Diamond, Jared. The
Third Chimpanzee :
The Evolution and Future of the Human Animal.
Molecular genetic studies of the last half-dozen years have shown that we continue to share over 98 percent of our genetic program with the other two chimps. The overall genetic distance between us and chimps is even smaller than the distance between such closely related bird species as red-eyed and white-eyed vireos. Thus, we still carry most of our biological baggage with us. (2)
Since
Our unique qualities have been responsible for our present biological success as a species. No other large animal is native to all the continents, or breeds in all habitats from deserts and the Arctic to tropical rainforests. No large wild animal rivals us in numbers. But among our unique qualities are two that now jeopardize our existence: our propensities to kill each other and to destroy our environment. (p. 3)
There’s nothing new about prophecies to the effect that the world’s end is near if we don’t repent. What’s new is that the prophecy is now likely to come true, for two obvious reasons. First, nuclear weapons give us the means to wipe ourselves out quickly; no humans possessed this means before. Second, we already appropriate about 40 percent of the Earth’s net productivity (i.e., the net energy captured from sunlight). With the world’s human population now doubling every forty-one years, we soon shall reach the biological limit to growth, at which point we shall have to start fighting each other in dead earnest for a share of the world’s fixed pie of resources. (3)
We can convince ourselves of the inevitable outcome of our current shortsighted practices just by examining the many past societies that destroyed themselves by destroying their own resource base, despite having less potent means of self-destruction than ours. (p. 5)
It would be absurd to think that a human hallmark such as art, language, or aggression depends on a single gene. Behavioral differences among individual humans are obviously subject to enormous environmental influences, and it’s very controversial what role genes play in such individual differences. (p. 27)
But whether an individual human grows up to be fluent in English or Korean is independent of genes and dependent solely on childhood linguistic environment, as proved by the linguistic attainments of Korean infants adopted by English-speaking parents. (p. 27)
If our ethical code makes a purely arbitrary distinction between humans and all other species, then we have a code based on naked selfishness devoid of any higher principle. If our code instead makes distinctions based on our superior intelligence, social relationships , and capacity for feeling pain, then it becomes difficult to defend an all-or-nothing code that draws a line between all humans and all animals. Instead, different ethical constrains should apply to research on different species. (p. 30)
That whole long tenure of Homo erectus and early Homo sapiens outside Africa was a period of infinitesimally slow cultural change. In fact, the sole candidate for a major advance was possibly the control of fire, for which caves occupied by Peking Man provide one of the earliest indications in the form of ash, charcoal, and burnt bones. Even that advance – if those cave fires really were man-lit rather than caused by lightning – would belong to Homo erectus, not Homo sapiens. (p. 37)
The identify of the ingredient that produced the Great Leap Forward poses an archaeological puzzle without an accepted answer. It doesn’t show up in fossil skeletons. It may have been a change in only 0.1 percent of our DNA. What tiny change in genes could have had such enormous consequences? (54)
Like some other scientists who have speculated about this question, I can think of only one plausible answer: the anatomical basis for spoken language. Chimpanzees, gorillas, and even monkeys are capable of symbolic communication not dependent on spoken words. Both chimpanzees and gorillas have been taught to communicate by means of sign language, and chimpanzees have learned to communicate via the keys of a large computer-controlled console. Individual apes have thus mastered “vocabularies” of hundreds of symbols. While scientists argue over the extent to which such communication resembles human language, there is little doubt that it constitutes a form of symbolic communication. That is, a particular sign or computer key symbolizes a particular something else. (54)
Given this capability for symbolic communication using sounds, why have apes not gone on to develop much more complex natural languages of their own? (55)
The answer seems to involve the structure of the larynx, tongue, and associated muscles that give us fine control over spoken sounds. Like a Swiss watch, all of whose many parts have to be well designed for the watch to keep time at all, our vocal tract depends on the precise functioning of many structures and muscles. Chimps are thought to be physically incapable of producing several of the commonest human vowels. If we too were limited to just a few vowels and consonants, our own vocabulary would be greatly reduced. (p. 55)
That’s why it’s plausible that the missing ingredient may have been some modifications of the protohuman vocal tract to give us finer control and permit formation of a much greater variety of sounds. Such fine modifications of muscles need not be detectable in fossil skulls. (55)
I don’t suggest that the Great Leap Forward began as soon as the mutations for altered tongue and larynx anatomy arose. Given the right anatomy, it must have taken humans thousands of years to perfect the structure of language as we know it – to arrive at the concept of word order and case endings and tenses, and to develop vocabulary. (55-56)
