SYLVIA is a very good cook. She makes a particularly fine roast ham, using a family recipe that begins, unusually, by cutting a section off both ends of the meat. One day, a friend dropped by while she was preparing the dish. “Why are you doing that?” he asked, as Sylvia carefully trimmed the ham. “Because that’s the way my mother always does it,” said Sylvia. But it got her wondering – why did her mother start that way?
A few days later Sylvia was at her mother’s house. “When you make that special ham, why do you start by chopping the ends off the meat?” she asked. “Because that’s the way my mother taught me,” came the response. Sylvia knew she had to get to the bottom of this. She picked up the phone and called her grandma. “Tell me Gran, when you used to make your roast ham, why did you always start by cutting the ends off?” The old woman paused for a moment in recollection. “Because I didn’t have a big enough pan,” she replied.
The story of Sylvia’s ham illustrates what is so unusual about the way in which humans learn. We have a tendency to faithfully copy the actions of others without question, especially when we are young. At first glance such unquestioning imitation seems foolish. Like Sylvia, we may end up doing silly things for no good reason. Psychologists Gyorgy Gergely from the Hungarian Academy of Sciences in Budapest and Gergely Csibra of Birkbeck, University of London don’t see it that way. To them, our talent for high-fidelity copying is among our greatest assets. They think that our species is uniquely adapted to both receive and pass on knowledge and skills. What’s more, they argue, this everyday education – which they call pedagogy – is at the root of the rich cultural life that marks us out from all other animals.
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We are not the only cultured animal on the planet. Examples of cultural traditions have been discovered recently in all sorts of species, from fish and birds to cetaceans and apes. Yet culture in non-human animals is a far cry from the all-pervasive and highly symbolic cultural world we create. Even among chimps, whose cultural practices are second only to our own, researchers have so far found just 40 or so learned traditions that differ between various wild populations. Some groups, for example, use stones to crack open nuts, others clasp hands above their heads while grooming, and among those that fish for termites there are at least three different ways of doing it (Behaviour, vol 138, p 1481). Could some of the differences between human and other animal cultures lie in the way we learn?
A classic study from 1988 demonstrates that young children tend to learn by imitation – just as Sylvia watched her mother make roast ham and then faithfully copied the technique. Andrew Meltzoff from the University of Washington in Seattle got 14-month-old infants to watch as a woman turned on a light box by leaning forward and touching it with her forehead. A week later when presented with the light box, two-thirds of the infants performed the head action to switch on the light, even though they could have more easily done it using their hands.
Primatologists had assumed that ape cultural practices must likewise be passed on by imitation. Some of the most influential researchers have come to question this idea, however, reasoning that if this were the case, customs would spread much faster. Close observation of primates in the wild seems to confirm this. It appears that instead of imitation – copying both the method and outcome of a task – chimps often emulate: they attend more to the result of the behaviour they have been watching, and then they figure out their own way to achieve it.
The difference between the way chimps and humans learn is clearly illustrated in a study with children and captive chimps published last year by Victoria Horner and Andrew Whiten of the University of St Andrews, UK. They compared the methods that 3 and 4-year-old children used to retrieve a reward from a puzzle-box with those used by 2 to 6-year-old chimps under two conditions, one where the box was transparent, showing its mechanism, the other where it was opaque. With the opaque box, chimps imitated all the demonstrator’s actions, but when they could see the workings, they only reproduced those actions that actually functioned to open the box. Children, on the other hand, were happy to faithfully copy all the actions even when they could see that some of them were ineffectual (Animal Cognition, vol 8, p 164).
“Chimps can imitate, but if they can work things out for themselves then they will”
These results suggest that chimps can imitate, but if they can work things out for themselves, then they will. Whiten speculates that some wild chimpanzee behaviours such as termite fishing, in which the effects of a tool inserted into a mound cannot be seen, might be imitated. Most chimp cultural practices, however, tend to be more transparent, allowing the mechanism or relevance of actions to be observed. “Most tool-use behaviours are probably learned by chimpanzees via emulation learning,” says Michael Tomasello from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
Information overload
At first glance, the chimps appear to be taking the more sensible approach. So what sent humans down a different learning path from other apes? Whiten suggests that it could be down to the sheer amount of stuff we have to learn. “Because humans have massive cultural complexity, children need to learn quickly how to do many, many things, and they can modify techniques later if need be,” he says. “Imitation is quicker because it provides a ready-made solution to the problem.” Whiten suspects that the nature of the behaviours that chimps learn mean that speed may not be the crucial factor. “It may benefit apes to maintain their flexibility,” he says.
Gergely and Csibra go further. They think the crucial difference between chimps and humans rests on how easy it is to figure out which of their elders’ actions are important to achieve a desired result. Not only does a child have to learn many things, but the function of what they are learning is also often opaque. That is particularly true for cultural practices for which much of the content is symbolic – why clap to show appreciation, for example, or swallow a sticky red liquid to help ease a cough? So the best policy for human infants differs from chimps.
The problem with blind imitation, as Sylvia found out, is that you may find yourself doing things that are completely pointless. What you really need is someone to show you how to perform a task and indicate which bits are important, rather than just letting you watch what they do. This is where the human facility for pedagogy comes in.
Gergely and Csibra assert that babies are born with a “pedagogical stance” – a suite of innate adaptations that helps them soak up information from their elders. But equally important to pedagogy is the way parents ensure children learn. Parents are motivated to share information with their offspring to direct their learning, say the researchers. The human tendency to teach certainly marks us out from other primates. “There is very little evidence for teaching in apes, beyond mere facilitation,” says Whiten. In other words, they may perform a difficult task such as nut cracking when another individual might be watching, and may even hand over the hammer, but they don’t seem to actively demonstrate the task to one another.
