“To illustrate,” say Charnov and Bull, “if an individual finds itself in an environment where it can become a below average female or an above average male, selection will favor its becoming male because it can pass on more of its genes than if it were female.” And vice versa. “Selection may therefore favour ‘environmental sex determination’ (ESD) because of the control it allows an individual.” Fine, that seems reasonable—but several complicated assumptions lie behind this simple statement.
One assumption is that the evolutionary fitness of an individual (as tallied, always, by how many offspring survive) is measured relative to other individuals of the same species and the same sex. In other words, a male alligator competes only against other male alligators for the right to leave a large share of descendants. Another assumption made by Charnov and Bull is that the environment in question is patchy, with some patches conferring heightened advantage on females, other patches conferring heightened advantage on males.
From these two givens, Charnov and Bull argue that natural selection “should most strongly favour ESD when 1) the offspring enters an environment, away from the parent, which has a large effect on its lifetime fitness . . . and 2) the offspring and the parent have little control (or predictive ability) over which patch type the offspring enters. These conditions make it unfavourable to determine sex at conception because of the possibility that a male will enter a patch that is much more favourable for a female, or the reverse.” So ESD allows an individual to match its own sexual identity with the particular patch of environment that will heighten its prospect under that identity—not by choosing the patch, but instead by choosing the sexual identity.
Among alligators the patch differences seem to be a matter of temperature at which the eggs are incubated. Nests built on dry levee (according to that elaborate field study, done in Louisiana) tend to stay warmer than ninety-three degrees F. and to yield males. Nests built on wet marsh tend to stay cooler than eighty-six degrees and to yield females. In either case the environment during incubation may have a large effect on lifetime fitness, because that temperature difference translates to size of the individual at hatching, which in turn affects how soon the individual will reach breeding size. Females have a greater need than males do to reach breeding size quickly, because their allotted span of breeding years is much shorter. (That part applies also to humans, providing an evolutionary rationale for why prepubescent fifth-grade boys should find themselves mystified by their classmates’ burgeoning breasts.) The consequence of all this is that cool nest temperatures—which turn out larger baby alligators—give most females a head start toward breeding size. So if an individual alligator is relatively small at the time of hatching, it will fare better in the lifelong Darwinian competition as an average male than as a below average female. And, fortunately, ESD will have already matched its sex to its best prospects.
But what about those ridiculous Bonellia? They seem to be covered equally well by the Charnov-Bull model. In this case the patchiness of the environment is a matter of presence or absence of female Bonellia. The larvae can’t control where they travel, and the adult females are sessile, traveling nowhere at all. When any one larva encounters a female, that fact has great effect on its lifetime fitness, because it means that the little devil will have an opportunity to mate. Otherwise he would be forced to take his own chances as a female, with some jeopardy of permanent spinsterhood. ESD again is the matchmaker. ESD lets him be all he can be.
The moral: Identity is such a crucial affair that one shouldn’t rush into it.
No doubt that seems perfectly natural to a spoon worm. Some of us “higher animals,” on the other hand, don’t have the luxury of such a convenient biological postponement. And probably our Bonellia would be horrified, or silenced in pity, if he (or she, depending) could see the desperate, bizarre ways by which we humans must try to cope with the intractable dilemma of self.
II
WILD NOTIONS
THE DESCENT OF THE DOG
A Tempered View of Canine Evolution
Let’s begin slowly, with a relatively safe statement: Not all dogs are bad.
