This is one of my all-time favorite Gould essays. The theme is genetic determinism and evolutionary psychology. The hook is a discussion of Charles Davenport's claim that some people have a wanderlust gene (W) that makes them undesirable as immigrants to the United States.
Of course, no one would now defend Davenport's extreme view of single genes determining nearly every complex human behavior. Most colleagues eventually rejected Davenport's theory; he lived into the 1940s, long past the early flush of Mendelian enthusiasm and well into the modern era of understanding that complex traits usually record the operation of many genes, each with a small and cumulative effect (not to mention a strong, and often predominant, influence from nongenetic environmental contexts of growth and expression). A single gene for anger, conviviality, contemplation, or wanderlust now seems as absurd as a claim that one assassin's bullet, and nothing else, caused World War I, or that Darwin discovered evolution all by himself, and we would still be creationists if he had never been born.Take this lesson to heart. You should never oppose a valid evolutionary argument just because you don't like the ethical implications.
Nonetheless, in our modern age of renewed propensity for genetic explanations (a valid and genuine enthusiasm when properly pursued), Davenport's general style of error resurfaces on an almost daily basis, albeit in much more subtle form, but with all the vigor of his putative old gene - yes, he did propose one - for stubbornly persistent behavior.
We are not questioning whether genes influence behavior; of course they do. We are not arguing that genetic explanations should be resisted because they have negative political, social, or ethical connotations - a charge that must be rejected for two primary reasons. First, nature's facts stand neutral before our ethical usages. We have, to be sure, often made dubious, even tragic, decisions based on false genetic claims. But, in other contexts, valid arguments about the innate and hereditary basis of human attributes can be profoundly liberating.
Consider only the burden lifted from loving parents who raise beautiful and promising children for twenty years and then "lose" them to the growing ravages of schizophrenia - almost surely a genetically based disease of the mind, just as many congenital diseases of bodily organs also appear in the third decade of life, or even later. Generations of psychologists had subtly blamed parents for unintentionally inducing such a condition, then viewed as entirely environmental in origin. What could be more cruel than a false weight of blame added to such an ultimate tragedy? Second, we will never get very far, either in our moral deliberations or our scientific inquiries, if we disregard genuine facts because we dislike their implications. In the most obvious case, I cannot think of a more unpleasant fact than the inevitable physical death of each human body, but a society built on the premise that King Prospero will reign in his personal flesh forever will not flourish for long.
On the other hand, you should rigorously oppose silly evolutionary arguments no matter what the ethical implications.