What are the human adaptations underpinning pedagogy? The first step in the successful transfer of knowledge is for a teacher to get a student’s attention. The slow, high-pitched voice we tend to use to talk to infants may have a hand in this. “Newborns pay more attention to a source talking to them in infant-directed speech, or ‘motherese’, than to a source speaking in an adult-directed way,” says Csibra. For example, studies done more than a decade ago show that even at 2 days old, infants look at a chequerboard for longer when they can simultaneously hear a sing-song voice than when they hear a normal voice (Child Development, vol 61, p 1584). Csibra points to research by Nobuo Masataka from Kyoto University, Japan, showing that the preference for motherese is even found in babies born to congenitally deaf parents.
The eyes have it
Eye contact is also crucial. Last year, Teresa Farroni of Birkbeck and colleagues published a study showing that newborn infants less than a week old will spend longer looking at pictures of upright faces than upside-down ones, even when the “faces” are just abstract black and white shapes. The infants also preferred representations of eyes in which the pattern of light and dark would allow them to tell the direction of gaze (Proceedings of the National Academy of Sciences, vol 102, p 17245). “This all suggests that infants are most attracted to stimuli appropriate for social interaction and acquiring social information,” says Csibra, one of the study’s co-authors. Babies seem instinctively to seek out eye contact.
In an adaptation of Meltzoff’s light-box experiment, Gergely and his co-workers revealed just how important these attention-grabbing devices are in pedagogy. A demonstrator showed two groups of 14-month-old infants how to turn the light on using her forehead, but in only one of the groups did she try to get each infant’s attention before the demonstration. “When gestures such as eye contact with the infant or motherese were not used before the demonstration, most infants did not use the unusual head action to switch on the light,” says Gergely. When the demonstrator got their attention first, 11 out of 17 infants imitated her, while in the other group only five out of 17 used their head to turn on the light.
Having secured an infant’s attention, a teacher next has to indicate what she is teaching. The two simplest ways she can do this are by shifting her gaze or pointing. Farroni and her colleagues have shown that even 4-month-old babies are sensitive to gaze shift (Cognition, vol 7, p 705). The importance of this could explain the unique almond shape and visible white sclera of the human eye, as these make the direction of gaze shift more obvious. Infants also use pointing and looking to indicate that they are interested in finding out more about an object or activity.
Before a child learns to talk and understand speech, the whole process of pedagogy takes place via gestures and sounds. For Gergely and Csibra, this mirrors its evolution in our pre-linguistic ancestors. They trace the origins of pedagogy back to when hominins started producing complex tools, such as flint hand axes. Gergely and Csibra argue that the mental gymnastics required to make and store tools with specific and permanent functions, often requiring other tools in their manufacture, would have necessitated a new way of passing on information. When fashioning a handle for an axe, for instance, it would be difficult for a naive onlooker to know what the toolmaker was intending to do with this creation. So the only way our young hominin ancestors could learn from their elders was to imitate their actions while being guided by their teachers.
According to Gergely, the roots of human language may also be traced back to this development. He suggests that intentional and directed gestures may have been employed to teach and learn before speech emerged, and may even have provided some of the mental building blocks for language evolution. The idea finds favour with Michael Corballis of the University of Auckland in New Zealand, whose own theory suggests that human language evolved initially through gesturing, only later using the vocal channel. “If pedagogy evolved in the context of tools, and if language was intimately tied to pedagogy,” he says, “then it makes sense to suppose that language was initially gestural. That is, teachers would have used mime as well as hands-on demonstration to indicate how tools were to be made and used.”
Once language did evolve, the scope of pedagogy would have been enormously expanded. “One might well argue that pedagogy itself was restricted until the vocal channel became fully available, which could be why tools underwent so little change for so long,” Corballis says. He and others think that language emerged around 100,000 years ago, a period marked by a burst of cultural activity – including innovations in tool production after 2.5 million years of relative stagnation. When this happened, it would have created a positive feedback loop, argues Gergely, generating an increasingly rich cultural heritage. “Complex human culture and pedagogy must have co-evolved,” he says. “The more complex a cultural form, the more opaque the reasons behind it, and the more difficult it is to acquire them by simple, unguided observation.”
Of course, pedagogy is not the only unusual human trait that has allowed us to build a cultural world far more sophisticated than that of any other animal. Many experts believe a crucial step was the evolution of our ability to read each other’s thoughts and intentions, because this underlies the cooperation and coordination that are central to all sorts of cultural artefacts, from the Egyptian pyramids and national governments to symphonies, religions and global communications. But Gergely and Csibra point out that the ability to communicate new and task-relevant information to one another is an even more basic prerequisite for collaboration.
“Newborns pay more attention to someone talking to them in ‘motherese’”
Besides, what makes human culture so special is its complex and symbolic nature. The power of Gergely and Csibra’s idea is that it highlights the mechanisms by which we pass on this rich but opaque cultural inheritance. It doesn’t matter that many of our cultural practices and ideas have obscure origins or are difficult to comprehend, we can still benefit from them simply by learning from others. The downside, though, is that if we never ask “why”, we may end up chopping the ends off our ham for no good reason.
For copyright reasons, the graphic that accompanied this article in the print edition of New Scientist cannot be made available online.
