Extraterrestrial Civilizations - Isaac Asimov [6]
Anatomical distinctions were sought, some little bodily structure that might be present in human beings alone and not in other animals, and most particularly not in apes. None has ever been found.
In fact, the superficial resemblance between ourselves and other primates, and in particular between ourselves and the chimpanzee and gorilla, becomes all the deeper on closer examination. There is no internal structure present in the human being that is not also present in the chimpanzee and gorilla. All differences are in degree, never in kind.
But if anatomy fails to establish an absolute gulf between human beings and the most closely related nonhuman animals, perhaps behavior can do so.
For instance, a chimpanzee cannot talk. Efforts to teach young chimpanzees to talk, however patient, skillful, and prolonged those efforts may be, have always failed. And without speech, the chimpanzee remains nothing but an animal. (The phrase dumb animal does not refer to the lack of intelligence of the animal, but to its muteness, its inability to speak.)
But might it be that we are confusing communication with speech?
Speech is, we may take for granted, the most effective and delicate form of communication of which we are aware, but is it the only one?
Human speech depends upon human ability to control rapid and delicate movements of throat, mouth, tongue, and lips, and all this seems to be under the control of a portion of the brain called Broca’s convolution, named for the French surgeon Pierre Paul Broca (1824–1880). If Broca’s convolution is damaged by a tumor or a blow, a human being suffers from aphasia and can neither speak nor understand speech. Yet such a human being retains intelligence and is able to make himself understood, by gesture for instance.
The section of the chimpanzee’s brain equivalent to Broca’s convolution is not large enough or complex enough to make speech in the human sense possible. But what about gesture? Chimpanzees use gestures to communicate in the wild; could that use be improved?
In June 1966, Beatrice and Allen Gardner of the University of Nevada chose a one-and-a-half-year-old female chimpanzee they named Washoe and decided to try to teach her a deaf-and-dumb language of gestures. The results amazed them and the world.
Washoe readily learned dozens of signs, using them appropriately to communicate desires and abstractions. She invented new modifications, which she also used appropriately. She tried to teach the language to other chimpanzees and she clearly enjoyed communicating.
Other chimpanzees have been similarly trained. Some have been taught to arrange and rearrange magnetized counters on a wall. In so doing, they showed themselves capable of taking grammar into account and were not fooled when their teachers deliberately created nonsense sentences.
Young gorillas have been similarly trained and have shown even greater aptitude than chimpanzees.
Nor is it a matter of conditioned reflexes. Every bit of evidence shows that chimpanzees and gorillas know what they are doing, in the same sense that human beings know what they are doing when they talk.
To be sure, the ape language is very simple compared to the language of human beings. The human being is enormously more intelligent than apes, but again the difference here is one of degree rather than kind.
BRAINS
To anyone considering the comparative intelligence of animals, it is clear that the key anatomical factor is the brain. Primates have larger brains in general than the large majority of nonprimates, and the human brain is the largest primate brain by a good deal.
The brain of an adult chimpanzee weighs 380 grams (13½ ounces) and that of an adult gorilla weighs 540 grams (19 ounces or just under 1¼ pounds). In comparison, the brain of an adult male human being weighs on the average 1,450 grams (3¼ pounds).
The human brain is not, however, the largest that has ever evolved. The largest elephants