The Tell-Tale Brain: A Neuroscientist's Quest for What Makes Us Human

Now take a look at the dancing nymph in Figure 7.7 whose twisting torso is almost anatomically absurd but who nevertheless conveys an incredibly beautiful sense of movement and dance. This is probably achieved, once again, by the deliberate exaggeration of posture that may activate—indeed hyperactivate—mirror neurons in the superior temporal sulcus. These cells respond powerfully when a person is viewing changing postures and movements of the body as well as changing facial expressions. (Remember pathway 3, the “so what” stream in vision processing discussed in Chapter 2?) Perhaps sculptures such as the dancing nymph are producing an especially powerful stimulation of certain classes of mirror neurons, resulting in a correspondingly heightened reading of the body language of dynamic postures. It’s hardly surprising, then, that even most types of dance—Indian or Western—involve clever ritualized exaggerations of movements and postures that convey specific emotions. (Remember Michael Jackson?)

FIGURE 7.7 Dancing stone nymph from Rajasthan, India, eleventh century. Does it stimulate mirror neurons?

The relevance of the peak-shift law to caricatures and to the human body is obvious, but how about other kinds of art?² Can we even begin to approach Van Gogh, Rodin, Gustav Klimt, Henry Moore, or Picasso? What can neuroscience tell us about abstract and semiabstract art? This is where most theories of art either fail or start invoking culture, but I’d like to suggest that we don’t really need to. The important clue to understanding these so-called higher art forms comes from a very unexpected source: ethology, the science of animal behavior, in particular, from the work of the Nobel Prize–winning biologist Nikolaas Tinbergen, who did his pioneering work on seagulls in the 1950s.

Tinbergen studied herring gulls, common on both the English and American coasts. The mother gull has a prominent red spot on her long yellow beak. The gull chick, soon after it hatches from the egg, begs for food by pecking vigorously on the red spot on the mother’s beak. The mother then regurgitates half-digested food into her chick’s gaping mouth. Tinbergen asked himself a very simple question: How does the chick recognize its mom? Why doesn’t it beg for food from any animal that’s passing by?

Tinbergen found that to elicit this begging behavior in the chick you don’t really need a mother seagull. When he waved a disembodied beak in front of the chick, it pecked at the red spot just as vigorously, begging the beak-wielding human for food. The chick’s behavior—confusing a human adult for a mother seagull—might seem silly, but it isn’t. Remember, vision evolved to discover and respond to objects (recognize them, dodge them, eat them, catch them, or mate with them) quickly and reliably by doing as little work as needed for the job at hand—taking short-cuts where necessary to minimize computational load. Through millions of years of accumulated evolutionary wisdom, the gull chick’s brain has learned that the only time it will see a long yellow thing with a red spot on the end is when there’s a mom attached to it at the other end. After all, in nature the chick is never likely to encounter a mutant pig with a beak or a malicious ethologist waving around a fake beak. So the chick’s brain can take advantage of this statistical redundancy in nature and the equation “long thing with red spot = mom” gets hardwired into its brain.

In fact Tinbergen found that you don’t even need a beak; you can just have a rectangular strip of cardboard with a red dot on the end, and the chick will beg for food equally vigorously. This happens because the chick brain’s visual machinery isn’t perfect; it’s wired up in such a way that it has a high enough hit rate in detecting mom to survive and leave offspring. So you can readily fool these neurons by providing a visual stimulus that approximates the original (just as a key doesn’t have to be absolutely perfect to fit a cheap lock; it can be rusty or slightly corroded.)

But the best was yet to come. To his amazement, Tinbergen found that if he had a very long thick stick with three red stripes on the end, the chick goes berserk, pecking at it much more intensely than at a real beak. It actually prefers this strange pattern, which bears almost no resemblance to the original! Tinbergen doesn’t tell us why this happens, but it’s almost as though the chick had stumbled on a superbeak (Figure 7.8).