How do animals know how to behave during play bouts? This is far from perfectly clear, but there is evidence of a variety of forms of signaling behavior, beginning with the invitation to play, which in the case of dogs is known as the play bow: the dog crouches on its front legs and bows while its hind legs remain erect. This apparently means “I want to play,” and will be reciprocated by a play bow from a possible partner.103 Gregory Bateson referred to this behavior as “metacommunication” because it not only signals a willingness to play but indicates the kind of behavior that will follow, that is, not real fighting and such, but play fighting.104 The canine play bow may be repeated during a play bout, which may mean “I still want to play.” Primates have a variety of gestures that indicate a willingness to play and to abide by the rules of play. A common one among chimpanzees is a raised arm that is the equivalent of the play bow among dogs, though there are several other chimpanzee gestures the can indicate a willingness to play.105 During the course of play a yelp or a nip may be telling the partner that he is getting too rough and to cut it out. If one partner persists in being too rough, the game comes to a sudden end, or turns into a real fight.
One reason animal play has been a problematic field, with some researchers even doubting the possibility of studying it, or denouncing other researchers as being anthropocentric in their interpretations, is that we know (or think we know) all too well what is going on. Indeed, a dog may give us a play bow and we may proceed to play with the dog. The social play of very young children is remarkably similar to social play in animals. It is in the act of play that we can see in animals just those things that many have said only humans have and have denied that animals have: a sense of self, an ability to understand what is going on in the mind of another, a capacity for very delicate and choreographed cooperation, for example, and, if these characterizations seem to be overreading, then certainly, at a minimum, shared intention and shared attention.
Science, as I will discuss further below drawing on Martin Buber, has some pretty clear rules that require an I-It relation between scientist and the object of study. The scientist must maintain an austere objectivity that inevitably makes the object into a thing. In the observation of play, and even more clearly in actually playing with an animal, it is almost impossible not to have an I-You relation, which arouses suspicions that one is not really doing science.106 On the other hand, as de Waal has indicated at several places, something like an I-You attitude may be a valuable source of information, and treating animals as if they were pure mechanisms may blind us to what is really going on. One could see this as using an I-You relationship in a utilitarian way and thus undercutting its real meaning, but in reading de Waal and some of the other students of animal play as well, one senses both a genuine respect for the otherness, the You-ness, of the animals being studied, while also conducting careful objective research. After all, the multiple realities of which I-It and I-You are examples are never watertight but often overlap. It may be that such overlapping, as when a metaphor leads a scientist to a theoretical breakthrough as we saw in Chapter 1, can be the source of creativity.
A great deal of energy has been spent on showing how much humans differ from any other animal, and when it comes to language and, in any but a rudimentary sense, culture, humans really are different. However, I have made a considerable effort to show how deeply we are shaped by a very long biological history. Sex and aggression in some form or other go all the way back and are surely still powerful forces in humans today. Nurturance, in the form of parental care, the earliest behavior that we can call love, goes back to early mammals more than 200 mya. Dominance hierarchy is probably as old as mammal societies. Among behaviorally complex mammals, certainly among chimpanzees, patterns recognizably like ethics and politics have appeared, how long ago we don’t know, but probably millions of years ago. And mammalian play, the seedbed of later capacities, goes back probably at least as far.
We did not come from nowhere. We are embedded in a very deep biological and cosmological history. That history does not determine us, because organisms from the very beginning, and increasingly with each new capacity, have influenced their own fate.107 But our remarkable freedom, which I am happy to affirm, is embedded in a cosmological and biological matrix that influences everything we do. It is a science fiction fantasy that we, or mechanisms that we create, can simply jump out of this history into pure self-determination. We live in a world that includes our own minds and bodies, and we need to respect the world we live in. Remembering all these things, we can now consider how we are different, really different, from all other creatures.
Homo Sapiens
Some 5 million (or more) years ago the lineages leading to modern humans, Homo sapiens, divided from the ones leading to the chimpanzees. We have no reason to believe that members of the chimpanzee lineage 5 million years ago were identical with contemporary chimpanzees. They have evolved in that period just as we have. In spite of this period of considerable divergence, we do share a lot with the chimpanzees, more than with any other species, but there is a lot we don’t share. We would like to have a clear picture of what happened to the lineages, now long extinct, that led to our genus after the separation from the lines leading to chimpanzees and gorillas; and what happened, some 2 million years ago or more, to the first members of the genus Homo-namely, Homo habilis and, a little later, Homo erectus-which are also extinct but much more recently so. But our evidence, consisting almost exclusively of skeletal fossils and stone tools, answers only a few of our many questions. The beginnings of richer arrays of archaeological evidence date back only to a period when, we believe, the speciation of Homo sapiens was already under way-some 250,000 years ago. Just how very late that is in geological time is indicated by James Costa: “Another approach compresses the geological timescale into a calendar year: reckoning from an earth origin [4.5 billion years ago in real time] at midnight on January 1, a simple calculation shows that all of human existence, from the earliest appearance of Homo sapiens, comes late on December 31, beginning about 11:49 PM.“108
There has been much speculation about Homo erectus, because of the anatomical similarities to modern humans; H. erectus originally had a smaller brain, but it grew larger over time. There is a tendency to see them as something like modern hunter-gatherers, though with simpler technology and a language, if they had one at all, with a much simpler grammar than any known human language.109 But hard evidence is scarce, so I will speak from here on mainly of our own species, whose early history is almost as obscure as the history of our earlier lineages, with only a glance over the shoulder, so to speak, at earlier members of our genus.
