Pancake Evolution: A Novel & Engaging Illustration of Natural Selection

Despite the primacy of evolutionary theory in the field of biology, a minority of individuals in the United States accept this fundamental concept (Miller et al., 2006). Educators have developed numerous methods to teach the concept of natural selection (e.g., Heim, 2002; Kalinowski et al., 2013; Hildebrand et al., 2014; Hongsermeier et al., 2017), but misconceptions among high school and college students are rampant (Gregory, 2009; Yates & Marek, 2015).

While no pedagogical technique is universal in its ability to promote scientific literacy, analogies are particularly helpful in explaining abstract scientific concepts because they promote higher-level thinking and the understanding of the new concepts (Gardner, 2016). One example of this is the use of familiar foods to illustrate complex scientific concepts. The use of food to illustrate scientific concepts has been shown to be more effective than standard science curricula for primary school students (Duffrin et al., 2010; Hovland et al., 2013), but few secondary and postsecondary science curricula utilize food. Here, we present a novel method to teach fundamental tenets of evolution through natural selection using pancakes and familiar food ingredients (see Table 1). These biology core ideas are requirements for meeting High School Next Generation Science Standards LS4B/LS4C and for all introductory college biology courses. All analogies have the potential for fostering misconceptions, so Table 1 also shows potential misconceptions.

Briefly, pancake batter is used to represent a shared genotypic background, to which variations (i.e., novel alleles or phenotypic traits) are introduced in the form of added ingredients. These novel “food alleles” – ingredients like chocolate, paprika, pickles, and bacon bits – represent variation at a food “gene.” Students first make pancakes with a single random ingredient, representing acquisition of the first novel “food allele.” The pancakes are then eaten, judged, and scored on the basis of their palatability, using the students’ taste preferences as environmental selective pressures. Particularly delicious pancakes persist, representing an adaptive benefit of the novel allele, while unpalatable pancakes, given low scores, are abandoned (representing death without reproduction). Thus, the most delicious alleles in the first generation are perpetuated to the next generation, where new food genes similarly acquire novel alleles. This represents subsequent acquisition of new diversity at different genes. And by perpetuating this process of adding novel ingredients, tasting, and judging palatability across multiple rounds (i.e., generations), students illustrate the process of selection for adaptive combinations of alleles in a given environment and selection against maladaptive combinations.

After preparation of pancake batter and ingredients, this laboratory can be completed in 60–90 minutes, making it conducive to both class and laboratory time periods. For each student group, materials needed include a portable electric hot-plate burner, small frying pan, spatula, pancake batter, and various ingredients (student food allergies and dietary restrictions influence selection of ingredients). A food-safe space is needed; we have used a physics laboratory and an outdoor classroom, but numerous other campus options are available.

First, students are divided into two large groups: “Pancake Producers” (with each pancake produced representing an offspring) and “Pancake Judges” (representing the environment in which offspring are born and, therefore, the selective pressure shaping population traits).

Pancake Producers are divided into groups of two or three students. Identical pancake batter is provided for all groups, representing similar genetic composition, and each group is then given a unique ingredient (for examples, see Table 2). Clear instructions are given to each Pancake Producer group and each Judge (see Tables 3 and 4). Once a single large pancake with the novel ingredient is made, the pancake is sliced into small pieces and distributed to the Judges for a “blind” rating on a scale from 1 (completely inedible) to 10 (delicious); instructors can create their own taste scale. A high score represents successful reproductions of the recipe (or the offspring, following the analogy; for an example, see Table 5, generation 1).

After tabulating the results of generation 1, the previous Judges become the new Pancake Producers, and the two top-ranking pancake ingredients are used in the next batch. Half of the newly assigned Pancake Producers will use winning ingredient 1 from generation 1, and the other half winning ingredient 2. Each producer group is also assigned a new ingredient at random (via coin flip or use of a random number generator; see Table 5, generation 2). Thus, during the second generation, each pancake will have two ingredients, and the environment has changed. If time allows, a third generation of pancakes can be produced using the same method.

For advanced learners, modifications to this laboratory can easily be made to illustrate more complex evolutionary concepts. Table 6 presents alterations to the protocol that can be used as analogies for genetic drift, neutral theory, evidence for evolution, and cladistics, and instructors are encouraged to develop other modifications.

Two methods were used to assess the ability of this laboratory to improve student understanding of natural selection: (1) evaluation of scores on natural selection questions on examinations, compared to scores on other topics on the same examinations; and (2) evaluation of student lab reports in which students were asked to write a paragraph describing how the activity illustrated the theory of natural selection using the following terms: adaptation, selection, genetic variation, trait variation, environment, and population.

Table 7 shows that, depending on the question, between 78% and 100% of students correctly answered natural selection questions. The total quiz and exam averages (covering topics other than evolution) were 58% and 73%, respectively, showing greater understanding of natural selection. A paired t-test (alpha level 0.05) indicated that students answered more natural selection questions correctly (M = 88.4, SD = 16.2) than non–natural selection questions (M = 71.4, SD = 13.7) on the same examination (t₆₈ = 2.0, p < 0.001). In addition, 100% of students attempting the lab report assignment at the conclusion of the activity correctly explained how the lab illustrated natural selection (n = 75).

We have found this short laboratory exercise to be an engaging method to teach fundamental principles of natural selection. This interactive activity uses an analogy to assist student learning by building on students’ own relevant knowledge, a pedagogically supported technique (Glynn, 1994).

Such noncontroversial activities are particularly needed in regions where lack of acceptance of evolution is founded in identity-protective cognition. In such areas, simply providing scientific information fails to foster acceptance of scientific conclusions, and other means of teaching the concepts are necessary (Walker et al., 2017). Our students truly enjoy the pancake-making exercise, and evidence shows that they learn much from this demonstration. Many common misconceptions, such as “survival of the fittest” and “individual evolution,” are easily identified and articulated by students after completing this lab.

We wish to thank the many undergraduates at Maryville College who participated in this laboratory. Funding for this project was provided by Maryville College Division of Natural Sciences and by a grant from the U.S. Department of Education (no. P116Z100249).