Random behavior increases evolutionary fitness? Looks that way.

At last, scientists have begun to decipher that most thrilling moment of urban predation: you fix the cockroach in your sights; without taking your eye off him, you slowly remove one shoe; and you stalk, ever so stealthily, toward your quarry.

What you long to know, of course, is which way he will dash. But what scientists have discovered, I regret to report, is that the roach defies such divination. Just as the deadly heel swings down, the roach will make a sudden rotation, then scurry, and that quick swivel is his vital secret.

The turn will position him in one of four orientations: he’ll point himself roughly 90, 120, 150 or 180 degrees away from the wind your shoe creates. But which of the four will it be? Aye, there’s the rub. For that, it turns out, is highly unpredictable.

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...[T] the cockroaches got me thinking about cases in which adaptation calls not for perfect tuning or precise definition, but rather for something more like their opposite: an absence of definition, a dash of chance. If that roach were always to flee in one predefined direction, its predators would soon catch on. You’d know exactly where to aim the heel. But in choosing his path at random, the roach achieves an adaptive unpredictability.

Once you start looking for this sort of thing, you find it everywhere. When some animals are searching for food, they make occasional random turns, which take them into fresh territory, and also happen to make their paths look like certain kinds of random walks — probabilistic outcomes for which mathematicians have special names.

And evidently, among some species of prey, the response to an oncoming predator is to do as much unpredictable, weird and pointless stuff as possible, increasing the probability that the attacker will a) be totally confused, b) decide that messing with such a crazy character is too risky, or c) infer that the prey is infected with a strange — and possibly transmissible — parasite. (O.K., I made that last one up, but I bet we could find an example.)

A Dash of Chance (Aaron Hirsh, writing a guest column in The New York Times)

This reminds me, oddly, of something master strategist and systems theorist Herman Kahn is reported to have said - I'm having a bad week with Google and can't find the exact quote, but the gist of it is: in a game of "chicken" (in which two automobiles accelerate towards each other on a long straight stretch of road, until one driver loses his nerve and veers away) the only way to play is to show up drunk, wrench the steering wheel off and toss it out the window.