David P. Barash writes in The Chronicle Review:
In the bad old days, many people, including some evolutionary biologists who should have known better, partook of a misleading dichotomy: genes or experience, DNA or culture, instinct or intelligence. Animals were supposedly ruled by genes/DNA/instinct, and people by experience/culture/intelligence. In recent years, the great majority of scientists have come around to the realization that that dichotomy, like so many others (heaven vs. hell, organism vs. environment, black vs. white, you’re either with us or you’re with the terrorists), is a misrepresentation of reality. Things interpenetrate. Every phenotype — the observable characteristics of a living thing — derives from the interaction of genotype and environment. When it comes to behavior, that means that every action comes from instinct and intelligence, acting together. Just as it is meaningless to attribute someone’s height to genes or environment, it is also absurd to claim that, say, 3’6″ of a woman’s stature is because of her ancestry and 2′ her nutrition; every inch of her 5’6″ is a consequence of genes and experience, acting together. Moreover, intelligence, which involves the degree to which behavior can be modified by an individual’s experience, is itself an adaptive trait, with natural selection having endowed different species with different amounts and kinds of intelligence. How much, and what kind? Well, that’s a matter of which species, which is to say, a question of what’s adaptive, and for whom.
Nonetheless, as to the intelligence of animals — more precisely, the attitudes of people toward the intelligence of animals — we still encounter a peculiarly bimodal distribution of opinion: On the one hand are those who reject it altogether. Intellectual inheritors of René Descartes and Jacques Loeb, they claim that animals are essentially automata, whose behavior can be explained entirely by reflexes or “forced movements,” without postulating — or acknowledging — the existence of any internal mental processes. Like Gertrude Stein’s famous observation about Oakland, those who deny animals any intellect or subjective mental life maintain, in effect, that “there isn’t any there there.”