The Myths of Genetic Predestination and of Tabula Rasa

THE MYTHS OF GENETIC PREDESTINATION AND OF TABULA RASA* THEODOSIUS DOBZHANSKY^ Mankind becomes increasingly dependent on science and technology for survival. Yet the relations between science and society are far from always harmonious. Scientific discoveries sometimes conflict with accepted beliefs. Scientists may then be pressured to desist from their investigations and even to renounce their findings. The most widely known case is that of Galileo. Cardinal Bellarmine said that Galileo's "pretended discovery vitiates the whole Christian plan of salvation." BeIlarmine was right ifthe "plan" is understood as he understood it. Galileo complained about "the principal professor of philosophy whom I have repeatedly and urgently requested to look at the moon and the planets through my glass [telescope], which he pertinaciously refuses to do." In a way, the professor was also right. Nothing that he might have seen in Galileo's telescope could have induced him to change his fixed views. The antievolutionists in California (who call themselves creationists) are a kindred lot. Not all of them are roundly ignorant of the evidence for biological evolution. Yet no conceivable evidence is meaningful to them. No matter what the evidence shows, they resist it. Among biological sciences, genetics has perhaps the greatest pertinence to human problems. Its relevance encompasses philosophical and historical issues—whence mankind came, whither it may be going, what its place is in nature's order. It encompasses also more immediately practical topics—physical and mental health and disease, receptivity to training and education, susceptibility to personality-molding pressures, and constraints of the physical and socioeconomic milieu. Moreover, the theoretical and the practical issues are not in separate compartments. They are interdependent. The more directly relevant a scientific discipline is to human affairs, *Versions of this article have been given as the Frank Tannenbaum Memorial Lecture at the annual meeting of the University Seminars, Columbia University, on April 23, 1975, in New York City; at the University of California, Santa Barbara, on April 30, 1975; (in Spanish translation) at the Universidad Nacional Autonoma, Mexico City, on May 13, 1975; and at the University of Minnesota, Minneapolis, on June 27, 1975. tAdjunct Professor of Genetics, University of California, Davis, California 95616. 156 I Theodosius Dobzhansky · Genetic Predestination the more liable it is to conflict with some popular beliefs and preconceptions . Genetics has had and continues to have the unenviable distinction of being embroiled in such conflicts. The shameful story of the suppression of genetics in the Soviet Union is sufficiently recent and sufficiently publicized not to need recitation here. A politically adroit charlatan was able to convince the ruler of a great country that genetics is subversive to the established religion of dialectical materialism. He was also able for a quarter of a century to play havoc with his country's agriculture, under the pretext of having invented incredibly efficacious techniques to improve it. Genetics suffered a different kind of maltreatment at the hands of race and class bigots during the first half ofthe current century. They claimed genetics to be the scientific basis of their inhuman and sinister notions. This came to a climax in the Nazi ideology and Nazi misdeeds. In some circles genetics continues to be under suspicion on this score. The heredity-environment or nature-nurture problem has been a battleground for at least a century. The discord is about the relative importance of hereditary and environmental factors in the development of human traits, particularly behavioral ones. The spectrum of opinions ranges from what I like to call the myth of tabula rasa to the myth of genetic predestination. Myths are invented to explain beliefs or natural phenomena the causes of which are too complex and insufficiently well known to be explained in precise and indisputable ways. It is not overoptimistic to hope that in science myths are eventually displaced by accounts so well substantiated as to compel agreement of all but hopelessly closed minds. With the nature-nurture problem, such a happy state is not yet in sight. For this reason, I believe that didactically the most effective way to examine the problem is to start with the two polarized myths, in full awareness that they have sprung more from biases and preconceptions than...