Copycats and Contrarians

by Michelle Baddeley

  In slime moulds, what form does cooperation take? Evolutionary biologist Paul B. Rainey studies Dictyostelium discoideum and has developed some interesting ideas about how and why slime moulds cooperate. Slime mould cells live in soil where they feed off the bacteria released by decaying leaves and animal droppings. In good times, each individual cell takes the form of a single-celled amoeba and moves around randomly, hoovering up bacteria. Sometimes, however, the environment throws up challenges. Nutrients become scarce. Then, chemical signals in the amoeba trigger a process of metamorphosis. The individual cells aggregate and self-organise to become a multicellular slug. Some of the amoebae metamorphose into the slug’s stalk cells. Other amoebae form spores at the tip of the stalk cells and these are quickly released into the environment, ready to thrive when environmental conditions improve again. The stalk cells are not so lucky – they wither and die. The mystery here is why a single-cell organism would sacrifice its own reproductive chances to form the stalk cell of a multicellular organism – a dead-end in evolutionary terms. The stalk cells’ genotype may die out at the same time as the stalk cells because these cells have no chance to reproduce. What if the negative environmental changes turn out to be temporary? In this case, each slime mould cell would have had a better chance of survival and reproduction if it had remained as a lone amoeba. Paul Rainey postulates that the single-cell slime moulds are evolutionarily programmed to balance risks. If they do join the other cells then they may land up as stalk cells. But, if they are luckier, they may form part of the slug that can reproduce via the release of spores. Rainey argues that the fate of the self-sacrificing slime mould cells is essentially bad luck.13 Some slime mould cells are winners, others are self-sacrificing losers. Perhaps we share more in common with slime moulds than we might imagine.

  Slime moulds illustrate the point that cooperation sometimes emerges not because the individual animal benefits, but because it helps a species to survive. Ants, too, are a highly cooperative species and they exhibit similar behaviours to self-interested human herding, as we explored in chapter 1. Ants also engage in social learning. The economist Alan Kirman was interested in the connections between animals’ social behaviour and economic theory. He drew on observations from entomologists who had noticed that ants do not forage evenly across different food sources. When they are choosing between two sources of food, armies of ants tend to focus intensively on one or other of the sources. To explain this phenomenon, Kirman developed an ‘ant model’ of social learning. Kirman argues that the ants’ copying behaviour is a manifestation of their recruitment activity. A single ant discovers a new source, they transfer this knowledge to other ants via an exchange of chemical signals, and in this way ant armies are recruited to forage one food source to the exclusion of another. There are benefits for the ant group if one food source is exploited more intensively than another because, by cooperating, the ants can forage more effectively. Eventually, the armies of ants will switch to the other source, perhaps when the first source has been depleted sufficiently. This social coordination helps the whole ant colony to survive. Apparently anomalous ant behaviour, difficult to explain from one ant’s perspective, has an explanation that links to survival for the entire ant colony.14

  Sociable animals

  High levels of sociality and social functioning are shared across the animal kingdom. The biologist E.O. Wilson described some exemplars of social behaviour, the eusocial animals, which are characterised by their social sophistication. Eusociality is seen across a diversity of species, including ants, bees, wasps, termites and naked mole rats.15 The concept of eusociality links to the idea that groups are favoured over individuals. Eusocial animals possess a sophisticated social awareness and they share highly developed instincts for cooperation. Eusocial animals practise ‘kin selection’: individual animals sacrifice their own chances of survival in order to favour the reproductive success of their relatives. In the organisation of eusocial animals’ communities more broadly, altruism is a powerful force. Eusocial animals form strong, sometimes monogamous pair-bonds. They share caring for their offspring not only with their partners but also with other adult animals. Eusocial animals live in extensive colonies populated by overlapping generations of individuals. Within these colonies, there is a division of labour across different tasks, some of which eliminate an individual colony member’s potential for reproduction (the worker bee is a well-known example).16 Each individual animal has no independent purpose, and the colony functions more like a single animal.

  The concept of eusociality is fascinating from a social science perspective too. It takes us back to some of the descriptions of mobs and collective herding that we looked at in chapter 2 – including the influential work of the psychologist Gustave Le Bon. Le Bon used a biological analogy to describe mobs. He explained how mobs form as a human body forms. Like the cells within a living body, the individuals in the mob have no independent life of their own. For Le Bon, the mob is like a

  being formed of heterogeneous elements, which for a moment are combined, exactly as the cells which constitute a living body form by their reunion a new being which displays characteristics very different from those possessed by each of the cells singly.17

  Le Bon’s insights suggest a way to build a link between the psychological and the biological explanations for grouping and herding. The psychology that brings mobs together has its corollary in behaviours observed in eusocial animals, in which the individual animal has no identity of its own, in the same way that the individual cells of a body have no independent existence. The concept of eusociality can also illustrate the differences between collective herding and self-interested herding. Collective herding is not always and obviously in the individual animal’s self-interest, but it does work well from the group’s perspective.

