Carl Zimmer reports for the NY Times (archived) on the meaningful gestures of chimps and other apes:
In the 1960s, Jane Goodall started spending weeks at a time in Gombe Stream National Park in Tanzania watching chimpanzees. One of her most important discoveries was that the apes regularly made gestures to one another. Male chimpanzees tipped their heads up as a threat, for example, while mothers motioned to their young to climb on their backs for a ride. Generations of primatologists have followed up on Dr. Goodall’s work, discovering over 80 meaningful gestures made by not only chimpanzees, but also bonobos, gorillas and orangutans.
Now researchers are using these gestures to peer into the minds of apes. Some even think they offer clues about how our own species evolved full-blown language. “Certainly, gestures played a big role,” said Richard Moore, a philosopher of language at the University of Warwick.
In the 1980s, Michael Tomasello, then a young comparative psychologist, pioneered the first theory about ape gestures based on observations of infant chimpanzees in captivity as they grew into adults. He noticed that the baby apes made gestures to their mothers and, as they matured, developed new gestures directed at other chimpanzees. Based on his observations, Dr. Tomasello argued that gestures develop among apes as simple habits. If a baby repeatedly tries to grab food from its mother’s mouth, for example, the mother may eventually start to give it food while the baby is still stretching out its arm. The baby, in turn, may stop bothering with the full action.
According to Dr. Tomasello’s ritualization idea, apes don’t use gestures to communicate the way we do. When we point to a cannoli in a pastry shop, we know the gesture will make the baker understand that’s the one we want to buy. But according to the theory, an ape doesn’t get inside the head of other apes when it makes a gesture. The animal simply learned that the gesture delivered what it wanted.
By the 2010s, however, some primatologists saw some serious problems with that theory. It predicted that there would be a lot of variety in the gestures that emerged from one-on-one interactions between apes. But large-scale surveys of chimpanzees showed that they all made the same gestures. Some of those movements were even shared across different species.
The critics developed a new theory rejecting the idea that apes spontaneously developed gestures. Instead, they proposed that gestures were encoded in the genes, much as a courtship dance is encoded in a bird’s DNA. The inherited gestures that helped apes reproduce were favored by natural selection. “Gestures are innate,” said Richard Byrne, a primatologist at the University of St. Andrews in Scotland, who helped develop this theory.
But Kirsty Graham, a former student of Dr. Byrne’s, grew dissatisfied with the innate theory as well. “We’re saying it makes more sense that 80 gesture types are all genetically encoded?” recalled Dr. Graham, who now teaches at Hunter College in New York. “Is this really the simpler explanation?” Dr. Graham discovered that Dr. Moore shared her skepticism, as did Federico Rossano, a comparative psychologist at the University of California, San Diego, who got his Ph.D. with Dr. Tomasello. The trio unveiled a third theory last month in the journal Biological Reviews. “It’s a story that we hope will reconcile existing data and divergent views,” Dr. Moore said.
Apes, they argue, do not inherit specific gestures, but they do inherit the sense that they can use gestures to communicate with other chimpanzees. The animals create new gestures by borrowing — or “recruiting,” in the scientists’ lingo — movements that apes commonly make.
The theory explains some observations that did not make sense otherwise, she said. Primatologists have noticed, for example, that when an ape fails to get something it wants through a gesture, it may move so that the other ape can see it more clearly. If the gesture were just a learned, habitual motion, the animal wouldn’t be able to display it so flexibly, Dr. Graham said. “They’re being intentionally produced, in a goal-directed way,” she said.
The recruitment view offers an explanation for how apes can share so many gestures even if they are not innately programmed. Apes end up making the same gestures because they have similar bodies that move in similar ways. As a result, it’s easy for them to interpret the meaning of gestures simply by thinking about what they do with their own bodies. Dr. Graham argues that the recruitment view offers new ideas about why apes struggle to recognize gestures that are easy for us to understand, such as finger-pointing. Those movements have no clear connection to what the apes do with their bodies in their everyday life.
