1.1 Background of the study
1.2 The Scientific Reception of Darwinism
1.3 Metaphysical concerns on theory of evolution
1.4 Methodological objections on theory of evolution
1.5 Reconsidering the Nature of Science
1.6 From Physics to Evolutionary Biology
1.7 From Empiricism
1.8 Toward a Naturalistic Model of Scientific Practice
This chapter examines the background information to the study, the evolution of man - scientific evidence, the scientific reception of Darwinism (Darwin's Theory of Evolution - the premise Darwin's theory of evolution - natural selection Darwin's theory of evolution - slowly but surely, Darwin's theory of evolution - a theory in crisis), metaphysical concerns on theory of evolution, methodological objections of theory of evolution, reconsidering the nature of science from physics to evolutionary biology, from empiricism, toward a naturalistic model of scientific practice and conclusion of the study.
1.1 Background of the study
The modern theory concerning the evolution of man proposes that humans and apes derive from an apelike ancestor that lived on earth a few million years ago. The theory states that man, through a combination of environmental and genetic factors, emerged as a species to produce the variety of ethnicities seen today, while modern apes evolved on a separate evolutionary pathway. Perhaps the most famous proponent of evolutionary theory is Charles Darwin (1809-82) who authored The Origin of Species (1859) to describe his theory of evolution. It was based largely on observations which he made during his 5-year voyage around the world aboard the HMS Beagle (1831-36). Since then, mankind's origin has generally been explained from an evolutionary perspective. Moreover, the theory of man's evolution has been and continues to be modified as new findings are discovered, revisions to the theory are adopted, and earlier concepts proven incorrect are discarded.
Evolution of Man - Scientific Evidence - The theory of evolution of man is supported by a set of independent observations within the fields of anthropology, paleontology, and molecular biology. Collectively, they depict life branching out from a common ancestor through gradual genetic changes over millions of years, commonly known as the "tree of life." Although accepted in mainstream science as altogether factual and experimentally proven, a closer examination of the evidences reveal some inaccuracies and reasonable alternative explanations. This causes a growing number of scientists to dissent from the Darwinian theory of evolution for its inability to satisfactorily explain the origin of man.
One of the major evidences for the evolution of man is homology, that is, the similarity of either anatomical or genetic features between species. For instance, the resemblance in the skeleton structure of apes and humans has been correlated to the homologous genetic sequences within each species as strong evidence for common ancestry. This argument contains the major assumption that similarity equals relatedness. In other words, the more alike two species appear; the more closely they are related to one another. This is known to be a poor assumption. Two species can have homologous anatomy even though they are not related in any way. This is called "convergence" in evolutionary terms. It is now known that homologous features can be generated from entirely different gene segments within different unrelated species. The reality of convergence implies that anatomical features arise because of the need for specific functionality, which is a serious blow to the concept of homology and ancestry.
The importance of evolution to the biological sciences is a point that has been acknowledged in the science education literature. Indeed, the standard practice has been to pay obeisance to its centrality by citing Dobzhansky’s (1973) well-known statement regarding the sense making powers of Charles Darwin’s theory in the opening paragraph of articles on the subject. The enthusiasm, with which this point is embraced, however, has not been matched by a corresponding increase in scholarly attention. Evolution remains a relatively under researched topic within the science education community (Cummins, Demastes, & Hafner, 1994). The lamentable fact remains that “large numbers of people reject the theory of evolution, and the science education community has done little to help teachers present evolution in a way that will ameliorate this situation” (Smith, Siegel, & McInerney, 1995, p. 23). This state of affairs presents problems not only for the teaching and learning of evolution, but also for the public perception of science as a whole, of which evolution is clearly the most publicly suspect representative.
Although the field has recently shown signs of life, one of the reasons for its neglect, apart from its factious history in the United States, may stem from the seemingly difficult and amorphous nature of the subject matter itself. It is fairly well established that most students, as well as members of the general public, view the biological world from a kind of pre-Darwinian perspective.
