic drift simulator

Mutation:

• University of Utah’s “Learn.Genetics”
• NIH’s “Genetics Home Reference”

Misconceptions about evolution:

• AAAS Science Assessment. Topics: Evolution and natural selection
• New Scientist’s “Evolution: 24 myths and misconceptions”

***

Valla’s films are basically digital renderings of classic flipbooks used by cartoon animators and by following the steps in the activity outlined below, teachers can easily recreate the experience of the films with students in the classroom. In addition, they can use this exercise to teach an array of evolutionary principles and concepts.

If learners can trace lines they can perform this activity. As a collaborative endeavor, this activity works with a minimum of two participants and, theoretically, has no maximum group size. With 50 tracings per book, it takes about 50 minutes to complete.[D] At the end, students will have created flipbook animations that “evolved” merely because each of their tracings, no matter how diligently drawn, was slightly different from the previous one.

Materials

·       One pencil or pen for each participant

·       Two blank flipbooks for each participant. There are several ways to fashion flipbooks. They can be small blank notebooks with at least 50 plain white sheets that are slightly transparent for tracing purposes. A much cheaper method is to fasten sheets of copier paper together with a binder clip. The paper should be cut down with a paper cutter to pages with roughly 3 inches (or 8 cm) on each side and not too much larger than that because large books beg for large drawings that slow down the activity. To get seamless animation while flipping through the flipbook, the flipping edges of the pages need to be lined-up, so tap the stack of pages on a table top to settle them all together on one edge before clipping them together and beginning the drawings.  Once the flipbook drawings are underway, the clip cannot be moved or removed.

Procedures

1.     Set the stage. Prior to performing this activity, provide students with background information  on flipbook animation and on concepts of common ancestry, the Tree of Life, evolution, and mechanisms of evolution (natural selection, mutation, and genetic drift). 

***

Questions to gauge knowledge and spark interest before the activity

Teachers will need to choose the questions that are appropriate for their students’ learning level and for the particular evolutionary lessons they want to address.         

Change through time and common descent—What is evolution? What is the evidence for it? How does it occur? What is the concept of common ancestry that is used to build the Tree of Life?

Evolutionary mechanisms—What is natural selection? What are other ways that evolution occurs besides natural selection? What is genetic drift and how is it different from and similar to natural selection? What is a mutation? What causes mutations? How frequent are mutations? What keeps mutations from happening more frequently than they do? Are mutations always bad? How could something that starts as a mutation in an individual end up in more and more individuals in a population over generations and through time?

The nature of evolution—Is evolution progressive? Is there a goal? Does it always result in improvement over earlier forms?

***

2.     Draw the templates.

a.      Have students put their names on the front covers of their books.

b.     Have them open one of their flipbooks to the last page and draw something. Keep it a simple line drawing so that it does not take longer than 10 seconds to trace. The drawing can be an unknown shape, like a doodle or scribble (known here as “unrecognizable”; Figures 1-4). Or the drawing can be a symbol like a number or letter, an amoeba or Mona Lisa (known here as “recognizable”; Figures 5-8). It is important that both types of templates are represented because the “recognizable” templates may experience stabilizing natural selection. That is, tracers of familiar shapes may have stronger expectations about how their tracing should appear. If they have such expectations, they may trace with fewer mistakes and/or correct the mistakes that previous tracers have made. But the “unrecognizable” templates may experience less, if any, of this conservative influence. Do not explain the rationale to the students yet because it will be part of the discussion after the completion of the exercise. The bottom line is that teachers make sure that both unrecognizable and recognizable templates are created. They may also want to encourage some students to draw creatures (see explanation in “concluding remarks”).  

c.      Optional modification: I had several students use identical templates—rather than having each student draw a unique one—so that they could witness several different lineages, not just two, evolving from a common ancestor (Figures 1-8). The only downside to this modification is that students are not given the opportunity to create their own templates. Also, teachers may wish to copy and cut out the templates from Figures 1-8 and glue them in the flipbooks before handing them out to students. This would allow students to compare their results (i.e. descendants) with the ones published here.

d.     Have the students carefully trace their template into their second book. Each of them will now have two flipbooks with identical templates. They may rotate the tracing so that the second template is oriented differently in the book.

3.     Introduce the activity. Briefly describe Step 6—that they’re about to pass the books around and each of them will trace the tracing of the person who went before them until the books are filled up. The result will be flipbooks that contain animated movies of the tracings beginning with the original templates.  

