The Meaning of Human Existence (10 page)

Let’s grant the dream of many science fiction writers and astronomers alike that civilized E.T.s are out there, even if at this almost incomprehensible distance. What might they be like? Permit me to make a second educated guess. By combining the evolution and peculiar properties of hereditary human nature with known adaptations by millions of other species in the great biodiversity of Earth, I believe it’s possible to produce a logical albeit very crude hypothetical portrait of human-grade aliens on Earth-like planets.

E.T.s are fundamentally land-dwellers, not aquatic
. During their final ascent in biological evolution to the human grade of intelligence and civilization, they must have used controlled fire or some other easily transportable high-energy source to develop technology beyond the earliest stages.

E.T.s are relatively large animals
. Judging from Earth’s most intelligent terrestrial animals—they are, in descending
rank order, Old World monkeys and apes, elephants, pigs, and dogs—E.T.s on planets with the same mass as Earth or close to it evolved from ancestors that weighed between ten and a hundred kilograms. Smaller body size among species means smaller brains on average, along with less memory storage capacity and lower intelligence. Only big animals can carry on board enough neural tissue to be smart.

E.T.s are biologically audiovisual
. Their advanced technology, like our own, allows them to exchange information at various frequencies across a very broad sector of the electromagnetic spectrum. But in ordinary thinking and talking among themselves they use vision just like us, employing a narrow section of the spectrum, along with sound created with waves of air pressure. Both are needed for rapid communication. E.T.s’ unaided vision may allow them to see the world in ultraviolet in the manner of butterflies, or some other, still unnamed primary color outside the range of wave frequency sensed by humans. Their auditory communication may be immediately perceived by us, but it could also easily be at too high a pitch, as used by katydids or many other insects, or too low, as practiced by elephants. In the microbial worlds on which the E.T.s depend, and in probably most of the animal world, most communication is by pheromones, secreted chemicals that convey meaning in their
smell and taste. The E.T.s, however, cannot employ this medium any more than we can. While it is theoretically possible to send complex messages by the controlled release of odor, the frequency and amplitude modulation required to create a language is possible across only a few millimeters.

Finally, might E.T.s read facial expressions or sign language? Of course. Thought waves? Sorry, I don’t see any way that’s possible, except through elaborate neurobiological technology.

Their head is distinct, big, and located up front
. The bodies of all land-dwelling animals on Earth are elongated to some extent, and most are bilaterally symmetrical, with the left and right sides of their bodies reciprocal mirror images. All have brains with key sensory input located in the head, adapted in location for quick scanning, and integration, and action. E.T.s are no different. The head is also large compared to the rest of the body, with a special chamber to accommodate the necessarily huge memory banks.

They possess light to moderate jaws and teeth
. Heavy mandibles and massive grinding teeth on Earth are the marks of dependence on coarse vegetation. Fangs and horns denote either defense against predators, or competition among males of the same species, or both. During their evolutionary ascent, the ancestors of the aliens almost
certainly relied on cooperation and strategy rather than brute strength and combat. They were also likely to be omnivorous, as are humans. Only a broad, high-energy meat-and-vegetable diet could produce the relatively large populations needed for the final stage of the ascent—which in humans occurred with the invention of agriculture, villages, and other accoutrements of the Neolithic revolution.

They have very high social intelligence
. All social insects (ants, bees, wasps, termites) and the most intelligent mammals live in groups whose members continuously and simultaneously compete and cooperate with one another. The ability to fit into a complex and fast-moving social network gives a Darwinian advantage both to the groups and to individual members that form them.

