The culture of apes and other animals

On presenting Professor Whiten with the Sir James Black Senior Prize, Professor Alan Alexander, General Secretary of the RSE, said the award was for his outstanding contribution to the understanding of the importance of a secondary inheritance system and the role it plays in concert with genetic inheritance and individual learning.

Beginning his lecture, Professor Whiten asked, what do we mean by ‘culture’? For instance, The Sunday Times has a section called Culture, which covers theatre, books, cinema and the arts generally. That could be termed ‘High Culture’, Professor Whiten said. But is that a broad enough definition? When scientists talk about culture, it means everything that is learned through social learning and persists long enough to be called ‘tradition’. Such traditions make up cultures, of which there are many different examples around the world, involving what we wear, what we eat, how we eat and how we communicate through oral and written language.

However, although human beings are so richly cultural, does that mean that chimpanzees do not have cultures as defined above? For that matter, what about bees, crocodiles or rats? Answering either ‘yes’ or ‘no’ is too simplistic, Professor Whiten said. To help us decide, culture could be split into three main aspects.

Population-level patterning of traditions in time and space is the first. Human traditions vary by region and also change over time, but so do animal examples such as birdsong, in which dialects vary from area to area, even amongst species. The second aspect is cultural content; for example, both humans and chimpanzees use tools and technologies and the fact that they do so allows useful comparisons to be made. The third aspect is social transmission, or how culture is passed on, through such processes as imitation or teaching.

So what is chimpanzee culture, Professor Whiten asked? Fifty years ago, next to nothing was known about wild chimpanzee life, but subsequent research has discovered an extraordinary amount. Between 10 and 20 years ago, it became apparent that chimpanzees behave in different ways across Africa, as people do.

To build on this, Professor Whiten and his team have carried out a two-phase investigation, based on an accumulation of 150 years across research sites. They first simply asked what were common chimpanzee behaviour patterns in some areas but not in others, and this yielded 65 candidate cultural variants.

In phase two, these variants were then filtered to identify 39 behaviours – such as food processing, tool use, social behaviour, grooming techniques and courtship – that were customary or habitual in some areas but absent in others, without any apparent ecological or genetic explanation, and were thus inferred to be traditions. “This was quite a revelation,” Professor Whiten said. “Here we had a very rich picture of chimpanzee traditions that you can call culture.”

One example is using a natural hammer, made of wood or stone, to crack open a nut; a behaviour widespread in West Africa but absent in areas elsewhere. Successful nut cracking has to be learned, Professor Whiten explained. The shell cannot just be bashed with a stone or the nut will be crushed as well, and the technique can take up to a decade to perfect.

So how is this behaviour passed on? To find out, researchers studied chimps on an island sanctuary in Lake Victoria, in East Africa, where nut cracking does not occur in the wild. One older chimp was trained to crack nuts while younger animals watched. These younger animals learned to crack, whilst those who saw no model did not.

Two general conclusions have been drawn from the research, Professor Whiten said. The first is that wild chimpanzees have multiple and diverse traditions – a propensity that has probably been there since humans and chimps, our closest animal relatives, shared a common ancestry. The second conclusion is that each community is unique in its behaviour. Professor Whiten said that in the same way that it is possible to tell where in the world somebody lives because of their cultural repertoire, he can now tell which part of Africa a chimpanzee comes from, by its behavioural profile.

But, he added, there were still “nagging doubts” about whether all the differences are due to social learning. What scientists would ideally do is translocate chimps from one area to another to see if their behaviour spread. However, as this would be unethical, researchers have carried out studies in captive chimp centres.

In one, in each of two groups of chimpanzees a high-ranking female was shown a different technique to extract food from an artificial foraging device. When they had learned their technique, they were reunited with their group and the other chimps could watch. The different behaviours duly spread within each of these groups, forming a local tradition.

This posed the question, can techniques spread from group to group? A second experiment was conducted in which chimp groups seeded with different techniques could watch each other as they acquired a new skill. The researchers found these chimpanzees also had the capacity to spread behaviours from group to group.

This led Professor Whiten to ask what the process is by which culture is transmitted. Are chimpanzees imitators – copying what others do – or emulators who see what effect the tool can have then work out how to do it for themselves? “They may appear to be imitating – aping – others,” Professor Whiten said, “but are they, instead, working out how the world works and then reinventing the necessary technique, which is quite a clever approach?”

Further experimentation, however, in which chimps saw only the results of an action without being shown how to do it, found the animals were unlikely to be purely emulators. They could not work it out for themselves, Professor Whiten explained. By contrast they can watch another of their species perform a task and then copy it.

Despite this, could there be an element of both imitation and emulation in chimpanzee behaviour? Professor Whiten said he believed there could be a form of “intelligent imitation” that sat between the two ends of the spectrum. An emulation/imitation switching experiment was carried out with a group of chimpanzees and a group of young children.

The first step was showing both groups how to extract a reward – food for the chimp, a sticker for the children – from a black box. Both groups were given a tool – a stick – and went through a ritual that involved first poking the stick into the top of the black box and then into the front to extract the reward. The children and the chimps watched this and copied both steps. Two other groups then experienced the same, except that the box was transparent, so now it could be seen that the action in the top hole was ineffective. Surprisingly, the children continued to use the original technique, even though it seemed clear that poking the stick in the top was irrelevant. However, the chimps stopped copying the first of the two actions, realising it was irrelevant. This showed an element of intelligent imitation, Professor Whiten said.

What the children did has now been called “over-imitation”, Professor Whiten said. As a species, we are perhaps so deeply cultural that it pays to to operate a “rule of thumb” in which we copy most adult behaviour faithfully.

A similar rule of thumb is conformity – doing what a majority of others are doing simply because everybody is doing it. Professor Whiten outlined an example from an experiment with wild vervet monkeys, in which some groups were given nice-tasting pink food and horrible-tasting blue food. Other groups were given the opposite. The monkeys learned to eat the nice food and leave the horrible food.

Four months later, the coloured foods were brought back, but now with no nasty-tasting additive, and the new crop of infants all copied their mothers in eating only what they perceived to be good food, even though both blue and pink foods were now perfectly edible – an example of strong vertical cultural transmission.

However, male vervet monkeys can, and do, switch groups as they mature. When they did this, despite what they had learned previously, they also switched their preferred colour of foods – an example of how the conformity rule of thumb works. “When in Rome, do as the Romans, particularly if you are a vervet monkey,” said Professor Whiten. “That’s conformity.”

So what is the difference between animal and human culture, Professor Whiten asked? Human culture is demonstrably cumulative and passed down through the generations, he said, building on what has gone before. Humans have progressed from stone tools thousands of years ago to 500 different types of hammer in Birmingham during the Industrial Revolution. “That’s what we can uniquely achieve,” Professor Whiten added.

But although humans may be at the pinnacle of culture, can any animals also accumulate culture? There is evidence that they can, Professor Whiten said. When chimpanzees hunt for termites, the elaborate tool set they use to extract the insects from deep subterranean nests cannot have been developed in one generation. There is the likelihood of cumulative culture, but it is minimal compared to the human case.

In conclusion, Professor Whiten asked why all this is important for animals and humans. First, it shows that as well as an inheritance system based on genetics, there is a secondary system, based on social learning. It also shows that although the culture of humans may be distinctive, quite rich foundations are shared with our closest relative – the chimpanzee – and other big-brained animals. In fact, more basic foundations of social learning are demonstrably widespread across the animal kingdom.