But if the missing ingredient did nosiest of changes in our vocal tract that permitted fine control sounds, then the capacity for innovation would follow eventually. It was the spoken word that made us free. (56)
I’ve argued that we were fully modern in anatomy and behavior and language by forty thousand years ago, and that a Cro-Magnon could have been taught to fly a jet airplane. If so, why did it take so long after the Great Leap Forward for us to invent writing and build the Parthenon? The answer may be similar to the explanation why the Romans, great engineers that they were, didn’t build atomic bombs. To reach the point of building an A-bomb required two thousand years of technological advances beyond Roman levels, such as the invention of gunpowder and calculus, the development of atomic theory, and the isolation of uranium. Similarly, writing and the Parthenon depended on tens of thousands of years of cumulative developments after the arrival of Cro-Magnons – developments that included the bow and arrow, pottery, domestication of plants and animals, and many others. (56)
Until the Great Leap Forward, human culture had developed at a snail’s pace for millions of years. That pace was dictated by the slow pace of genetic change. After the leap, cultural development no longer depended on genetic change. Despite negligible changes in our anatomy, there has been far more cultural evolution in the past forty thousand years than in the millions of years before. (56)
We are unusual in having sex mainly in private and for fun, rather than mainly in public and only when the female is able to conceive Ape females advertise the time when they are ovulating; human females conceal it even from themselves. (p. 61)
Enormous cultural influences obviously operate on our motivation for providing child care or seeking extramarital sex, and there is no reason to believe that genes contribute significantly to differences among individual people in these traits. (p. 63)
Finally, sex organs don’t exist in isolation: they are adapted to their owners’ social habits and life cycle, which are in turn adapted to food-gathering habits. In our own case that means, among other things, that evolution of human sex organs has been intertwined with that of human tool use, large brains, and child-rearing practices. Our progress from being just another species of big mammal to being uniquely human therefore depended on the remodeling not just of our pelvises and skulls, but also of our sexuality. (p. 68)
Human food-gathering habits require a social system in which a male retains his relationship with a female after fertilizing her, in order to assist in rearing the resulting child. (pp. 69-70)
Whatever the main biological function of human copulation, it isn’t conception, which is just an occasional by-product. In these days of growing human overpopulation, one of the most ironic tragedies is the Catholic Church’s claim that human copulation has conception as its natural purpose, and that they rhythm method is the only proper means of birth control. The rhythm method would be terrific for gorillas an most other mammal species, but not for us. In no species besides humans has the purpose of copulation become so unrelated to conception, or the rhythm method so unsuited for contraception.
(p. 78)
For animals, copulation is a dangerous luxury. While occupied in acto flagrante, an animal is burning up valuable calories, neglecting opportunities to gather food, vulnerable to predators eager to eat it, and vulnerable to rivals eager to usurp its territory. (p. 78)
Any social system with rules of conduct is open to the risk of individuals’ cheating when they find the advantages of cheating to outweigh the burden of sanctions. (p. 84)
While sociobiology is thus useful for understanding the evolutionary context of human social behavior, this approach still shouldn’t be pushed too far. The goal of all human activity can’t be reduced to the leaving of descendants. (p. 98)
That’s because our life-style depends on transmitted information. As language evolved, far more information became available to us to pass on than previously. Until the invention of writing, old people acted as the repositories of that transmitted information and experience, just as they continue o do in tribal societies today. Under hunter-gatherer conditions, the knowledge possessed by even one person over the age of seventy could speel the difference between survival and starvation for the whole clan. Our long life span, therefore, was important for our rise from animal to human status. (p. 23)
Instead, our uniqueness lies in the cultural traits that rest on those genetic foundations and that in turn give us our power. Our cultural hallmarks include spoken language art, tool-based technology, and agriculture. (p. 137)
Among our darker qualities, murder has now been documented in innumerable animal species, genocide in wolves and chimps, rape in ducks and orangutans, and organized warfare and slave raids in ants. (p. 170)
Think of all the human suffering caused by the sad truth that beautiful, sexy women or handsome, Porsche-owning men often prove to have miserable genes for other traits. It’s no wonder that so many marriages end in divorce, as we belatedly realize how badly we chose and how flimsy our criteria were. (p. 175)
Human history largely consists of the details of groups’ killing, enslaving, or expelling other groups. The winner takes the loser’s land, sometimes also the loser’s women, and thus the loser’s opportunity to perpetuate genes. But group cohesion depends on the group’s distinctive culture – especially its language, religion, and art (including stories and dances). (p. 178)
