How to Win the Evolution War: Teach Macroevolution
By Kevin Padian
Click Here for PDF Version of this page.
Original article in the Evolution Education and Outreach Journal (now freely available): Go to http://link.springer.com/journal/12052
select volume 3 issue 2 and search for the title ("How to Win the Evolution War...")..
Available also at eScholarship Universithy of California, at
If the American public understood what is actually known about the major evolutionary transitions in the history of life and how we know about them, uncertainty about evolution would drop precipitously, creationist arguments would fall on deaf ears, and public education in biology would make much more sense than it now does. Macroevolution must take a much more prominent place in K-12 science teaching. To do so, a curriculum must be redeveloped at both K-12 and college levels, so that preparation in macroevolution is a required part of K-12 biology preparation [emphasis added].
Author Padian points out in his article that “nothing substantial about macroevolution is in the framework or syllabus of any state, so not only will it not be taught, it will be discouraged from being taught.” Now we have some good news! Note that this article was published June 2010, before publication of the national NGSS (Next Generation Science Standards, 2013), or even the Framework for K-12 Science Education (2012) on which the NGSS is based. In the NGSS, there are at least three Performance Expectations (PEs) that deal with macroevolution (though that label is not used). The middle school standards for Natural Selection and Adaptations lists these two PEs:
MS-LS4-1: Analyze and interpret data for patterns in the fossil record that document the existence, diversity, extinction, and change of life forms throughout the history of life on Earth under the assumption that natural laws operate today as in the past. [Clarification Statement: Emphasis is on finding patterns of changes in the level of complexity of anatomical structures in organisms and the chronological order of fossil appearance in the rock layers.] [Assessment Boundary: Assessment does not include the names of individual species or geological eras in the fossil record.]
MS-LS4-2: Apply scientific ideas to construct an explanation for the anatomical similarities and differences among modern organisms and between modern and fossil organisms to infer evolutionary relationships. [Clarification Statement: Emphasis is on explanations of the evolutionary relationships among organisms in terms of similarity or differences of the gross appearance of anatomical structures.]
The high school standards for Natural Selection and Evolution lists just this one PE:
HS-LS4-1: Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence. [Clarification Statement: Emphasis is on a conceptual understanding of the role each line of evidence has relating to common ancestry and biological evolution. Examples of evidence could include similarities in DNA sequences, anatomical structures, and order of appearance of structures in embryological development.]
FINALLY!, we have national standards that expect students to learn about macroevolution – the big picture of evolution. Even better, the emphasis is on the evidence, especially multiple lines of empirical evidence. Of course, states in the USA are not required to adopt these new standards. But a few states already have, and many more probably will adopt the NGSS, perhaps with some modifications. Hopefully, those three macroevolution PEs will be retained as is.
What teachers do not get with this is a curriculum for teaching to those standards, nor do they automatically get special training to do that. Some districts in some states may provide this, or they may not. This is where ENSIweb comes in. We have many excellent, classroom-tested, interactive lessons that address macroevolution in various ways. They are free. Each has detailed instructions for using them, along with the materials needed and the expected kinds of responses to discussion questions (primarily for teachers unfamiliar with this subject).
Let me be more specific: Here are some ENSI lesson ideas relevant to each of the three PEs described above:
For MS-LS4-1: Seeking patterns in the fossil record? Take a look at the ENSI lesson Patterns in Time, where the emergence of the different classes of vertebrates is clearly recorded in the fossil record. The first members of each “class” clade (fishes, amphibians, reptiles – including birds, and mammals) make their first appearance many tens of millions of years apart. In addition, each new class carries the same characteristics as its predecessor, plus some modifications of earlier features that become characteristic of the new class. The earliest forms of each new class exhibits a mix of features shared by the previous class plus some of the new features – true intermediate or transitional forms. In addition, the Becoming Whales lesson reveals a series of fossils that provides a clear pattern of increasing whaleness. And most importantly, our Skulls Lab does much the same, using a series of fossil hominin skull casts. If you really want to see excited students, give them a chance to study and compare those hominin skulls. By doing so, they discover (over geological time) increasing numbers of human-like traits alongside decreasing numbers of ape-like traits. It’s inescapable: a changing mosaic over time. By the way, evidence if human evolution is not included in the NGSS, but it’s also not excluded! There are many excellent examples of evolution in human lineages, so use it as much as possible. But use it properly (as described in the ENSI lessons). Because of its novelty and interest, students generally find this material very engaging.
For MS-LS4-2, the Becoming Whales lesson again works well. This is a straightforward lesson in which students experience the discoveries of a series of pre-whale fossils, noting the features that show their increasing “whaleness.” As each fossil discovery is placed at its measured age on a geological time scale, a graded sequence from tetrapod to clear ocean-going whaleness develops. Then, doing the Whale Ankles and DNA lesson, students discover two other lines of evidence pointing to the origin of whales from a particular group of tetrapods that shares its ancestry with modern day hippos (an excellent example of how multiple lines of empirical evidence reinforce the picture of common ancestry (PE HS-LS4-1).