4.     Make predictions. Ask the students: What will your book’s animation be like? What will the last picture in your book look like? Will your two books’ animations be identical? What does the template symbolize in evolutionary terms? What do your two flipbook animations symbolize?

5.     Establish the rules

·       Trace as best as you can, but in a brief amount of time.

·       Joking is fine, but do not give anyone grief for “messing up” a flipbook with their mistakes. Everyone’s tracings are imperfect copies. 

·       You may only look at the page that you are tracing. You may not flip back and look at any previous drawings in the book that build up as this activity goes along.

·       You must pass the book to the next tracer in a way that keeps it open to your drawing (i.e. the drawing that the next person will trace).

6.     Trace in an assembly line to build the flipbooks.

1. Each student will turn one page down over the template and trace it and then pass the book to the right.
2. Each tracing should take a few seconds and, ideally, everyone should take roughly the same amount of time.
3. Trace, pass, trace, pass, and repeat to fill all pages of the book.

7.     Observe, discuss, and explain the evolving animations. When filled-up, make sure each flipbook makes its way back to its owner. Each student will have two flipbook animations of the evolution of their template drawing, starting with the template and ending with the last tracing. Now they are ready to explain the evolution that occurs in their books.

Results

Figures 1-4. “Unrecognizable” template (i.e. ancestor; center circle) and the resulting drawings (i.e. descendents) after 50 tracings carried out in different flipbooks (i.e. divergent evolutionary paths).

Figures 5-8. “Recognizable” template (i.e. ancestor; center circle) and the resulting drawings (i.e. descendents) after 50 tracings carried out in different flipbooks (i.e. divergent evolutionary paths).

***

Questions to gauge understanding and to spark further study after the activity

Teachers will need to choose the questions that are appropriate for their students’ learning level and for the particular evolutionary lessons they want to address. 

Results—What happened to the templates? Were your predictions correct? Were there differences in the outcomes of the identical templates? Describe the differences in size and shape (morphology) between your template and your final drawings: What were the trends, if any, through time? Did any new traits appear? Did any old traits disappear?  Look around at the other flipbooks and distinguish “recognizable” from “unrecognizable” templates (as described in Step 2b):  Were there any differences in the outcomes of their evolution?

Evolutionary mechanisms—How can you explain what happened to your drawings? What caused the evolution in your flipbooks? Explain the evolutionary history of the last drawing in each of your flipbooks.

Speciation and species concepts—Are the final drawings in your two flipbooks different species from your template (i.e. their common ancestor)? Are the two final drawings different species from each other? Can you identify the moment (i.e. the particular tracing) when a new species originated?

Luck, chance, randomness, and non-random constraints—What does luck, chance and randomness have to do with evolution? Is natural selection random? Look at the differences and similarities between any two neighboring pages in a flipbook. Are there many major differences between the two tracings? What does this suggest about phylogenetic and developmental constraints in evolution? Is evolution predictable? Are there any hypothetical evolutionary changes to an organism, like Homo sapiens, that are implausible or highly unlikely?

Scales of variation and modes of inheritance—Are your animations symbolic of the evolution of a strand of DNA, a protein, a cell, a single-celled organism, a tissue, an organ, a multicellular organism, or a population? Are your animations depicting the results of asexual or sexual reproduction through time? What are the differences for each, in terms of how variation gets into the next generation?

Explaining human evolution—List hypotheses for the evolution of variation in human nose shape. Point out which hypothesis most closely mimics the process in your flip book animation. Describe, in as much detail as possible, how the different hypotheses could be tested. Include materials and methods. Then discuss any problems that you can anticipate with confidently supporting one hypothesis over another and suggest some possible workarounds or solutions to those problems.

Complexity, progress, and perfection—Would you describe your final drawings as more complex than your template? What about the reverse? Would you say that your animations depict progress? Progress and perfection are valued in our society, so what’s the trouble with perceiving human evolution to be progressive, or to be striving towards perfection or some ideal form?

***

  

Concluding remarks

            This activity illustrates the impact of luck on evolution—when chance is a factor (mutation and drift) and when it is not (natural selection). Students may also use the flipbooks to learn the principles of common ancestry, divergent evolution, and speciation. More advanced students can explore concepts of inheritance, species identification, developmental constraints, complexity, and evolutionary progress.

