(This post originally appeared on December 6, 2008. My apologies for not leaving it up, and for the excellent comments being gone.)
A little while ago, in a different context, Rick Lucke asked an interesting question, which essentially is this:
Are there any other animals that think the way humans do?
That's a hard question to answer with a simple yes or no. But in this post I'll take a shot at it, by exploring a few paths toward an answer. Even if these paths peter out, we may end up with a better grasp of why this is a hard question. The first direction we'll go in draws on ideas in the philosophy of mind, where I'm little better than a well-informed layman; the second direction draws on an article in the journal Animal Behaviour that I wrote earlier this year.
Let's begin by looking at a slightly different question: Are there any other human beings that think the way I do? This turns out to be a hard question to answer completely. We know a great deal about the physiology and functioning of the brain, and we have tools that let us observe what's going on as we think. At some level, yes, the areas of my brain that light up when I walk and talk correspond to the same areas of your brain when you do.
Is that enough? Not quite. Those signals coming from my brain as I talk, producing pretty colors on the fMRI screen, can only give the coarsest approximation of what I'm talking about. More generally, while we know something about how signals are processed in the brain, the information content (the semantics) of those signals generally remains entirely a mystery. By analogy, consider my hooking up a recording device to the ABS system on your car. Any given recording will tell me when you'd braked, but I'd be able to make only rough guesses about where you were driving. I'd have to ask you.
Back to animals: Unfortunately, we can't ask them what they're thinking. Worse, their brains don't look quite like ours. We might be able to map out correspondences, but where's the ground truth? It could turn out that we're measuring and comparing the wrong things. (Thomas Nagel explored the philosophical angles in a famous paper in 1974, "What is it like to be a bat?") Again by analogy, we might be saying, "These two boxes are about the same size, are both plugged into the wall, and have about the same number of buttons and lights on the front. Yes, my Tivo and my DVD player must have the same function."
So one answer to the question of whether some animal thinks the way we do is maybe--but it would still be hard to tell if it were the case.
Even if animals can't talk (and I'm over-simplifying here, because I'm not really up on the animal communication and language literature) we do have an out. We can watch what they do. Some animals turn out to be remarkably capable problem solvers. Here's Betty, a New Caledonian crow that made a splash in the animal cognition literature. She can be seen in the video below bending a hook out of a straight piece of wire in order to retrieve a bucket of meat from an experimental apparatus.
I met the Oxford zoologists who worked with Betty (now deceased) at a workshop in 2005. Betty was an Einstein among birds; the behavior shown in the video is all the more remarkable when you know that it's the first example of spontaneous tool manufacture observed in an animal. Betty was raised in captivity and had never even seen a wire hook before. It turns out that some crows do use create and use hooks in the wild, but Betty's ability to deliberately fashion a hook from unfamiliar material was surprising.
Almost as surprising is the performance of the great apes and other non-human primates in solving problems. (See a comment I left on bbd's blog
for a funny story from Benjamin Beck's landmark book, Animal Tool Behavior
.) For example, chimpanzees in the wild have been observed propping up stone anvils with other stones, to provide a more level surface for breaking nuts using another stone as a hammer. In the laboratory, young chimpanzees have undergone tests based Piaget's theory of cognitive development and have exhibited some of the same characteristics of human infants (for example, up to the substage at which object permanence is understood). There are two excellent and accessible books on non-human primate cognition: Primate Cognition
, by Michael Tomasello and Josep Call, a comprehensive outline of the field up to the late 1990s, and Folk Physics for Apes
, by Daniel Povinelli, a cautionary account of how experiments on apes should be carried out and interpreted.
So, we run intelligence tests and eventually get a feel for just how much animals think the way we do. Is there the problem? Yes, and it's been recognized since 1898 among animal cognition researchers, in the form of Morgan's Canon:
In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of the exercise of one which stands lower in the psychological scale.
For example, it turns out that the simplest animals to use tools, a capacity we might associate with intelligence, are wasps. We'd be reluctant to say that the cognitive mechanism underlying human tool use is the same as in a wasp--they've only got a few hundred neurons. More generally, even if we observe an animal solving specific hard problems, there's no guarantee that it's solving problems the way we would. Far from being able to tell whether human beings and animals are thinking in the same way, we have discovered in our own work that it's even hard to characterize behaviors precisely enough to claim that human beings and animals are doing the same thing, even under laboratory conditions. Inferences are required, and they're not always reliable.