Something I get asked occasionally as someone who works on animal cognition is ‘what makes humans different from other animals?’ This is a tough one, because, as humans are of course animals, it is much easier to list the similarities between us and other animals in our behaviour and how our brains process things than the differences. Furthermore, whether you are a philosopher, psychologist or biologist, you might tend to answer this question quite differently. However, at least four main components of being human include an ability for open-ended language, theory-of-mind, self-awareness (although see this) and culture. In addition to these, some people would argue for a number of other abilities including episodic memory, planning, morality, teaching, causal reasoning and insight, all of which can either be found in other animals in some form, or are difficult to unequivocally demonstrate in either human or non-human animals.
Although culture is considered a hallmark of ‘being human’, this too is difficult to consign strictly to our species. In our day to day language, we use the word ‘culture’ in many different contexts and assume others know what we mean (I have to admit that since moving to the US I probably comment on ‘American culture’ on a daily basis, normally with reference to the lack of knowledge about how to make a good cup of tea). For biologists, culture can roughly be thought of as consisting of three stages. The first stage is the ability to learn from or copy other individuals (‘social learning’). This has been found in a wide variety of animals, including birds, dogs, tortoises, bumblebees, dolphins, and chimpanzees to name a few. If this learning from other individuals then spreads throughout a group, it can become a ‘tradition’, where many individuals within a particular group are displaying the same behaviour. For example, perhaps you copy what your friend is drinking at the pub – this would be social learning. Before you know it, everyone is also drinking the same drink just because everyone else is (I have a theory this is how jägerbombs got so popular), and this behaviour has become a tradition. Indeed, jägerbombs became so much of a tradition in one city in the UK that they had to be banned. Some people would equate a tradition with a culture, whereas others would argue that a group of animals need a combination of many different traditions to constitute having a culture. So, if a group of people copied each other’s drinking habits, followed by what they ate afterwards (let’s say a deep-fried mars bar), and then embarked on some vocal imitation in the form of some drunken singing, this would constitute a culture (it might perhaps be called a drinking culture). There is also discrepancy in how the behaviour has to be socially learned: some would say that only by imitating or being taught a behaviour from another individual is enough to warrant the term ‘culture’; just ordering that jägerbomb because you saw one sitting on the bar when you arrived isn’t enough to be considered the start of a tradition.
Working out whether an observed behaviour in a group of animals is evidence of a culture and how it arose isn’t an easy task. Because animals can’t tell us how they’re learning from other animals, or why they adopt particular behaviours, scientists need to use carefully-designed experiments and observations to tease apart what might be causing a particular behaviour found in a group of individuals.
Two new studies, both published in Science, have highlighted the importance of social learning and culture in two very different animals: vervet monkeys and whales. The study with vervet monkeys is unique in that it’s the first time that non-human primates in the wild have been shown to adopt a local tradition, instead of using their own individual knowledge. In humans, we know that we will often adopt what other individuals are doing when we enter a new group. For example, when you travel to a foreign country you might copy where the locals are eating, as you presume that their local knowledge is better than your own, or perhaps just because you want to fit in. It seems that vervet monkeys might do the same thing.
To look into this, Erica van de Waal, Christele Borgeaud and Andrew Whiten established a local ‘tradition’ in four groups of wild vervet monkeys in South Africa, totally 109 individuals. To do this, they gave each group of monkeys two different trays of corn, one dyed blue and one dyed pink. For two of the groups, the pink corn was made to taste bad, and for two of the groups the blue corn was made to taste bad. Over time, the monkeys in these groups learned to avoid the distasteful corn, and only eat the other colour.
The food was then removed, so that the young monkeys could mature without having ever encountered the coloured food themselves. Four to six months later, once they were old enough to eat solid food, the two colours of food were reintroduced to the groups, this time without either of the foods being distasteful. The adults that had experienced the distasteful food before generally still avoided that food, even months on. The only cases where the food that had been distasteful before was eaten was by lower ranking males when they could not access the other food, due to it being monopolised by more dominant individuals. All 27 of the young monkeys that had never experienced the coloured food before copied their mothers’ choices. Just like with human infants, the young monkeys copied what their mothers did, as at this young age this is most likely to be the best strategy for survival.
However, the really interesting result comes not from what the young monkeys did (as cute as they might be), but from some of the males in the group. In vervet monkeys, the groups they live in consist of an alpha male, subordinate males, several females and their offspring. While the females never leave their family group, the males will leave once they reach sexual maturity, and migrate to other groups, often multiple times, with the aim of eventually becoming an alpha male. In this study, ten males moved from groups where they had been eating one type of food into a group where they ate the other (six from blue to pink, and four from pink to blue). Once they joined the new group, the majority of them abandoned their preferences they had had in their previous group, and now adopted the preferences that this group had. This conformity to the local norm, even when it goes against their own knowledge, shows the importance of learning from others in this species. Whether this is social conformity (wanting to fit in with what the others are doing) or informative conformity (copying others because they may have information that is useful to you, like which of the local foods are toxic) can’t be told from this data alone.
To add an extra intriguing twist, the only male that did not adopt the local preferences was already the dominant male in his new group. When I spoke to van de Waal about this, she described it as ‘really quite puzzling’, because before the male ate himself, he saw the dominant females and their offspring eating, ‘so it’s not like he was the first one to come to eat, he had seen what the others had been doing’. I asked van de Waal whether the finding that this dominant male didn’t copy the others could be evidence of social conformity (just wanting to fit in) rather than informative conformity (copying others because they probably know something you don’t- in this case avoiding potentially toxic food). Van de Waal conservatively said, ‘the sample size is one. Maybe he’s just a stupid male that doesn’t look at what the other group members are doing… in order to know whether this is instead related to social conformity we’d need to have plenty more cases like Lekker [the dominant male] to say, when you’re dominant you don’t care.’
Like van de Waal says, it will take more research in the future to definitively say whether this is social conformity, informative conformity, or a combination of the two. What this study has shown us is that these primates have the ability to disregard what they have learned themselves in favour of the knowledge of other individuals. It's hard not to look at these animals without thinking about ourselves. Indeed, the willingness to adopt local traditions may be the foundation of culture in human society.
This article is the first part of a two-part series on animal culture. The second part discusses another new exciting finding from humpback whales.
All vervet monkey photos taken by Erica van de Waal
van de Waal, E., Borgeaud, C., and Whiten, A. (2013). Potent Social Learning and Conformity Shape a Wild Primate’s Foraging Decisions. Science 340, 483-485.