01/21/2007 08:22 pm ET | Updated May 25, 2011

Squirrels & Suppression elaborate hypothesis

The Squirrels

Where I live now, drivers are frequently obliged to stop in the middle of the street to avoid squashing squirrels. I live in North Carolina, and the Eastern gray squirrel has a scientific name, Sciurus carolinensis, that suggests I am living in their biological epicenter.

These rodents are -- by best accounts -- around 30 million years old, making them our great great great grandparents in evolutionary terms; and their adaptability to multiple climates, as well as urban landscapes, suggests they will be around long after we have figured out how to commit collective suicide. They are so thick in my own suburban neighborhood that we could harvest them for meat now without putting a dent in their population. Our abundance of white oak trees sheds tons and tons of acorns each year -- a squirrel staple -- and squirrels are voracious omnivores, even occasionally indulging in cannibalism.

They have adapted through changing coloration almost before our eyes, with black varieties emerging in urban centers in our lifetime; but their behavioral patterns are more ancient inscriptions. Cars have been around for a century, more or less, with an explosive proliferation in the last 50 years. The result is a fatal mismatch.

Squirrel defensive patterns emerged to cope with other threats -- hawks, owls, weasels, raccoons, foxes, coyotes, bobcats, and big snakes. Today, we can add to that, dogs and cats; but they themselves are still behaviorally etched with hunting patterns they carry from their feral cousins. My own dog hunts them relentlessly in the back yard, and the squirrels win around 99 times out of a hundred... whereupon they bark back at the enraged pooch from the trees.

What the squirrel has perfected over the aeons is a combination of deception and footwork that matches the predators' tactics.

When faced with a potential threat, the squirrel shifts her tail back and forth, flicking it in the same way a fisherman jiggles an artificial lure to attract the predator's eye, or the way a bullfighter agitates a cape to deceive his victim. A squirrel's tail can be bitten off fairly easily, leaving the rest of the squirrel intact to live on; and predators typically orient on movement. Squirrels can even heat their tails up to fool pit vipers, serpants that orient on thermal signatures from their prey.

In conjunction with this tail-deception, the squirrel does a kind of rapid-rewind two-step dance as the predator closes in, weaving back and forth like a boxer to set up a repetitious pattern of oscillation by the predator. At the last moment, in a kind of rodent jui-jitsu, Sciurus carolinensis breaks the rhythm of the back-and-forth, and dives 45 degrees lateral to the accelerating predator. The charging animal overshoots the squirrel, and by the time she can turn to remount an attack, Sciurus has scampered up some vertical surface, whereupon she can leap from tree to tree, or roof to tree, or tree to power line, and make her escape.

Over 30 million years, the species itself has recognized a pattern, and adapted its defensive tactics all the way into a fixed neural pathway. When the squirrels on my street see an oncoming car, this amazing adaptation fails. They are reacting to a conscious predator, and the car is neither conscious, nor a predator. It's just a car. The Gotcha Two-Step that lets the gray squirrels run up trees to talk trash back to my mutt doesn't throw the car off at all. It is simply a terminal display without an audience, unless the driver sees the squirrel and slows down.

The Mirrors

There is an intuitive contradiction between the notion of intent and the kind of instinctive pattern embodied in our exemplary squirrel. If the behavior cannot change, then the idea of what the squirrel does or does not intend to do is silly. Intention implies the ability to choose between alternative courses of action. We also know, from experience, that humans can, in fact, make choices that demonstrate what we call "intent." There is a bewildering myth that these choices are unconditioned and decontextualized -- to which we will return further down -- but we can deliberate and choose between A and B, or even A and B and C, et al. And this intent -- which corresponds to and interacts with bipedal locomotion, manual dexterity, symbolic memory, and language (also highly symbolic) -- has augmented, altered, and in some sense atrophied our instinctive, or heritable species pattern recogntion.

If we place a resident of the same street that proves so hazardous to squirrels in a hypothetical situation matching that of an ancestor a mere 200 years ago, that modern person is unlikely to thrive for more than a few days. Place them in a situation similar to that of our own species 5,000 years ago -- an evolutionary blink -- and s/he would perish in short order. Yet people in the planet right now, people who are in every sense members of the same species as us, who actually do live in circumstances that are similar to the conditions hypothesized above, and who get by.

What this strongly suggests is that human nature is not plastic, but that plasticity is a key aspect of human nature. If we accept that suggestion, then it raises the question: What is the matrial basis of this plasticity, and this capacity for intent? Part of the answer seems to come from research on something called a mirror neuron.

Vittorio Gallese, of the European Science Foundation, explains:

About ten years ago we discovered in the macaque monkey brain a class of premotor neurons that discharge not only when the monkey executes goal-related hand actions like grasping objects, but also when observing other individuals (monkeys or humans) executing similar actions. We called them "mirror neurons". Neurons with similar properties were later discovered in a sector of the posterior parietal cortex reciprocally connected with area F5.

The observation of an object-related hand action leads to the activation of the same neural network active during its actual execution. Action observation causes in the observer the automatic activation of the same neural mechanism triggered by action execution. We proposed that this mechanism could be at the basis of a direct form of action understanding.

Further studies showed that in humans the multilocal concentrations of mirror neurons are highly concentrated and active. Moreover, they are somatotopically organized for actions that a subject observes and imitates in others; that is, when a FULL ANALYSIS