The “recruiting” idea makes sense to me (a completely ignorant outsider). And the conclusion is much more cautious than the “gestural origin of language” stuff we mocked a couple of years ago:
But Dr. Rossano and his colleagues see a more distant connection from gestures to language. Our ape ancestors evolved an unprecedented flexibility in how they learned gestures and how they used them in their social lives. That’s a vital element of human language, too. “Where does that flexibility in use and learning come from?” Dr. Rossano said. “It probably comes from the flexibility in gestures.”
i guess i’ll be the cranky one, as usual on this stuff.
we know that many species of many kinds (corvids, primates, and others) teach each other to do all kinds of things. we know that one way that works for some primates, for oral and gestural communication in particular, is by exposure during their youth: being around other members of their species who use these forms with each other and with the young animal (partly as direct use, partly as demonstration). it is a mystery to me that researchers on other primate species (and other critters) feel such a desperate need to find a whole different explanation.
i’m also unsure why there’s a need to posit a genetic chomskyan language organ to drive that separate explanation, rather than simply the capacity to learn through observation (and when directly taught), which is pretty well established.
where’s old billy o when you need him?
The idea seems to be that ape gestures are all what in human terms you would call iconic, but can still be imitated and altered.
That does seem both plausible in itself and also to offer a possible sort of primate substrate system on top of which the characteristic human elaborated symbol-pushing might later have been added.
Hey, if I fail in my duty to be cranky, somebody has to pick up the mantle!
Let me just note since I assume not everyone will have already known it that Carl Zimmer is older brother to the noted lexicographer Ben Zimmer. Whether Carl is less ignorant about linguistics-type matters than the typical journalist (for that reason or otherwise) is an empirical question, and maybe it was possible to get through this particular story without the writer showing his hand on that.
i do not see more iconicity in chimps communicating negation by “tipp[ing] their heads up” than in bulgarians making the same gesture to the same end. to my eye the gesture is pretty classically symbolic in both – if we exclude the kind of just-so-stories that the evopsych/sociobio types love to spin, probably in this case involving ideas about canine teeth as inherently threatening that have more to do with bram stoker than anything else. i’m sure if we looked, we could find more than one ethnologist who described the balkan version of the gesture as solely indicating “a threat”, for the same reasons that it’s presented to us that way in chimps.
The topic is far from new. Have these scientists not read, perhaps not even heard of, Darwin’s other great book, The Expression of the Emotions in Man and Animals (1872)? And why does that seem a greater failing than a modern physicist not reading Newton, if the latter is even a failing?
It’s been decades, but I still remember some bits. For instance, that extreme fright can in fact make your hair stand on end. The book has illustrations, including two photographs of a woman in an insane asylum (Bedlam?) who suffered from bouts of extreme anxiety. One, taken when she was feeling relatively calm, shows an ordinary curly-haired woman. In the other, taken when she was having one of her periodic panic attacks, she looks like Marge Simpson, with her hair (too curly to stand up straight) piled up roughly a foot higher.
I imagine it’s difficult to find pictures of sane people with their hair standing on end, since a really close lightning strike or rampaging hippopotamus will tend to terrify the photographer as well, or at least take him by surprise so he can’t click in time. All the more so in Darwin’s day, when taking a photo took quite some time. I wonder if security cameras have recorded instances more recently.
Which reminds me. I once saw a man literally break out in a cold sweat. Large beads of sweat popped out all over his face in a fraction of a second. I was working in a record store (remember those?) near the University of Chicago in 1976, and a bunch of steel workers from the South Side mills came in after work on a Friday to spend some of their paychecks. One of them left an envelope with 8 or 10 (or more, I didn’t count) hundred-dollar bills in it on the counter, while he took his new LPs to his car. That was of course a huge amount of money in those days. There were at least a dozen other people crowded around the counter at the time, and it would have been very easy for any one of them to grab it. However, I saw it happen and whose it was, grabbed it myself, and ran out and caught him as he was getting into his car across the street. That’s when he broke out in a cold sweat. I imagine that was his rent money and food for his kids money and more. Of course, I didn’t tell him I was pedantically thinking “So that’s what ‘breaking out in a cold sweat’ means!”, just “Woah, be careful!” or something like that. He was of course profusely thankful, but also totally stunned. I suspect he was having visions of family evicted, kids starving, wife divorcing him, himself lying in the gutter, and so on. Not that I asked! I hope he managed to drive home without hitting anything.
Isn’t it the case that pointing (i.e., “ostension”) isn’t just _a_ gesture, it’s _the_ gesture, the sine qua non of language? In other words, isn’t there an “upper limit” you hit, as a species, if don’t possess a genuine “theory of mind”?
Otherwise, isn’t this “recruitment” theory just repackaged operant conditioning? — Ape 2 sees Ape 1 do a silly dance, ape gets banana; Ape 2 does silly dance, gets banana, “rehearses” silly dance in memory so that it may be available to consciousness (?) later.