Over the course of three trials of this activity, I found that there were observable degrees of evolutionary change in all flipbooks, whether they had unrecognizable or recognizable templates (Figs. 1-8). Even if there seemed to be conservative influences on the recognizable templates as predicted in Step 2b, evolution still occurred simply because human tracers are not perfect. The various degrees of distance between template and results (e.g. Figure 5) nicely demonstrate the various speeds of evolutionary change, with some organisms retaining more ancestral traits than others.

There was another sort of issue with the recognizable templates, specifically the ones that represented creatures. Some of my students who had these templates (Figures 7 & 8) were the only students to ignore chance and instead describe their animations with natural selection. For example one student explained that, “What started as a lizard evolved to a blob maybe because it could survive better without legs.” Another wrote, “Natural selection may have occurred in my animation because of environmental changes that caused the need for certain features on the body.”  These answers reveal common misunderstandings of natural selection (which are due in no small part to our pedagogical language: 9), but they also illuminate a deeper struggle with accepting and identifying randomness in evolutionary scenarios. Because this activity is designed to help overcome these issues, I recommend that teachers encourage some students to draw templates of creatures so that these fundamental problems, if present, are more likely to surface.

Although natural selection is not responsible for the evolution in the flipbook animations, teachers should not forget to discuss how natural selection is involved in this activity: it is the non-random process behind our cells’ ability to copy DNA without making many mistakes and it is mimicked by tracing in the flipbooks. However, like tracing drawings, DNA replication is imperfect and the chance variations that arise are a fundamental component of evolution.

With these flipbooks students can see for themselves, albeit in a symbolic way, how random mutations can contribute to complexity by flipping through the “recognizable” flipbooks backwards (from the last tracing to the template). When viewed in reverse, the animations evolve from (perceived) simplicity to (perceived) complexity. And when students are reminded that all the mistakes in the tracings (i.e. the mutations) are still the same and that it’s just the sequence of these mistakes that differs in the reverse view, a dialogue is opened up about the roles of chance and deep time in the evolution of complex life (10).  Students can reflect on whether chance mutations and drift could have produced a flipbook that started with a blob and ended with a symbol. After gaining this insight, they are better poised to question the relevance of probability-based arguments against evolution and the origin of life (11). 

The roles of luck, chance and randomness too often take a back seat to natural selection and this activity is meant to help introductory students achieve a more complete view of evolution from the start. Although I cannot guarantee that every student will be evolutionarily enlightened or artistically inspired by this activity, it will provide teachers and students with tools for overcoming some of the mistaken assumptions about evolution that we so often inherit and propagate.

Acknowledgments

            Thanks to B. Bailey, N. Bailey, A. Collado, J. Conrad (and the lizard), W. Harcourt-Smith, G. Felda, C. Mesyef, D. Nelson, B. Shearer as well as the students in my two sections of ‘APG 201: Human Origins’ at The University of Rhode Island during the Fall 2011 semester for providing valuable input during the development process.  Thanks also to Anne Buchanan, Norman Johnson, Kevin Stacey, and Ken Weiss for their most helpful comments on the manuscript. Clement Valla’s art was the spark and I’m grateful for it.

References

1.      Helgason A,  et al. (2009) Sequences from first settlers reveal rapid evolution in Icelandic mtDNA pool. PLoS Genet 5(1): e1000343. doi:10.1371/journal.pgen.1000343

2.      Lahti DC, Johnson NA, Ajie BC, Otto SP, Hendry AP, Blumstein DT, Coss RC, Donohue K, Foster SA (2009) Relaxed selection in the wild. Trends in Ecology and Evolution 24: 487-496.

3.      Yoshiura K, et al (2006) A SNP in the ABCC11 gene is the determinant of human earwax type. Nature Genetics 38: 324-330.

4.      Weaver TD, Roseman CC, Stringer CB (2007) Were neandertal and modern human cranial differences produced by natural selection or genetic drift? J Hum Evol 53: 135-145.

5.      Gould SJ, Lewontin RC (1979) The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. Proc R Soc Lond B 205: 581-598.

6.      Weiss KM, Dunsworth HM (2011) Dr. Pangloss’s nose: In evolution, cause, correlation, and effect are not always identical. Evolutionary Anthropology 20:3-8. 

7.      Johnson NA, Lahti DC, Blumstein DT (in press) Combating the assumption of evolutionary progress: Lessons from the decay and loss of traits. Evolution: Education and Outreach.

8.      Gillings MR (in press) How evolution generates complexity without design: Language as an instructional metaphor. Evolution.

9.      Nehm RH, Rector M, Ha M (2010) "Force Talk" in evolutionary explanation: Metaphors and misconceptions.  Evo Edu Outreach 3:605–613.

10.   Nilsson DE, Pelger S (1994) A pessimistic estimate of the time required for an eye to evolve. Proc R Soc Lond B 256: 53-58.

11.   Morris HM (2003) The mathematical impossibility of evolution. Back to Genesis, 179. El Cajon, CA: Institute for Creation Research. Available via the Internet. Accessed 2011 December 22.

---

[A] Estimated roughly with the equation 2.5 x 10^-8 mutations per generation, per 6 billion nucleotides based on published rates (e.g. Pelak et al., 2010.PLoS Genetics 6(9): e1001111).

[B] I cannot find a reference containing this hypothesis, but I cannot find one containing a selection-based hypothesis for ape tail loss either.

[C] For just one example of a scholarly treatment of these issues see ‘Race’ is a Four-Letter Word by C. Loring Brace (Oxford University Press, 2005).

[D] This estimate is based on three trials with ten, 25 and 30 students, respectively. However, making 50 tracings takes just as long with 25 students as it does with 125 students. This time estimate of 50 minutes only includes time for instruction and drawing. It does not include the time spent priming the students on evolutionary concepts and discussing the results. For my students, those discussions continued for the rest of the semester because the flipbooks were a useful touchstone for new concepts down the line. 

Behind the article 

It’s tough to get a paper accepted for publication. This one was rejected from an education series in a scientific journal. I chose to submit there because it's open access (and was prepared to pay if the fee wasn't waived) and the series is billed as a forum for classroom activities, not education research. 

I consider the three reviews (below) to be pretty supportive, especially #2, and think that with just a few revisions I could ameliorate the first reviewers' concerns about citing more literature.

But the academic editor’s concerns about assessment, as outlined in the cover letter (also below), which also echo #3's concerns about Intelligent Design (ID) would require much more work to address. Those issues, along with the extremely low-tech methods (just my hunch), is why I think that they rejected my paper rather than ask me to revise it.

Clearly a lot of my article's shortcomings stem from the fact that I am a college professor and not a trained primary-secondary school teacher, who must meet particular standards of evaluation and assessment. I might also have a poor understanding of the minds of students who are learning biology in high school (or younger). My attempt to transcend those things and address common difficulties that we all share with understanding and teaching evolution... at all levels of learning... well, it failed to be seen as that... perhaps because I failed at doing that! 

I chose not to submit elsewhere because I don’t know of many other open access journals that publish lesson plans and, from my personal perspective, I don't see the point of publishing a lesson plan if it’s not open access. I bet you’re thinking that tenure’s the point. Well, if my choices are (a) submit somewhere else and risk burying it in a journal that few will see, or (b) turn my focus to other publications for my tenure portfolio and make this activity available, now, to anyone with Internet access who visits us here on the Mermaid’s Tale...

...then, I’ll take b.

I'm posting the letter and reviewer comments (with my comments in italic red) for a few reasons: (1) if you decide to try this activity, the comments will help you anticipate any issues or problems you may have; (2) you can see the kind of reviews that a paper like this gets and the sorts of things that people require of evolution lesson plans; (3) it's in the spirit of open access which is what this manuscript has been about from the start of my writing it. 

Article submitted on December 28, 2011, Reviews back on February 10, 2012 

So swiftly returned!

Dear Dr. Dunsworth,

Thank you very much for submitting your manuscript "Luck of the draw: Evolving flipbooks mimic non-selective processes" for review by _________. As with all papers reviewed by the journal, yours was assessed and discussed by the editors. In this case, your article was also assessed by an academic editor with relevant expertise and three independent reviewers. Based on the reviews, I regret that we will not be able to accept this manuscript for publication in the journal.

The reviews are attached, and we hope they may help you should you decide to revise the manuscript for submission elsewhere. I am sorry that we cannot be more positive on this occasion.

Overall, the reviewers and the academic editor thought the approach is innovative, though should be more firmly grounded in the prior work dealing with students' understanding of "random" and evolutionary processes.

I honestly thought it was grounded in common knowledge, but I should have cited this and this. (A useful side tip: I perform pre- and post-tests at the beginning and end of each semester with a survey that I built thanks to Cunningham and Wescott's paper. The survey really helps me gauge where students are and where they end up so that each semester I can hopefully help them end up even better. This semester I showed them last semester's stats on day one, tackling some of the issues head-on, like the fact that before taking my course 8% of them think dinosaurs and humans lived at the same time in the past, and 84% think that new traits arise because they need to.)

