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今天的话题比较“跨界”，但相信大家会感兴趣的，GMAT似乎也很喜欢这题材
选自近期的Science，速度是interview（也推荐作为听力练习），越障是"News Focus".
Enjoy!
[计时一]
Exploring The Foundations Of Human Cumulative Culture
Host – Kerry Klein
They may be our cousins, but orangutans and other primates are nowhere near humans in
terms of technological achievement, social organization, or culture. And it’s humans’
capacity for building off of one another—an integral part of our so-called cumulative
culture—that has allowed us to build up so much in so little time. But how did we
develop such advanced methods of learning in the first place? Kevin Laland of the
University of St. Andrews spoke with me about his team’s quest to pinpoint the social
and cognitive processes that underlie humans’ ability to acquire and transmit knowledge.
Interviewee - Kevin Laland
We’re interested in trying to explore the evolutionary routes of the human capacities of
cumulative culture. If you think about it, humans have these cultural traditions that will
accumulate refinements over time thereby allowing technology and other cultural
achievements to build up in complexity and diversity. Think of satellites or particle
accelerators or modern medicine – these are not things that any one individual has
devised, they reflect the inventions of thousands of individuals over long periods of time.
If you contrast animal cultures on the other hand, or animal social learning, they’re
clearly capable of learning from each other. They acquire knowledge about foraging
behaviors, for instance, or anti-predator behavior from each other. And sometimes we
see some simple traditions exhibited, but seemingly they don’t exhibit this cumulative
quality – there’s no sort of improvement or refinement over time, at least not obviously.
So we set out to understand why that should be. And there are a number of hypotheses
out there in the literature. It could be to do with cognitive differences between humans
and other animals; it could reflect social factors. So we carried out an experiment to set
out firstly to establish whether other animals might be capable of cumulative culture if
put to the test, even if they don’t actually exhibit it naturally and then to try and
understand if not, why that should be and to measure a whole bunch of predictor
variables that potentially might explain why they might fail to exhibit this capability.
[362 WORDS]
[计时二]
Interviewer - Kerry Klein
Are there any other species at all that we suspect might also have developed this
cumulative culture, or is it only humans?
Interviewee - Kevin Laland
Well, there are no clearcut examples of cumulative culture in other species. There are
certainly one or two cases where people have made claims of cumulative culture. For
instance, in chimpanzees, we see that some populations of chimpanzees who use stone
tools as hammers to crack open nuts and others will combine those stone hammers with
stone anvils –place the nut on an anvil and then use the hammer to crack it open. So
some people have argued that this is a reflection of cumulative learning. The trouble is
we don’t know the history of this time series. So it’s a kind of plausible story, but it
equally seems just as likely that some individuals could have independently invented the
use of the stone tool and the hammer because it’s not so devastatingly complex that it’s
hard to imagine that any individual could invent it themselves. You can contrast that
with, you know, a computer – it’s just really hard to imagine that any one individual
could have invented a computer and invented all of its component parts and all of the
technology necessary for it. So we humans clearly have the capability to produce cultural
knowledge and technology that goes way beyond what any individual can produce. But
that’s not at all clear for other animals.
Interviewer - Kerry Klein
Right. Okay. So your study here involved, you know, asking the question why and how
have humans developed this cumulative culture where other animals have not, or at least
we don’t think that they have. So what were some of the key questions that you had to
ask, and how did you go about answering them?
[306 WORDS]
[计时三]
Interviewee - Kevin Laland
Well the key issue is to, first of all, identify whether the animals were indeed capable of
cumulative culture in spite the fact they don’t show it in nature; and secondly to ask if
they don’t exhibit this capability, what explains that? What co-variants with the
performance of the individuals that do well explaining their performance in the task. So
what we did was we devised this puzzle box, which could be solved at three different
levels or stages, each one building on the earlier. My graduate student, Lewis Dean, then
presented this puzzle box to groups of capuchin monkeys, groups of chimpanzees, and
groups of nursery school children recording their performance on the task, but also, at the
same time, recording whether there was any evidence for any of these potential predictor
variables. For instance, did we see any signs that individuals were helping each other,
teaching each other, giving each other verbal instruction, giving each other rewards,
scrounging from each other, monopolizing the puzzle box, and so on and so forth? And
so we could then look to see whether any of these potential predictors explained
performance in the task.
Interviewer - Kerry Klein
So for your non-human subjects here, what made you choose chimps and capuchins?
Interviewee - Kevin Laland
Yeah, well that’s a good question. We chose chimpanzees and capuchins for a couple of
reasons really. Firstly, these are two species of animals that exhibit quite sophisticated
social learning and behavioral traditions. So the evidence for simple forms of cultures
that are strong in these two species, as in any. But there’s also the reason that
chimpanzees are our closest living relatives, and so they’re a natural comparator to
humans. And then you might use another species, for instance, the capuchins as a kind of
outgroup to help you interpret any differences observed between chimpanzees and
humans. So that’s the rationale behind our choice of those two species.
