Definitions are important. A prerequisite of virtually any rational discussion is agreement on a common terminology. Without common terms there may be little meaningful dialogue. Changing or obscuring definitions however is a time-honored tactic used by creationists to wriggle out of an intellectual position they find undesirable.
Georgia Purdom, PhD, of the creationist ministry Answers in Genesis promotes erroneous definitions of evolution so that she may accept obvious examples of natural selection without having to also accept that natural selection is a mechanism of biological evolution. The tactic is not of her own invention but one employed by generations of hardcore creationists unwilling to concede the reality of evolution even in the smallest of doses. In some circles, one’s creationist bona fides are apparently tarnished by the admission that natural selection is indeed a mechanism underlying even the slightest evolutionary change.
When faced with undeniable, empirical examples of natural selection in action the dedicated creationist’s only escape is to change the definitions of natural selection or evolution or both. Purdom has done this in videos, public lectures, in print and in blog posts and while I’m uncertain as to whether these misrepresentations are borne out of deliberation or ignorance the effect is the same, namely to confuse her audience and make scientists appear to be the ones who are equivocating and inventing sliding definitions. In fact they are not. The real definitions of both natural selection and evolution are entirely unequivocal.
Georgia Purdom defines natural selection.
Purdom outlines her definitions of natural selection and evolution in The New Answers Book (2006), in a 2012 video on the Answers in Genesis website and in a 2015 blog post on the Answers in Genesis web site. Purdom’s main case for decoupling natural selection from evolution appears in The New Answers Book (2006). Her first definition of natural selection is derived from an anthropology textbook.
“Evolutionary change based on the differential reproductive success of individuals within a species.” (Park 2002)
Purdom cites two additional definitions of natural selection; one from the Public Broadcasting System’s website in a glossary for the National Geographic Society documentary Strange Days on Planet Earth and the other from an online glossary on a website for lessons on dinosaurs geared towards elementary age school children in Australia. The Park (2002) definition is incomplete but broadly speaking in line with virtually every other scholarly definition of natural selection. The other two definitions Purdom provides are not far off either, although, one says natural selection is also known as “survival of the fittest” and while this is a synonym for natural selection in popular culture, virtually no modern evolutionary biologist would interchange “survival of the fittest” for natural selection.
It is puzzling that Purdom would use these rather obscure and in some cases juvenile sources for her definition of natural selection when volumes of scholarly work have been published on natural selection dating back over 150 years (see Bell 2008 for a review). There are entire academic books written solely about natural selection. One wonders why someone with Purdom’s educational background could find no more scholarly sources for her definitions than a 14 year old introductory anthropology textbook, a website for a nature documentary and a children’s educational site for dinosaurs?
The definition of natural selection is well known among scientists and hardly controversial. Natural selection is the differential contribution of progeny to the next generation by some individuals relative to others because, and this is the important part, these individuals carry varieties of genes that promote comparatively greater survival and/or reproductive success. The selection bit alone however is not evolution. Selection by itself is only one part of the definition of natural selection as a mechanism of evolutionary change. It is the change in the composition of the population from one generation to the next that is the response to selection and this response is by definition, evolution. As long as some of the variation in contributing to the next generation is at least in part due to variation in genes then that means some varieties of genes, and their associated traits, will be more prevalent than others in the next generation. Voila, evolution!
Different authors may reword the definition of natural selection but the basic concept has changed little since Darwin’s original description (Darwin 1859). It may be described as evolution based on “differential reproduction of individuals within a species” (Park 2002) or the “sorting of reproductive success” (Stearns 2014) or as “heritable variation in the rate of replication [that] causes evolution through selection” (Bell 2008) but the concept remains the same in virtually every scholarly definition of natural selection.
Simply put, this change from one generation to the next in the prevalence of some versions of genes relative to others is the most basic level of biological evolution. Evolution is the response to natural selection. As long as variation in reproductive success is at least in part due to variation in genes then the two are completely inseparable. The incremental change in populations from one generation to the next is a component within a much larger process of large-scale evolutionary change. Purdom, keeping with the creationist penchant for both catch phrases and linear progressions, borrows the term “molecules-to-man” to describe evolution at larger scales. Purdom and her colleagues may place arbitrary limits to the amount of change natural selection may ultimately achieve but this does not mean that there is no evolution as a result of selection. Once they accept fluctuations in bill size across generations in Darwin’s finches or microbial antibiotic resistance they are by definition conceding to some degree of evolutionary change, whether they like it or not. Natural selection describes change across generations in a reproducing population but that population may be one of molecules, cells or individual organisms. In fact, natural selection occurring among competing cells within a multicellular individual is a foundational idea in modern cancer biology (Merlo et al. 2006).
However, contrary to virtually all of modern science, Purdom claims that natural selection does not result in evolution. She even concedes that natural selection may lead to new species but doesn’t even admit this to be a form of evolution. Purdom’s avoidance of the “E-word” at this point is starting to seem almost pathological. This begs the question, if the response of a population to selection is not evolution, and even speciation is not evolution, what is Purdom’s definition of evolution?
Georgia Purdom defines evolution.
Purdom gives several definitions of evolution but this one deserves some attention as it speaks volumes to her capacity to formulate a scholarly argument grounded in the actual definitions used by evolutionary biologists. After all, as a creationist Purdom is a critic of the evolutionary model and as such one would expect her to be criticizing the field of evolution as it is rather than criticizing some version of the field that she has invented. It is no different than an atheist critique of Christianity on the basis of a Christian belief in human sacrifice. Such a critique would and should be considered absurd because it is a belief that simply doesn’t exist within any Christian community or at best is some perversion of Christian theological tenants with regards to the crucifixion and resurrection. Such arguments would rightly constitute straw men critiques of Christianity to be sure.