Although it is language and the cultural developments to which language contributed that most clearly differentiate us from our closest primate relatives, the origin of language is still an unsolved problem. As Peter Richerson and Robert Boyd have written, “A little scientific theorizing is necessary to convince us that the existence of human culture is a deep revolutionary mystery on a par with the origins of life I would like to defer consideration of culture and language until after I take a look at some of our physical differences from other primates, though it is always possible that some of those differences too may be partly due to culture.
Humans are an altricial species, that is, unlike precocial mammals, the young are born helpless, in a sense “premature,” because developments that would have taken place in the womb are completed after birth in a state that needs constant parental care.1” Humans, moreover, are born exceptionally prematurely. As a result of bipedalism-legs specialized for walking and running, another uniquely hominid feature among mammals-the pelvis of the mother is more constricted than in our four-legged ancestors, meaning that the baby must be born with its head small enough to come through the birth canal without serious injury to the mother. This is one of several design defects of human beings, causing the frequent deaths of mothers in childbirth throughout our history.
This very prematur
e baby is born naked, as are other primate babies, but unlike our primate cousins who are soon covered with fur, humans remain naked throughout life, with the exception of hair on the head and around the genitals. This is one feature of what is called neoteny, the retention into adulthood of traits previously seen only in the very young. At birth the faces of chimpanzee and human babies are rather similar, but the flat face and high forehead of the juvenile is retained by humans, whereas chimpanzees develop jutting jaws, large teeth, and receding foreheads. Some speculate that another feature of neoteny is that the high learning capacity of the young is retained by humans throughout their lifetime. Others reject the “myth of juvenilization,” another term for neoteny, and argue instead that human development shows “adultification,” that is, a greater continuous development beyond that of comparable species.“2 Still others insist that human development is a “mosaic” of juvenilization and adultification, indicating that both processes have long been at work. For example, “Thus, against the ape background, we have hyper-adult brains and cranial vaults but juvenilized jaws.“113
Extended parental care is characteristic of the great apes, particularly of the chimpanzees: compared even to other apes, chimpanzees mature slowly, remaining in contact with their mothers until 16 to 24 weeks as compared to about 4 weeks among baboons. They nurse until 4 or 5 years of age and are dependent on their mothers until the age of 8, though after weaning they forage for themselves. 114 In the great apes, births are spaced 6 to 8 years apart to allow the mother, who is resistant to allowing others to care for her offspring, to see it to maturity. Human infants may nurse that long, but usually less, as the space between births averages 3 years. For foragers who are constantly on the move, caring for even one baby is difficult for the mother, so others had to be involved in child care. Cooperative breeding-that is, shared parental care-is common among birds and known from a variety of vertebrates, including some primates, but, as noted, absent among the great apes.
Sarah Hrdy has argued that the emergence of cooperative breeding in our genus, probably several hundred thousand years ago, was a major transition with important consequences. She links cooperative breeding among hominids, well before the emergence of Homo sapiens, to the emergence of emotional modernity, that is, the capacity of human infants to relate to others with what de Waal calls, as we noted above, “a superior grasp of their place in the world and a more accurate appreciation of the lives of those around them.” Great ape babies, whose mothers share their care with no others, have the capacity for a kind of direct emotional relation to their mothers, especially in their first few weeks of life, but never learn to generalize that capacity to others and even lose it in relation to their mothers at an early age. Human babies, from the beginning cared for not only by mothers, but by mothers’ mothers, aunts, older female siblings, and possibly even by nonrelatives, do not lose this capacity for close emotional synchronization with others but go on developing and generalizing it. This development, Hrdy argues, began among hominids and significantly precedes development of the large brains that mark the emergence of our anatomically modern species, Homo sapiens, and behaviorally modern humans with the development of language and culture.”’
Hrdy links the emergence of cooperative breeding and emotional modernity to the remarkable egalitarianism found among hunter-gatherers, as compared to either the other great apes or to human society after agriculture, which we will analyze more fully in Chapter 4.116 But if Hrdy is right, the leading edge of the series of transitions that have led to humans becoming something radically new, what Terrence Deacon pointed to when he wrote that “biologically we are just another ape; mentally we are a whole new phylum of turns out to be our turn toward greater involvement of the whole society in parental care and its attendant emotional developments.