This has been documented by researchers in science education and has commonly been taken as the starting point for developing new strategies for teaching evolution in schools (Demastes, Trowbridge, & Cummins, 1992). One approach that has demonstrated promise involves introducing students to the historical precursors of Darwin’s theory. The success of this technique, indeed for a good number of the instructional interventions tried so far, has nonetheless been limited (see, for example, Jensen & Finley, 1996). Broad-scale student mastery of evolutionary theory has proven to be quite elusive—a conclusion uniformly reached in the science education literature (Demastes et al., 1992). It has also been reported that even a significant number of science teachers have serious questions when it comes to evolution (Eve & Dunn, 1990).
The pervasiveness and persistence of these difficulties suggest, perhaps, that we look for a deeper explanation than any so far considered. The historical parallels between student experiences in the biology classroom and the experiences of 19th-century scientists are particularly instructive in this regard, though not for the reasons commonly supposed. There existed in Darwin’s time a fundamental mismatch between the view of science endorsed by Darwin’s contemporaries and the implicit model of science on which he based his theory of evolution by natural selection. The significance here lies not in the similarity between any initial student conceptions and early evolutionary ideas, but rather in the historical longevity of the mismatch between these two views of science.
Past characterizations of science, historically derived from physics, internalized a broadly empirical and experimental bias that failed to accommodate key issues evolutionary biology introduced to the scientific community. There has been little done over the past century to reconcile these views, especially in science education, resulting in a situation that continues to impede the development of effective instruction in evolution. The specific difficulties students have understanding evolution are less perplexing when considered in light of the resistance Darwin encountered from the scientific community of his own time. A careful examination of the scientific reception of evolution in the 19th century reveals interesting parallels with current accounts of student learning that suggest positive directions for new work in evolution education research.
1.2 The Scientific Reception of Darwinism
Darwin's Theory of Evolution is the widely held notion that all life is related and has descended from a common ancestor: the birds and the bananas, the fishes and the flowers -- all related. Darwin's general theory presumes the development of life from non-life and stresses a purely naturalistic (undirected) "descent with modification". That is, complex creatures evolve from more simplistic ancestors naturally over time. In a nutshell, as random genetic mutations occur within an organism's genetic code, the beneficial mutations are preserved because they aid survival -- a process known as "natural selection." These beneficial mutations are passed on to the next generation. Over time, beneficial mutations accumulate and the result is an entirely different organism (not just a variation of the original, but an entirely different creature).
Darwin's Theory of Evolution: Natural Selection - While Darwin's Theory of Evolution is a relatively young archetype, the evolutionary worldview itself is as old as antiquity. Ancient Greek philosophers such as Anaximander postulated the development of life from non-life and the evolutionary descent of man from animal. Charles Darwin simply brought something new to the old philosophy -- a plausible mechanism called "natural selection." Natural selection acts to preserve and accumulate minor advantageous genetic mutations. Suppose a member of a species developed a functional advantage (it grew wings and learned to fly). Its offspring would inherit that advantage and pass it on to their offspring. The inferior (disadvantaged) members of the same species would gradually die out, leaving only the superior (advantaged) members of the species. Natural selection is the preservation of a functional advantage that enables a species to compete better in the wild. Natural selection is the naturalistic equivalent to domestic breeding. Over the centuries, human breeders have produced dramatic changes in domestic animal populations by selecting individuals to breed. Breeders eliminate undesirable traits gradually over time. Similarly, natural selection eliminates inferior species gradually over time.
Darwin's Theory of Evolution: Slowly But Surely- Darwin's Theory of Evolution is a slow gradual process. Darwin wrote, "…Natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap, but must advance by short and sure, though slow steps" (Darwin, 1859). Thus, Darwin conceded that, "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down" (Ibid. p. 158).
Such a complex organ would be known as an "irreducibly complex system". An irreducibly complex system is one composed of multiple parts, all of which are necessary for the system to function. If even one part is missing, the entire system will fail to function. Every individual part is integral (Behe, 1996). Thus, such a system could not have evolved slowly, piece by piece. The common mousetrap is an everyday non-biological example of irreducible complexity. It is composed of five basic parts: a catch (to hold the bait), a powerful spring, a thin rod called "the hammer," a holding bar to secure the hammer in place, and a platform to mount the trap. If any one of these parts is missing, the mechanism will not work. Each individual part is integral. The mousetrap is irreducibly complex (Illustra Media, 2002).