We Americans live today amid a plague of domestic dogs, a ridiculous and outrageous proliferation of the species, true, but not every one of those animals is damnable beyond redemption. Not every one has had its soul twisted by misery and neglect, spending long days chained or fenced within a tiny yard and taking its revenge by barking at the neighbors. Not every one is ill-trained, intermittently hysterical, half insane from sensory deprivation. Not every one is indulged to prowl free, defecating on other folks’ lawns and reorganizing other folks’ garbage, playfully snapping the necks of other folks’ cats. A few dogs, worthy beasts, help blind people to cross streets. Several reportedly perform ranch chores. Dozens of canines in the U.S. alone fulfill a useful service as the quiet, well-behaved pets of old people and shut-ins. The rest, unfortunately, are as we know them. But dogs are a sensitive subject; some dog owners, like some tobacco smokers and most members of the Ku Klux Klan, tend to be passionately defensive about what they are pleased to think of as their own rights. Consequently you find two diametrically opposed and equally extremist points of view: on the one hand, that all dogs are irredeemably noxious and should be banished, at least from our cities and suburbs, by enlightened legislation; and on the other hand, that some dogs are okay, at least some of the time. My own view is a moderate one that falls about halfway between these two.
Brothers and sisters, as the Lord is my witness: We got too many dogs.
A reliable estimate puts the total U.S. dog population at about sixty million, and that figure has risen by ten million over the past decade. Roughly five million are unclaimed strays held in animal shelters, awaiting adoption or execution, but meanwhile pet dogs are still breeding away. As I write this sentence there are six lunatic barkers within earshot (and one charming old mongrel with sad friendly eyes, next door, who maintains a monk-like silence). That’s just too many. The situation is crazy. The dogs of America are—individually and demographically—out of control.
Of course we also have too many cats. Let no smug feliphile deny that. But there are a couple of important differences. First, cats are generally far quieter and less intrusive. They just don’t have the vocal equipment, the heft, or the territorial instincts to assert themselves as conspicuously as dogs do. Second, when a human society has too many cats, it is mainly the cats who suffer. People drown them. Set them on fire for kicks. Hang them, in cute little nooses. Club them to death and toss the carcasses into the trash. Thereby achieving some sort of sorry equilibrium. It’s less trouble that way, evidently, than exercising a modicum of foresight to get the females spayed and the males neutered. When a society has too many dogs, however, people and dogs both suffer. The extras (aside from those strays who end up in animal shelters) are not killed, but instead are given away or sold cheaply to persons who have no idea what a dog needs in terms of training and attention and sheer physical space, and who are not in a position to supply those things if they did know. Result: miserable, desperate dogs who share out that misery generously to the humans all around them.
It wasn’t always this bad. Dogs come from a noble lineage, a lineage full of intelligence and good character—they are closely related to wolves, after all. Many paleontologists even think that domestic dogs are directly derived from a small Asian subspecies known as Canis lupes pallipes, the Indian wolf. But the descent of the species Canis familiaris (to which all domestic breeds belong) is like a parable on the subject of bad company. They began losing their dignity about 10,000 years ago, when they first cozied up to humanity—the greased chute to degradation. We adopted them, we tamed them, we began breeding them selectively to our own sick tastes and mad purposes; we gave them squashed faces and curly tails and sawed-off legs, brain damage and hip dysplasia and hemophilia, permanent psychological infantilism; we generally brought out the worst in them. Among other particulars, we perfected the b
ark.
How did such sadomasochism ever start? Some people cherish a romantic belief that, in its earliest form, the dog-and-man association was a hunting partnership. According to this notion, our hunter-gatherer ancestors of the middle Stone Age reached an implicit understanding with certain canines to cooperate in the chase: The dogs were faster and better armed, the humans were smarter and more devious, both groups were social communicators, and the meat could be shared. But it’s a fairy tale. No basis whatsoever in evidence. Reputable archaeologists guess, instead, that the dog’s first role in civilization was to eat garbage.
Wild dogs were welcomed as scavengers, it seems, to the fringes of those nomad camps. The dogs cleaned up what would otherwise stink and draw flies. When a camp was moved they tagged along as walking garbage Disposalls. Tolerated, at a distance. Eventually they became familiar and permanent. Hunting and shepherding and sled-pulling and being coddled as pets all came later—not to mention their role as watchdogs.