Here is one of Purdom’s “recent” and “notable” definitions of evolution.
“Unfolding in time of a predictable or prepackaged sequence in an inherently, or at least directional manner.” Gould 2000 as cited in Ham 2006.
This is clearly a misquotation. The actual quote from Gould (2000, 2002) goes like this.
“"Evolution", from the Latin evolvere, literally means “to unroll” – and clearly implies and unfolding in time of a predictable or prepackaged sequence in an inherently progressive, or at least directional manner.” Gould 2002 pg. 243.
Purdom cites, or rather miscites, this definition to claim that inherit in an evolutionary biologists’ definition of evolution is some notion of directionality and goes on to claim that because natural selection has no direction then it does not result in evolution. This is simply untrue. In fact, this definition is from Stephen Jay Gould’s (2000) essay titled “What does the dreaded “E” word mean, anyway?” published in Natural History, and reprinted in the collection of essays I Have Landed (Gould 2002). This passage is explicitly intended by Gould to represent the vernacular usage of evolution as it would have been used in 19th century English and not as a definition of evolution as it is currently used by modern scientists. Purdom is in this instance taking Gould's words entirely out of context. Hardly new territory for creationists.
Darwin himself only used the term evolution, or rather in this case the past-tense verb evolved, only once in The Origin of Species (1859) at and only at its close. Darwin says,
“There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.” Darwin (1859)
The example above notwithstanding, Gould points out that Darwin tended to avoid the term evolution, at least initially, when talking about the process of change in populations over time precisely because the common vernacular usage of the term evolution in the English language implies a predictable, directional progression or unfolding process.
“Thus, on these two fundamental grounds – absence of inherent directionality and lack of predictability – the process regulated by natural selection could scarcely have suggested, to Darwin, the label “evolution”, an ordinary English word for sequences of predictable and directional unfolding.” Gould 2002 pg. 245.
Evolution was not an invention unique to Darwin but was an idea batted around for decades prior to Darwin, however, it was seldom defined by a linguistically loaded term like evolution but more neutral terminology, like transmutation, was often used. Darwin knew full well that his mechanism by which populations change over time was not directional with some ultimate goal in mind or leading inexorably to some cartoonish “molecules-to-man” ladder of progression. Darwinian natural selection is not and never was conceived as being directional and nor is evolution in the broad sense.
“Pre-Darwinian concepts of evolution – a widely discussed, if unorthodox, view of life in early nineteenth-century biology – generally went by such names as “transformation,” “transmutation,” or “the development hypothesis.” In choosing a label for his very different account of genealogical change, Darwin would never have considered “evolution” as a descriptor because this vernacular English word implied a set of consequences contrary to the most distinctive features of his own revolutionary mechanism of change – the hypothesis of natural selection.” Gould 2002 pgs. 242-243.
Had Purdom bothered to read the full essay from which she borrows her definition of evolution she may have seen that Gould was referring to the commonly understood, general, vernacular English definition of evolution at the time and not the specific definition used by modern scientists. To the contrary, much of the essay is Gould explaining why the original vernacular meaning of the word evolution is such a poor descriptor of the modern scientific definition.
Darwin himself tended to use more accurate and descriptive terminology such as “descent with modification.” The term evolution gained popularity because while Darwin solidified the general case for life changing over time, his mechanism was less popular at a time when many saw the history of life as necessarily being progressive and directional. It is for this historical reason that the term evolution gained traction, but no modern scientist uses it in this way. The notion that evolution is synonymous with directional change and some pre-ordained progress largely ended by the early 20th century. Purdom’s claim that natural selection does not result in evolution requires her not only to adopt a 19th century vernacular definition of evolution that Darwin himself would not use alongside natural selection, but, to also completely ignore the modern usage of the term.
Creationism is infamous for its half-truths, selective citation, straw man arguments and misquotation, especially of the late Stephen Jay Gould. Purdom’s attempt at separating natural selection from evolution is another in in a long line of predictable creationist misinformation right down to the requisite misquote of Gould. Such pathological aversion to the “E-word” is not characteristic of all creationists but for some their religious convictions are so threatened that they will leap through virtually any semantic hoop to avoid conceding even the slightest modification shaped by a definitively evolutionary process.
Bell G. 2008. Selection: The Mechanism of Evolution, 2nd edition. Oxford University Press. Oxford.
Darwin C. 1859. The Origin of Species. Random House Inc. reprint edition 1993.
Gould S. J. 2000. What does the dreaded “E” word mean, anyway? Natural History 109(1): 28–44.
Gould S. J. 2002. I Have Landed: The End of a Beginning in Natural History. Belknap Press, reprint edition 2011.
Ham K. ed. 2006. The New Answers Book: Over 25 Questions on Creation/Evolution and the Bible. Master Books.
Merlo L. M. F., J. W. Pepper , B. J. Reid & C. C. Maley. 2006. Cancer as an evolutionary and ecological process. Nature Reviews Cancer 6:924–935.
Park M. A. 2002. Introducing Anthropology: An Integrated Approach, 2nd edition. McGraw Hill.
Stearns S. C. 2014. Natural Selection, Adaptation, and Fitness: Overview. In: The Princeton Guide to Evolution. Editor in Chief: J. B. Losos. Princeton University Press, Princeton NJ.
 Well, at least some creationists view the acceptance of any evolution by natural selection as a threat. Intelligent design proponents have little problem with admitting that there is indeed some evolutionary change via natural selection, at least within the limits their ideology allows.
 The phrase “survival of the fittest” was coined not by Darwin but by Herbert Spencer and does not appear until the 5th edition of Darwin’s The Origin of Species (1859). The phrase is widely recognized by evolutionary biologists today as a tautology (i.e. a circular argument) and never used among professional biologists.