Solution Toolmaking Species Are Rare

Man is a toolmaking animal.

Benjamin Franklin (attributed by James Boswell, Life of Johnson)

The road from the first eukaryotic cells to the animals we see today was tortuous and, many would argue, far from inevitable. There might be several hurdles to overcome before animals species can flourish, and perhaps the answer to Fermi's question lies in those hurdles. But let us suppose that once the eukaryotic cell has developed, then it is all downhill from there; given enough time, advanced animal life will definitely appear on a planet. Does it then follow that an animal species capable of building a radio telescope will develop? Maybe not.

People have long sought to identify one defining characteristic of mankind — one attribute distinguishing Homo sapiens from the animals on Earth. A trait often proposed for this role is tool use and toolmaking. "Man the Toolmaker" is a powerful image. If toolmaking is unique to humans, if among the billions of species that have ever lived on Earth Homo sapiens alone has mastered the intricacies of tools, then we might have a resolution of the Fermi paradox. Perhaps tool use and toolmaking are rare anywhere in the Galaxy. And without tools to build spacecraft or construct beacons, it is presumably impossible for a biological species to make their presence known across the depths of space.

There is a major difficulty with this suggestion: many species use tools and quite a few species make them.

For example, several species of birds use twigs to pry out grubs from the bark of trees. Sea otters place anvil stones on their chests and use them to smash open crab shells. Wasps use small pebbles to help hide the entrances to burrows where they have laid eggs. Egyptian vultures pick up rocks in their talons and drop them on ostrich nests to crack open the eggs. The list of tool use among animals is a long one. Of course, none of these examples are what we understand by tool use. These animal behaviors are all highly stereotyped; they are specific, repetitive responses to particular problems. Change the nature of the problem and these creatures are lost. Nowhere do these animals display insight; those elaborate displays are the intelligent result of brainless evolution.

If we require better examples of tool use, then we are forced to look at the primates. At this point Homo sapiens begins to seem special, if not unique, for even among the primates there are relatively few "real" examples of tool use. Apart from the great apes, which we will come to in a moment, the only primate that spontaneously uses tools in the wild is the capuchin monkey (the type of monkey employed by organ-grinders). Field workers have observed capuchins put stones and sticks to a variety of uses; among other things, the monkeys use them to obtain food and repel predators. In laboratory settings, capuchins learn to use sticks to obtain nuts from different experimental setups. However, capuchins have no real understanding of the principles of tool use, nor any comprehension of why a particular technique might work or fail. Watch them, and it is clear that they engage in trial-and-error prodding and poking.

Of all the animals, it is the chimpanzee that seems to make the most creative use of tools in the wild. The chimpanzees of West Africa, for example, use a hammer stone and an anvil stone to crack open nuts (and they make a better job of cracking nuts than I do at Christmas). Suitable stones can be in short supply, and the chimpanzees often have to carry them over long distances to a source of nuts. These chimps plan ahead. The chimpanzees of Tanzania use a variety of twigs for a variety of purposes, and the twigs are modified beforehand if necessary. These chimps are making tools. They also employ various items of foliage for a variety of functions — banana leaves are used as umbrellas, smaller leaves are used to wipe off dirt, and chewed leaves are used as sponges. Perhaps even more impressive is the achievements of Kanzi — touted by some as a veritable Edison of the animal kingdom. Kanzi is a bonobo (a species that, along with its sibling species, the chimpanzee, is our nearest relative in the animal kingdom). Among many other accomplishments, Kanzi has mastered the rudiments of stone tool production. (This particular accomplishment should not be oversold, however. Kanzi was taught how to take rock cores and from them make stone flakes capable of cutting a cord. After about one year, Kanzi had spontaneously made several improvements and advances to the flake-making technique it had been taught. The stone flakes it produced were small items, however; Kanzi clearly had no understanding of the properties of rock and no insight in how best to fracture rock to obtain large, useful flakes. Furthermore, bonobos have never been observed to use tools in the wild. Kanzi had the benefit of intensive training and teaching by humans.)

figure 71 These mesolithicflint tools — small blades and a scraper — are 9000 to 8500 years old. Their construction is quite beyond the abilities of animals.

The lesson to be learned from these examples is perhaps this: animals use tools because they can. Tool use is less an indicator of the natural "intelligence" of an animal than a reflection of manipulative abilities (and the evolutionary adaptations its species has made to fit a particular ecological niche). A bird can use its beak for a variety of purposes, an elephant can use its trunk, and a chimpanzee is fortunate in possessing a hand that can manipulate objects in several ways. However, a camel, or a cow, or a cat, is never going to be a natural tool user — not because these creatures are inherently inferior to birds or less intelligent than chimpanzees, but simply because they lack the requisite manipulative ability. Presumably if they could use tools, they would.

Mankind is fortunate: our species possesses a hand that permits a quite astonishing range of actions. (Count how many different ways you configure your hand to carry out tasks during a typical day. You will be surprised.) We are excellent toolmakers because we have the manipulative abilities to be excellent toolmakers — and when this is combined with our other traits, such as language and social living, it is not difficult to understand why our use of tools is qualitatively different from that of other species. (The view I have described above is rather different from the traditional view, which says we are better toolmakers than other animals because we are more intelligent than other animals. But one can make a strong case for saying that early man's use of tools was one of the drivers of increasing human intelligence — intelligence that was then co-opted for other purposes. The neuronal circuitry required to control the precision manipulations of the human hand, and to govern activities like the throwing of projectiles at moving prey, is phenomenal — and quite beyond the capacity of any present-day robot.)225

We have to ask, then: what is the chance that an extraterrestrial species will follow the same sort of evolutionary route that man followed? Of course, an extraterrestrial does not need five-fingered hands in order to build a radio telescope; the course of evolution does not have to be identical. But in order to develop advanced technology it will need some sort of precision-manipulative ability (whether using claws, tentacles or something beyond our imagination) combined perhaps with other characteristics such as stereoscopic vision. We have no way of knowing how probable or improbable such an evolutionary outcome would be. But I for one find it difficult to believe that no other species could have evolved the requisite toolmaking abilities. Toolmaking is perhaps one more hurdle that has to be overcome before a species can communicate, yet one more way in which a world full of life can still fail to produce a civilization capable of communicating with us. But surely this cannot be the sole explanation of the Fermi paradox.

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