For this last function they were outfitted with a new sort of voice. It was a voice lacking all modulation and felicity, but which carried and penetrated exceptionally well, with its sharp pulses of energy confined within an unwavering range of frequencies, its cough-like bursts of pure graceless noise—a voice offering the same musical quality as the sound of a pouting child whacking away at a cinder block with a cheap meat cleaver. The canine bark: one of mankind’s first acts of genetic planning, and an enduring monument to our own fearful territoriality. Like the spear and the loin cloth, it might well have been useful in its day.
But some people claim even today that their yappy little curs function as watchdogs—though it’s a mystery to me why anyone would be foolish enough to rely on a warning system that delivers twenty false alarms every day. My own theory is that those “watchdog” people value their poodles and their scotties not for warning but as personal surrogates, less inhibited and more articulate than themselves, and take vicarious emotional satisfaction as the dogs deliver that shrill and mindlessly angry message to the outside world.
Wolves generally don’t bark. Wolves howl melodically. Coyotes seldom bark. They yodel and yelp. From the Congo jungle comes an ancient domestic dog breed known as the basenji that also, bless its very soul, almost never barks. Basenjis were highly valued for their discretion by the Pygmies, who used them for hunting antelope in the Ituri forest. So quiet were these basenjis, in fact, that sometimes the human handler fitted one with a collar from which hung a gourd rattle, just so he could keep track of where the dog was. No one knows why basenjis originally fell silent, or retained the ancestral barklessness, but one very plausible reason would be that they were terrier-sized animals living among leopards, and therefore learned quickly the value of inconspicuousness. All honor to the good sense of the basenji. Unfortunately, most dog breeds did not evolve in the presence of leopards.
They evolved in the presence of humans, who are selectively deaf. It is a scientifically demonstrable fact that many people do not even hear the noise of their own dog. Generally that’s because they tie the dog up in a backyard and go off to work downtown, leaving their pet to bark tirelessly at passing children and other dogs and the free-lance writer across the alley.
Why does a dog bark at all? One scientist who has spent the past twenty years studying dog behavior and origins, Michael W. Fox, says that “dogs may bark during greeting, play-soliciting, threat, defense, care-soliciting, distress, contact-seeking, or during group vocalizations. Barks may be simple or complex, e.g., growl-barks, repeated barks with howl-like endings and yelp-barks. This contextual variety indicates that the sound itself may not always convey specific information but rather attracts the attention of their receiver.” In other words, they bark for every damn reason you can imagine, and sometimes for no reason, other than boredom. (And boredom is liable to be a large factor in the life of even a modestly bright animal left captive in a yard.) As far as attracting the attention of the receiver—there is no doubting the bark’s effectiveness for that. I can vividly recall one occasion, for instance, when a pair of toy terriers had solicited my attention with such success that at 3 A.M. I got up, put on pants and shoes, walked down two flights of stairs, and crossed a street in order to throw three garbage cans over a fence at them. Like the dogs, I was seeking contact.
But of course fairness (and, even more so, my desire for continued matrimonial amity) requires me to note that not all breeds of domestic dog are equally loathsome. Golden retrievers seem to have a fair measure of charm and mental health. Toy poodles are at the other extreme, obviously. Malamutes and Siberian huskies are wonderfully handsome and tend to have a fine quiet poise about them, probably in direct correlation with the closeness of their relationship to the original wolf. Basenjis, as we’ve seen, should be a role model for all. And cocker spaniels are paragons of hysteria: According to one set of studies, cockers started barking with less provocation, and continued barking with more persistence, than all other breeds tested. Take a cocker spaniel at eleven weeks old, lock it behind chain link on a small patch of grass, and you have a barking machine unequaled throughout nature. One cocker in those studies set a record of infamy by barking 907 times in a ten-minute period. Interestingly, the same researcher also found from autopsy data a trend among cocker spaniels for hydrocephaly. All of which may or may not be consequent from mankind’s having bred cockers toward a steeply angled forehead.
