Undergraduate Biology Should Teach More Evolution

I have been researching the literature in science education, specifically neuroscience, genetics, and microbiology, and I’m surprised to find that not much import is given to the theory of evolution (or natural selection). Given that “Nothing in biology makes sense except in the light of evolution” (a 1973 essay), I really expected to find a unit on evolution or at least this theme within the curricula of these disciplines.

Neuroscience

Kerchner, Hardwick, and Thornton surveyed faculty of undergraduate neuroscience programs to determine which “Core Competencies” were most important for undergraduate neuroscience majors (for the record, when I was an undergrad, very few colleges offered this field of study as a major, it was regarded to be a specialty reserved for graduate study — for example, you could major in biology, molecular genetics, biochemistry,  evolution-ecology-organismal biology, and microbiology, but not neuroscience at Ohio State).  The three most important core competencies for a neuroscience program:  1. Ability to engage in critical & integrative thinking, 2. Basic neuroscience knowledge, and 3. Scientific Inquiry / Research Skills (in that order). Interestingly, quantitative ability was ranked the least essential by the greatest proportion of faculty.

Within the component of Critical Thinking, they listed: 1. Ability to read & analyze a primary research paper, 2. Ability to critique & develop experimental designs, 3. Ability to integrate findings from diverse fields to develop a testable hypothesis … as the three most essential.

Within the component of Basic Neuroscience Knowledge, they listed: 1. Understanding the cellular and molecular function of neurons, including how they communicate (79% said essential), 2. Understanding basic neuroanatomy (45% said essential), 3. Understanding behavior and cognition, as they relate to neuroscience, 4. Understanding of sensory and motor systems, as they relate to neuroscience, and 5. Understanding development and plasticity of the nervous system (only 21% said essential) …. as the five most essential.

Nowhere in their paper did they mention that understanding evolution or natural selection of the nervous system as an essential core competency of undergraduate neuroscience training. This really surprises me because there are two obvious teaching examples that cover critical thinking and basic knowledge.

A simple teaching example (to me anyway), would be to discuss symmetry of multicellular animals and the differences in their nervous systems. In radial organisms, like jellyfish & starfish, the neuroanatomy is relatively simple, and limited to a neural network, and not a centralized structure; in bilateral organisms, there is directionality to the sensory organs and so complexity and specialization develops over evolutionary space. What is it about the body plan of bilateralism when variations on existing structures open new niches in which nervous systems can develop?

The second obvious example is to discuss the eye. The eye is an extension of the central nervous system, with neural fibers going directly to the brain (not via the spinal cord like sensory nerves in the skin or motor neurons in skeletal muscle). The fully developed and functional eye is given as an example by creationists and intelligent design proponents as an example of what they call “irreducible complexity.” The idea here is that none of the components could exist or be useful or be selected for without the other components. That is, the lens wouldn’t have developed without something to focus light onto (the retina) and the retina could not function to transmit signals without focused light from the lens (this is the major flawed premise of the argument) and so the eye must have been designed whole from nothing.  Obviously this is not true. The planarians are a family of flatworm that has two eyespots which sense light. It only has a few photoreceptors and pigment cells; no lens, no muscle to direct it; no image is formed in the nematode’s “brain.” You could imagine that detecting light and then changing behavior in response to it (probably swim away!) conferred an advantage that allowed those who responded better & faster to breed more, leading to the species alive today. We could assign ecological niches to the various components of eyes and photoreceptor bundles across species and interpolate selection processes that led to emergence of the eyeball. In fact, the eye evolved independently in cephalopods (e.g., octopuses & squids) from chordates (e.g., humans). In developing an undergraduate neuroscience curriculum, I would at least have being able to place basic neuroscience knowledge in the context of the theory of evolution as part of a core competency (which exercises critical thinking skills).

One more note on the Critical Thinking Skills. I find it fascinating that this was ranked as the most important competency of an undergraduate neuroscience program. In the same paper, they also noted that ability to use various laboratory methods was ranked fairly low. This strikes me because most students seem to want to focus on these technical skills and to spend time exercising and practicing these tasks more than the critical thinking. I think that faculty ranked it fairly low on the importance scale because we know with experience that, as technology progresses, the laboratory techniques change. What undergraduate students learn to master in the lab will likely be outdated and irrelevent by the time they are practicing scientists (or not — maybe just citizens with knowledge of neuroscience, or primary care physicians); so this takes back seat to critical thinking skills, despite what students find most exciting/interesting. We should find a way to integrate critical thinking into laboratory techniques teaching. This is difficult because most labs are cook-book style exercises in following instructions (you’d be surprised how many students are poor at this), without much critical thinking. This is why I would emphasize model building from data and hypothesis testing in any/all lab techniques.

I digressed, though. I wanted to talk about a paper from Journal of Higher Education, which used an evidence-based assessment of pedagogies that improve  Critical Thinking Skills over the course of a bachelor-degree education by Lisa Tsui (I think it’s gated, email me for a copy). Essentially, she found that programs that involve an intense assignment or course on writing does the best at fostering critical thinking skills. So despite what students may want from neuroscience (get their hands dirty), the best way to improve critical thinking is to plop them down in a library and make them write.

Genetics

Rosemary Redfield wrote an article in PLOS Biology last year calling to overhaul the Genetic Canon, specifically calling for re-ordering how concepts are introduced. While I agree with her assertion, that the Canon as is, is outdated (read her article), I disagree with the solution. She calls for the new syllabus to have “Personal Genomics” first, under the (perhaps correct, perhaps misguided) belief that students want to know how a field or topic affects them personally in order to develop an intellectual interest. (My opinion is that catering to this tendency stunts their intellectual development and makes them narcissists). Genetics and molecular genetics are some of the key substrates for evolution and I feel that if students are taking Intro Genetics after General/Intro Biology, they will be primed for this discussion right off the bat. Start big, then work small. Show them how complex all of life is; how diverse mechanisms of information transfer (genetics) across generations is; show them how these mechanisms are both (1) A product of natural selection from diversity, and (2) Drive diversity. It can be a super exciting look at the wonderment of the world around us and that we do understand lots of it and we can understand it more, but she instead starts with recommending the narcissism card.

Amino acid sequence alignment of homologous genes from three related genes. Horizontal distance represents genetic divergence. Note high conservation for FKBP1A (green) and high diversity for FKBP4 &5; FKBP5 sequence emerges within the FKBP4 clade.

Amino acid sequence alignment of homologous genes from three related genes. Horizontal distance represents genetic divergence. Note high conservation for FKBP1A (green) and high diversity for FKBP4 &5; FKBP5 sequence emerges within the FKBP4 clade.

I’ve been working on a  cool exercise that I think could be incorporated into an Introductory Genetics course. I tested it out with a high school student who was volunteering in my lab last summer, so I am confident that a smart group of undergrads should be able to carry it out. That is, a simple phylogenetic analysis of gene sequences. I did this as a side-exercise for my PhD project. My PhD project had nothing to do with evolution or genetics, but I was interested in seeing how these gene pairs developed over evolutionary history. This figure is from my dissertation. These genes, FKBP4 and FKBP5 are related. FKBP5 is a copy of FKBP4, but FKBP5 lacks certain functional components, and so acts as a competative inhibitor to FKBP4 wherever the two are in the same place, potentially interacting with the same substrates. This introduces another level of complexity and regulation for a cell to control the FKBP4 functions. FKBP5 emerged relatively recently.

Conclusion

Teach more evolution. It’s fun, it’s fascinating. It fosters critical thinking.

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2 Responses to Undergraduate Biology Should Teach More Evolution

  1. I agree whole-heartedly that an understanding of evolution in central to all of biology.

    For the past couple years, I have added Shubbin’s ‘Your Inner Fish’ as a parallel discussion throughout the semester (i.e. we discuss about a chapter a week). Students seem to like the book and find it entirely accessible. Further, it does a good job to keep us thinking about relationships and homology all through the course.

    But, what I really wanted to comment on was your idea of having students look at related gene (sequences) in the context of phylogenetic trees. I do that to a limited degree and find that it can be very interesting to students. They have heard that all life shares a universal code and they understand that’s what underlies recombinant protein production, etc.. However, actually seeing the mix of messiness and order that actual DNA illustrates is invaluable.

    • citizensci says:

      Thanks! Do you teach “Your Inner Fish” in an Intro Genetics course? I think that would be a great idea. Looking at related gene sequences also gets them primed to using NCBI resources, which teaches them how to research/find information they need in general, and how to use these specific tools that’ll be useful for grad/med school should they choose to go. Did you have them use the “Homologene”tool?

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