Digging deep: Exploring college students' knowledge of macroevolutionary time

Abstract

Some ability to comprehend deep time is a prerequisite for understanding macroevolution. This study examines students' knowledge of deep time in the context of seven major historical and evolutionary events (e.g., the age of the Earth, the emergence of life, the appearance of a pre‐modern human, Homo habilis). The subjects were 126 students recruited from psychology, education, and biology classes at two universities. They were assigned to stronger and weaker background groups based on their college‐level biology coursework. Subjects provided startlingly large time ranges for all questions, ranging over several orders of magnitude (e.g., from 1,000 to 600 billion years ago for when most dinosaurs became extinct), coupled with the strong tendency to underestimate how long ago the events occurred. Converting absolute time estimates to relative time estimates allowed subjects' knowledge of the spacing of the events to be examined and also provided a clearer picture of their patterns of over and underestimation. The results of this study suggest that many students are without an effective conceptual framework to make sense of very large time frames. Although there were no consistent differences in the accuracy of students' responses as a function of their biology background, the weaker background students showed greater variability, providing more time estimates at both the low and high extremes. We describe a pedagogical strategy that uses a relative approach presenting major evolutionary events as they unfolded in time and advocate a tool from professional practice to depict events in time and space. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 311–332, 2009

From Tree to Map: Using Cognitive Learning Theory to Suggest Alternative Ways to Visualize Macroevolution

“…For example, including a time scale on diagrams may help viewers better conceptualize evolutionary time (Catley and Novick 2009). Presenting diagrams oriented horizontally or radically may help viewers avoid the misconception that taxa at the top of the tree are superior to those below them (e.g., Catley and Novick 2008;Torrens and Barahona 2012).…”

“…Time in tree diagrams should be read from the root of the tree to the tips of the branches, as the metaphor of a growing tree suggests to readers. However, research shows that students may assume an incorrect temporal orientation (Gregory 2008) or not orient themselves temporally at all unless a time scale is explicitly included (Catley and Novick 2009). The problem of continuity between ancestral and descendent phyla is a bit more complex because the units of evolution are clades rather than groups with fixed characteristics (O'Hara 1988).…”

“…First, it draws upon an alternative visual (Catley and Novick 2009) metaphor for macroevolution. Second, it incorporates various interactive features that facilitate a more dynamic representation of macroevolution than that which can be shown in a paper-based diagram.…”

“…While text in the visualization does describe some evolutionary processes, the pictorial (Catley and Novick 2008;Gregory 2008;Catley and Novick 2009;Catley et al 2010;MacDonald 2010;Torrens and Barahona 2012). Therefore, this comparison is necessarily focused on features that are found across a range of diagrams.…”

“…In particular, the passage of time may be difficult to convey in traditional tree diagrams. Unless a time scale is explicitly made part of a static diagram, readers have a difficult time situating the macroevolutionary record in evolutionary time (Catley and Novick 2009). While the current iteration of the DEM lacks a constant time scale, the animation itself provides a sense of time's passage.…”