E.T.s have a small number of free locomotory appendages, levered for maximum strength with stiff internal or external skeletons composed of hinged segments (as by human elbows and knees), and with at least one pair of which are terminated by digits with pulpy tips used for sensitive touch and grasping
. Since the first lobe-finned fishes invaded the land on Earth about four hundred million years ago, all of their descendants, from frogs and salamanders to birds and mammals, have possessed four limbs. Further, among the most successful and abundant land-dwelling invertebrates are the insects, with six locomotory appendages, and spiders, with eight. A small
number of appendages is therefore evidently good. It is moreover the case that only chimpanzees and humans invent artifacts, which vary in nature and design from one culture to the next. They do so because of the versatility of soft fingertips. It is hard to imagine any civilization built with beaks, talons, and scrapers.

They are moral
. Cooperation among group members based on some amount of self-sacrifice is the rule among highly social species on Earth. It has arisen from natural selection at both the individual and group levels, and especially the latter. Would E.T.s have a similar inborn moral propensity? And would they extend it to other forms of life, as we have done (however imperfectly) in biodiversity conservation? If the driving force of their early evolution is similar to our own, a likely possibility, I believe they would possess comparable moral codes based upon instinct.

It might not have escaped your attention that I’ve thus far tried to envision E.T.s only as they were at the beginning of their civilizations. It is the equivalent of a portrait of humanity drawn during the Neolithic era. Following that period our species worked its way by cultural evolution, across ten millennia, from the rudiments of civilization in scattered villages to the technoscientific global community of today. It is likely by chance alone that extraterrestrial civilizations made the same leap
not just millennia ago but thousands of millennia ago. With the same intellectual capacity we already have, and possibly a great deal more, might they have long since engineered their own genetic code in order to change their biology? Did they enlarge their personal memory capacities and develop new emotions while diminishing old ones—thereby adding boundless new creativity to the sciences and the arts?

I think not. Nor will humans, other than correcting disease-causing mutant genes. I believe it would be unnecessary for our species’ survival to retrofit the human brain and sensory system, and, in one basic sense at least, it would be suicidal. After we have made all of the cultural knowledge available with only a few keystrokes, and after we have built robots that can outthink and outperform us, both of which initiatives are already well under way, what will be left to humanity? There is only one answer: we will choose to retain the uniquely messy, self-contradictory, internally conflicted, endlessly creative human mind that exists today. That is the true Creation, the gift given us before we even recognized it as such or knew its meaning, before movable print and space travel. We will be existential conservatives, choosing not to invent a new kind of mind grafted on top of or supplanting the admittedly weak and erratic dreams of our old mind. And I find it comforting to believe that
smart E.T.s, wherever they are, will have reasoned the same way.

Finally, if E.T.s know of Earth’s existence at all, will they choose to colonize it? In theory, it may have seemed possible and contemplated at any time by many of them over the past millions or hundreds of millions of years. Suppose a conqueror E.T. species has arisen somewhere in our neighborhood of the galaxy since the time of Earth’s Paleozoic Era. Like our species, it was from the beginning driven by an impulse to invade all of the habitable worlds it could reach. Imagine that its drive for cosmic lebensraum began one hundred million years ago, in an already old galaxy. Also, imagine (reasonably) that it took ten millennia from launch to reach the first habitable planet; and from there, with the technology perfected, the colonists devoted another ten millennia to launch an armada sufficient to occupy ten more planets. By continuing this exponential growth, the hegemons would have already colonized most of the galaxy.

I’ll give you two good reasons why galactic conquests have never happened, or even begun, and hence why our poor little planet has not been colonized and never will be. A remote possibility exists that Earth has been visited by sterile robot probes, or in some distant future age might yet be visited, but they will not be accompanied
by their organic creators. All E.T.s have a fatal weakness. Their bodies would almost certainly carry microbiomes, entire ecosystems of symbiotic microorganisms comparable to the ones that our own bodies require for day-to-day existence. The E.T. colonists would also be forced to bring crop plants, algae-equivalents, or some other energy-gathering organisms, or at the very least synthetic organisms to provide their food. They would correctly assume that every native species of animal, plant, fungus, and microorganism on Earth is potentially deadly to them and to their symbionts. The reason is that the two living worlds, ours and theirs, are radically different in origin, molecular machinery, and the endless pathways of evolution that produced the life-forms then brought together by colonization. The ecosystems and species of the alien world would be wholly incompatible with our own.

