|posted 1 September 2003|
William H. Calvin, A Brief History of the Mind (Oxford University Press 2004), chapter 1.See also http://WilliamCalvin.com/BHM/ch1.htm
The bonobo is overthrowing established notions about where we came from and what our behavior potential is.... Even though the bonobo is not our ancestor, but perhaps a rather specialized relative, its female-centered, nonbelligerent society is putting question marks all over the hypothesized evolutionary map of our species. Who could have imagined a close relative of ours in which female alliances intimidate males, sexual behavior is as rich as ours, different groups do not fight but mingle, mothers take on a central role, and the greatest intellectual achievement is not tool use but sensitivity to others?
– Frans de Waal, 1997
When Chimpanzees Think
The way we were, 7 million years ago?
What is it like, to be a chimpanzee? Are they us, just without language and metaphor? Maybe, as cartoonists suggest, they even talk silently to themselves? (Probably not.)
When we don’t understand something like the weather or an animal’s mind, we attempt an analogy to something we do know – such as our own familiar mental states or social strategies. Sometimes this works, and sometimes it doesn’t. If we don’t understand what causes the rain, we may fall back on our knowledge of human social strategy – and assume that a person is in charge of the rain, a person who can be influenced with flattery or gifts or begging. (Sometimes it happens to rain afterwards, and you are persuaded that you were successful.)
And so it is natural enough to suppose that our pets can think. Our pets certainly display emotions, and it is reasonable to assume they have feelings (unexpressed emotions). They certainly have purposeful states of mind – with a single glance, I can tell whether our cat Brin is in her assiduous “mousing mode.”
Because dogs are so sociable, we ascribe even more humanlike mental states to them. But we also know that they aren’t playing with a full deck of human mental abilities. Despite their considerable spatial abilities – they can catch balls and intercept frisbees in mid-air – most can’t untangle their leash from a tree. Nor do most learn from repeated experience to avoid entanglement. Leashes didn’t figure in their evolutionary past, and their on-the-fly improvisational abilities just aren’t up to the task. Most monkeys have the same problem, though many apes can unwind a tangled leash.
We also feel an affinity to the apes because they romp and play – but then, so do most mammals, at least as juveniles. A bonobo may even play what looks like a solo version of blindman’s buff. I’ve watched Kanzi (the language-reared bonobo in Atlanta), holding a hand over his eyes or draping a blanket over his head – and then showing off his remaining navigation ability.
The bonobos are also sociable in humanlike ways, with much hugging and kissing, reassuring touches, reconciliation after social tension, and doing favors for friends. Unrelated female bonobos build coalitions to control the brotherhood of males. (I once got slapped by Kanzi’s sister Panbinisha for moving a big chair; male bonobos grab attention by tumbling heavy objects, and females try to head off such “display behaviors.” So I got treated like a bonobo male that was showing off.)
Great apes may not be as sociable with humans as a dog that thinks you are its pack leader, or a cat that mistakes you for its mother, but among themselves our closest relatives clearly have a substantial fraction of instinctive human social behavior. It might have been present in the common ancestor we shared with them, about 7 million years ago.
If you read the book on the web (uncomfortable but
possible), consider buying a book as a gift for a friend.
(We live and learn and pass it on.)
Click on a cover for the link to amazon.com.
Yet there are at least a hundred ways in which the smartest of the apes differ from us. This concentration on making a list of “uniquely human” abilities is a top-down approach, and it attempts to pare away the icing on the cake in order to expose the apelike cake beneath.
There’s another complementary approach that might be called “bottom up” as it talks of the perceptual and cognitive abilities common to all the primates, then looks at what emerges with the ape-level mentality, before the hominid icing comes along. Since the rest of the book necessarily has a lot of the uniquely human distinctions, let me start with bottom-up.
The commonalities are extensive. All of the familiar mammals live in pretty much the same world of analyzing sensations and making movements as we do. They recognize familiar objects and they can navigate quite sensibly among them, even taking novel shortcuts to return home (but then, so can ants – with a brain smaller than a pinpoint).
The basic building blocks of behavior, the nerve cells, are pretty much the same in all animals. I’ve listened in on their chirping electrical conversations in animals ranging from sea slugs to humans, and the basic cellular principles don’t change very much. The numbers change, especially in the newer parts of the cerebral cortex where a lot of the associations are done between unlike things. The neocortex is only a few millimeters thick (say, several coins worth) but it is crumpled, with hills and valleys from all the infolding. Were you to flatten out cortex on a sheet of paper, you’d find that a rat’s cortex takes up about the area of a large postage stamp, a monkey’s covers a postcard, chimps require a whole sheet of typing paper, and that humans have about four times as much.
Mammalian brains are all laid out similarly, housing the movement command center up front and analyzing sensations toward the rear, with the “where” aspects closer to the top of the head than the “what” conceptual aspects, with the emotional overlay orchestrated from the base of the brain. Furthermore, the circuits and modules become ever more elaborate. Human brains all run on the same hierarchy of chemical and electrical mechanisms but they are compounded into circuits that progress from handling simple categories up to human-only parables.
The first step up from simple perception is lumping things together into “what” categories. Many mammals can create categories of objects, using similarities in color, shape, and texture (but then so can African grey parrots). Some mammals have the rudiments of number sense (usually 1,2,3, then skipping to “many”). Though they’re not so good at “how” and “why,” they can remember “what” is “where” and even “when,” as in the case of chimps revisiting distant fruit trees when they are due to ripen.
If you live in larger social groups, remembering “who” may profit from a larger brain. And if you are into sharing things, recalling “who owes what to whom” is important in shaping advantageous social choices and avoiding the inevitable freeloaders. (Everyone loves a freebie.)
It isn’t all rote memory or stimulus-response, either. You sometimes see creative inferences and insightful problem solving, especially in the apes. Chimps have enough mental ability to occasionally engage in deception: they can lie because they have some sense that others don’t know what they know. That puts them in a new league. Chimpanzee Politics and Machiavellian Intelligence are serious academic titles about our closest cousins, not publisher’s hyperbole.
Even though they pay attention to social happenings in the manner of other primate societies, chimps and bonobos don’t augment this with gossip (and more than half of human discourse is catching up on who did what to whom). Chimps throw sticks and stones in an effort to intimidate but rarely as a hunting technique. They are never seen practicing their technique to improve their accuracy or versatility. Nor do the apes exhibit much in the way of shared attention, nothing like the way in which a child directs an adult’s attention to a third object. (“Look at that!”)
There is also no sustained “paying attention” in special settings, such as our campfire. At least one bonobo accustomed to human ways has learned to feed a small bonfire. But even if the great apes were to master fire starting and had the attention span to tend a campfire for hours, it seems unlikely that they have the psychology to watch a storyteller for very long, even a mime. Too dull, compared to interacting one-on-one, like bored children in church? Or too abstract, involving categories that are simply too many steps removed from here-and-now reality? Or maybe working memory doesn’t last long enough?
Of course, just because great apes don’t exhibit a behavior in the natural setting doesn’t mean that they aren’t capable of it, if exposed to the subject by skilled tutors when they are young. If reared in language-rich surroundings, bonobos turn out to be capable of simple forms of word-based communication. They will sometimes point at things, to direct your attention, in a way not seen in the wild. They can understand never-heard-before sentences as complex as “Kanzi, go to the office and bring back the red ball” about as well as a two-and-a-half year old child.
They don’t produce such novel sentences themselves, getting stuck (so far, more attempts are in progress) at the stage of two- to three-word sentences and not progressing to longer sentences. A two-and-a-half year old child is, of course, on the verge of blossoming forth into long sentences with syntax. The child is also very acquisitive, picking up nine new words every day in the preschool years and going on to vocabularies of over 50,000 words. The apes have to be laboriously taught new words and seldom learn more than several hundred.
So remember to distinguish between latent capacity and actual practice. The apes are likely capable of many things they don’t, in practice, perform – probably because they are not acquisitive of new words and underlying grammar in the manner of human infants. Finding out what is actually impossible for them is a difficult job, which is why you have to treat “uniquely human” claims as provisional.
The archaeologist Steven Mithen, in his A Prehistory of the Mind, compares the chimpanzee’s termite fishing stick with a human’s line and reel, with specialized hooks and weights. The chimp manufactures the tool using the same hand and arm movements as used for other behaviors, while the actions that humans use to carve a spear or craft a bowl are unique gestures. Chimpanzees don’t think up new functions for the same tool, the way a human will use a cutting tool to dig dirt out of a small crack. And when a new tool or gesture is invented, other chimpanzees are slow to pick up its functionality. In humans, imitation rapidly spreads the innovation through the population, sometimes improving it via copying errors.
We tend to assume that bigger brains are better – so that apes, with twice as large a brain, are an improvement over Old World monkeys. Not by some measures: monkeys often outcompete apes and, over the last 10 million years, the number of ape species has been declining while the number of monkey species has been increasing.
Head to head with the chimps of Uganda, monkeys can strip the trees of ripening fruit faster, they can reproduce more frequently, and so forth. Perhaps the ape brain is more versatile in some situations, such as improvising during climate crashes, but – except for eating one occasionally – the smarter apes sure don’t dominate the monkeys in the business-as-usual forest settings.
And the apes don’t necessarily make use of their bigger brains. The gorilla needs his extra long gut (to extract calories from that 50 pounds a day of low-quality plant food) far more than his big brain. The omnivorous chimps and bonobos can readily switch what they eat, having both a multitalented brain and a more versatile digestive tract. But the other surviving great apes have settled into vegetarian niches that don’t require their intelligence. Ditto the marine mammals, which don’t need their bigger brains for making a living by filtering plankton or catching smaller fish, for which fish-sized brains seem to suffice. But that doesn’t mean that brains downsize accordingly, to save on calories. Backing up isn’t easy in evolution.
Did you ever walk into a room and forget why you walked in? That's how dogs spend their lives.
– the comedian Sue Murphy
Think ahead. The apes do some of it, but how far ahead, and in what detail?
Multistage planning involves much more than what you see in a squirrel preparing for winter by hoarding nuts. That’s just a simple instinct that every squirrel is born with, triggered by the days getting shorter and more melatonin being released from the pineal gland every night because darkness lasts longer. It’s a wonderful biological example of that lesson from mindless automata, that complicated patterns can arise from the interaction of several simple relationships.
No learning, no planning – a timeless here-and-now mental life ought to suffice for the squirrel, with the melatonin simply providing a lingering bias to what most interests the squirrel during the daytime. Planning usually involves novelty, not something seasonal that all of your ancestors had to do without fail. Getting ready for winter is too important to be left to learning or improvisation.
All animals have a behavioral repertoire. They can focus on one behavior and hold it ready, like a cat about to pounce, or a monkey ready to grab the fruit when the dominant male finally looks the other way – but they are not planning in depth or detail, something we humans are very good at. The great apes have some migrations that look, at first, as if they might qualify as planning. But like most seasonal migrations, the leaders have been over the track for some years in the past as followers. That’s learning, not planning. Young chimps learn a minor form of staged food preparation, what it takes to crack tough nuts rather than shatter them. But it takes them six long years of fumbling practice, not a moment of insight followed by a marked improvement in technique. Outside of the half-hour time scale of intentions, a chimp or bonobo doesn’t seem to prepare for tomorrow.
It was initially supposed that planning and communication would have big payoffs for organizing a hunt. Chimpanzees (and bonobos, though there is much less data) do hunt small animals, mostly monkeys and bush pigs. They seem to have all the basic group moves, someone covering each of the possible escape routes of a treed monkey.
Creativity is also infrequent; there is no evidence for an ape planning a novel course of action in any depth. (This, too, could be overturned next year; I’m just reporting on the current lack of evidence.) We anticipate our next handhold in climbing a tree, but the really difficult versions are when you have to plan multiple stages of the action in advance, rather than just groping your way along while guessing one stage ahead. The driver who uses grand slalom tactics in freeway traffic, leaving a trail of flashing brake lights in his wake, does not really need higher intellectual function to assist him, only the apelike abilities to swing through the trees, looking ahead to the next handhold. Planning in depth is what I am focusing on here, what you need to imagine several preparatory stages, as in a college course schedule or a new crop rotation.
What chimps don’t do gives us some insight into their planning capacities. If chimps could plan ahead, they would be the terror of Africa (and probably extinct by now), but they’re not. And you can’t just argue that they’re peaceful. Chimpanzee groups actually patrol the boundaries of their usual territory, looking for all the world like an army patrol that reforms into single file, keeps quiet, and stops occasionally to listen carefully before moving on. They may engage in shouting matches with the neighbors, judging group size, but they seldom get into battles. Yet when the chimp patrol finds a lone chimp from the neighboring group, you see what looks like human gang warfare, five-on-one affairs that leave behind a dying chimp, its throat or genitals chewed out, great strips of skin pulled loose. (Bonobo groups are larger and they often mingle peacefully when encountering one another. They have not been seen patrolling their borders.)
With a little foresight added to that aggressiveness, chimps could conduct raids in the middle of the night. A little more and they could make war on whole groups of neighbors using stockpiling of supplies, practiced maneuvers, and coordinated attacks. But they don’t.
It may be that, instinctively, humans are less violent than chimps – but our planning abilities certainly amplify what violent tendencies there are, as does our propensity to form up in ad hoc teams spontaneously (truly impressive in emergencies, but formed instead into fan clubs they sometimes happily beat up another such ad hoc group).
No one sees much evidence of logical planning in the chimps, and certainly not the sort of planning (so handy for serious warfare) where two or three novel stages have to be worked out in advance of acting. They probably lack complex thought, as did the bipedal woodland apes of our ancestry. The big question is when this plan-ahead capability arose in hominid evolution.
Learned staging and innovative on-the-fly staging are, perhaps, different things that evolved at different times. Much of my virtual campfire tale is about how slowly we acquired those two types of staging. The hard part turns out to be the innovations. While it is easy to create random variations, it is much more difficult to discover, offline, the combinations that are safe and useful. You need coherence, where a lot of things fit together satisfactorily, before acting. That’s what is probably not well developed in the apes, or in the woodland ape that walked upright in the late Miocene. (And maybe such coherence competence wasn’t even present in modern-looking humans of 100,000 years ago.)
A sense of the future may also have been missing at this stage of human evolution. I don’t mean this in any simple sense like squirrels hoarding for winter. Nor in the “what happens next” sense that our cat must experience when she sees two adults heading her direction with a medicine dropper in hand. That she has a pretty good notion of what happens next is just learning. It doesn’t mean that she is likely to speculate about losing her teeth in old age. Nor is she capable of reflecting on the fact that losing the last set of opposing molars is how elephants die.
I think that, before structured thought, our ancestors mostly had a here-and-now mental life with little structured interpretation of the past. And probably not much on-the-fly contingent planning. They saw death every day but, without much ability to speculate about the future, they couldn’t conceive of their own mortality.
The chimps lack language and symbol, virtually lack true teaching, and [there is no] evidence of the sort of metacognition – awareness of mental process – that is the essence of human culture.
– Melvin Konner, 2001
In one sense, the bonobo is a fifth subspecies of chimpanzee (they can all interbreed). But the bonobo (shown here), isolated on the left bank of the Congo from the other chimps for about 2 million years, developed enough differences in anatomy and behavior to be called a separate species, Pan paniscus. They are also endangered by forest clearing and hunting (the bushmeat trade follows the new roads). The other chimpanzees, Pan troglodytes, and the gorilla are now critically endangered by both hunting and an Ebola epidemic.
To order a
copy of one of my more recent books, click on a cover for the link to amazon.com.
copyright ©2003 by William H. Calvin