[326 WORDS]
[计时四]
Interviewer - Kerry Klein
So in the end, how did all of these groups perform – the humans, the capuchin monkeys,
and the chimps? Were there any major differences or similarities?
Interviewee - Kevin Laland
Yeah, so we didn’t find any evidence for cumulative culture in either the chimpanzees or
the capuchins. We had one female chimpanzee who managed to solve the puzzle box at
the highest stage, the third stage. But it didn’t seem to spread to any of the other
chimpanzees. And we did have conditions in our experiment where there were trained
demonstrators, which were other trained chimpanzees, who exhibited, who demonstrated
the solving of the task, but that didn’t seem to enhance their behavior either. We had the
sort of conditions where the learning was scaffolded so you couldn’t move onto the
second stage unless you’d kind of progressed on the first stage. And none of these
manipulations seemed to help with chimpanzees to get to the highest level. And
similarly, with the capuchins, we’ve seen no evidence at all of any cumulative cultural
learning in them. And that contrasts starkly with what we see in the children where in
spite of having a lot less time to access the puzzle box, we see evidence for cumulative
culture in five of the eight groups of nursery school kids we studied with multiple
children solving the task to the highest level. So there really were quite strong
differences between humans and the other two species.
Interviewer - Kerry Klein
And did the other primate species here surprise you in any way? Were there any
behaviors that they possessed that you were not expecting?
[275 WORDS]
[计时五]
Interviewee - Kevin Laland
Well, it was more the other way around really. There is a literature that suggests that
chimpanzees, in particular, are very good at imitation. There are scientific reports of
them exhibiting prosociality and helping others. But we saw none of that at all. In our
behavior, we saw the children approach the task in a very social way, in a collaborative
way, helping each other, teaching each other, giving each other rewards. And this I think
reflects the fact that they understand that the other individuals are also trying to solve the
task, and they have the same motivations and goals. So they went about this exercise in a
very collaborative, social way; whereas the chimpanzees and the capuchins seemed to go
about it sort of all for themselves, essentially undertaking this exercise as a means to
procure resources solely for themselves. We did wonder whether there might be some
tolerated theft that mother chimpanzees might, for instance, let their offspring take food
that they themselves had retrieved. In fact, we found exactly the opposite – the mother
chimpanzees were stealing food from their babies. So the differences between humans
and the other two species were actually more stark than we had imagined going into this
exercise.
Interviewer - Kerry Klein
So is this capacity for collaboration the key here to our cumulative culture? What’s your
overall interpretation of these results?
Interviewee - Kevin Laland
Yeah, so our findings really fit very nicely with an argument that’s been made by
Michael Tomasello and his colleagues. He’s a professor of psychology and evolutionary
anthropology at the Max Planck Institute in Leipzig, and he’s argued for many years that
humans differ from other animals according to a package of sociocognitive capabilities
which includes the ability to teach, to imitate very accurately, to help each other through
verbal instruction and to use language in general, and, of course, this tendency for
prosociality and our collaborative nature. And those arguments really fit very nicely with
our findings. And how well a child does in the task really does seem to co-vary very
strongly with how much teaching they receive, how much verbal instruction they receive,
how much they imitated, how many acts of prosociality they benefited from. So there
seems to be a strong link – at least in the context of our experiment – between those
sociocognitive capabilities that Tomasello and his colleagues have emphasized and this
capability for cumulative culture that we were investigating experimentally. So we
suspect that that really is the key set of attributes that seems necessary for the ratcheting
we see in culture in humans.
[438 WORDS]
Source:
Science Magazine Podcast
Transcript, 2 March 2012
http://podcasts.aaas.org/science_podcast/SciencePodcast_120302.mp3
(0:49-10:46)
越障
ANIMAL COGNITION
‘Killjoys’ Challenge Claims Of Clever Animals
LONDON AND CHICHELEY—It seems that hardly a week goes by without a new report about animals performing marvelous feats we once thought only humans could do: Crows make tools, chimpanzees seem to mourn their dead, and rats supposedly empathize with one another’s pain.
Charles Darwin, were he alive today, might approve this trend. “The difference in mind between man and the higher animals,” he wrote in The Descent of Man, “… is one of degree and not kind.” For many researchers, the new evidence represents a welcome shift from behaviorist paradigms often associated with psychologist B. F. Skinner, which denied nonhuman species anything approaching advanced cognition (Science, 25 January 2008, p. 404). Yet recently, some researchers have been pushing back against attributing humanlike qualities to other animals without considering cognitively simpler explanations.
