Biology Tells a Good Story: Teaching Evolution Using BioInteractive Resources

I am always fascinated by the wild stories that are told with biological evidence: “Human Chimeras That Already Exist” … child’s fetal stem cells can stay in mom’s body for years and be enlisted to heal mom; “DNA Analysis Confirms Authenticity of Romanovs’ Remains” … Anastasia is not living in Chicago; “Tracing Septic Pollution Sources Using Synthetic DNA Tracers: Proof of Concept” … we know whose poo is polluting the water!

There is no hiding from our DNA. Our DNA tells who we are related to and how. But the DNA we use to know our family tree in our immediate and distant human relatives is also the same tool we can use to know our more extended family relatedness in biological evolution. And DNA is not the only biological tool we can use to tell our story of evolution. Like these wild biology stories of chimeric twins and pollution detective work, the story of evolution is also amazing science explained with biological evidence.

Sometimes, students’ thinking parallels society’s: they have the misconception that biological evolution is a topic of controversy. HHMI BioInteractive resources give me the tools to move students away from this idea. The BioInteractive learning tools allow me to teach biological evolution as a threaded narrative in the whole story of life on Earth. By teaching evolution as a logical tie to our learning in every unit, students are able to make sense of the “controversy” and know the science behind the real evolution story — and use genetic comparisons as key pieces of evidence for evolution.

So, although my classes have a later unit called “Evolution,” I integrate key components of evolution into our earlier units as well. When we start our year with topics on cells, bioenergetics, and inheritance, students also learn how DNA changes provide variation among individuals within populations and how those variants can lead to some individuals surviving better than others in ever-changing environments. In other words, they begin to learn about biological evolution. BioInteractive’s short films and Click & Learn resources for human variation in lactase persistence and bitter taste in particular set the stage for student learning about evolution. Students learn why humans have evolved to show variation in the ability to digest lactose milk sugars and in the ability to taste bitter substances.

Next, students learn how biochemistry and cell signaling pathways work to determine pigmentation in both rock pocket mice of the desert and in humans. They make the connection that the MC1R gene determines pigmentation in both species and that humans share genes with other organisms. In the rock pocket mouse video and worksheet activity, students look at the amino acid sequences of the protein receptors coded for by the wild-type and mutated MC1R genes of mice. They compare the sequence differences to hypothesize why they can result in cell signaling and gene regulation differences that lead to different pigment production, resulting in either tan or black mice. As with the bitter taste and lactase-persistence resources, students learn how selective pressures, such as dark lava flows versus light desert sand, resulted in evolving populations.

After fun with mice, our learning shifts gears to finding out how MC1R gene variants in humans also result in the production of different amounts of pheomelanin and eumelanin protein in human skin. Using the BioInteractive assessment/interactive video on human skin color, students learn how and why humans have adapted to UV light exposure, and how the pigmentation of our skin allows us to survive in the face of conflicting biological needs: the need to obtain UVB for vitamin D production, and the need for protection from UV so that it doesn’t destroy folate (a vitamin needed during embryonic development). An “aha” moment for students! Evolution requires variation, selection, and the ability to pass on selective advantages to offspring!

Once students know that populations of mice and “men” are both evolving due to changing environments and selective pressures, our focus then turns to understanding how elements of natural selection apply to the evolution of stickleback fish. We use the “Modeling the Regulatory Switches of the Pitx1 Gene in Stickleback Fish” activity to learn how changes in Pitx1 gene expression can affect stickleback body development, and how those changes, with the appropriate selective pressures, can play a role in stickleback evolution. More variants, more fun, more evolution learning! By this time, students understand that evolution explains many things in biology, and that learning evolution isn’t just a solitary unit in the year or a topic for controversy, but rather an overarching theme to everything we learn all year long!

After completing the first four units of study — biochemistry, cells, cell signaling, and cell membranes — by the fourth week of class this fall, a student class feedback survey showed that 85.7% of my students self-identified as better understanding the mechanisms of evolution as related to life on Earth. Knowledge is power!

The science of evolution tells the story of how life on Earth has changed over time. Support for evolution comes from evidence, and as I observe students continuing to learn these concepts later in the course, I don’t hear the whispers and questions and discussions of controversy that marked my teaching of evolution in years past. And to think we haven’t even started the evolution “unit”!