In addition, the academic editor worried that the activity runs the risk of confusing students by omitting a big piece of the process (selection).  

I assumed that selection would be covered well in other ways and that this activity would complement those efforts.

The reviewers also point out that it is unclear how the activity could be evaluated so that others could determine its efficacy relative to other activities.

If this is how teachers operate, then I’ve got a lot to learn. I didn't have a control group either. Never do!

The evaluation suggestions will be difficult to access, since many rely upon how "different" two drawings are, something that will be difficult to measure accurately and consistently.

It's hard not to jump to this conclusion: If you can’t assess the students’ work easily, then don’t have them do those things or think about those things. Alternatively, it could mean that to publish a lesson plan you must provide teachers with ways to assess the all the things that they ask of their students. Maybe this is one of the big differences between college and everything that comes before it.

For example, because individual viewers may well have different views as to whether or not the flip animations differ from the template, an exercise controlling for or illustrating the bias in viewer perspectives would seem necessary.

This is an exercise that illustrates the subjectivity. I think the issue here is that I should have included explicit instructions for counting, measuring or otherwise evaluating traits and their changes over time, and in deciding whether different drawings should be called separate species or not, rather than suggesting that teachers merely ask students to do all that on their own. But to me setting students free to do those things is a pretty important, and effective, part of the process assuming that the fundamental concepts will be covered in class as follow-up (something I assume teachers would do if speciation and classification were topics that they chose to address with the flipbooks). I think this is, again, my limited experience and college-level bias showing.

Even more problematic, however, is the possibility that students might take away the message that rather than random processes, overlaid by selection, account for increasing complexity in evolution, it is the work of an "intelligent designer." This is obviously not your intent, but something that Reviewer 3 points out may occur.

I had a hunch I’d get pinned for unintentionally promoting ID and I thought I was anticipating some of that in my concluding remarks. If teachers take on those issues (and I hope they do!) there are myriad resources out there to support them starting here and here on the MT and also here: http://ncse.com/.

I hope you appreciate the reasons for this decision and will consider _________ for other submissions in the future. The support of the community is essential if open access publishing is going to succeed, so thanks again for your interest.

Sincerely,
Editor
------------------------------------------------------------------------
Reviewer Notes:

Reviewer #1: While the author has identified a challenging educational issue - differentiating drift and selection as mechanisms of evolution - I found the framing of the problems and the connections to the instructional activity tenuous. There is an extensive literature dealing with students conceptions of "random" event, evolution, and teleological reasoning, none of which were referenced here. The activity was clearly described and sufficient context was supplied to support a teacher interested in adopting it for classroom use. There was, however, no evidence that the activity support the intended learning outcomes or that students enjoyed the lesson. I think we need to have a wide range of strategies for engaging students in evolutionary reasoning and in certain situations this resource may provide a mechanism for raising students awareness about the potential role of drift in evolutionary change. Unfortunately, I don't think this manuscript fits well in this journal and I believe it would be strengthened by connecting it to existing educational research.

Reviewer #2: The paper Luck of the Draw: Evolving flipbooks mimic non-selective processes describes an activity where students create flipbooks by tracing over drawings of either recognizable or unrecognizable templates.  Because tracing is not perfect, and students repeat the tracing effort over many pages, the final outcome provides an example of how small random changes can lead to evolution.  The paper is extremely well written, and the idea of the flipbooks very creative.  The author provides exceptional resources, including links to teaching tools explaining the art of animation, to leading questions for student follow-up and assessment of understanding.  The added figures help the reader visualize the degree of variation that can accumulate over the course of the exercise.  The focus on helping students understand how random events influence evolution is great.  The author correctly identifies a significant problem - too many activities focus on selection, and students, who are already challenged in understanding the concept of random, all too often believe evolution equals natural selection.  Many of the antievolution arguments focus on the perceived impossibility of random events resulting in the evolution of complex structures.  Helping students understand how random events might influence evolutionary change is a very worthwhile educational strategy.