The result would be a biological train wreck. The first to perish would be the alien colonists. The residents—us and all of Earth’s fauna and flora, to which we are so exquisitely well adapted—would be unaffected except briefly and very locally. The clash of worlds would not be the same as the ongoing exchange of species of plants and animals between Australia and Africa, or between North and South America. It’s true that considerable damage to native ecosystems has recently occurred due
to such intercontinental mixing, caused by our own species. Many of the colonists hang on as invasive species, especially in habitats disturbed by humans. A few manage to crowd native species to extinction. But it is nothing like the vicious biological incompatibility that would doom interplanetary colonists. In order to colonize a habitable planet, the aliens would first have to destroy all life on it, down to the last microbe. Better to stay at home, for a few more billion years anyway.

This brings me to the second reason why our fragile little planet has nothing to fear from extraterrestrials. E.T.s bright enough to explore space surely also understand the savagery and lethal risk inherent in biological colonization. They would have come to the realization, as we have not, that in order to avoid extinction or reversion to unbearably harsh conditions on their home planet they had to achieve sustainability and stable political systems long before journeying beyond their star system. They may have chosen to explore other life-bearing planets—very discreetly with robots—but not to undertake invasions. They had no need, unless their home planet was about to be destroyed. If they had developed the ability to travel between star systems, they would also have developed the ability to avoid planetary destruction.

There live among us today space enthusiasts who
believe humanity can emigrate to another planet after using up this one. They should heed what I believe is a universal principle, for us and for all E.T.s: there exists only one habitable planet, and hence only one chance at immortality for the species.

11

The Collapse of Biodiversity

T
hink of Earth’s biodiversity, the planet’s variety of life, as a dilemma wrapped in a paradox. The paradox is the following contradiction: the more species that humanity extinguishes, the more new species scientists discover. However, like the conquistadores who melted the Inca gold, they recognize that the great treasure must come to an end—and soon. That understanding creates the dilemma: whether to stop the destruction for the sake of future generations, or the opposite, just go on changing the planet to our immediate needs. If the latter, planet Earth will recklessly and irreversibly enter a new era of its history, called by some the Anthropocene, an age of, for, and all about our one species alone, with all the rest of life rendered subsidiary. I prefer to call this miserable future the Eremocene, the Age of Loneliness.

Scientists divide biodiversity (keep in mind, I mean all the rest of life) into three levels. At the top are the
ecosystems, for example meadows, lakes, and coral reefs. Below it are the species that make up each of the ecosystems in turn. And at the base are the genes that prescribe the distinguishing traits of each of the species.

A convenient measure of biodiversity is the number of species. When in 1758 Carl Linnaeus began the formal taxonomic classification still in use today, he recognized about twenty thousand species in the entire world. He thought that he and his students and helpers might be able to account for most or all of the world fauna and flora. By 2009, according to the Australian Biological Resources Study, the number had grown to 1.9 million. By 2013 it was probably 2 million. Yet this is still only an early point in the Linnaean journey. The actual number in nature is not known even to the nearest order of magnitude. When still-undiscovered invertebrates, fungi, and microorganisms are added, estimates vary wildly, from five million to one hundred million species.

Earth, to put the matter succinctly, is a little-known planet. The pace of mapping biodiversity has also remained slow. New species flood laboratories and museums everywhere, but are being diagnosed and named at a pace of only about twenty thousand a year. (I have described about 450 new species of ants from around
the world during my lifetime.) At this rate, and taking a low-end estimate of five million species remaining to be classified, the task will not be completed until the middle of the twenty-third century. Such a snail’s pace is a disgrace of the biological sciences. It is based on the misconception that taxonomy is a completed and outdated part of biology. As a result this still-vital discipline has been largely squeezed out of academia and relegated to natural history museums, themselves impoverished and forced to reduce their research programs.