LETTER TO THE BOOKSHELF
A letter regarding Kim Sterelny's review of Darwin's Cathedral
The review by R. and K. Numbers of David Sloan Wilson's recent book, Darwin's Cathedral: Evolution, Religion, and the Nature of Society (March-April 2003) bespeaks a surprisingly naive interpretation of Darwinian evolution and the neo-Darwinian dialogue. To say that "Natural selection acts only on heritable traits" and then exclude the obvious inheritance of learned behaviors from the selection process is to throw the whole advantage of cultural learning for human survival (and all the genes that make it possible!) out with the bathwater of the sort of inheritance of acquired traits that Lamarck proposed. When Darwin argued for "heritable" traits, he could not define exactly what he meant, since Mendel's work was yet unknown, as was the entire basis of physical inheritance.
What the Numbers totally miss, and which is increasingly acceded to today, is that genes do not act independently of the milieu in which they function. Hence, environment, including social environment, can influence gene expression. Natural selection acts not on "genes" but on phenotypes, the result of this cooperative gene/environment interaction. And particularly, behaviors as complex as those of primates, that are either adaptive or not, are an inevitable outcome of this kind of interaction. Only the very simplest of our "behaviors" (e.g. certain reflexes) can be directly attributed to genetically wired pathways. Almost all human behavior is only loosely defined genetically, and the details are acquired during early life as a result of (mainly) cultural experience. To argue, as the Numbers do, that the nature of that cultural experience does not have selective value by helping humans, and the groups they necessarily must live in, survive and adapt to their surroundings goes against any sort of ordinary logic.
As I have tried to point out in my recent book on human nature, it is the "meaningfulness" provided by cultural narratives that promote the cohesion and coordination of human societies, without which no individual human, regardless of his or her genes, could survive. It is obviously this capacity to create meaningful cultures that was selected for during the Pleistocene (or before?), and it is amazing how poorly this is recognized by a certain group of hardcore neo-Darwinists, who, of course, have captured the popular press by the very simplicity of their arguments, which make entertaining reading. In my book, I point out the enormous role of world views, including religions, in the survival of human groups, and explain their usefulness—and also, mal-adaptiveness when they become too rigid.
Yours truly,
Mary E. Clark
Cottage Grove, OR
Reviewers Ronald L. Numbers and Karen Steudel Numbers respond:
It hurts to be called scientifically naive and illogical by such an eminent scholar as Mary Clark, a leader in the discipline of "conflict resolution" and a celebrated discoverer of "new modes of thinking." And it's downright embarrassing to have to be reminded that Darwin was unfamiliar with Mendelian genetics. We may be addicted to old modes of thinking, but Clark reminds us of countless undergraduates, who (naively?) suppose that "selection" should favor any trait that enhances an organism's ability to survive. That does appeal to what Clark calls "ordinary logic." However, most biologists, not just "hardcore neo-Darwinists," have concluded that natural selection acts only on heritable traits. Clark correctly notes that the genetic basis for intelligence—the ability to learn and to interact in sophisticated social settings—is inherited. But it is incorrect to suggest that learned behaviors themselves are inherited. This lack of inheritance is why humans have such a long period of juvenile and adolescent dependence. Of course, human culture is important to our survival, but only heritable traits are subject to natural selection. Perhaps "new modes of thinking" prompt Clark to think otherwise, but for now we're sticking with the old-fashioned science of Darwin and Mendel.
Karen Steudel Numbers, Chair
Department of Zoology
University of Wisconsin-Madison
Ronald L. Numbers
Hilldale Professor of the History of Science and Medicine
University of Wisconsin-Madison