"Six million years ago, what set our ancestors on the path from ape to human?".
Subject: Evolutionary biology (Analysis)
Human evolution (Analysis)
Author: Dougherty, Michael
Pub Date: 02/01/2011
Publication: Name: The American Biology Teacher Publisher: National Association of Biology Teachers Audience: Academic; Professional Format: Magazine/Journal Subject: Biological sciences; Education Copyright: COPYRIGHT 2011 National Association of Biology Teachers ISSN: 0002-7685
Issue: Date: Feb, 2011 Source Volume: 73 Source Issue: 2
Geographic: Geographic Scope: United States Geographic Code: 1USA United States
Accession Number: 259466262
Full Text: (a) NARRATOR: Humans: without a doubt, the smartest animal on Earth. Yet we're unmistakably tied to our ape origins. Millions of years ago, we were apes, living ape lives in Africa. So how did we get from that to this? What happened? What set us on the path to humanity? [Opening narration]

(b) NARRATOR: But Selam's brain was only around 75 percent of its adult size, suggesting it was growing up slower. Childhood would have been her time to learn, o learn the survival strategies her family group needed to live in a dangerous world. Perhaps this set the stage for our longer human childhood when culture is handed down. But is there any other evidence Selam's brain was becoming more human and less ape? To find out, compare a human brain to a chimp's.

Wait a minute, don't apes still exist? In fact, aren't humans apes? The title and script above are taken from NOVAs "Becoming Human" series, which aired in November 2009. Such statements perpetuate common misconceptions about human evolution. If they struck you as incorrect, then you probably understand evolution well enough to avoid conveying these misconceptions to your students. Yes, apes still exist, humans are apes, and humans didn't evolve from apes. Humans and apes evolved from a common ancestor. Unfortunately, that understanding escaped the producers.

Human evolution is one of the most difficult topics to teach well, and one of the most controversial. For those reasons, it is essential that learning materials be accurate. Sadly, NOVA-a commonly used and typically reliable curriculum resource for biology teachers--opted in this case for pithy and dramatic language over more accurate but less familiar language. With that choice, NOVA missed a nice opportunity to help students, teachers, and, perhaps more importantly, a large audience of adult viewers to correct or avoid a common misconception about human evolution. Handled differently, this was a chance to distinguish direct ancestry from evolutionary branching and divergence from a common ancestor through descent with modification.

This brief editorial attempts to do only two things: (1) call attention to this unfortunate and avoidable error; and (2) suggest a way to turn that error into a teachable moment for your students, especially if you plan to use this otherwise informative program.

Errors in public presentations of science, as with errors in science itself, should be identified and corrected whenever possible, lest our silence be taken as assent. In this case, my intent is not to embarrass PBS or NOVA but to make certain that the producers of such influential shows realize that the scientific and teaching communities expect better.

The "Becoming Human" series has already been broadcast nationally and is available via DVD and online through NOVAs Web site. If you are planning to use "Becoming Human" in your teaching, consider integrating the excerpts above (and others, particularly in Part I) to elaborate on the fundamental principles of human evolution. Take advantage of the series' misstatements to challenge your students to think about the difference between "humans evolving from apes" and "humans and other apes evolving and diverging from common ancestors."

Ask your students to pinpoint the errors and suggest that each student or pair of students rewrite the passages to make them correct. Consider having a brief discussion about possible reasons why the content was presented incorrectly--for example, ignorance on the part of the writers. Interestingly, it is only the program copy written for the narrator that systematically uses incorrect statements about human evolution; the experts who are interviewed speak more accurately This distinction might provoke the students to consider other possibilities, such as a desire for dramatic effect (e.g., imagining nonhuman apes actually turning into humans) or concern that the public would be unable to understand the concept of common ancestry The misstatements in this exercise could also be used as the basis of quiz or exam questions.

When students understand common ancestry, many of the objections to evolution raised by creationists and the otherwise misinformed lose traction. "Becoming Human," despite its shortcomings, can be used productively to advance that crucial learning objective.

DOI: 10.1525/abt.2011.73.2.2



MICHAEL DOUGHERTY, a long-time NABT member, is Director of Education at The American Society of Human Genetics, 9650 Rockville Pike, Bethesda, MD 20814; e-mail: mdougherty@ashg.org. NOVA's "Becoming Human" series is available online at www.pbs.org/ wgbh/nova/evolutionlbecoming-human-part-1.html.
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