Children’s Ability to Learn Evolutionary Explanations for Biological Adaptation

Research Findings: Evolution by natural selection is often relegated to the high school curriculum on the assumption that younger students cannot grasp its complexity. We sought to test that assumption by teaching children ages 4–12 (n = 96) a selection-based explanation for biological adaptation and comparing their success to that of adults (n = 30). Participants provided explanations before and after a 10-min, analogy-based tutorial illustrating the principles of variation, differential survival, differential reproduction, inheritance, and population change. Although younger children (ages 4–6) showed minimal evidence of learning these principles, older children (ages 7–12) showed robust evidence of doing so, learning them at rates equivalent to adults. Participants of all ages, however, provided nonevolutionary explanations for biological adaptations (i.e., explanations referencing need, growth, and creation) nearly as often at posttest as they did at pretest. Practice or Policy: These results suggest that older elementary school-age children can be taught evolutionary concepts but that learning such concepts does not lead to the automatic replacement of nonevolutionary views of biological adaptation, which must be addressed separately. Evolution by natural selection is the theory that unifies all biological phenomena, yet evolution is rarely taught to children. Children are expected to begin their biology education without reference to the very principles that structure and organize the field. The U.S. National Research Council, for instance, recommends that elementary school students learn about anatomy, physiology, taxonomy, and ecology but not evolution (National Academy of Sciences, 2013). Evolution is recommended for inclusion only in the high school curriculum. Ideas related to evolution are recommended for inclusion in the elementary school curriculum (e.g., heredity, biodiversity, trait variation, extinction), but evolution itself is waylaid for several years. The consequence of this recommendation is that children learn about biological systems (e.g., life cycles, food chains, symbiosis) and biological processes (e.g., digestion, respiration, reproduction) without reference to the historical pressures that gave rise to those phenomena and thus without explanation for their form or function. Some children may never learn those explanations, even in high school, as evolution is either taught poorly or not taught at all. A recent survey of U.S. high school biology teachers found that only 28% teach evolution as an uncontroversial fact, supported by ample data. Most teachers (60%) avoid the topic as much as possible, and some (12%) explicitly advocate for creationism (Berkman & Plutzer, 2011; see also Nehm, Kim, & Sheppard, 2010). The scientific community has recognized, for several decades now, that “nothing in biology makes sense except in the light of evolution” (Dobzhansky, 1973), yet many students learn biology in the absence of such light. One reason why children are shielded from the concept of evolution is that evolution is a controversial topic (Blancke, De Smedt, De Cruz, Boudry, & Braeckman, 2012; Lombrozo, CONTACT Andrew Shtulman [email protected] Department of Psychology, Occidental College, 1600 Campus Road, Los Angeles, CA 90041. © 2016 Taylor & Francis EARLY EDUCATION AND DEVELOPMENT 2016, VOL. 27, NO. 8, 1222–1236 http://dx.doi.org/10.1080/10409289.2016.1154418 Shtulman, & Weisberg, 2006). Most U.S. citizens deny that humans have evolved from nonhuman ancestors strictly by natural means, favoring either creationist explanations or quasi-creationist explanations in which God guides evolutionary change (Newport, 2010). Many people also see evolution as antithetical to positive social values, like altruism, equality, and self-determination (Brem, Ranney, & Schindel, 2003). But controversy surrounding evolution is not the only reason why children are shielded from the concept. Another is that evolution is difficult to understand, and children are viewed by many as cognitively ill-equipped to handle that complexity (Carmichael, 2009). Dozens of studies have shown that evolution is difficult to understand even for college-educated adults (for reviews, see Gregory, 2009; Kampourakis, 2014; Shtulman & Calabi, 2012). Evolution, or population-level changes in the frequency of heritable traits, is driven by selection, or the differential survival and reproduction of the varied organisms within a population, yet most adults do not conceive of evolution in these terms. Rather, most adults conceive of evolution as the uniform transformation of all members of the species, with each organism producing offspring more adapted to the environment than the organism itself was at birth. According to this view, mutations are not random; they occur in a direction that would benefit the organism, and all organisms within the population are assumed to acquire the same mutations at the same time (Bishop & Anderson, 1990; Brumby, 1984; Shtulman, 2006; Shtulman & Calabi, 2013; Shtulman & Schulz, 2008). Underlying this misconceived view of evolution are three widespread and early developing inductive biases: teleology, essentialism, and intentionality. Teleology is the idea that an organism’s traits can be explained by their function (Kelemen, 2012; Lombrozo & Carey, 2006). Teleology allows people to recognize that wings exist for flying and that lungs exist for breathing, but it causes them to ignore the historical origin of those traits (i.e., selection over a population of individuals who once possessed only the precursors of those traits). Essentialism is the idea that an organism’s traits are byproducts of its hidden nature or essence (Gelman, 2003; Gelman & Rhodes, 2012). Essentialism allows people to recognize that gray baby flamingos will grow to be pink and that flat-nosed baby rhinos will grow to have horns, but it causes them to ignore variation in those traits and the consequences of such variation (i.e., differential survival and differential reproduction). And intentionality is the idea that organisms act on the environment in ways that further their goals and desires (Evans, 2008; Johnson, 2000). Intentionality allows people to recognize that holes in the beach are the handiwork of crabs and dams in the river are the handiwork of beavers, but it causes them to interpret crabs and beavers as intentionally designed themselves (e.g., by a divine force or divine intelligence). Intentionality can also cause people to assume that evolution is driven by the intentions of the evolving organisms (Legare, Lane, & Evans, 2013). Each of these biases serves a valuable function when applied to the properties of individual organisms but can lead to misconceptions when applied to the properties of entire species, causing adults to misconceive evolution (Sinatra, Brem, & Evans, 2008). These biases are widespread and early developing, emerging prior to any formal instruction in biology (Coley & Tanner, 2012). Children are thus vulnerable to the same kinds of evolutionary misconceptions as those observed among adults. Indeed, young elementary school-age children have been shown to prefer intentional (i.e., creationist) explanations of biological adaptation to evolutionary explanations (Evans, 2001), and older elementary school-age children have been shown to prefer essentialist explanations (Samarapungavan & Wiers, 1997) and teleological explanations (Berti, Toneatti, & Rosati, 2010) to strictly selection-based explanations. Evolution is thus difficult to grasp at all ages, but no study has shown that evolution ismore difficult to grasp at younger ages than at older ages. Evolution may actually be easier to grasp at younger ages, before children have acquired as much experience viewing the biological world through the lenses of teleology, essentialism, and intentionality. When students are introduced to evolution in high school (or college), they have spent more than a decade of their lives reasoning about biological phenomena in explicitly nonevolutionary terms. Introducing younger students to evolution could potentially bypass this obstacle, as they have yet to encode as much biological information in those terms. Children are predisposed to construing biological traits as purpose-based, nonvariable, and intentionally designed, EARLY EDUCATION AND DEVELOPMENT 1223