Evolution is considered a unifying theme in biological science (National Research Council [NRC], 1996). Evolution is such a powerful idea that its application to all grade levels can serve as a guide for instruction and curriculum alignment (Haury, 1996). Scientific organizations such as the American Association for the Advancement of Science (AAAS) and the National Academies of Sciences (NAS) stress the significance of evolutionary theory in biology and advocate teaching evolution in schools (Blackwell et al., 2003; Haury, 1996; NAS, 2008). According to Blackwell et al. (2003), "Without evolutionary theory, biology is divested of needed theme, coherence, understanding, and interpretation of relationships." Evolutionary theory provides connection among biological topics, accentuating the investigative nature of science and power of scientific discoveries.
The tenets of evolutionary theory have been at issue among scientists, philosophers, religious leaders, and the public since Darwin first revealed his ideas over 150 years ago (Brem et al., 2003). Today, teaching evolution in public schools continues to be viewed with disparagement by many in positions of power and decision-making. Throughout the U.S., state boards of education are making decisions that may eliminate or severely limit students' opportunity to learn about evolutionary theory. In Kansas and Oklahoma, the state boards of education have modified or removed evolution from the state objectives (McKeachie et al., 2002). The state of Texas reviews the status of teaching evolution in 2008 as they work to revise their state science education standards. Also in 2008, the Texas Higher Education Coordinating Board debated the acceptance of a science education Masters' degree program emphasizing creationism from the Dallas-based Institute of Creation Research Graduate School. These actions indicate an alarming trend that impacts the nature and quality of learning experiences that science teachers are able to provide for their students.
Notwithstanding such omnipresent controversy, evolution is a core theme underlying the biology curricula. Along with the science of evolution, removing evolution from curricula also eliminates the historical perspective such topics bring to the table. Dagher and BouJaoude (1997) support the need to maintain such controversial topics in science, contending, "Most of the revolutions in the history of science involved challenges to worldviews." Evolution makes clear the case that many new theories in science challenge current views and ways of thinking and, in so doing, exemplify the very nature of science as a discipline.
Though evolution continues to endure great public scrutiny, in the scientific community evolution is the key to understanding life. As stated by the National Academy of Sciences (NAS, 2008),
... evolution is a core concept in biology that is based
both in the study of past life forms and in the study of
the relatedness and diversity of present-day organisms.
The rapid advances now being made in the life sciences
and in medicine rest on principles derived from an
understanding of evolution.
Evolution is multi-purposeful, such that students may learn the science of what the theory states, the social significance of the theory, and its importance in understanding the very nature of science as tentative and dynamic. Evolution epitomizes what science is, meaning that the theory is supported by empirical, data-driven evidence and explanations (National Academy of Sciences, 2008). Clearly, new evidence in evolutionary theory has altered scientific understandings through time and will continue to do so as new discoveries and evidence are added to the existing knowledge base. But evolutionary theory also has implications regarding the way human behavior is interpreted, human notions of spirituality, and the purpose of human existence (Brem et al., 2003). It is important to recognize that spirituality and the philosophical purposes of life are separate aspects of human existence from the science of evolution, as they are not based on empirical data and evidence. …