For HS-LS4-1, do the Chromosome Fusion lesson (or its more dramatic variation: Mystery of the Matching Marks). Along with the Skulls Lab, these lessons provide increasingly compelling evidence for the common ancestry of humans and chimpanzees. The Mystery… lesson also emphasizes the multiple lines of evidence as it builds dramatically from a gunshot, much like a crime scene analysis.
There are several other ENSI lessons you can also use to facilitate student learning about those three Performance Expectations. Try different ones with different classes, or in different contexts at different times in your course. Go to the Evolution Index page and scan through the nearly 40 lessons. I’m sure you will find many useful lesson to help meet the Next Generation Science Standards.
MAIN POINTS IN THE ARTICLE:
Teach phylogenetics (cladistics). In fact, Padian says, phylogenetics is very useful in understanding evolution, so it should be taught before the units on evolution and the diversity of life. See UC Berkeley's Excellent Resource at Understanding Evolution. Also, see the several effective ENSI lessons in the "Classification & Relationships" category of the Evolution Lessons index.
Most important concept that needs to be conveyed to students:
"We know a tremendous amount about how major groups of organisms originated, how major new adaptations evolved, and how fundamental ecological shifts took place in the great lineages of plants, animals, and other creatures throughout the history of life." "Using the integration of information from fossils, genetics, developmental biology, embryology, and phylogenetics, we can now say confidently that we have limned the major outlines—and many important details—of great evolutionary events such as the Cambrian explosion of animal life, the origin of tetrapods, the rise of dinosaurs and the evolution of birds and their flight, the origin of mammals, the origin of whales, and many others.” Click here for details. Padian presented this information at the Dover “intelligent design” trial in 2005.
Also at the trial, fellow biologist Ken Miller presented compelling material about “how we know that the bacterial flagellum had structural and functional antecedents among other simpler bacteria, how we know about the evolution of the human immune system, and why humans have two fewer chromosomes than other apes simply because two pairs fused in the course of human evolution (and so contain two centromeres—one functional, the other not). [Click here for details]. This material is not straightforwardly explained in American textbooks and state curricula, and it is what creationists are most afraid of having schoolchildren understand.” [Editor’s note: The ENSI lessons on Chromosome Fusion and Mystery of the Matching Marks gives students the experience of suggesting (hypothesizing) what must have happened to give us one fewer pair of chromosomes than chimps and gorillas, then testing that idea.]
The author also suggests a number of topics often taught in biology that should be omitted or significantly modified, therefore making room for the more useful and academically more valid topics. For example, eliminate Lamarck’s ideas, especially about how species change. They have not been confirmed scientifically, and its treatment in current textbooks is inaccurate anyway. Also, omit any detailed treatment of the species concept. Instead, be sure students understand at least some of the ways speciation happens. This is the basis of macroevolution.
Avoid superficial treatments of the history of life on earth. Just reference a “sensible annotated chart of geologic time” to provide a sufficient overview, then “document examples of how we know what we know about the evolution of some major groups and adaptations.” [Editor’s note: This is exactly the kind of understanding that the NGSS expect. The ENSI lesson Patterns in Time does a nice job of this, as does Becoming Whales.]
Finally, avoid any extensive treatment of Linnaeus’ classification system. His basis turned out to be superficial and invalid. In his Origin of Species, Darwin insisted that all classification should be based on genealogy (what we now call phylogenetic relationship.
Author Padian also discusses what the Creationists don’t want students to know, and why that is. This knowledge can help you understand their perspective, and how it ignores the reality of the well-established evidence of evolution we’ve had for decades, and how we’ve come to understand it. [Editor’s note: I have found that much of evolution that some people say they don’t “believe in” can be traced to misinformation about both evolution and the nature of science. Hence, an important part of our teaching goal is to replace that misinformation with accurate information. They can accept it, or not, but at least they should have correct information (and understanding) on which to base their position.] Padian offers some ideas on how to teach what we really know about evolution.
With insight to how the education industry works, the author suggests ways to change the system to improve evolution education, some of which have already been done. This is followed by suggestions for what teachers can do to bring about an effective and accurate evolution education. This includes teaching “how we know what we know about macroevolution, and the patterns and processes that describe the major changes in the history of life.” In doing this, the focus must be on the 40-50% of the people who are reasonable and uncommitted, but currently uneducated (or mis- educated) about the problem. The 25% of people who are totally committed to their negative views about evolution are unlikely to be receptive to that information, and can only distract us from our job of teaching about how science—and evolution—works.