The changes that take place in the structure of the chimpanzee head and face undoubtedly have to do with adaptations for feeding and fighting. The fact that the human head and face are structurally similar from childhood to adulthood is but one of many indications that humans lack the physical specializations of many other species. Other animals can outrun us and, with claws and teeth and sheer muscle strength, outfight us if we face them without weapons. It has sometimes been said that humans specialize in being generalists, and, of course, in being intelligent. However, we need to note some remarkable human bodily capacities that developed along with our growing cognitive capacities. Other apes lack two skills that are important for humans: the ability to throw accurately, undoubtedly helpful for hunting with weapons, and the ability to keep together in time, without which skillful dancing would be impossible. As Kathleen Gibson puts it:
Humans are certainly surpassed by many other animals in strength and speed, and they fall short of most apes in arboreal locomotor skills and in pedal manipulative capacity. It is doubtful, however, whether any animal exceeds humans in the ability to construct novel body postures and rapid, smoothly produced, sequences of novel postures, such as those that are used in dance, swimming, gymnastics, some complex tool-making-using endeavours, mime and gestural sign languages.”’
As Gibson suggests, the capacity for rapid, flexible, and novel bodily movement goes together with the development of communicative skills, even when those skills may be prelinguistic. Although some might interpret the human lack of physical specialization as due to biological degeneration linked to neoteny, Gibson reminds us that such losses are compensated by the development of remarkable and unprecedented, though general and flexible, bodily skills.
Biologists have long noted some parallels between the effects of domestication of animals and features like neoteny among humans. Terrence Deacon has written, “We are in many ways a self-domesticated species. Would it be too humbling to see ourselves as a somewhat genetically degenerate, neurologically dedifferentiated ape? Reframing humanness in biologically degenerative terms is not to deny that we are in many ways more complex, both neurologically and behaviorally than other ape species.””’ Behind this statement is an argument too complex for me to go into here, but it arises from the recognition of developmental processes that, though under the general control of the genome, operate with considerable flexibility and, under certain circumstances, creativity, even as they act to buffer the impact of mutations on what Kirschner and Gerhart called “conserved core processes.” From deep in the evolutionary past there is a balance, or a dialectic, between conserved structures and innovative variations. However, under conditions of “relaxed selection,” when the genetic controls under the pressure of natural selection are relaxed, this dialectic may be enhanced. There is a release of “form-generating properties [that] derive from the self-organizing tendencies of molecular and cellular interactions rather than from relationships to environmental conditions. Paradoxically, this suggests that selection may actually hinder the evolutionary `exploration’ of alternative functional synergies, and that the relaxation of selection may play an important role in the evolution of increased functional complexity.” 120
I have argued that parental care among mammals has created a kind of relaxed selection from its very beginning, in sheltering newborns from direct selective pressures, and that animal play, with its innovative possibilities, is a response to that relaxed selection.121 But if human beings are “selfdomesticated,” we can see the beginnings of something like self-domestication from the appearance of the first altricial mammals. If this is a correct interpretation, then it is probably an exaggeration to assume a radical separation of humans from all other animals in their freedom from instinctual control and their need to rely on learned behavior for controls supplied biologically in other animals.122 Not only do other animals, at least some species of mammals, have a significant degree of freedom with respect to instinctual controls, but biological drives (to use a less loaded term than “instinct”) are still powerful among humans: sex and aggression, nurturance and dominance, can be culturally influenced, but never eradicated. In evolution, it seems, continu
ity and innovation go together, even reinforce each other.
If the self-domestication of mammals leads to a childhood free enough to create intricate and innovative forms of play, the place of play in our own species, where in some important sense we never leave childhood, should be significant indeed. Let us take a look at the earliest evidence for what Homo sapiens was up to. Although simple stone tools have been found that date from more than 2 million years ago, the Acheulian stone industry, involving fairly sophisticated flaking of what are commonly considered axes, goes back perhaps to Homo erectus, almost 2 million years ago, and then the making of stone tools continues with increasing sophistication, but no significant change in form, right up to early Homo sapiens, who may have used such tools as recently as 100,000 years ago. Even though human brain size was growing markedly during this period, and a variety of cultural and social innovations that have not left physical traces may have occurred, the stability of the main tool industry leaves us without tangible evidence of significant cultural change.
Until relatively recently there has been a tendency to see this stability as having been interrupted some 40,000 to 50,000 years ago by what was called the “human revolution,” when a whole array of evidence at European sites rather suddenly appeared. But beginning in the late 1990s a series of finds at African sites has either pushed the dates of the “revolution” back to 60,000 to 80,000 years ago or replaced the revolution idea altogether with the argument for the gradual development of sophisticated physical evidence from some 250,000 to 200,000 years ago, when the speciation of Homo sapiens was well under way.123
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