  Teaching orcas

  As we saw above, gathering for safety is a self-interested choice, but animals herd together for other reasons besides self-interest. From the perspective of the whole herd, the safety of individual animals also increases the chances of survival for the group as a whole. In this way, collective herding overwhelms each animal’s individuality. Large animal herds often have a nature that cannot be explained solely in terms of the individual animals that comprise them. Like Le Bon’s human mobs from chapter 2, the whole herd is something different from the sum of its parts. Wildebeest are a case in point. Individually timid, a herd of a million wildebeest gathered together makes an impressively loud noise.18 It is a frightening and powerful force, with a large and independent nature of its own.

  Social mammals also give us two examples of sophisticated social behaviours: teaching and culture. Orcas are one example. Orcas live their lives with their families, in ‘pods’. Yet, like humans, female orcas stop reproducing in mid-life. In evolutionary terms this is a puzzle. What evolutionary explanation might there be for older orca females to live such a long post-reproductive life? International teams of behavioural ecologists thought that post-reproductive orcas might be able to teach us something about human menopause, until recently thought to be simply an otherwise inexplicable modern artefact of advances in public health and medicine.

  Orca pods form matriarchal hierarchies. One much-studied pod is the J Pod, living in the Salish Sea, a network of waterways off the west coast of southern Canada and the northern United States. The J Pod was headed by the female orca J2, aka ‘Granny’, who had been studied by teams of behavioural ecologists ever since she was first photographed by Dr Ken Balcomb in 1967. She was the oldest orca known to humans, and is believed to have died in 2016 at an impressive age, possibly a hundred years old. She was in excellent health until her last sighting, in fact appearing much fitter than many much younger males. She probably had her last calf in her thirties or forties; certainly, she was never observed with a calf of her own during the last four decades of her life.

  Behavioural ecologists think that orcas like Granny who live long post-reproductive lives play a range of cr
ucial roles in orca society. One common theory is the grandmothering hypothesis, an idea used to explain why human females live so long after they have lost their capacity to reproduce. Older females without infants of their own can help younger females rear their offspring, increasing the survival chances of the whole group. In human populations, for example, there is evidence that children with grandmothers are more likely to survive longer.19

  There are social learning explanations too, consistent with some economists’ models of self-interested herding and social learning, but with an additional twist. Older orca females retain important social and environmental knowledge, and they teach this to the younger orcas, helping them to learn how to navigate their hunting grounds. This sharing of information is not just about younger orcas watching older orcas. Behavioural ecologists define teaching in terms of an individual incurring some cost to themselves in the process of imparting knowledge to others.20 Teaching is more sophisticated and complex than learning. Learning just requires one individual to observe another, and an animal being observed by a social learner is passive, not necessarily encouraging or even noticing that another animal is learning by watching what they do. Teaching, on the other hand, is a consciously cooperative process. Both teacher and student are actively engaged in the process of sharing information and knowledge. Behavioural ecologists also note that teaching involves a level of self-sacrifice. The teacher incurs ‘opportunity costs’. While they are teaching, they lose the opportunity to spend their time and effort looking after themselves, instead sacrificing their own interests to help another animal. Teachers may not benefit at all as individuals. Teachers do, however, help the group and therefore the species, so, from an evolutionary perspective, teaching serves an important social purpose. Teaching is certainly what Granny seemed to be pursuing in her later life. Lines of orcas would follow her during their salmon hunts. When Granny noticed younger orcas deviating from the path that she had set, she would hit the water with her tail, warning them to follow her. It was an interactive process.

  The role played by older orcas in teaching and social support is complex and nuanced. Researchers noticed that Granny’s bond with her son was particularly strong. Male orcas have a much shorter lifespan than the females, living to just thirty or so years whilst females commonly live beyond eighty years old. Like Granny, the surviving older female orcas in the J Pod also spent much more time with their sons than with their adult daughters. They shared salmon with their sons but not with their daughters, perhaps reflecting some ecological form of cost-benefit analysis. Supporting a son’s reproduction is less costly than supporting a daughter’s reproduction because sons mate with orcas from other pods, and those other pods carry the cost of the sons’ calves, so it makes sense to give sons preferential treatment. If a son survives for longer, then he is more likely to reproduce, and when his calves are born they will not be a drain on his mother’s pod’s resources. On the other hand, if a daughter survives to reproduce then the pod will bear the costs of raising her calf. The researchers’ actuarial calculations show that orca sons with living mothers survive for much longer than those without. When a mother dies, the mortality risk for her surviving son increases eightfold, whereas for a daughter it is much less.

  Animal cultures

  Culture is another phenomenon driven by our herding instincts and observed in numbers of social species, not just humans. Some of our evolved strategies reflect the evolution of culture over long periods of time.21

  The sociobiologist Richard Dawkins has worked on extending Darwinian evolutionary concepts into the social realm, as in his path-breaking 1976 book The Selfish Gene. In this book, Dawkins asserts that Darwinian principles operate beyond genes and in the social world too. Memes – the human social equivalent of genes – are the ideas that move between us all, via language for example. Memes are the essential building blocks of our social interactions. They are the ideas and norms replicating via a process of memetic contagion through cultures and societies.22 So, copycats are essential to this process. Although Dawkins’ views are controversial amongst modern scientists23 – the extent to which our destinies are formed by social institutions as well as our genetic makeup is a matter of dispute in sociobiology and evolutionary psychology – there is a basic consensus on how Darwinian principles of natural selection also apply in the social world.

