Masters of the Planet (13 page)

What made the intellectual leap to stone tool making possible is not something we can hazard with any confidence at this point, although the refinement of motor skills and of higher cognitive functions almost certainly went hand in hand. But the fact that the first stone tools—the first step in an epic transformation—were made by creatures whom we can—with reservations—characterize as “bipedal apes,” inaugurates a pattern that we will see recurring repeatedly over the entire span of hominid evolution: new technologies (reflecting new and more complex behaviors) do
not
tend to be associated with the appearance of new kinds of hominid. It was old kinds of hominid that started to do new things, even though those new things always seem to indicate a step up in cognitive complexity.

We will return to the typical hominid pattern of innovation. But first, it might be interesting to ask if we are in a position to form any impression at all of what kind of sense of the world around them—or of themselves—those bold small-bodied bipeds possessed. We can infer a lot about how their lives might have looked to an observer. But did they share with us any aspects of the unique modern human form of inner experience? There is no way to answer this question with any precision; but one thing that we can do is to set an approximate baseline by looking at other organisms and asking what we demonstrably share with them, and by extension with the early hominids.

One obvious issue to start with is the sense of self. In the very broadest of meanings, every organism has a sense of itself versus the other. From the simplest unicellular creature on, all living things have mechanisms that allow them to detect and react to entities and events that lie beyond their own boundaries. As a result, every animal may be said to be self-aware at some level, however rudimentary its responsiveness to stimuli from outside might appear. On the other hand, human self-awareness is a highly particular possession of our own species. We human beings experience ourselves in a very specific kind of way—a way that is, as far as we know, unique in the living world. We are each, as it were, able to conceptualize and characterize ourselves as objects distinct from the rest of Nature—and from the rest of our species. We
consciously
know
that we—and others of our kind—have interior lives. The intellectual resource that allows us to possess such knowledge is our symbolic cognitive style. This is a shorthand term for our ability to mentally dissect the world around us into a huge vocabulary of intangible symbols. These we can then recombine in our minds, according to rules that allow an unlimited number of visions to be formulated from a finite set of elements. Using this vocabulary and these rules we are able to generate alternative versions or explanations of the world—and of ourselves. It is this unique symbolic ability that underwrites the internalized self-representation expressed in the peculiarly human sense of self.

In between the two ends of the spectrum, linking the primordial and the symbolic styles of self-awareness, there presumably exists a near-infinite array of states of self-knowledge. Yet because alien cognitive states are among the few things human beings find it impossible to imagine, let alone to experience, any discussion of such intermediate forms of self-knowledge—such as that possessed by our early ancestors—is fraught with huge risks of anthropomorphizing. When we try to understand how other organisms comprehend particular situations, or their place in society, or indeed their place in the world, our tendency is always to impose our own constructs. The temptation is to assume that beings of other kinds are seeing and understanding the world somehow as we do, just not as well or as fully. Yet the truth is that we simply cannot know, still less
feel,
what it is subjectively like to be any organism other than ourselves, modern
Homo sapiens.

The extraordinary human cognitive style is the product of a long biological history. From a non-symbolic, non-linguistic ancestor (itself the outcome of an enormously extended and eventful evolutionary process), there emerged our own unprecedented symbolic and linguistic species, an entity possessing a fully-fledged and entirely individuated consciousness of itself. This emergence was a singular event, one that involved bridging a profound cognitive discontinuity. For there is a
qualitative
difference here; and, based on any reasonable prediction from what preceded us, the only reason for believing that this gulf
could
ever have been bridged, is that it
was.
And since that extraordinary event self-evidently did take place, the question becomes one of where and how. To answer this, though, we need to establish that starting point. This is no easy task,
and
how difficult it is in practice is well illustrated by the investigation of self-recognition.

Back in the mid-nineteenth century, Charles Darwin placed a mirror on the floor between two orangutans housed at the London Zoo. He recorded a variety of reactions made by the orangutans to their reflections, but was vague as to what, if anything, he had specifically concluded from the experiment. There the matter rested for almost a hundred years, until the cognitive psychologist Gordon Gallup, noting that the norm among animals was to treat mirror images as other individuals, carried out a more controlled test. Gallup exposed two juvenile chimpanzees to full-length mirrors for several days, and watched how they responded to the images of themselves they saw reflected. Over this period, self-directed behaviors increased, while social reactions to the mirror images declined, suggesting that the individuals were learning to recognize the images as themselves. The chimpanzees were then anesthetized, and red marks were applied to their faces. Once they were reintroduced to the mirrors, self-directed behaviors intensified, many of them aimed at the marks. In contrast, marked chimpanzees without prior mirror experience failed to respond in this way, suggesting that self-recognition had indeed been learned by the first group during the habituation period. Similar testing of macaques produced contrary results, implying to Gallup that these monkeys lacked the chimpanzees' capacity for learning self-recognition.

Since Gallup's pioneering study, the “mirror test” has become the standard yardstick for self-recognition among vertebrates, and a wide variety of species has been tested. Human beings naturally need to learn mirror self-recognition (MSR) just as the chimpanzees did; but adults to whom sight has been restored do so quickly, and most human infants can manage the trick at 18 to 20 months of age. Young apes develop more rapidly than human children in many respects, but studies building on Gallup's original have shown that MSR is rare among chimpanzees under eight years old: it is basically an adult ability. By now, MSR has been demonstrated not only in chimpanzees but also in bonobos, orangutans, and gorillas, although not all tested individuals of these species have shown it. Outside the human–great ape group MSR is evidently extremely rare among vertebrates (though elephants, dolphins, and certain
birds
may display it); and to the extent it occurs, different underlying mechanisms are almost certainly at work than those operating in great apes and humans. But although its expression in apes and humans is almost certainly a unique property of this group, uncertainty still remains as to what exactly MSR is revealing: what it means in terms of the precise aspects of consciousness that the approach explores.