Darwin's Theory of Evolution in crisis - Darwin's Theory of Evolution is a theory in crisis in light of the tremendous advances we've made in molecular biology, biochemistry and genetics over the past fifty years. We now know that there are in fact tens of thousands of irreducibly complex systems on the cellular level. Specified complexity pervades the microscopic biological world. Molecular biologist Michael Denton wrote, "Although the tiniest bacterial cells are incredibly small, weighing less than 10-12 grams, each is in effect a veritable micro-miniaturized factory containing thousands of exquisitely designed pieces of intricate molecular machinery, made up altogether of one hundred thousand million atoms, far more complicated than any machinery built by man and absolutely without parallel in the non-living world" (Denton, 1986).
And we don't need a microscope to observe irreducible complexity. The eye, the ear and the heart are all examples of irreducible complexity, though they were not recognized as such in Darwin's day. Nevertheless, Darwin confessed, "To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection seems, I freely confess, absurd in the highest degree" (Darwin, 1859).
There were a variety of responses to the 1859 publication of On the Origin of Species. These ranged from solid endorsement to arrant condemnation within the scientific community—to say nothing of the reaction of the general public. Among the critical responses documented, one can find two primary threads of objection. The first and most profound concerned the strong naturalism of Darwin’s theory. The scientific community in Victorian England operated within a theistic context that presupposed notions of intelligent design and purpose in the world (Ruse, 1979). Darwin’s theory of evolution by natural selection directly challenged the need for such metaphysical commitments and was understandably met with resistance for doing so. The second objection related to apparent methodological irregularities in Darwin’s work that for many threw into doubt the validity of his conclusions. Both categories of objection stand out as significant not only historically but, more important for this article, for evolution education today. A brief summary of the historical reception will provide the background necessary for drawing out the implications for science education.
1.3 Metaphysical concerns on theory of evolution
The general scientific uproar surrounding the publication of Darwin’s Origin had surprisingly little to do with the empirical claims on which his theory was based. It was uncommon to find disagreement over the basic assertions Darwin made about the variability of species, the survival rates of young, the plasticity of domestic animals, and the like. These claims and the abundant examples Darwin marshaled in their support were accepted without palpable controversy.
Rather, it was his philosophical approach as a whole and its consequences for the place of humans in nature that flew in the face of the prevailing assumptions of the time. Darwin’s commitment to a completely naturalistic explanation of the origin and diversity of organisms, now seen as his most significant contribution to biology (Bowler, 1983), was then viewed by many as a dangerous materialism that eliminated divine agency from the history of life on earth. This notion of the divine reinforced deeper philosophical commitments to essentialism and teleology that presented formidable obstacles to the easy acceptance of evolution by natural selection.
Essentialism, the belief in the existence of discrete kinds each with a universal essence, lays claim to the deepest philosophical roots in Western thought (Hull, 1973). Early Aristotelians argued such kinds existed independently in nature, while Platonists believed such universal essences were located only in the realm of ideas. In one form or another conception of natural kinds, or types, was the foundation of early systems of biological classification in which species were identified and grouped according to their unchanging observable characteristics. Any deviations from the type were viewed as inconsequential developmental aberrations (Mayr, 1991). Such typological thinking was a key component in the anatomical theories of French and English biologists such as Cuvier and Owen in the first half of the 19th century and was also common to the German morphologists of the time (Nyhart, 1995; Russell, 1916).
1.4 Methodological objections on theory of evolution
Apart from the fundamental assumptions that made up the content of Darwin’s theory was the methodology he employed in their justification—a point with which many of his contemporaries took issue. Although some methodological criticism derived, no doubt, from prior metaphysical objections to evolution, there were also scientists who, although sympathetic to Darwin’s conclusions, were sincerely troubled by the means he used to arrive at them. The early 19th century was a time when many eminent natural philosophers in Britain were systematically laying down the foundations of scientific methodology (Hull, 1973). Classics in this field were John Herschel’s Preliminary Discourse on the Study of Natural Philosophy (1830) and John Stuart Mill’s System of Logic (1843). These works set the standard against which Darwin’s work was judged and, fairly or not, found wanting. The difficulties British scientists had reconciling the explanatory success of evolution by natural selection with its apparent methodological shortcomings reveal a great deal about the gap between the nature of science as practiced and the nature of science as perceived.