Was it Detroit? Of late, that seems increasingly likely. Perhaps we diverged from the sensible path there, blinded not atomically but just by the gleam in Henry Ford’s eye. Beyond Detroit our wrong path became a paved road. It straightened, losing its comfortable country-lane curves, and it broadened, becoming multi-laned. The asphalt metastasized, appearing suddenly everywhere, as parking lots in apple orchards, as clover leafs where corn once grew. In my own hometown, a quarter of the land has been sacrificed to the automobile. Each citizen here has 2.13 square meters of parks to himself. Each car has 87.12 square meters of streets. To support my car in the manner to which it is accustomed, on that vast estate I have ceded to it, like other average Americans, must work one fourth of my life.

With the automobile have come suburban sprawl, 50,000 deaths a year, a lacework of off-road tire tracks across the desert, and hatred of the Arabs. Sixty percent of all pollutants in U.S. air (10,800 metric tons a day in the air above Los Angeles along, and in the lungs of that city’s school children) rumble forth from the internal-combustion engine. “The current American way of life is founded not just on motor transportation,” Lewis Mumford wrote more than 20 years ago, “but on the religion of the motorcar, and the sacrifices that people are prepared to make for this religion stand outside the realm of rational criticism.” Mumford had yet to see gasoline shortages or those lines in which angry motorists sacrificed one another’s lives. (The cars of the slain drivers continue to idle over their fallen owners. Over their fallen servants, rather for in truth the car was owner of the man. The idling engines were making a sound, if only we had ears for it, very much like a chuckle.)

But by now everyone has seen the monster in the Model-T, and the problem is older than that. Was it in the well-intentioned work of men like Hippocrates, Joseph Lister, and Jonas Salk? Having depressed the human death rate, medicine has released the grim potential in human fertility. At our present rate of growth, as I.J. Cook has pointed out, everything in the known universe will be converted into humans in a few thousand years, and the ball of humanity will be expanding outward at the speed of light. (In trying to trace our wrong turn, it is tempting to look for some startling new phenomenon, and the one Cook describes certainly would fit the bill--a squirming mass of people expanding outward at the speed of light.) Or is our problem with numbers less medical than philosophical?

Did it begin in the Judeo-Christian ethic, in the biblical injunction to multiply and subdue? The Bible, with its radical new doctrine that this planet was God’s gift to man, certainly didn’t help. Our attitude toward Earth was healthier when we were pagans who believed that spirits resided in everything, that man and beast were on equal footing--bears becoming men occasionally, men becoming owls--and that a tree had to be placated before you chopped it down.

But it’s unfair to blame the Bible. Hindus and Buddhists have proved that they can breed and subjugate as efficiently as Jews or Christians can. Was our mistake, then, the invention of agriculture? With agriculture, human numbers made their first big lurch forward and transformation of the planet’s vegetation by human agency accelerated. But that transformation had begun earlier, of course. Hunters were torching the grass to drive game long before farmers learned to burn the woods so they could make their clearings. Maybe the bad invention was fire. Or, perhaps it was the tool. The stone-tipped spear, clasped by the hairy and opposable thumb, appears to have been an instrument of extinction of a caliber formerly wielded only by God. There is much speculation, and some evidence, that hunter-gatherers had profound effects on earthly faunas long before agricultural advancement ever allowed men to settle in cities. Paleolithic man in Europe and North America may have helped exterminate the megafauna of those continents, the mammoths and giant bison. We were, then working at the eradication of huge animals millennia before the invention of the exploding harpoons and the factory ship. We were deforesting the Near East long before the chain saw. We were extending the borders of North African deserts long before the dune buggy.

The question of where we went wrong is as problematic as that of determining at what point hominids became men. Perhaps it’s the same question. We may need to backtrack further, however. Back to a time before we became properly us, “far back along those converging roads where cat and man and weasel must leap into a single shape,” as Loren Eiseley has put it. Maybe the mistake was that first primitive animal. Maybe the bad invention was fire, all right--the metabolic kind. Perhaps our error was endothermy.

The endotherm, the “warm-blooded” animal, generates in each of its cells about four times the chemical heat that the ectotherm, or “cold-blooded” animal generates. The endotherm’s insulation, in the form of fur or feathers, is superior. While the ectotherm’s workday begins only when the sun has warmed it, the endotherm’s begins anytime the mood strikes.

The new system, inaugurated in the Triassic, conferred a great competitive advantage on its converts. It opened up higher latitudes, colder seasons, and the night. It was a prerequisite, on this planet at least, for high intelligence. It looked awfully good. But it had a high cost. The energy budget for a population of endotherms is 10 to 30 times higher than for a population of ectotherms of the same weight. When Victorian zoologists first dissected Nile crocodiles, they were amazed to find that the stomachs of most of them were empty. The discovery did not seem to jibe with the monster’s crooked and toothy smile, its voracious reputation.

