The rise and fall of the third chimpanzee

have found today that turkeys build radio transmitters but no receivers, while kangaroos build receivers but no transmitters. The fossil record might have shown dozens of now-extinct animals experimenting over the last half- billion years with metallurgy and increasingly complex electronic circuits, leading to electric toasters in the Triassic, battery-operated rat traps in the Oligocene, and finally radios in the Holocene. Fossils might have revealed 5-watt transmitters built by trilobites, 200-watt transmitters amidst bones of the last dinosaurs, and 500-watt transmitters in use by sabertooths, until humans finally upped the power output enough to be the first to broadcast into space.

But none of that happened. Neither fossils nor living animals—not even our closest living relatives, the common and pygmy chimpanzees—had even the most remote precursors of radios. It is instructive to consider the experience of the human line itself. Neither australopi-thecines nor early Homo sapiens developed radios. As recently as 150 years ago, modern Homo sapiens did not even have the concepts that would lead to radios. The first practical experiments did not begin until around 1888; it is still less than 100 years since Marconi built the first transmitter capable of broadcasting one mere mile; and we still are not sending signals targeted at other stars, though the 1974 Arecibo experiment was our first attempt.

I mentioned early in this chapter that the existence of radios on the one planet known to us seemed at first to suggest a high probability of radios evolving on other planets. In fact, closer scrutiny of Earth's history supports exactly the opposite conclusion: radios had a vanishingly low probability of evolving here. Only one of the billions of species that have existed on Earth showed any proclivities towards radios, and even it failed to do so for the first 69,999/70,000 ths of its seven-million-year history. A visitor from outer space who had come to Earth as recently as the year 1800 AD would have written off any prospects of radios being built here. You might object that I am being too stringent in looking for early precursors of radios themselves, when I should instead look just for the two qualities necessary to make radios, intelligence and mechanical dexterity. The situation there is little more encouraging. Based on the very recent evolutionary experience of our own species, we arrogantly assume intelligence and dexterity to be the best way of taking over the world, and to have evolved inevitably. Think again about that quote from the Encyclopaedia Britannica: 'It is difficult to imagine life evolving on another planet without progressing towards intelligence. Earth history again supports exactly the opposite conclusion. In reality, vanishingly tew animals on Earth have bothered with much of either intelligence or dexterity. No animal has acquired remotely as much of either as have we; those that have acquired a little of one (smart dolphins, dexterous spiders) have acquired none of the other; and the only other species to acquire a little of both (common and pygmy chimpanzees) have been rather unsuccessful. Earth's really successful species have instead been dumb and clumsy rats and beetles, who found better routes to their current c finance.

We have only still to consider the last missing variable in the Green Bank formula for calculating the likely number of civilizations capable of interstellar radio communication. That variable is the lifetime of such a civilization. The intelligence and dexterity required to build radios are useful for other purposes that have been our species' hallmark for much longer than have radios and that will be the subject of the remaining chapters in this book: purposes such as mass-killing devices and means of environmental destruction. We have become so potent at doing both that we are gradually stewing in our civilization's juices. We may not enjoy the luxury of an end by slow stewing. Half-a-dozen countries now possess the means for bringing us all to a quick end, and still other countries are eagerly seeking to acquire those means. The wisdom of some past leaders of bomb-possessing nations, or of some present leaders of bomb-seeking nations, does not encourage us to believe that there will be radios on Earth for much longer.

It was an extremely unlikely fluke that we developed radios at all, and more of a fluke that we developed them before we developed the technology that will end us in a slow stew or fast bang. While Earth's history thus offers little hope that radio civilizations exist elsewhere, it also suggests that any that might exist are short- lived.

We are very lucky that that is so. I find it mind-boggling that the astronomers now eager to spend a hundred million dollars on the search for extraterrestrial life have never thought seriously about the most obvious question: what would happen if we found it, or if it found us. The astronomers tacitly assume that we and the little green monsters would welcome each other and settle down to fascinating conversations. Here again, our own experience on Earth offers useful guidance. We have already discovered two species that are very intelligent but technically less advanced than us—the common chimpanzee and pygmy chimpanzee. Has eur response been to sit down and try to communicate with them? Of course not. Instead we shoot them, stuff them, dissect them, cut off their hands for trophies, put them on exhibit in cages, inject them with AIDS virus as a medical experiment, and destroy or take over their habitat. That response was predictable, because human explorers who discovered technically less advanced humans also regularly responded by shooting them, decimating their populations with new diseases, and destroying or taking over their habitat. Any advanced extraterrestrials who discovered us would surely treat us in the same way. Think again of those astronomers who beamed radio signals into space from Arecibo, describing Earth's location and its inhabitants. In its suicidal folly that act rivalled the folly of the last Inca emperor, Atahuallpa, who described to his gold-crazy Spanish captors the wealth of his capital and provided them with guides for the journey. If there really are any radio civilizations within listening distance of us, then for heaven's sake let's turn off our own transmitters and try to escape detection, or we are doomed.

Fortunately for us, the silence from outer space is deafening. Yes, out there are billions of galaxies with billions of stars. Out there must be some transmitters as well, but not many, and they do not last long. Probably there are no others in our galaxy, and surely none within hundreds of light-years of us. What woodpeckers teach us about flying saucers is that we are unlikely ever to see one. For practical purposes, we are unique and alone in a crowded universe. Thank God!

PART FOUR WORLD CONQUERORS

Part three discussed some of our cultural hallmarks and their animal precedents or precursors. Several of those hallmarks are ones that we are proud of, though one (agriculture) has proved to be a mixed blessing and another (chemical abuse) an unmitigated evil. Those cultural hallmarks—especially language, agriculture, and advanced technology—have been the causes of our rise. They are what permitted us to expand over the globe and become world conquerors. That expansion, though, consisted of more than our conquering areas previously unoccupied by the human species. It also involved the expansion of particular human populations that conquered, expelled, or killed other populations. We became conquerors of each other, as well as of the world. Thus, our expansion has been marked by yet another human hallmark that has animal precursors and that we have taken far beyond its animal limits—namely, our propensity to kill other members of our species en masse. Along with our environmental destructiveness, it now poses one of the two potential causes for our fall.

To appreciate our rise to the status of world conquerors, recall that most animal species are distributed over only a small part of the Earth's surface. For example, Hamilton's frog is confined to one forest patch of thirty-seven acres plus one rock-pile covering 720 square yards in New Zealand. The most widespread wild land mammal other than humans used to be the lion, which as of 10,000 years ago occupied most of Africa, much of Eurasia, North America and northern South America. Even at the time of its greatest extent, though, the lion did not reach Southeast Asia, Australia, southern South America, the polar regions, or islands. There are even more widespread bird species that occur on all continents except Antarctica, such as the barn owl or peregrine falcon, but they too are absent from many islands, high elevations, cold climates, and all the oceans.

Humans used to have a typically mammalian restricted distribution, in warm, non-forested areas of Africa. As recently as 50,000 years ago, we were still confined to tropical and mild-temperature areas of Africa and Eurasia. Then we expanded in turn to Australia and New Guinea (around 50,000 years ago), cold parts of Europe (by 30,000 years ago), Siberia (by 20,000 years ago), North and South America (around 11,000 years ago), and Polynesia (between 3,600 and 1,000 years ago). One dramatic stage in this expansion of ours into a large realm