The Treatment of Geological Time & the History of Life on Earth in High School Biology Textbooks

Abstract

concept of evolution is fundamental to the study of modern biology. It is a key element of the National Science Education Standards (National Research Council, 199(5) and is recognized as an essential component of the curriculum in position statements of the National Science Teachers Association and the National Association of Biology teachers (see National Academy of Sciences, 1998). Since all of the definitions of evolution (e.g, organic change over tune' or descent with modification) imply a temporal element, the presentation of evolution in the biology curriculum should include some sense of the timespan over which evolutionary events have occurred as well as an overview of the life forms at various points tit geological time. fit addition, the evidence that supports these claims and the reasoning processes that scientists use to study historical events should he a standard element in any presentation of the principles of scientific inquiry. In spite of the importance of geological in evolutionary biology, misconceptions about historical events in the history of life on Earth are common. For example, a recent survey by the National Science Foundation found that almost 50% of the general public believes that humans and dinosaurs coexisted (National Science Board, 2000). Misconceptions about geological are also common in biology teachers. A survey of high school biology teachers the Indiana reported that 12.5% of respondents agreed or strongly agreed with the statement, The age of the Earth is less than 20,000 years, while 15% accepted the statement, With few exceptions organisms on Earth carne into being at about the same (Rutledge & Warden, 2000). same two statements received higher levels of support among high school biology teachers in texas (Shankar Skoog, 1993). Surveys and opinion polls like these suggest that ideas about geological tittle that tile scientific community rejected long ago are durable elements of the public view of evolutionary biology. Although there may be many explanations for the persistence of alternative conceptions about evolutionary time, the difficulty in comprehending the enormous spans involved in Earth history must be among the most pervasive. Keown (1988) noted the lack of an accurate understanding in both students and adults of the vast spans of over which evolutionary events occur. In a study of 10- and 11-year-old English schoolchildren, Trend (1998) found that students had a relative sense of (e.g., and extremely ancient), but they lacked a clear chronology of geologic events. Similarly, Marques and Thompson (1997) found that 14- and 15-year-old students did not distinguish between the origin of the universe and the origin of the Earth. huge numbers involved in the geological timescale cause similar confusion among adults. In fact, teacher conceptions of geological often include age estimates of 1 trillion years for events that are perceived to be extremely ancient (Trend, 2001). These observations reflect the abstract nature of deep time (see Gould, 1987) and suggest potential areas of difficulty as students attempt to reach a meaningful understanding of the enormity of geological and the biological events that occurred across that span. Glenn (1990) has documented as decline from 1900 to 1989 in the amount of space devoted to the history of life in high school earth science textbooks, but we are aware of no similar study in biology textbooks. Given the overfill reduction in evolution coverage in biology texts (Rosenthal, 1985), we might expect the treatment of historical aspects of evolutionary biology to be limited. In this article, we present the results of a survey of 11 high school biology textbooks in which the following questions were addressed: 1. To what extent do texts discuss the logical processes and historical inferences that support many, of the claims relating to evolutionary biology? …