Besides malnutrition, starvation, and epidemic diseases, farming brought another curse to humanity: class divisions. (p. 187)
Hunter-gatherers have little or no stored food, and no concentrated food sources like orchards or herds of cows. Instead, they live off the wild plants an animals that they obtain each day. Everybody except for infants, the sick and the old join the search for food. Thus there can be no kings, no full-time professionals, no class of social parasites who grow fat on food seized from others. (pp. 187-188)
All those cultural differences used to be ascribed to genetic superiority of conquering “advanced” peoples over conquered “primitive” one. However, no evidence of such genetic superiority has been forthcoming. The likelihood of genetics’ playing such a role is refuted by the ease with which the most dissimilar human groups have mastered each other’s cultural techniques, given adequate learning opportunities. (p. 219)
Xenophobia comes especially naturally to our species, because so much of our behavior is culturally rather than genetically specified, and because cultural differences among human populations are so marked. (p. 221)
Perhaps the commonest motive for genocide arises when a militarily stronger people attempts to occupy the land of a weaker people, who resist. (p. 289)
Another common motive involves a lengthy power struggle within a pluralistic society, leading to one group’s seeking a final solution by killing the other. (p. 289)
There is little doubt that Stalin and Hitler set new records for number of victims, because they enjoyed three advantages over killers of earlier centuries: denser populations of victims, improved communications for rounding up victims, and improved technology for mass killing. (p. 297)
How do today’s genocidists wriggle out of the conflict between their actions and a universal code of ethics? They resort o one of three types of rationalizations, all of which are variations on a simple psychological theme: “Blame the victim!” (p. 299)
Possessing the “right “ religion or race or political belief, or claiming to represent progress or a higher level of civilization, is a second traditional justification for doing anything, including genocide, to those possessing the wrong principle. (p. 300)
Much as we damn twentieth-century technology, it is blurring the distinction between “us” and “them” that makes genocide possible. While genocide was considered socially acceptable or even admirable in the pre-first contact world, the modern spread of international culture and knowledge of distant people has been making it increasingly hard to justify. (p. 307)
In every area of the world that paleontologists have studied and that humans first reached within the last fifty thousand years, human arrival approximately coincided with massive prehistoric extinctions. (p. 355)
Overhunting – killing animals faster than they can breed – is the main mechanism by which we’ve exterminated big animals, from mammoths to California grizzly bears…The second mechanism by which we exterminate is through intentionally or accidentally introducing certain species to parts of the world where they didn’t previously occur…Habitat destruction is the third means by which we exterminate. (pp. 358-359)
To conclude, let’s place matters in perspective by comparing the two clouds I mentioned at the outset as hanging over our future. A nuclear holocaust is certain to prove disastrous, but it isn’t happening now, and it may or may not happen in the future. An environmental holocaust is equally certain to prove disastrous, but it differs in that it’s already well underway. It started tens of thousands of years ago, is not causing more damage than ever before, is in fact accelerating, and will climax within about a century if unchecked. The only uncertainties are whether the resulting disaster would strike our children or our grandchildren, and whether we choose to adopt now the many obvious countermeasures. (p. 362)
Among our hopeful signs, there are many realistic, often-discussed policies by which we could avoid disaster, such as by limiting human population growth, preserving natural habitats, and adopting other environmental safeguards. Many governments are already doing some of these obvious things in some cases. (p. 366)
Starvation, pollution, and destructive technology are increasing; usable farmland, food stocks in the sea, other natural products, and environmental capacity to absorb wastes are decreasing. As more people with more power scramble for fewer resources, something has to give way. (365)
There are many grounds for pessimism. Even if every human now alive were to die tomorrow, the damage that we have already inflicted on our environment would ensure that its degradation will continue for decades. Innumerable species already belong to the “living dead,” with populations fallen to levels from which they cannot recover, even though not all individuals have died yet. Despite all our past self-destructive behavior from which we could have learned, many people who should know better dispute the need for limiting our population and continue to assault our environment. Others join that assault for selfish profit or out of ignorance. Even more people are too caught up in the desperate struggle for survival to be able to enjoy the luxury of weighting the consequences of their actions. All these facts suggest that the juggernaut of destruction has already reached unstoppable momentum, that we too are among the living dead, and that our future is as bleak as that of the other two chimpanzees.