An alternative avenue to understanding the sense of self in nonhuman primates was thus taken by the monkey researchers Robin Seyfarth and Dorothy Cheney, who adopted the psychologist William James' distinction between the two components of self-awareness: the “spiritual” (one's “psychic faculties and dispositions”), and the “social” (knowledge of being one of many distinct individuals embedded in a group). Like human beings, monkeys are intensely social, and Seyfarth and Cheney looked at how individual vervet monkeys and baboons appeared to understand their places in the social hierarchy. The reasonable assumption here was that a primate cannot exhibit a sense of “them” without also possessing a sense of “I”; and, from looking both at kin relations and at the dominance hierarchies to which the monkeys belonged, Seyfarth and Cheney concluded that they did indeed recognize other group members as individuals, behaved toward them in appropriate ways, and hence appreciated their own individuality vis-à-vis their fellows. This seemed to indicate that on some level they had a sense of the social self.

On the other hand, this kind of self-awareness was clearly different from that of human beings. For, while they are certainly able to behave appropriately in complex social settings, vervets and baboons are, as far as one can tell, unaware of the knowledge that allows them to do so. In Seyfarth and Cheney's words, they “do not know what they know, cannot reflect on what they know, and cannot become the object of their own attention.”

No observer would deny that great apes possess more complex cognitive and behavioral repertoires than monkeys do. Still, it is far from clear just how far they exceed them in these last respects, and particularly in the ability for self-reflection. Some great apes, like our friend Kanzi, are highly adept users of symbols in experimental situations. They can recognize and respond precisely to words and even to combinations of words, and they can choose visual symbols adroitly on a computer
screen.
But whether this means that they are also able to manipulate such symbols mentally in such a way as to produce objective images of themselves is doubtful. In general, the apes' use of symbols seems to be additive: they can comprehend short strings of concepts (“take,” “red,” “ball,” “outside”), but they do not recombine them according to mental rules to produce new notions: ideas of the possible, rather than of the observed. The chimpanzee manner of dealing with symbols is thus is inherently limited, since lengthening lists of symbols rapidly become confusing, and ultimately meaningless.

Daniel Povinelli, a distinguished researcher of chimpanzee cognition, proposed a few years ago that a fundamental distinction between the ways in which chimpanzees and humans view the world is that, while humans form abstract views about other individuals and their motivations, “chimpanzees rely strictly upon observable features of others to forge their social concepts. . . . [They] . . . do not realize that there is more to others than their movements, facial expressions, and habits of behavior. They [do] not understand that other beings are repositories of private, internal experience.” It also implies that individual chimpanzees do not have such awareness of themselves, either. They
experience
the emotions and intuitions that arise in their own minds; and they may act on them, or suppress them, as the social situation demands or permits. But, just as in Povinelli's words they “do not reason about what others think, believe and feel . . . because they do not form such concepts in the first place,” it seems legitimate to conclude that this exclusion also applies to self-reflection. Because, if individual chimpanzees lack the ability to perceive that others have internal lives, it is highly probable that they also lack equivalent insight into their own interior existences.

Profound as it is, this cognitive difference between us and them may not always produce radically distinctive observable behaviors; and indeed the ways in which chimpanzees and humans behave sometimes appear strikingly similar. Still, we should be wary of overstating these similarities. The behavioral resemblances we perceive are conditioned by an enormously long shared evolutionary history, and by the resulting structural similarities. But, as Povinelli would point out, similar observable behaviors may also hide mental processes that differ greatly in form and complexity.

So,
for all the manifold talents that chimpanzees possess, that cognitive gulf still yawns. Among all those organisms that we can study in the world today, it appears that only modern human beings show “spiritual self-awareness” in William James' sense; and even his “social self-awareness” appears to differ dramatically in quality between humans and nonhuman primates. Still, even though a lot of evolutionary water has flowed under the bridge on both sides since human beings shared an ancestor with any ape, most authorities find it reasonable to conclude that cognition of the kind we see among chimpanzees (and among other great apes as well) provides us with a reasonable approximation of the cognitive state from which our ancestors started some seven million years ago. To return to Povinelli's words, one may reasonably assume that those ancestors were “intelligent, thinking creatures who deftly attend[ed] to and learn[ed] about the regularities that unfold[ed] in the world around them. But . . . they [did] not reason about unobservable things: they [had] no ideas about the ‘mind,' no notion of ‘causation.'” In the human sense, they had as yet no idea of self. This is a very plausible characterization of our lineage's cognitive starting point; but at the same time it more or less exhausts what can usefully be said on this subject, based on our existing knowledge of comparative cognition.

The next question is, of course, to which of our known ancestors does Povinelli's characterization apply? In all probability, if we were able to directly observe the very early hominids we met in
chapter 1
we would find that Povinelli's depiction fit them well enough; and we have no compelling reason for believing that it would not also have applied very broadly to the earliest
Australopithecus afarensis.
Still, if it was indeed
A. afarensis
(or something very like it) that introduced stone tool making, as the Dikika (and Bouri) evidence seems to suggest, then we have to reconcile the Povinelli viewpoint with the significantly advanced cognitive achievements of those first stone tool makers. For there is no doubt that the first hominids who made stone tools and used them for butchering carcasses were displaying evidence of an entirely new and radical way of interacting with the world around them; and there is no reason to believe that this innovation might not have had internalized effects too. The simplest and most plausible way of explaining this apparent discrepancy is to suggest that the cognitive
potential
to make
stone
tools was born in the large genetic alteration that must have been involved in the acquisition of the new and radically different bipedal body form; and that this potential lay dormant for some time before being expressed in the invention of stone tool making.