Guns, Germs, and Steel three: Operant Conditioning
Diamond defines an animal that is a "candidate for domestication" as any terrestrial herbivorous or omnivorous animal species (one not predominantly a carnivore) weighing on the average over 100 pounds (45 kilograms). Of 148 "candidate" species, only 14 have actually been domesticated, and of those, five account for the vast majority of individuals world wide.
One of the major characteristics that make a putative candidate not-domesticable is the species ability to be tamed. Zebras are biologically very similar to horses. But nobody tames or domesticates zebras. The reason, Diamond explains, is that no matter how long one keeps a zebra in captivity, it will kill you if it gets the chance. Their "personality" is simply not amenable to taming or domestication.
When I took psychology in college, operant conditioning was taught as irrefutable fact; all animals, including humans, respond to reinforcement and punishment in predictable ways. I recognized then and mainstream psychology recognizes now that there is a lot more to final behaviour than conditioning alone, and behaviorism has been abandoned as a stand-alone explanation for all behavior. Still, until I read Diamond's chapter on animal domestication, I took it for granted that operant conditioning was an undisputed major force in molding all animals' (including humans) behaviour.
Fourteen out of 148 created this suspicion in my mind: dogs and pigeons respond to operant conditioning. Dolphins and humans do too, some of the time. But perhaps most
animals do not; and perhaps the behaviorist extrapolations from o-c experiments have been greatly overrated.