“The closer you get to humans, the worse the science gets”…
Oh, that’s real. In my spontaneous introverted* fits of rage, I quite involuntarily pull the corners of my mouth downwards and backwards so the exposure ends with my canines. (The upper ones. The jaws stay closed, so you can’t see the lower ones; they’re inside.) It’s actually quite close to the rage face lots of comic-strip figures make, where the mouth stays closed in the middle and opens only on the sides.
…and one of the triggers for these is… certain types of smile – but only when nobody is around, meaning the smile has to be on a billboard or something. Completely irrational. (Also, no fear is involved; it goes straight to rage.) Another (that does involve fear) is being suddenly, unexpectedly being barked at by a dog that is close by (though I don’t need to see the dog, let alone its teeth in particular) – keep in mind I have not been around dogs enough to have developed any mode of communication with them or even watched them communicate with each other.
* I don’t make a sound or any further movements.
It’s not like canine teeth can only ever be threatening; there’s for example that Japanese trope of using them to indicate cuteness (I can’t find it on TV Tropes, alas), and indeed the canines of little kittens don’t make them any less cute for me. But… the option is there and must be innate.
No. Pointing is very widespread among humans, but there are cultures where, if you point at something and ask “how do you call that”, they tell you “finger”.
That’s not the recruitment, that’s “Dr. Tomasello’s ritualization idea”.
if you point at something and ask “how do you call that”, they tell you “finger”.
I remember reading, in my UT Austin days, that some Old Greek Philospher claimed that cats will look at your finger, but dogs will look wohin you’re pointing.
To this day I haven’t been able to find a source for that. It does seem to be kinda true, from my limited experience. Don’t know about you folks, but I can easily corroborate what I want to believe.
Well, when cats want to show you something, they sit down and stare at it. No silly business with paws or claws.
One probably connected thing that I’ve read is that, although chimpanzees are in general much cleverer than dogs, they cannot do tasks which need them to recognise that the experimenter is trying to help them, whereas dogs can (presumably as a consequence of millennia of socialising with human beings.)
Pointing with a finger in West African cultures (at least ones I’ve lived in) is understood, but regarded as very rude. You point with your lips. (And you should never point at a person with a finger.)
“…than dogs”
…then humans too, by transitivity.
About apes and gestrues (LH’s post):
Two things got mixed up here, the “etymology” of gestures and their availability for conscious use.
You can connect them within the first theory, but they are very different in the other two.
“Innate” simply says nothing about either. It is a theory of their transfer from one ape to another. The predictions are:
(1) a Mowgli ape who has grown in the concrete jungle among wild humans will make same 80 gestures as civilised apes who grow up in normal jungle.
(2) no ape will expand her vocabulary.
But this says precisely nothing about their availability for conscious use – even though strangely most people think it somehow means “inavailable”.
Also it says nothing about whether they’re encoded in detail or they are just (e.g.) what a baby ape is likely to invent given her body and environment (so 1. above is not entriely correct).
As for the new theory – it speaks of the “etymology”, byt for some reason supports it with conscious use.
“Also it says nothing about whether they’re encoded in detail or they are just (e.g.) what a baby ape is likely to invent given her body and environment (so 1. above is not entriely correct).”
Or well, of course you can propose a differen “innate”, which means they’re encoded. But to be ‘science’ rahter than yet another silly attempt of dumb humans to pretend that they are smarter than apes (1) it must be tested as a theory of encoding distinct from the thoery of spread (described above) (2) there must be a theory of encoding….And, again, to my surprise many people understand “innate” this way, Kirsty Graham (a biologist?) among them. If any of present biologists clarify the matter for me, I’ll be grateful. As far as I understand the second theory was not anyhow tested and we don’t have a theory of encoding, so “encoded” simply means “we have no idea what it is”
And you should never point at a person with a finger
Well, that is seen as rude in polite society in many parts of Europe, too, and in other cultures as well. But perhaps in Western Africa the opprobrium or sanctions for doing so are more severe?
In South-East Asia, people don’t point with the index finger, they form a fist from four fingers and then rest their thumb on the curled inwards index finger, pointing with this fist-thumb combination. My wife, who finds pointing rude independent of whether the target is human or not, took a liking to that kind of pointing, so I still use it even back in Europe when pointing at things with her around.
In South-East Asia, people don’t point with the index finger, …
This just in (the Sinosphere/most of SE Asia is gearing up for Mid-Autumn Festival)