The true monster was not the croc, of course, but the bespectacled, apparently mild-mannered scientist peering into its stomach. (If some intelligent extraterrestrial lizard had dissected a sampling of Victorian zoologists, it would have been appalled by the evidence of real voracity--the crumpets, marmalade and kidney pie in each stomach.) We endotherms are the gas guzzlers of the animal kingdom. We are the double-carburetored, fuel-injected muscle cars of the phylum Chordata. Auto makers are mistaken in naming their economy vehicles Rabbit and Colt. More appropriate would be Salamander, Frog, Scorpion, Iguana.

We have pulled out and roared past the oxcart of the ectotherms, but the planet is paying the price. “A star is a planet whose inhabitants experimented with nuclear power,” Alan Watts once said, inventing an improbable cosmology to make a good point. Maybe Watts’ axiom could be amended: A star is a planet where life experimented with endothermy. The intense, dazzling liberation of energy in the fission bomb is, perhaps, just a sublimation, an inevitable product, of the chemical liberation that occurred in the cells of the first endotherm. And it is possible too, that endothermy -- or its equivalent in a life system based not on carbon but on silica or something else-- is inevitable, barring cosmic accident, once life has begun. Whether or not stars arise from intelligent tinkering--and it seems unlikely on local evidence that there was ever that much brain power in the universe. Still there may be, in stellar evolution, a fuzzy analogue at least.

Shortly after the life of a planet enters the endothermic stage, things may always become white-hot. Two years ago at a conference on the biology of marine mammals, I heard a lecture given by a marine scientist who entertained some doubts about endothermy. The scientist--I have forgotten his name--suggested that endothermy in the sea in the forms of cetacean and seal, might not have been a good idea. He was being deliberately heretical. The conference hall was full of young biologists who had become whale advocates, which seems to be a nearly inevitable development among whale researchers. His purpose was mostly playful, to shake up his colleagues. But, his point was interesting.

The ocean, as he reminded the gathering, is an ecosystem of peculiar interdependencies, a country where the sheep eat the litters of the wolves. The reproductive methods of marine mammals--a method land-evolved--were a totally foreign introduction. With sea mammals, a single calf or pup is reared carefully by its mother and its tribe. There are no millions of translucent little porpoise fry, no sea lion fingerlings left over to feed the fish on which adult porpoises and sea lions feed. Marine mammals take a lot from the sea and give back little. Throughout long lifetimes they eat tons of fish and squid, burn a lot of calories to keep warm, and generally have a good time. They return only their excrement and finally their cadavers. Anyone who has seen the fearlessness and speed with which the dorsal fin of a killer whale cuts the surface, then slices through a school of ectothermic salmon; anyone who has watched dolphins spend the whole morning leaping and playing, their time freed by having echo-located their prey so efficiently the previous night--that person must have sensed the possible truth in what the scientist suggested: that these animals are just a little too good.

But marine mammals have a convincing defense. They have passed, with high grades, the test of time. Whales have practiced their style of endothermy in the ocean for 60 million years, seals for 30 million. From all the evidence, they and the ocean have mutually adjusted. In the Miocene 20 million years ago, the whale brain achieved its nearly present form, making whales the brightest creatures on this planet. Somehow they passed on an intact and bountiful ocean to their descendants. They moderated their numbers. They have not become a blubbery mass occupying all the known universe and expanding outward at the speed of light. The problem then must be in the appendage we have in place of a flipper.

The human hand, deceptively clammy at high school dances, but endothermic at its core, is the culprit. The notion is hardly original with me. Peter Sellers, for one, knew it, consciously or not, in his portrayal of Dr. Strangelove. We are all Dr. Strangelove as portrayed by Sellers. Strangelove’s hand has a life of its own, saluting the Führer at unexpected moments, fidgeting spasmodically despite its owner’s desperate efforts to control it, lulling him, and trying to escape in a fingerwalk down the armrest. We must master our hands, obviously and far better than Strangelove did in the movie. It is too late to grow flippers.

It is not too late to learn to communicate with cetaceans. There have been a number of previous arguments for trying to do so. One is for the sake of cetaceans. “I look at language as a weapon in the long term fight for whales.” Jean-Paul Fortom-Gouin, of Florida’s Delphic Research Institute told me last year. “If you can prove they can talk--if you can think that they can talk--then the only ethical position is to stop killing them until you can find out.” A second argument is for the sake of humans, that we might experience intelligent companionship on an earth where the opportunities for that companionship are few. “It is worth at least a wistful thought,” Loren Eiseley writes, “that someday the porpoise may talk to us and us to him. It would break perhaps the long loneliness that has made man a frequent terror and abomination even to himself.” A third argument is for expanding human horizons. “We can hear whales singing,” writes Joan McIntyre, of project Jonah. “If we pay attention and let them live, perhaps we will hear them speak in their own accents, their own language. It would be an extravagant reward to experience, by empathy, a different band of reality.”

But an even stronger argument might be made for our very survival. If we can somehow bridge the 60 million years of cultural separation, discovering a language intelligible to both sides, we humans might learn the cetacean’s secret: how a smart, hot-blooded animal can amuse itself for millions of years without burning the place up.