  Cultural traditions form to bind societies and communities together, and cultural conformity helps species to survive. Herding plays an essential role in the transmission of culture and, in turn, culture helps to mould the social norms that reinforce animals’ instincts to herd and imitate. Cultural norms also form the social structures against which contrarians can rebel. Cultural norms have been observed in a number of species, including whales and dolphins.24 Behavioural ecologists have found that chimpanzee populations acquire local traditions in foraging for ants. Some chimps will use small sticks to collect a few ants at a time, eating the insects from the sticks. Other chimps will use a long stick and wait for many more ants to accumulate and then scoop them all into their mouths with their hands.25 Behavioural ecologists believe that different styles of ant-eating represent different forms of chimp culture.26

  Andrew Whiten, a psychologist from the University of St Andrews, devised an experiment to test whether cultural norms would spread through groups of monkeys. He and his colleagues studied 109 vervet monkeys living in the South African province of KwaZulu-Natal. In the first stage of the experiment two separate groups of monkeys were fed corn dyed different colours. One group was fed pink corn spiked with bitter leaves, and unspoilt blue corn. The second group was fed the opposite: their blue corn was spiked with bitter leaves and their pink corn was naturally appetising. The first group learned to prefer blue corn, the second to prefer pink corn. To capture whether the monkeys had learned from others, the researchers then observed the behaviour of twenty-seven baby monkeys born to the original monkeys. This younger generation was not exposed to any nasty-tasting corn. The researchers had given them the opportunity to enjoy both pink and blue corn, neither spiked with bitter leaves. So for the baby monkeys, they had no reason to favour one colour of corn over another – all the corn, whether pink or blue, was equally palatable. Even so, the baby monkeys copied their mothers in favouring just one colour of corn, either pink or blue.

  So far, all of this is consistent with the social learning models we have already explored. But then the researchers noticed something else as well. Ten male monkeys moved from one group to the other. Monkeys who had been brought up in the pink-corn-preferring group moved to the blue-corn-preferring group, and vice versa. These migrant monkeys very quickly acquired the cultural norms of their new group and shifted their preferences away from one colour to the other. These monkeys had not tasted spiked corn and had not been taught by their mothers to avoid a specific colour of corn. There was no obvious objective reason for these monkeys to change their preference from blue to pink corn, or vice versa, other than the social influence of the other monkeys around them. The researchers attributed the monkeys’ switch towards conformity with their new community to the power of cultural norms. Parallel phenomena have also been observed in humpback whales – with whales copying feeding traditions used by other whales, even though these were no more effective as hunting strategies.27

  Cultural differences have been observed in other – ‘lower’ – species too. To assess the influence of cultural differences in a more controlled way, behavioural ecologists have studied the migration routes and schooling patterns of a species of fish called the French grunt. The schooling behaviours observed in different populations persisted beyond the grunts’ lifespan. To understand why, the researchers took individual fish from one population and moved them to another population at a new site. Using their social learning skills, the new fish quickly adopted the traditions of their fellows in terms of feeding sites and migration routes. More interestingly, this experiment also allowed the scientists to exclude the possibil
ity that these foraging traditions were a product of environmental or genetic factors. When the fish were moved to a new site but were given no opportunity to observe the behaviour of the population of fish there, they did not adopt the same foraging patterns, but instead developed their own.28 The researchers concluded that the copying behaviours were not simple instincts, formed in response to the characteristics of resources available at different sites. They were social traditions paralleling humans’ different cultural norms and traditions, and driven by the same types of copying and herding behaviours.

  The evolution of human herding

  We have seen that evolutionary biology illuminates the social instincts that we share with other animals. So what are the key differences if both self-interested herding and collective herding have adaptive advantages in common? Evolutionary neuroscience provides us with a potential explanation, and can tell us more about humans’ evolved social instincts, including our instincts to herd.

  Modern humans, Homo sapiens, evolved around 200,000 years ago and were characterised not only by their opposable thumbs and upright posture but also by their large brains. According to some neuroscientists, our social instincts paralleled the evolution of our brains – which some biologists attribute to our high levels of sociality, a characteristic shared with other mammals.29 Evolutionary neuroscientists postulate that our brains have three distinct parts, each representing different stages in our evolutionary development. The brain stem is a remnant of our reptilian brain, the limbic system is a remnant of our mammalian brain, and the neo-cortex (of which our prefrontal cortex is one component) is an evolved feature of modern hominid brains.30 This schema is controversial. Some neuroscientists argue that evolutionary models of the brain are too simplistic. This simple idea is powerful, however, in suggesting that our behaviours reflect an interaction of primitive and sophisticated responses, each driven by different neural areas with different evolutionary histories.