Dobzhansky's Dictum: An Object Lesson for Critical Thinking

Article excerpt

Perhaps the most widely cited declaration of truth in the biological sciences was published in the March 1973 issue of The American Biology Teacher. "Nothing in Biology Makes Sense Except in the Light of Evolution" was the title of an article by world-famous geneticist and evolutionist Theodosius Dobzhansky (1973; posted with permission at http://people.delphiforums.com/lordorman/light.htm; Figure 1).

   Dobzhansky first published the title
   statement, in a slight variation, in a
   1964 article in American Zoologist,
   "Biology, Molecular and Organismic,"
   to assert the importance of
   organismic biology in response
   to the challenge of the rising field
   of molecular biology. The term
   "light of evolution"--or sub specie
   evolutionis--had been used earlier
   by biologist Julian Huxley. (http://
   en.wikipedia.org/wiki/Nothing_in
   _Biology_Makes_Sense_Except_in_the
   _Light_of_Evolution)

Dobzhansky (1973) quoted the renowned French philosopher and Jesuit priest Pierre Teilhard de Chardin (1881-1955) as follows: "Evolution is the light which illuminates all facts, a trajectory which all lines of thought must follow--this is what evolution is."

As with so many popular sayings, relatively few people have read the original source. Dobzhansky (1973) summarizes numerous biological facts that make logical sense only under the theory of natural selection, as an argument against supernatural creationism. "[W]hat a senseless operation it would have been, on God's part, to fabricate a multitude of species ex nihilo and then let most of them die out!" He discusses the diversity of living beings, the unity of life, comparative anatomy and embryology, adaptive radiation in Hawaii's flies, and the strength and acceptance of the theory of evolution. The following passages are especially noteworthy (Dobzhansky, 1973):

* "But what if there was no evolution, and every one of the millions of species was created by separate fiat? However offensive the notion may be to religious feeling and to reason, the antievolutionists must again accuse the Creator of cheating. They must insist that He deliberately arranged things exactly as if his method of creation was evolution, intentionally to mislead sincere seekers of truth."

* "Of course, at no stage of its development is a human embryo a fish, nor does it ever have functioning gills. But why should it have unmistakable gill slits unless its remote ancestors did respire with the aid of gills? Is the Creator again playing practical jokes?"

* "It is wrong to hold creation and evolution as mutually exclusive alternatives. I am a creationist and an evolutionist. Evolution is God's or Nature's method of Creation."

* "Any competent biologist is aware of a multitude of problems yet unresolved and of questions yet unanswered.. Disagreements and clashes of opinion are rife among biologists, as they should be in a living and growing science. Antievolutionists mistake, or pretend to mistake, these disagreements as indications of dubiousness of the entire doctrine of evolution. Their favorite sport is stringing together quotations, carefully and sometimes expertly taken out of context, to show that nothing is really established or agreed upon among evolutionists."

* Accusation & Rebuttal

Jerry Bergman is a creationist who has written several anti-evolution articles in the creationist website trueorigin.com. He attacked Dobzhansky's dictum in his 2006 article titled "The 'Nothing in Biology Makes Sense Except in the Light of Evolution' Myth: An Empirical Study and Evaluation (http://trueorigin.org/biologymyth.asp). Bergman reviewed college-level life-science textbooks and found that "Darwinism was rarely mentioned." From this, he concludes that the claim "Nothing in biology makes sense except in the light of evolution" is not true. The word "Darwinism" appears 18 times in his essay. Bergman appears to equate modern understandings of evolution with "Darwinism" and then notes that "Most biochemistry/ molecular biology, genetics, and cell biology texts we have used never, or hardly ever, mentioned Darwinism. …