Reviewer #3: This is a very good foundational activity for introducing evolutionary mechanisms.  The chief concern relates to the directionality and complexity issues raised in the concluding remarks, which may be an unavoidable result of the tracing instructions given to students. It seems as though attempts to trace will always result in degradation of initial templates into blobs, which feeds into the 2nd law and mathematical impossibility notions advanced by creationists. So while you may be able to introduce other mechanisms, is one doing so at the risk of demonstrating that the "intelligent designer" of the student themselves is really the take away lesson.  While the point of this exercise may be to raise awareness of the random aspects of evolutionary processes, it may not be clear to students (or pre-college teachers), that they should expect this sort of behavior from such a random process, and that the accumulation of order and complexity results from the overlaying of selection onto random variation.  One suggestion to be considered is to ask if it might be possible to give the students any other instruction that could lead to an accumulation of complexity, without being too Panglossian or feeding into even worse ID notions. Maybe something like "if you see an acute angle, make it into a loop", or something similar that might lead to feature accumulation without having students try to achieve a predetermined target shape. The concern still is that the reason for the variation to be introduced is being produced by the generator, not the system. For more advanced student audiences it seems appropriate to suggest that teachers provide some refutation of the mathematical impossibility argument based on the idea that specifying any specific outcome for a probabilistic system is difficult, but that some outcome has to result.

Part of what  this reviewer is picking up on with the flipbook metaphor/activity is that tracing errors seem to miss parts more than add parts. This would appear to play into Behe's and other ID/creationist arguments that  mutations only chip away at complexity rather than contribute to it. Obviously this activity is only a metaphor and it also cannot go without a companion lesson in selection (which helps a great deal with complexity). One way to avoid giving the impression that mutations only take away complexity would be to stick to unrecognizable templates. But I don't recommend doing that since the recognizables offer great opportunities for teaching the important random mechanisms that are the focus of the lesson. (See 'concluding remarks' where I explain how the recognizables are where students struggle to see the role of chance.) I think that I inadvertently encouraged this reviewer's concern with my wording in that second to last paragraph in the 'concluding remarks.' I should have pointed out how some resulting drawings appear more complex than the templates before going into the trouble with perceiving complexity in the recognizable ones. I think I underestimated how powerful this metaphor could be.


But, overall, regarding #3's issues... I am satisfied with what I laid out in my concluding remarks. Teachers may choose to face the complexity issue explicitly in class and if so they should probably discuss how mutations that cause variation do contribute to the evolution of complexity--even with a mutation that reduced the number of chromosomes in the human lineage, we consider ourselves more complex than chimpanzees who retained one more pair than we did. In the article I cited the famous eye evolution paper for demonstrating the evolution of complexity over time with the accumulation of small mutations. You could also discuss gene duplication's role in complexity. You could talk about hox gene expression in bat wings and bird beaks. You could discuss lactase enzyme production into adulthood and the various known SNPs to allow this in some populations. Even the famous sickle-cell and malaria example illustrates how mutations add to complexity. Ken and Anne have recently listed off a few examples here. Some of these issues raised by ID and anti-evolution folks aren't much more than semantic arguments and differences of perspective...which are issues that stray far from the real biological ones they claim to be about. The same is true, I suspect, for some debates within the evolutionary sciences.


Regarding the suggestion to ask students to deliberately change the drawings in directed ways... I'm uncomfortable with changing the human tracer away from what it is--an imperfect DNA copier--because I worry that would support notions of agency, religious and secular alike! (see my rant here) I also don't think that it's up to an evolution lesson to disprove agency because nobody can do that. What we can do is show how evolution occurs without agency (like we do with this activity). 
------------------------------------------------------------------------

My final thoughts and requests for teachers

These reviews have left me feeling a bit daunted about helping to strengthen evolution education at its earlier stages so that fewer people make it to college and through college so full of misconceptions. If the pre-college rule is that you can't teach something that can't easily be assessed or that you can't teach something that would possibly be fodder for creationists, then I think we risk miring ourselves in the status quo. Religious objections are only one  kind of obstacle to learning and teaching evolution, and letting that one obstacle dominate our pedagogy limits our ability to overcome the rest of them.

Teachers, if you try 'Luck of the draw' please consider the issues raised by the people who put time and effort into reviewing it. 

Take my word for it--students have a lot of fun with it and learn a lot from it. It's a great activity to have students perform if you're away traveling. They can meet somewhere more exciting than the classroom, trace the books together, then bring them back to the next class for discussion when you return.

Trust me, it's not complicated--it's just that there are so many concepts you can choose to run with!

And when you're all done, please leave feedback here. I'd love to know how it goes! I'd love to hear suggestions for improvement!

(c) Holly Dunsworth
Note: I know it's a blog, but this is where I chose to publish. That means, if you use this then find a way to cite it, please. Thanks and welcome to the future!


I'll gladly share a nice printer friendly version of 'Luck of the draw' with anyone who'd like it. Just let me know.