Given how easily we string the words animal and cognition together as if there were nothing to it—as if these words might even belong together!—it is hard to imagine the struggle we went through to reach this point. Some animals were considered good learners or hard-wired for clever solutions, but cognition was way too big a word for what they did. Even though for many people animal intelligence is self-evident, science never takes anything at face value. We want proof, which with regard to animal cognition has now become overwhelming—so much so, in fact, that we risk forgetting the immense resistance that we had to overcome. This is why I have paid ample attention to the history of our field. There were early pioneers, such as K?hler, Kohts, Tolman, and Yerkes, and a second generation, such as Menzel, Gallup, Beck, Shettleworth, Kummer, and Griffin. The third generation, to which I myself belong, includes so many evolutionary cognitivists that I am not going to list them here, but we too faced an uphill battle.
I can’t count the number of times I have been called na?ve, romantic, soft, unscientific, anthropomorphic, anecdotal, or just a sloppy thinker for proposing that primates follow political strategies, reconcile after fights, empathize with others, or understand the social world around them. Based on a lifetime of firsthand experience, none of these claims seemed particularly audacious to me. So one can imagine what happened to scientists suggesting awareness, linguistic capacities, or logical reasoning. Every claim was picked apart and held up against the light of alternative theories, which invariably sounded simpler given that they derived from the behavior of pigeons and rats in the confines of a Skinner box.
They were not always so simple, though—accounts based on associative learning can get quite convoluted compared to ones that merely postulate an extra mental faculty—but in those days, learning was thought to explain everything. Except, of course, when it didn’t. In the latter case, we clearly hadn’t thought long and hard enough about the issue at hand or we had failed to conduct the right experiments. At times, the wall of skepticism seemed more ideological than scientific, a bit the way we biologists feel about creationists. However compelling the data we bring to the table, they never suffice. Things must be believed to be seen, as Willy Wonka sang, and entrenched disbelief is oddly immune to evidence. The “slayers” of the cognitive view were not open to it.
This epithet comes from the American zoologist Marc Bekoff and the philosopher Colin Allen who early on picked up Griffin’s torch for cognitive ethology. They divided attitudes toward animal cognition into three types: the slayers, the skeptics, and the proponents. When first writing about this in 1997, slayers were still abundant:
Slayers deny any possibility of success in cognitive ethology. In our analyses of their published statements, we have found that they sometimes conflate the difficulty of doing rigorous cognitive ethological investigations with the impossibility of doing so. Slayers also often ignore specific details of work by cognitive ethologists and frequently mount philosophically motivated objections to the possibility of learning anything about animal cognition. Slayers do not believe that cognitive ethological approaches can lead, and have led, to new and testable hypotheses. They often pick out the most difficult and least accessible phenomena to study (e.g. consciousness) and then conclude that because we can gain little detailed knowledge about this subject, we cannot do better in other areas. Slayers also appeal to parsimony in explanations of animal behavior, but they dismiss the possibility that cognitive explanations can be more parsimonious than noncognitive alternatives, and they deny the utility of cognitive hypotheses for directing empirical research.1
When Emil Menzel told me about the prominent professor—clearly a slayer—who tried to ambush him but ended up with his foot in his mouth, he added an interesting side note. The same professor publicly challenged young Menzel to tell him what capacities he could possibly hope to find in apes that were not also present in pigeons. In other words, why waste your time on those willful, hard-to-control apes if animal intelligence is essentially the same across the board?
While this was the prevailing attitude at the time, the field has come around to a much more evolutionary approach, which recognizes that every species has a different cognitive story to tell. Each organism has its own ecology and lifestyle, its own Umwelt, which dictates what it needs to know in order to make a living. There is not a single species that can stand model for all the others, most certainly not one with a brain as tiny as a pigeon’s. Pigeons are plenty intelligent, but size does matter. Brains are the most “expensive” organs around. They are true energy hogs, using twenty times more calories per unit than muscle tissue. Menzel could simply have countered that since ape brains are several hundred times heavier than those of pigeons and hence burn vastly more energy, it stands to reason that apes face greater cognitive challenges. Otherwise mother nature indulged in a shocking extravagance, something she is not known for. In the utilitarian view of biology, animals have the brains they need—nothing more, nothing less. Even within a species, the brain may change depending on how it is being used, such as the way song-related areas seasonally expand and contract in the songbird brain.2 Brains adapt to ecological requirements, as does cognition.
We have also met a second type of slayer, though, and they have been even harder to deal with since they don’t share an interest in animal behavior. All they care about is humanity’s position in the cosmos, which science has been undercutting since the days of Copernicus. Their struggle has become rather hopeless, though, because if there is one overall trend in our field, it is that the wall between human and animal cognition has begun to resemble a Swiss Gruyère full of holes. Time after time we have demonstrated capacities in animals that were thought to set our species apart. Proponents of human uniqueness face the possibility that they have either grossly overestimated the complexity of what humans do or underestimated the capacities of other species.
Neither possibility is a pleasant thought, because their deeper problem is evolutionary continuity. They can’t stand the notion of humans as modified apes. Like Alfred Russel Wallace, they feel that evolution must have skipped the human head. Although this view is currently on its way out in psychology, which under the sway of neuroscience is edging ever closer to the natural sciences, it is still prevalent in the humanities and most of the social sciences. Typical is a recent reaction by the American anthropologist Jonathan Marks to the overwhelming evidence that animals pick up habits from one another, hence show cultural variability: “Labeling ape behavior as ‘culture’ simply means you have to find another word for what humans do.”3
How much more refreshing was David Hume, the Scottish philosopher who held animals in such high esteem that he wrote that “no truth appears to me more evident than that beasts are endow’d with thought and reason as well as men.” In line with my position throughout this book, Hume summarized his view in the following principle: