The #1 source for news about monkeys and apes

[Carrie McLaren <carrie AT stayfreemagazine.org>]

Part I in our dueling cognitive scientists series:


Lingua Franca, Volume 10, No. 3 - April 2000
MONKEYS WHO THINK
And the Cognitive Neuroscientist Who Loves Them
http://www.linguafranca.com/0004/monkeys.html

BY JENNIFER SCHEUSSLER

In the summer of 1980, Marc Hauser was a twenty-year-old animal-behavior
major with a summer job cleaning cages at a Florida tourist attraction
called Monkey Jungle. One day, he noticed a female spider monkey staring at
him with unusual intensity. Hauser moved closer; the monkey reached through
the bars of her cage, wrapped both hands around his neck, and cooed, gazing
deep into his eyes for several minutes. When her mate neared, she swatted
him away before resuming her attentions to Hauser.

What was she thinking and feeling? Hauser wondered. His efforts to
investigate came to nothing. The brief encounter turned out to be just a
one-afternoon stand. Although Hauser approached the spider monkey's cage
several more times that summer, she never responded to the hairless
primate's advances.

Such a story of uncanny interspecies connection would seem to fit right in
to the pages of recent popular accounts of animals and their amazingly
humanlike thoughts and emotions--books like Elizabeth Marshall Thomas's The
Hidden Life of Dogs or Jeffrey Masson's When Elephants Weep. Instead, the
tale kicks off Hauser's challenge to such authors and to what he sees as
their lazy anthropomorphism and occasional antiscience bias. In his new
book, Wild Minds: What Animals Really Think (Holt), the Harvard psychology
professor brings Darwinian theory and empirical rigor to bear on a subject
often clouded by both popular gullibility and scientists' disdain.

Evolution, Hauser argues, has endowed even the lowliest of the beasts with
rich mental lives, thanks to a "universal toolkit" of basic cognitive
abilities, plus whatever conceptual hammers, wrenches, and measuring sticks
each species needs in order to make a living in its ecological niche. An
unsurprising thesis, perhaps, now that the runaway success of such books as
Steven Pinker's The Language Instinct and How the Mind Works has sold many
lay readers on the Darwinian, modular view of the mind. Hauser, in fact,
embraces the label "evolutionary psychologist." But as he sees it,
popularizers of evolutionary psychology sometimes rely too heavily on
ingenious theoretical arguments and concern themselves too little with the
bedeviling details. Rather than offering firm answers, Wild Minds delves
into the messy, difficult business of bringing animal thinking out of the
realm of just-so stories and into that of solid empirical research.
--------------------

Hauser is hardly the first to try to knock Thomas, Masson, and company off
the bookshelf. Wild Minds is one of several recent dispatches bringing the
lay reader news from an increasingly visible field sometimes known as
cognitive ethology. A three-part documentary called Inside the Animal Mind
aired on U.S. public television this winter. Last November, when the
psychologist Irene Pepperberg published The Alex Papers, an account of her
twenty-two-year study of an African gray parrot's ability to grasp such
concepts as number and color, she made the front page of The New York
Times. Other recent books on the topic include Steven Budiansky's If a Lion
Could Talk, James L. Gould and Carol Grant Gould's The Animal Mind, and
Marian Stamp Dawkins's Through Our Eyes Only?

To its advocates, the rise of cognitive ethology reflects a regaining of
consciousness after a dark half century of behaviorist orthodoxy, which
held that all behavior, animal or human, was the result not of mental
events but of conditioned responses to external stimuli. Cognitive
ethologists trace their assumptions back to Charles Darwin, who insisted
that animals and humans exhibit no less evolutionary continuity in their
minds than in their kidneys, hearts, and toes. The field's critics,
however, suspect that talk of animal thinking and intention may owe less to
Darwin than to the embarrassing and dubiously anecdotal mentalism of his
protégé Georges Romanes, a popular lecturer who saw logisticating dogs and
conniving felines under every Victorian armchair.

Animals, of course, can't tell us what they think. It's a measure of the
difficulty of reading wild minds that many in the field--including Hauser,
the subtitle of his book notwithstanding--reject the use of such terms as
"thinking," "intelligence," and "consciousness" in favor of the less vague
and less inflammatory "cognition." But that hasn't stopped Hauser from
developing provocative arguments likely to give readers pause, whether they
see animals as cuddly little humans or mindless creatures of instinct.


Hauser's office office is on the ninth floor of Harvard's William James
Hall, the building where the arch-behaviorist B.F. Skinner shared his
quarters with maze-running rats and bar-pecking pigeons until his death in
1990. Hauser himself presides over a lab population of two dozen students;
six vervet monkeys, all named for jazz musicians; and seventeen
cotton-topped tamarins, named for such colleagues and friends as Pinker,
Tufts philosopher Daniel Dennett, and Harvard anthropologist Irven DeVore
(with whom Hauser co-teaches one of the most popular courses on campus,
"Human Behavioral Biology," informally known as "Sex").

Slight and boyish at forty, sporting a goatee, turtleneck, and clogs,
Hauser comes off more like an earnestly enthusiastic lab jockey than a
recently tenured professor who has just attempted to write the book on
animal minds. He's partial to words like "fun," "neat," and "wacky," and he
takes the time to respond politely to "vicious" e-mail from a dog owner
enraged by an excerpt from Wild Minds that appeared in Discover magazine
(the dog owner insists that his pooch can count to six; Hauser's research
has revealed that animal numeracy tops out at three or four). "Talking
about animals is a great way of demystifying science gently," he says. "One
of the great things about the field is a lot of it is so low-tech you can
almost do it with your pets."

For all his popularizing zeal, Hauser hasn't shied away from tweaking
orthodoxy within his field. One of his pet projects has been to retool
classic experiments in order to suggest that monkeys might be more than the
dumber cousins of the great apes that they are sometimes presumed to be.
Making frequent trips to Cayo Santiago, Puerto Rico, where he studies
free-ranging rhesus monkeys, he is one of the few researchers to examine
animals in both the lab and the field. "The real beauty," says Hauser, "is
the marriage between fieldwork, where you see the true ecological and
social problems that have shaped animal minds, and lab experiments, where
you can get more control."

Hauser was born in 1959 in Cambridge, Massachusetts, where his father was a
graduate student in physics at Harvard. A self-described jock who was
mostly interested in "having fun," he majored in animal behavior at
Bucknell, which was the only college in the country to offer such a
program. His first course, based on E.O. Wilson's Sociobiology, introduced
him to the adaptationist point of view. Soon he found himself puzzling over
philosophical conundrums involving animals. There was Ludwig Wittgenstein's
famous dictum, "If a lion could talk, we would not be able to understand
him." Then there was the twist on that idea by the ape researcher David
Premack, who postulated, "If a chicken had grammar, it wouldn't have
anything interesting to say." Finally, there was the philosopher Thomas
Nagel's famous 1974 essay, "What Is It Like to Be a Bat?" While it was
certainly like something to be a bat, Nagel concluded, a description of the
bat's inner world remained beyond reach. "It seemed to me at the time that
any one of these ideas might be right," Hauser recalls.

Despite its pessimism, Nagel's essay played a crucial role in the
development of cognitive ethology. Legend has it that Nagel wrote the essay
after attending a lecture by the co-discoverer of echolocation, the
zoologist Donald Griffin, who sometimes released bats in his lecture halls
to dramatize their ability to navigate by sonar. Griffin, in turn, was
inspired by Nagel to write The Question of Animal Awareness (1976), the
first in a suite of books that would challenge the behaviorist line and
launch the field of cognitive ethology, a phrase Griffin coined. Griffin's
Animal Thinking, published in 1984, gathered together the mounting but
neglected evidence that animals from baboons to bees to shrimp often act in
ways that suggest planning, intent, and awareness of other minds.

Had the eminent scholar lost his mind? Reviewing Griffin's 1992 follow-up
volume, Animal Minds, in The New York Times Book Review, the philosopher
Helena Cronin declared that Griffin had come out as "a sentimental softie."
The psychologist Hank Davis, a fierce defender of behaviorism, likened his
heresies to Salman Rushdie's The Satanic Verses. Puzzling even to some of
Griffin's sympathizers--Hauser included--was his insistence on seeing
"consciousness" behind ordinary instances of intelligent behavior. Some
have expressed particular bafflement at Griffin's suggestion that
consciousness might help compensate for the limited storage and processing
power of small-brained creatures.
Griffin's observations opened rich new areas for empirical research. In the
late 1970s, the primatologists Robert Seyfarth and Dorothy Cheney, a
husband-and-wife team at the University of California at Los Angeles, were
among the first to take up the challenge. In Kenya's Amboseli game
preserve, Cheney and Seyfarth, in collaboration with ethologist Peter
Marler, conducted the definitive research on one of the most astounding
discoveries in animal communication--that vervets had an elaborate system
of referential alarm calls that seemed to function almost like words. For
example, on seeing a snake, eagle, or leopard, a vervet emits a distinct
call that prompts other troupe members to take appropriate action. On
hearing the "snake" alarm, troupe members stand on their hind legs and
survey the surrounding grass. On hearing "eagle," they hide under a tree.
"Leopard" sends them scrambling into the tree's branches.

Sometimes the monkeys even use these calls deceptively--to gain the
advantage in a skirmish by suddenly scaring a rival monkey up a tree, for
example. (Whether such deception is truly intentional, however, is a matter
of considerable ongoing debate.) Cheney and Seyfarth also discovered that
despite this vocabulary, vervets were remarkably oblivious to certain
aspects of their environment. They would immediately give the "snake" alarm
call on seeing a snake, but the sight of a freshly laid python track seemed
not to disturb them at all.

In 1982 Hauser, then a graduate student, joined Cheney and Seyfarth in the
field. His dissertation would build on their research. Focusing on vervet
development, Hauser examined how the infant monkeys learned to heed the
less specific alarm calls that starlings issued to one another. But even as
he was pursuing this research, he was restless. He and some fellow graduate
students organized a seminar around the question of whether behavioral
ecology--the traditional study of animal behavior in the wild--was "dead."
As he explains it, "We all started realizing that while the field was still
exciting, people were really just finding more evidence for existing
theories in different species, kind of dotting i's and crossing t's." Some
of the students began fusing evolutionary theory with molecular biology.
Others, like Hauser, dug deeper into neurobiology and the cognitive
sciences.


This turn toward neuroscience brought Hauser closer to Peter Marler, his
mentors' mentor and his own hero in the field since 1970. A schoolboy at
the time, Hauser had been impressed by Marler's seminal Scientific American
article laying out the basic principles for comparing animal communication
and human speech. In 1988, Hauser began a postdoctoral fellowship with
Marler at Rockefeller University. At that point, Marler and his associates
were overturning some cherished notions. For example, many researchers had
held that although both humans and animals had anatomic brain asymmetries,
only in humans were these asymmetries functional. Not so, Marler
discovered. Japanese macaques, in fact, processed auditory signals better
through their right ears (connected to the left side of the brain), in much
the same way that humans favor their right ears for listening.

Hauser added some interesting findings to this foundation. In 1993, working
on Cayo Santiago, he found that the facial expressions of rhesus monkeys
began on the left side of the face, indicating that the right hemisphere of
the brain was in control. In humans, positive expressions, such as smiling,
begin on the right, while negative ones, such as those indicating fear or
surprise, begin on the left. Adult rhesus monkeys, oddly, only have
negative expressions, Hauser argues. Even the male's copulation grimace, he
says, reflects an emotion that is mixed at best, given the intensely
stressful and competitive mating situation, in which high-ranking males
often drive off subordinates in the middle of the act.

Such observations made their way into Hauser's 1996 book, The Evolution of
Communication (MIT), a 760-page survey of signals ranging from birdsong and
bat echolocation to firefly flashes and primate facial expressions.
Reviewers for such journals as American Anthropologist and Evolution
remarked on the book's ambition, clarity, and verve, not to mention the
fifteen-hundred-item bibliography. Not all linguists, however, appreciated
the comparative perspective on human language. Derek Bickerton of the
University of Hawaii, writing in Nature, chided Hauser for underplaying the
significance of syntax, which in his view crucially distinguishes human
language from birdsong and the like. Furthermore, he argued, vervet calls
are not really comparable to words and thus cannot be taken to suggest that
human language evolved from animal precursors.

Such reactions did not surprise Hauser. In the early 1990s, he recalls, he
had the "disturbing realization" that people working on human language and
cognition were not interested in comparable behavior in animals. "I
remember giving these talks to people who worked on humans," Hauser says.
"You could tell they enjoyed hearing about animals, but it didn't really
have any impact on their thinking. Although these findings on vervet
communication were absolutely fundamental, linguists would write them off
as not relevant to human language evolution, and cognitive scientists would
see the experiment as irrelevant because it was done in the wild, using
different methods."

Was it even possible, Hauser wondered, to interest researchers in a
collaboration across the species divide? The key, he came to believe, lay
in studying animals and human infants with the same techniques. At a 1992
comparative cognition conference at Cornell, Hauser attended a talk by the
developmental psychologist Renée Baillargeon, a pioneer of the so-called
looking-time technique. Researchers using this method would stage a sort of
magic show, observing infants to see how long they looked at phenomena that
were consistent with the logical properties of the world versus those that
were inconsistent. Using this technique, researchers were busy dismantling
the Swiss psychologist Jean Piaget's ideas about the ages at which infants
grasped such concepts as object permanence. The technique, however, had yet
to cross over into the animal kingdom. "The logic was so simple and
elegant," Hauser says, "I thought, I can use this on any animal."

Hauser applied looking-time technique in his investigation of animal
numeracy. The developmental psychologist Karen Wynn had already shown that
five-month-olds understand such simple arithmetic problems as 1+1=2. On
Cayo Santiago, Hauser staged a version of her experiment in which he showed
his monkeys two bright-purple eggplants, then covered the eggplants
momentarily with a screen. Once the screen was removed, the monkeys looked
longer when one eggplant had mysteriously disappeared than when both
remained. In another experiment, Hauser allowed the monkeys to choose
between two boxes containing different quantities of fruit. Up to four
versus three, they consistently went for the bigger snack--but they were
unable to distinguish between larger quantities.

"What's beautiful about this," Hauser says, "is that it matches precisely
what's found for human infants up to a year and it matches precisely what's
encoded in all natural human languages. All languages have words for one,
two, and three, but often after that it's just ëmore.'" The basic sense of
number, he argues, got wired into the brain before humans diverged from
other mammals. (In one of the few tossed-off speculations in Wild Minds,
Hauser suggests that trade among humans produced the selective pressure in
favor of our more precise counting systems.)

Nonetheless, Hauser and his students remain pretty much alone in applying
looking-time technique to animal studies. Some critics ask how one can tell
what animals are looking at in the field, especially since, in order to
avoid any chance of learning, the experiments are limited to one trial per
animal. "Yes, it's an uncontrolled situation," Hauser says. "There are a
thousand monkeys on the island, there are animals fighting or playing. But
we run huge samples--it's not just the study of Alex the parrot or Kanzi
the bonobo. If the effect is robust, the variations are going to wash out.
If it's vulnerable, we get nothing. But we get really consistent results.
When we get an effect, it's huge."

Hauser is so confident of his numeracy results that he includes a basic
sense of number in the innate universal tool kit he proposes in Wild Minds.
Also in the tool kit are an understanding of the characteristics of animate
versus inanimate objects and, more spectacularly, the ability to navigate
through space. Many animals can find their way by means of "dead
reckoning"--as when homing pigeons fly hundreds of miles over unfamiliar
territory by the constantly shifting stars. Some animals, Hauser argues,
also have the benefit of "cognitive maps," mental representations of their
territory based on its basic geometry and landmarks. Some researchers have
conducted studies suggesting that birds may understand such abstract,
relative concepts as above, below, and middle--notions that some scholars
have argued are dependent on language. Hauser has preliminary results
indicating that tamarins may also possess these concepts.

When it comes to the question of language, Hauser is cautious in making
strong claims for animals. He notes that Sue Savage-Rumbaugh's
controversial results with the bonobo Kanzi suggest that apes may be
capable of acquiring a sort of proto grammar. He also acknowledges that we
haven't gotten very far in decoding the signals that primates other than
vervets use in the wild. Indeed, Hauser and the Harvard anthropologist
Richard Wrangham are currently researching chimp vocalizations. At the same
time, Hauser says, whatever the complexity of the chimp mind, there aren't
enough "bits" of data in these grunt-exchanges to suggest that the animals
are having full-blown conversations--say, about the peculiar behavior of
the primatologists crouching by the bushes. "I feel pretty confident saying
that the level of information exchanged is nowhere near the richness of the
animals' social relationships or their representations of objects in the
world," he says. "There's just no way."

Ultimately, he speculates that animals are something akin to Gregor Samsa
in Franz Kafka's "The Metamorphosis": "severely handicapped" in their
ability to say what's on their minds. "These animals are whipping along
with all these concepts and no vehicle to express them with," he explains.
"Once that language capacity evolved in humans, what a revolution that must
have been. Suddenly, all this stuff that's inside can be put outside."



------------------------------------------------------------------------

Whether or not animals can be said to possess language, one can still ask:
Do animals have self-awareness? Do they have beliefs? What do they
understand about other animals' minds? Are they moral? Wild Minds gives
these issues ample consideration, but Hauser is clearly peeved that
fixation on such higher-order investigations lets chimps hog the limelight.
"First, there's this idea that humans are special and animals are not. In
primatology, there's the idea that chimps are special and all other apes
and monkeys are not. It's true, on some of the big questions, the most
interesting research has been done on chimps." But in a chimpocentric
world, he says, work on monkeys often gets "sideswiped."

Even on the big questions, Hauser has been trying to get his colleagues to
give monkeys a closer look. In 1994 he reran Gordon Gallup's classic 1970
experiment showing that chimpanzees are able to recognize themselves in
mirrors. When their heads were marked with a red dot, most of the chimps
that looked in the mirror would immediately touch the mark on their heads,
sometimes then sniffing their fingers. Since then, researchers have found
that orangutans and bonobos--but never monkeys--are similarly able to
recognize their reflections. (Curiously, only one gorilla--Koko, the
celebrity signing ape--has ever passed the test.)

The experiments, Hauser argued, failed to account for certain of the
monkeys' species-specific attributes. Tamarins, for example, which diverged
from the human and ape evolutionary line some fifty million years ago, have
virtually no facial expressions and do not attend to the face as much as
apes do. Therefore, he reasoned, relatively subtle markings like a small
dot on their dark skin are unlikely to interest them. So Hauser used a much
stronger mark, coloring his cotton-topped tamarins' spectacular tuft of
white hair with flamingo-pink Manic Panic dye. Before the dye was applied,
tamarins paid only brief attention to their mirrored selves. But on this
extreme bad hair day, they gazed into the mirror at length, most of them
touching their hair at least once.

Hauser's findings set off a testy exchange with Gallup, who criticized his
experimental design and rickety data. In Wild Minds, Hauser admits that
when he reran the tests adjusting for various criticisms, the monkeys
exhibited a "general failure." Still, he insists, "this should not be
interpreted as evidence that tamarins lack self-recognition." Besides,
Hauser says, his point was not just to stick up for monkeys but to argue
that the mirror test is "the wrong test" of self-awareness. He cites the
perplexing case of people with prosopagnosia, a rare condition that leaves
a person unable to recognize her own face in a mirror. There is no
evidence, he argues, that such people lack self-awareness. Mirror
self-recognition, therefore, does not tell us anything about animals'
"sense of self"--much less whether they are conscious, or have an awareness
of death, as some have gone so far as to suggest.

Still, Hauser is willing to indulge in some admittedly whimsical
speculation on the question. In 1997 he observed rhesus monkeys on Cayo
Santiago staring with fascination at pieces of a broken mirror. On his Web
site, he suggests that the mobility of these mirrors may have enabled the
monkeys to recognize themselves. "The logic might run like this: I am
holding a mirror in my hand. There is another monkey's face. It can't be
another monkey because I am not carrying one. It must be me."

If we can't be sure whether animals are aware of themselves, it might seem
even more difficult to determine whether they are aware of each other.
Might primates be said to have a "theory of mind"? The term, coined by the
ape researcher David Premack in 1978, generally refers to the recognition
that others have beliefs and that these beliefs can differ from one's own.

Although Premack's notion initially didn't spark much additional work with
apes, developmental psychologists took it up with alacrity. In a classic
test, a child watches while one puppet, named Sally, places a ball in a
basket in the presence of another puppet, Anne. At that point, Sally leaves
the room, and the child sees Anne move the ball to a box. When Sally
returns, the child is asked where Sally will look for the ball.
Four-year-olds will correctly indicate the basket, the original hiding
place. They understand that Sally has no way of knowing that the ball has
been moved. Younger children, however, think Sally will look in the box. It
seems they cannot distinguish between what they know about the situation
and what Sally knows. That is, they have no theory of mind.

Primate research into such questions picked up in the late 1980s. Some
writers, surveying the literature, conclude that the great apes, like
four-year-olds, have a theory of mind: They can grasp that others may have
false beliefs. But in Wild Minds Hauser is much more skeptical. He cites,
for example, one of a suite of experiments by Daniel Povinelli in which
chimpanzees gestured for food just as often from trainers wearing bags over
their heads or blindfolds over their eyes as from those with bags just to
the side of their heads or blindfolds over their mouths. They don't seem to
grasp the connection between seeing and knowing--in other words, that
someone who can't see them begging doesn't know they are there.

As badly as Povinelli's chimps tested, a control group of rhesus monkeys
did even worse. But as Hauser points out, the ordinary monkeys were
competing against an ape "dream team"--animals that had been "enculturated"
through language training and intense exposure to human artifacts and
situations. At the same time, he acknowledges, monkeys may not have much
need for a theory of mind. Since their family groups tend not to break into
smaller units, as chimps' do, and they are almost never alone, individuals
rarely differ substantially in what they know.

Despite his general doubts as to whether primates have a theory of mind,
Hauser nonetheless offers some tentative evidence that tamarins may
nominally understand that other minds can hold false beliefs. In designing
a nonverbal version of the Sally-Anne test for tamarins, Hauser took a cue
from the developmental psychologists Wendy Clements and Josef Perner of the
University of Sussex. This duo had observed that in the classic test with
human infants, before the three-year-olds answered, incorrectly, that Sally
would look in the second hiding place, they would spend a moment looking at
the first hiding place (where the returning Sally ought to think the ball
remained). Perhaps the younger children implicitly understood that Sally
held a false belief, Hauser speculated, even if they couldn't express their
understanding explicitly, in words. (As the cognitive scientist in Hauser
puts it, "Somewhere along the path from looking to speaking, there is a
computational error.")

In Hauser's test, which he carried out with his graduate student Laurie
Santos, a tamarin watches as Joe enters a room. Joe eats part of an apple,
hands the tamarin a piece, and then puts the rest in one of two opaque
boxes. When Joe leaves, the experimenter moves the apple into the second
box. Joe returns and looks for the apple. The tamarins stared longer when
Joe, against logic, looked in the second box, even though he hadn't seen
the apple being moved.

The paper has yet to be published in a scientific journal. One critic has
expressed doubts about the validity of the looking-time method for infants,
let alone primates. Another asked, since we know apes don't have a theory
of mind, why should we think monkeys do? Hauser calls this a "really weird"
phylogenetic claim. "You wouldn't say, ëHumans don't have echolocation, so
why should bats?' We know evolution works in weird ways."

Curiously, Hauser makes no mention of his theory-of-mind results with
tamarins in Wild Minds. "I didn't want to give the impression that all it
required was this one intelligent experiment by Hauser to show that the
field was all wrong," he says. "I tried really hard not to promote things I
didn't think were really solid." He mentions the best-selling books of his
close friend Steven Pinker. "Steve is a very forceful writer. If you read
The Language Instinct, you think, ëOh we've got the problem of language
acquisition solved.' But in fact we don't. And reading How the Mind Works,
you might think evolutionary psychology has all the answers, but there's so
much controversy in that field it's outrageous." For example, Pinker makes
a powerful case for the "cheater detector," or the idea that humans have a
built-in module for sniffing out deceivers. However, Hauser protests,
"there's also so much counterevidence" that isn't discussed.

Nonetheless, Hauser's notion of the mind as a collection of tools puts him
squarely on Pinker's side of the fence. Not all researchers in primate--let
alone human--cognition embrace this view. In his new book, The Cultural
Origins of Human Cognition, Michael Tomasello of the Max Planck Institute
for Evolutionary Anthropology argues that language and other specialized
skills don't reflect specialized modules. Rather, they spring from one
simple, "uniquely human biological adaptation." What's important is not the
full-blown understanding of false beliefs that emerges at around three and
a half but what he calls "the nine-month revolution"--the understanding
that others are intentional agents "like me" that emerges toward the end of
the first year. It is this understanding that allows us to share "joint
attention" with another person and to learn what they know.

One of the most surprising differences between humans and other
animals--one Hauser also emphasizes--is that only humans seem capable of
true imitation. That is, imitation not just of another's actions but of his
or her underlying intentions. Apes don't truly ape, and the monkey that
sees doesn't necessarily do. In Tomasello's opinion, this unique human
ability to understand the intentions of others is what made science
possible. Understanding of invisible causal forces like "intentions" and
"thoughts" evolved first to explain and predict the behavior of other
people. It was then "transported" to explain the behavior of inanimate
objects influenced by forces such as gravity. Strangely, our knowledge of
physics and chemistry may flow from our innate grasp of psychology.


Perhaps even more surprisingly, experiments with physics may help elucidate
some of the more mysterious aspects of animal psychology, including the
vexed question of where in the branching tree of evolution morality begins.
Ever the empiricist, Hauser offers an arresting line of argument based on
two very simple concepts. In one experiment, two-year-old children or adult
tamarins watched a researcher drop an object down an S-shaped pipe running
diagonally toward a box. Both the kids and the monkeys looked for the
object directly below the point where the object was released--and not in
the box, where the tube ended. They did this not just once but twenty or
thirty times in a row.

Children and tamarins are vulnerable to what Hauser calls "Kuhnian
perseverance," or repeating an action because their theoretical
framework--in this case, a "gravity bias"--drives them to do so. They are
also constrained by what he calls "Cartesian perseverance." According to
Descartes, rationality requires control over passionate impulses--and
animals are incapable of exercising such control. As a result, animals will
sometimes make the same passion-based blunders over and over again. Hauser
cites experiments in which chimps and macaques, faced with a hand or box
holding four treats and one holding a single treat, always picked the four
treats, even when the rule of the game was that they would get whatever
serving they didn't pick.

Morality would seem to have little to do with pellets of food dropping down
a tube. But such experiments, Hauser argues, show why animals, like
children, have no role in shaping rules of conduct. "To make an ethical
decision," he writes, "...we must choose between two or more alternative
possibilities. Sometimes the most tempting possibility is the wrong thing
to do."

Although Hauser believes animals have rich emotional lives, his skepticism
that animals have a true sense of self leads him to reject the notion that
animals experience empathy--that is, that they not only know what other
animals feel but also share in those feelings. Indeed, while there are some
reports of primates appearing to grieve for the dead, there are virtually
none of primates acting to comfort those in grief. But given Hauser's
tendency to find evidence among his monkeys for things he's not sure he
believes in more generally, perhaps it's not surprising that he's devising
an experiment for empathy.

The experiment will be an "ethical" version of those, conducted in the
1940s and 1950s, that examined rats' willingness to give each other nasty
shocks if it meant gaining access to food. In his primate version, Hauser
will play recordings of a monkey in serious distress to other monkeys. If a
listening monkey exhibits neurobiological signs of distress along with an
appropriate behavioral response, Hauser will consider calling it empathy.

In a way, empathy is where Hauser departs most clearly from Jeffrey Masson
and Elizabeth Marshall Thomas. The moral goodness of animals is precisely
what books like When Elephants Weep and The Hidden Life of Dogs insist on,
often with great eloquence. Some psychologists have pointed out that it is
humans' own considerable ability to empathize that leads us to
anthropomorphize animals--not to mention cranky computers, stalled car
engines, and forces of nature. Can Hauser's book help spark a Kuhnian
paradigm shift in the way the common reader conceives of animal minds?
Perhaps. After all, his work gives ample reason to respect animal minds
without presuming they are exactly like ours.

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Jennifer Schuessler is an assistant editor at The New York Review of Books.
Her article "The Visionary Company" appeared in the December/January 1999 LF