Pretrained hand signals tell the dog in the scanner whether a treat is forthcoming. This is how Greg studies activation of their pleasure centers. His goals are rather modest at this point, such as to show that similar cognitive processes in humans and dogs engage similar brain areas. Greg is finding that the prospect of food activates the caudate nucleus in the canine brain in the same way that it does in the brain of businessmen anticipating a monetary bonus.39 That all mammalian brains operate in essentially the same way has also been found in other domains. Behind these similarities is a much deeper message, of course. Instead of treating mental processes as a black box, as Skinner and his followers had done, we are now prying open the box to reveal a wealth of neural homologies. These show a shared evolutionary background to mental processes and offer a powerful argument against human-animal dualism.
Although this research is still in its infancy, it promises a noninvasive neuroscience of animal cognition and emotion. I felt as if I were at the threshold of a new era, while Eli trotted out of the scanner to lean his head on my knee and let out a deep dog sigh to signal his relief that all had ended well.
5 THE MEASURE OF ALL THINGS
Ayumu had no time for me while he was working on his computer. He lives with other chimps in an outdoor area at the Primate Research Institute (PRI) of Kyoto University. At any moment, an ape can run into one of several cubicles—like little phone booths—equipped with a computer. The chimp can also leave the cubicle whenever he wants. This way playing computer games is entirely up to them, which guarantees sound motivation. Since the cubicles are transparent and low, I could lean on one to look over Ayumu’s shoulder. I watched his incredibly rapid decision making the way I admire my students typing ten times faster than me.
Ayumu, is a young male who, in 2007, put human memory to shame. Trained on a touchscreen, he can recall a series of numbers from 1 through 9 and tap them in the right order, even though the numbers appear randomly on the screen and are replaced by white squares as soon as he starts tapping. Having memorized the numbers, Ayumu touches the squares in the correct order. Reducing the amount of time the numbers flash on the screen doesn’t seem to matter to Ayumu, even though humans become less accurate the shorter the time interval. Trying the task myself, I was unable to keep track of more than five numbers after staring at the screen for many seconds, while Ayumu can do the same after seeing the numbers for just 210 milliseconds. This is one-fifth of a second, literally the bat of an eye. One follow-up study managed to train humans up to Ayumu’s level with five numbers, but the ape remembers up to nine with 80 percent accuracy, something no human has managed so far.1 Taking on a British memory champion known for his ability to memorize an entire stack of cards, Ayumu emerged the “chimpion.”
Ayumu’s photographic memory allows him to quickly tap a series of numbers on a touchscreen in the right order, even though the numbers disappear in the blink of an eye. That humans cannot keep up with this young ape has upset some psychologists.
The distress Ayumu’s photographic memory caused in the scientific community was of the same order as when, half a century ago, DNA studies revealed that humans barely differ enough from bonobos and chimpanzees to deserve their own genus. It is only for historical reasons that taxonomists have let us keep the Homo genus all to ourselves. The DNA comparison caused hand-wringing in anthropology departments, where until then skulls and bones had ruled supremely as the gauge of relatedness. To determine what is important in a skeleton takes judgment, though, which allows the subjective coloring of traits that we deem crucial. We make a big deal of our bipedal locomotion, for example, while ignoring the many animals, from chickens to hopping kangaroos, that move the same way. At some savanna sites, bonobos walk entire distances upright through tall grass, making confident strides like humans.2 Bipedalism is really not as special as it has been made out to be. The good thing about DNA is that it is immune to prejudice, making it a more objective measure.
With regard to Ayumu, however, it was the turn of psychology departments to be upset. Since Ayumu is now training on a much larger set of numbers, and his photographic memory is being tried on ever shorter time intervals, the limits of what he can do are as yet unknown. But this ape has already violated the dictum that, without exception, tests of intelligence ought to confirm human superiority. As expressed by David Premack, “Humans command all cognitive abilities, and all of them are domain general, whereas animals, by contrast, command very few abilities, and all of them are adaptations restricted to a single goal or activity.”3 Humans, in other words, are a singular bright light in the dark intellectual firmament that is the rest of nature. Other species are conveniently swept together as “animals” or “the animal”—not to mention “the brute” or “the nonhuman”—as if there were no point differentiating among them. It is an us-versus-them world. As the American primatologist Marc Hauser, inventor of the term humaniqueness, once said: “My guess is that we will eventually come to see that the gap between human and animal cognition, even a chimpanzee, is greater than the gap between a chimp and a beetle.”4
You read it right: an insect with a brain too small for the naked eye is put on a par with a primate with a central nervous system that, albeit smaller than ours, is identical in every detail. Our brain is almost exactly like an ape’s, from its various regions, nerves, and neurotransmitters to its ventricles and blood supply. From an evolutionary perspective, Hauser’s statement is mind-boggling. There can be only one outlier in this particular trio of species: the beetle.
Evolution Stops at the Human Head