Evolution of the Chocolate Bar: A Creative Approach to Teaching Phylogenetic Relationships within Evolutionary Biology

Chocolate calms the mind, yet excites the senses. Chocolate also unites cultures. Chocolat (2000), a movie about a small town French chocolate shop, made millions internationally. Starring actors contributed partly to the film's success but the film also drew salivating viewers worldwide to the multiple applications of chocolate. With its stimulant properties, chocolate generally makes people feel good. Chocolate may also inspire creativity. For example, every day biologists can use chocolate's fortunate property of appearing in different shapes, sizes, and compositions to help students understand basic principles of evolution. Few students have visited the Galapagos to see Darwin's finches, but nearly all have sampled a variety of chocolate bars. Using chocolate as a "model organism" can make understanding key elements of evolution more palatable to the student. Chocolate represents an ideal model for exploration because it comes in many variations, some of which make good choices for describing evolutionary history and some of which change too much to be useful. In addition, a little Web research produces a timeline for the debut of different candies (Figure 1) that can lend insight into the construction of evolutionary trees. Figure 1. abridged history of the chocolate bar and candies. * 1890 George A. Bayle Jr., of St. Louis, Missouri, packages peanut butter in barrels and sells it for six cents a pound. * 1900 Milton S. Hershey of Lancaster, Pennsylvania, introduces the first Hershey's[R] Milk chocolate bar. * 1903 George Washington carver researches uses for peanuts. Peanut butter introduction to the world occurs a year later at the Universal Exposition in St. Louis. * 1920 Baby Ruth[R] candy bar is first sold, named for President Grover Cleveland's daughter. * 1928 Hershey introduced peanut butter cups later named after Harry Burnett (H.B.) Reese, a former dairy employee. * 1930 M & M/Mars introduces the SNICKERS[R] Bar, named for a favorite horse owned by the Mars family. One candy bar costs a nickel. * 1941 M & M'S[R] Plain Chocolate Candies (later M & M'S[R] milk chocolate Candies) introduced. * 1954 M & M'S[R] Peanut Candies introduced. * 1978 REESE'S PIECES candy is introduced. * 1982 REESE'S PIECES candy makes its big screen debut as "E.T.'s" favorite candy in the movie E.T., The Extra Terrestrial. * 1981 A European favorite since 1974, SKITTLES[R] Bite Size Candies are introduced in the U.S. by M & M/MARS. * 2001 SNICKERS[R] Cruncher premiers. * 2002 SNICKERS[R] with Almond Bars replace Mars Bar. * 2004 M & M'S[R] and chocolate bar merge into M-Azing[R] Crunchy and Peanut Butter versions. Sources: National Confectioners Association (http://www.candyusa.org/ Classroom/timeline.asp), http://www.peanutbutterlovers.com/history/, MM. All candies are registered trademarks. Teaching Evolution The theory of evolution (for bold words, see Figure 2, Glossary) is unfortunately and undeservingly fraught with controversy (Scott & Branch, 2003; Langen, 2004); most of it political (Weis, 2001). Despite its acceptance by the scientific community as the theory that explains how organisms change through time, innumerable debates flourish about when, where, or even why to teach evolution (NAS, 1998; Bybee, 2002). Still, even after one is undeniably convinced of the merits of teaching evolution, the practicality of such a task can be daunting and pose its own unique challenges (Bybee, 2001). Communicating such a monumentally critical theory as evolution may take on its own sense of arduousness, especially when sharing such ideas with newly-minted undergraduates or high school students who may or may not have experienced a progressive biology curriculum (Bybee, 2001; Langen, 2004). …