When evolution is discussed in the media, the same word is often used to name different things. Even those who are proponents of "evolution" do not always mean the same thing by the term. As a result, claims are sometimes made about evolution that purport to be factual, although they have not been demonstrated scientifically, or do not even belong to the realm of science.

What is popularly meant by "evolution" is not only the process by which the many distinct species of living beings have emerged (speciation), but also the process by which life itself originated from inanimate matter. Nineteenth-century naturalist Charles Darwin is widely recognized as the founding father of evolution, although he really had nothing of substance to suggest about "evolution" in the latter sense. Following Darwin, the two principal mechanisms of evolution of new species are generally said to be random variation and natural selection; in the twentieth century, scientists have looked especially to changes in an organism's genetic code in order to explain, or perhaps to specify, the notion of random variation.

For the sake of clarity and brevity, we shall identify three distinct conceptions of evolution that circulate in the media. These three all share a common origin or inspiration, but there are also notable differences between them - although these differences are rarely made explicit by those who talk about evolution.

Hence, "evolution" might mean either:

1. a process, involving random genetic variations and natural selection, that was and is a driving force in the development of life on Earth;

or

2. a process, involving random genetic variations and natural selection, that provides the exhaustive explanation for the development of life on Earth, from the very simplest living organisms all the way to human beings;

or

3. a process, involving random genetic variations and natural selection, that provides the exhaustive explanation of the existence and nature of all living beings, including human beings.

Statement #1 is very well established scientifically. There is plenty of paleontological and biological evidence to support it, and viruses, for example, are visibly evolving under our watch.

Statement #2 is at best a hypothetical statement, and is far from being proven. More than once in the history of science a theory said to provide a complete or final explanation of a set of phenomena has later been seen to be inadequate or even incorrect. Toward the end of the nineteenth century, for example, it was widely supposed that classical physics was able to explain, at least in principle, virtually all natural phenomena, apart from a few presumably unimportant exceptions. But it was in looking more carefully at these exceptions that scientists discovered Relativity and Quantum Mechanics, and classical physics no longer reigned supreme. Philosopher Karl Popper has argued, moreover, that falsification is the only source of real certainty in science (i.e., although a given scientific theory is supported by thousands of successful experiments, they don't yield absolute certainty about its truth, whereas a single counterexample does suffice to show that the theory is wrong or incomplete). Even though Popper's position has been criticized for being a bit excessive, it does correctly remind us that science develops in a tentative fashion, and that the relatively few categorical claims that it makes occur, so to say, at the outer edges of its normal activity. Additionally, in the case of evolution we are very far from possessing an exhaustive explanation of the development of life on Earth, despite the enormous strides biology, for example, has made over the last century.

It is important to recognize, in this regard, that many scientists have come to think that to explain the evolution of life on the planet, other mechanisms must be invoked: gene transfer, neutral mutation, and retroelements/transposons, to name only a few. Evidence for the existence of such mechanisms challenges the idea that the set of "variations" from which nature "selects" new types emerges only randomly, through the genetic mutations. Evidence has recently been discovered, for example, that certain epigenetic factors (i.e., factors not specified by DNA but rather derived from the environment and the organism's interaction with it) can be inherited, and this suggests new insights into the mechanisms of evolution. Developments such as this call into question the supremacy of the Darwinian view, which proposes to explain speciation solely through the dual mechanism of "random mutation and natural selection". Statement #2, in short, leaves ample room for scientific reflection, research, and debate.

Statement #3 entirely abandons the realm of science. Not only does it mistake statement #2 as an accomplished fact. It also founds itself on the unquestioned assumption that human life can be reduced entirely to its exclusively biological components. This conception of human existence is far from convincing, for there are numerous aspects of human life for which no credible biological explanation is currently available; nor is it at all clear how we could even begin to explain them in purely biochemical terms. What could it possibly mean to encode the human appetite for justice, truth, beauty, and love, or the self-awareness that attends them, in some gene or set of genes? Statement #3 simply assumes, without warrant and with little apparent awareness of what it ignores, that it is able to account for those dimensions of our humanity that find profound expression in the most powerful works of literature and the visual arts, and in the writings of great philosophers. No doubt, those dimensions of reality of particular interest to the biologist can have a very palpable impact on even the most exalted of human activities. One cannot expect a poet in the midst of an acute attack of appendicitis to compose memorable poetry. Yet from this it does not follow that the poet's muse resides in a small stretch of uninfected appendix.

Author Richard Dawkins offers us a paradigmatic example of the over-reaching characteristic of certain exponents of "evolution." Dawkins writes that "Darwinism encompasses all of life [.]. It provides the only satisfying explanation for why we all exist, why we are the way that we are." While he concedes that "our own existence once presented the greatest of all mysteries;" he nevertheless insists that "it is a mystery no longer because it is solved. Darwin and Wallace solved it."¹ In defense of statement #3, he has recourse to arguments that purport to be drawn directly from scientific agreement about statement #1 and from current scientific debates about statement #2. But the reasoning on display in his work actually operates at another level entirely, and falls very short of a scientific demonstration of "evolution" in the third sense we have enumerated.

Lacking an adequate scientific foundation, Darwinism becomes a quasi-philosophical system. When we read that "Darwinism encompasses all of life" we are reminded of the great ideologies of the 20^th centuries, which made similar claims to comprehensiveness, with what tragic results we all know. If random variation and natural selection are the ONLY two factors governing human life, all kinds of violence against human beings readily find justification. We see some glimpse of ideological Darwinism in certain positions on the end of life debate.

We think that a reasonable approach to reality is one that strives to take all factors into account. Evolution is a driving force in the development of life on Earth, nonetheless it does not represent an exhaustive and mechanical explanation of who we are. Our existence is a mystery. In the words of Nobel Prize winning physicist Albert Einstein, "One cannot help but be in awe when contemplating the mysteries of eternity, of life, of the marvelous structure of reality."² Or as another Nobel Prize winner, Richard P. Feynman, put it, "The same thrill, the same awe and mystery, come again and again when we look at any problem deeply enough. With more knowledge comes deeper, more wonderful mystery, luring one to penetrate deeper still." ³ Both Einstein and Feynman bear witness to the nature of every truly human initiative - including in a privileged way the activity of scientific inquiry - all of which express the struggle to unveil the meaning of reality.

References:

¹ R. Dawkins, introduction (pg X) and preface (pg XIII) of "The Blind Watchmaker", W.W. Norton, ed. 1996.

² A. Einstein, statement to William Miller, as quoted in LIFE magazine (2 May 1955).

³ R. P. Feynman, "The value of science" in Frontiers in Science: A Survey, ed. Edward Hutchings Jr. (New York, 1958), pg 262-63.