This more skeptical contingent was present in force at two recent back-to-back meetings sponsored by the Royal Society in London and Chicheley. At both, researchers explored what animals are really doing when they engage in seemingly complex behaviors, rather than reported still more discoveries of their impressive abilities.
“There’s an arms race to identify the most clever animals,” Lars Chittka, an animal psychologist at Queen Mary, University of London, said at the London meeting. “But what are we trying to demonstrate?”
Attempts to measure the gap between human and nonhuman minds have become like a “party game,” said experimental psychologist Cecilia Heyes of the University of Oxford in the United Kingdom. Some researchers blamed the news media, and even some scientists, for exaggerated interpretations of animal behavior. “People in the field often gravitate into two camps,” Daniel Dennett, a philosopher at Tufts University in Medford, Massachusetts, told Science. “There are the romantics,” those who are quick to see humanlike traits in animals, “and the killjoys,” who prefer more behaviorist explanations. “I think the truth is almost always in the middle.”
Crinkly bananas
In a talk at the London meeting titled “Simple Minds”, Heyes argued that many researchers discount associative learning—the expectation that two events, for example, a stimulus and reward, are connected. Heyes argued that this type of learning is ubiquitous among both animals and humans and remains a “contender” when interpreting animal experiments. As a case study, Heyes critiqued a paper on chimp altruism published last year in the Proceedings of the National Academy of Sciences. Researchers have been hard put to show that chimps have much desire to help each other out; unlike humans, they seem to do so only when pressured or pleaded with rather than spontaneously.
In the study, led by primatologists Victoria Horner and Frans de Waal of Emory University in Atlanta, chimps were given a choice between two different colored tokens. One color prompted the human experimenter to give a banana to both the subject chimp and another chimp in an adjacent enclosure whereas the other color resulted in food for the first chimp only. Chimps showed a significant preference for the token that led to a banana for both themselves and their partners. The team concluded that chimps are more altruistic than usually given credit for.
But Heyes pointed out that the bananas were wrapped in crinkly paper, so chimps could both hear and see when the partner got a reward. She suggested that the chimps may have begun to like the sound of the crinkly paper, “just as Pavlov’s dogs got to like the sound of a bell.” Thus they might have opted for the color choice that yielded a double shot of the noise.
Psychologist Sara Shettleworth of the University of Toronto in Canada says she “totally agrees” with Heyes’s reservations, and even Horner calls the arguments “thought-provoking.” But Horner argues that the chimps got only one reward no matter “how many rustling papers they heard.” Had associative learning been the primary mechanism operating, she says, the chimps would not have preferred one token color over another.
Although researchers still debate what’s behind the behavior of close human relatives such as chimpanzees, there was wide agreement with points made at the Chicheley meeting by cognitive scientist Derek Penn of the University of California, Los Angeles. His talk, titled “Animals Aren’t People,” included a blistering critique of a 9 December 2011 Science paper (p. 1427) that claimed that rats are capable of empathy—or, as Science’s online news coverage headlined the story, “Rats Feel Each Other’s Pain.”
In the study, neurobiologist Peggy Mason of the University of Chicago in Illinois and her colleagues trapped one rat in a small plastic restrainer that could be opened only from the outside; trapped rats gave alarm calls roughly 20% of the time. A second, free rat was placed nearby, and it soon learned to free its compatriot by opening the door. Free rats did not open the door when the trap was empty. The authors concluded that the helping rat reacted empathically to the distress of its fellow.
But Penn argued that the team hadn’t shown that either rat was truly in distress. The team didn’t perform at least one other important control, he said: using trapped rats that were not distressed. Playing videos of the experiments to the meeting, he pointed out that once the door was open, the free rat entered the trap and explored it with the trapped rat, suggesting that being in the trap was not that stressful.
Mason, who was not at the meeting, counters that once the trap was open, it became “an object to be explored, and in fact rats might prefer it to staying out in the open.” As for the lack of an unstressed control rat, Mason says the team now has an experiment under way suggesting that the more anxious the trapped rat, the more helping behavior is evoked. She agrees that rats probably are not aware of one another’s mental states, as humans are, but says the behavior her team observed is the “rodent homolog of empathy.”
Nevertheless, Penn argued that this and many other recent papers suffer from what is called “folk psychology”: interpreting animal and human behavior in “commonsense” rather than strictly scientific terms. Folk psychology, Penn said, gives animals humanlike reasons for what they do, such as “the rats helped free their cagemates because the caged rats were feeling scared.”
Penn’s talk evoked murmurs of agreement in the meeting room. “Our folk psychological labels carry a lot of specifically human baggage,” Dennett says, “which can be gradually jettisoned as we come to understand other ways of accomplishing many of the same basic cognitive tasks.”
[1097 WORDS]
Source: http://www.sciencemag.org/content/335/6072/1036.summary
Science 2 March 2012: Vol. 335 no. 6072 pp. 1036-1037
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