Why do dogs bark so much more—and so much more randomly, stupidly—than their wolfish ancestors? Michael Fox says: “The outstanding feature of the domestic dog—barking—may be attributed to artificial selection.” We humans are responsible. But that still leaves open the question of whether we produced this excessive barkishness by liberating a trait that was suppressed in wild canines, or by accentuating a trait that was otherwise barely present—by protecting the domestic dog from those leopards, or by choosing the mouthiest dogs of each generation as our favored breeders. And that question can’t be settled in isolation from the matter, also still in doubt, of the domestic dog’s direct ancestry. Fox tells us: “The origin(s) of the dog therefore still remains an enigma although one might conclude on the basis of this study that if the wolf were the sole progenitor of the dog, then dogs would howl more and bark much less than they do.”
So maybe it wasn’t the Indian wolf after all. Maybe that immediate ancestor to our domestic dogs was the jackal (with those elegantly wolf-like huskies and Malamutes reflecting some later cross-breeding back with real wolves). Maybe it was an earlier version of the Australian dingo. Maybe it was a missing link between dingo and jackal. Or possibly (and I offer this only as an hypothesis, understand) it was a cross between the hyena and the duck.
Hyenas have a certain dog-like majesty. The duck and the poodle have a similar sort of gait. And ducks are known to eat garbage. Furthermore, come to think of it, the quack is not so different from the bark. And don’t I vaguely recall an etymological tie, in the old Anglo-Saxon, between the very words for the two animals: a common origin in the form dok? It’s just a thought.
Anyway, from wherever they come, here they are. Sixty million Canis familiaris: as many dogs, now, as we once had bison. That’s a very sobering little gauge, in itself, of the degradation of America. Man’s best friend, don’t you know—at least so we are endlessly told. The dog is man’s best woof woof woof. But with friends like that, says I, who needs enemies? Bah, humbug.
STREET TREES
The Hard, Noble Life of a Stranger in a Strange Land
I have been trying to imagine what life is like for an urban tree.
This is especially difficult—not just the life, but the imagining of it—during winter, when that life itself seems to be absent and the poor creatures just stand around, leafless and woebegone, looking dead as bleached Hereford skulls in the desert. Of course they aren’t dead—but do they have reason to wish they were? That’s the question. In response comes a wooden silence. I’ve just gotten back from a walk through the sno
w-packed and tree-lined streets of the town where I live, during which I took care to scrutinize in their sphinx-like stolidity a selection of naked cottonwoods, ashes, dogwoods, weeping birches, maples, and two very grand old elms towering over the sidewalk in front of the house next door. Every one of them, with the season, looking desolate and mute. I hoped for a hint of empathic inspiration, a murmur or a squeak, but they weren’t obliging. No comment. Winter dormancy, that sort of stupor is called. By the time you read this, those same trees will have long since come a-flush with new greenery and I will be harboring a suspicion that they had only been gone on out-of-body experiences in the tropics. Even in summer, though, the life of a city tree can’t be easy.
Landscape architects make a distinction between the “natural” or “romantic” aggregations of foliage in a rolling urban oasis like Central Park and, on the other hand, the “street trees” that serve simply to border or punctuate lanes and boulevards. There is a large literature these days on the theory of urban park design and landscape planning. The romantic style is still in favor. Better yet is the new notion of preserving patches of “urban woodland,” indigenous, ragged, unmanaged. Street trees meanwhile tend to be the forgotten souls.
They grow up through that miserly gap of hard-packed dirt between sidewalk and curb, roots smothered, solitary, regimented like telephone poles, invisible as wallpaper. They get precious little attention and what they do get is often the cruelest sort. Occasionally someone will staple a poster into their bark. A dog stops to lift his leg. A drunk in a Chevrolet tries to park himself up in their branches. But no one puts a hose to their roots on a dry day in July, or gives them a fertilizer treatment in springtime, or sprawls out on a picnic blanket beneath to stare up and admire their canopy. Park trees, yes; lawn trees, yes; not street trees. Then, when they die, the city sends out a crew to fell them and grind them to chips. Otherwise they are ignored.
The Flight of the Iguana Page 7
