We have yet to explore the origins of these strong herding tendencies. We can look to behavioural ecology for evidence of the propensities towards self-interested and collective herding that we share with our animal cousins. And we can also look to evolutionary biology and evolutionary neuroscience to understand better how these responses have developed through our own evolutionary history. We shall explore these perspectives in the next chapter.
4
Animal herds
From the African plains to the Arctic tundra, huge numbers of animals all over the planet herd together to travel long distances. These animal herds are almost constantly on the move, escaping seasonal fluctuations in the weather and searching for new sources of food and water. Wildebeest, for instance, move together in enormous herds, often a million strong, as they make their 1,800-mile trip from the Tanzanian Serengeti to the Kenyan Masai Mara in the north, and then back again, chasing rainfall and fresh grass. Staying in one place risks death from starvation or thirst, but migration is also perilous. The wildebeest have to cross crocodile-infested waters and navigate other dangers. By herding together, the wildebeest balance the threats. The herd provides protection and increases the wildebeests’ individual chances of survival, at the same time helping to ensure the survival of the species.1
We share with other animals a surprisingly wide range of similar instincts to herd in groups. Why have we and many other species developed such a strong and symbiotic relationship with others around us? In this chapter, we shall explore insights from behavioural ecology and evolutionary biology to discover what lessons we can learn from the animal kingdom about the social instincts we share with many of our animal relatives.
Figure 5. Migrating wildebeest: herding together to survive the crocodiles.
Leopards versus wolves
Previous chapters have explored the differences between self-interested herding and collective herding. Just as our interactions with the groups around us are determined by differences in our characters and inclinations, so too are the social interactions between other animals. Sometimes animals are solitary. Sometimes they form coalitions in groups, for mutual benefit. Sometimes individual animals sacrifice themselves for their group and/or species.
Taking a closer look at the characteristics of leopards and wolves will illustrate some of the contrasts between the different types of human behaviour that we first outlined in chapter 1. There, we saw that economists often assume that our worlds are populated by a special type of individualistic, self-interested and self-contained agent – Homo economicus. Homo economicus can act independently of others because they are coordinated not by direct social interactions but by the Invisible Hand of the price mechanism. Given that herding is ubiquitous in the animal kingdom, especially amongst mammals, it is hard to think of any animal as self-contained as Homo economicus. Snow leopards might be the closest example. Fewer than 9,000 survive in the wild, and they are solitary creatures, living their lives in the mountainous alpine wilderness to ensure their own survival, without much contact with others of their species except when reproducing and defending their territories. Very few of us inhabit such solitary lives.
More sophisticated economic models capture the benefits we gain as self-interested individuals by cooperating and collaborating with others. We can learn from the herd, be protected by the group, or gain something tangible from collaborating with our fellows. Altruism plays no role in this. With self-interested herding, each individual animal prioritises its own needs and desires by collaborating with groups to ensure a better outcome for themselves. Such coalitions are common in the animal kingdom. When wolves hunt as a pack, for example, each individual wolf benefits from the coalition they join. Like the hunters in Rousseau’s stag hunt game, introduced in chapter 1, wolves can catch much bigger prey when they operate together.
Linking with some of the insights about herding heuristics that we explored in the previous chapter, some behavioural ecologists have shown that pack dynamics are characterised by simple heuristics. Cristina Muro and her research team created a computer simulation in which wolf avatars hunted virtual prey. The only information available to the virtual wolves was the location of the prey and the other wolves. The simulation incorporated two basic rules: the wolf avatars would not risk their lives, only moving towards the prey as close as was safe; and once each wolf had reached this safe distance, it was programmed to move away from the other wolves. Apart from this, all the wolf avatars were identical and autonomous. Muro and her team discovered that the patterns generated by the computer simulations closely mirrored the behaviour of real wolf packs. Previous studies had suggested that complex hierarchies and forms of communication enabled wolves to hunt effectively. Muro’s research suggested something simpler. In coalitions, wolves use simple rules that further their own interests, and in the process act in the interests of the wolf pack. If all the wolves hunt effectively together, then each individual wolf will benefit.2 The lessons can be extended to self-interested herding, supporting the idea that human coalitions may also be using simple heuristics and rules of thumb to ensure they gain as individuals from the collaborations they develop with others, with concomitant benefits for the group as a whole.
The social lives of penguins and dragons
Self-interested herding is seen in other animals too, not just mammals and sophisticated pack hunters. In fact, herding through social learning is endemic in the animal kingdom.3 Just as economists have suggested that we watch others when deciding which restaurant to pick, behavioural ecologist Étienne Danchin and his team postulated that animals glean important social clues about where to find food and mates from watching and copying what other animals are doing.4 We described one specific example of this social learning in the introduction: quolls avoid eating poisonous cane toads because they have been taught this behaviour by their parents, or observed it in other quolls. But social learning is not confined solely to mammalian and marsupial species.
The Adélie penguins of the Antarctic are stuck in the middle of the food chain: they eat krill and in turn they are eaten by leopard seals. A penguin hunting for food risks being hunted and eaten itself. Social learning is the individual penguin’s best strategy: each penguin waits to see whether the other penguins jump into the sea or not. Eventually, one penguin who is brave or hungry enough to take the risk makes the first leap. The other penguins watch to see how this penguin fares beneath the waves before judging if they should jump into the ocean too. If the first penguin survives, then the others herd behind, their collective behaviour determined by the prior penguin’s fate.
Animals we might usually think of as less sophisticated, such as lizards, also share a knack for social learning. An international team of researchers led by Anna Kis from the University of Lincoln studied bearded dragons living in the deserts of Australia. By observing fellow lizards, the bearded dragons learnt to retrieve food by opening a trapdoor – a relatively complex cognitive task.5 Just as the penguins and lizards got a good meal after engaging in a process of social learning, so a similar process is at work when people choose restaurants: we infer something about the quality of different restaurants from observing other people’s choices.
Angry birds
Self-interested herding also provides protection, as when crossing a busy road with a large group of other pedestrians rather than singly. This herding has two dimensions – animals copy each other, and they group together – and we can see examples of both used by animals to escape predators. The simplest types of copying for safety involve camouflage. The dusty dottyback, a copycat reef-fish living in the Indo-Pacific coral reefs, is able to change colour quickly to mimic surrounding fish, and this helps to reduce detection by predators.6 This in itself is not herding – but a similar effect of visual camouflage is achieved when many animals come together en masse. Predators struggle to focus on one target when lots of targets are gathered and moving together. Behavioural ecologists explain this as a dilution effect. T
he individual prey sought by predators is diluted within a large herd, making it hard for the predator to pick off lone targets easily. Within a herd, individual animals are less vulnerable.
Animals form coalitions, not only because packs of animals are better hunters together than alone, as we have seen, but also to protect themselves. Groups of animals can defend themselves effectively when they consciously work together. Meerkats, for example, are often observed taking it in turns as sentinels, watching out for danger.7 Black-headed gulls and other birds form coalitions to warn other birds about risks, and sometimes come together in a mob to attack predators.8 Domestic cats have experienced these tactics, including our cat Hobson. When he immigrated to Australia, his first experience of an antipodean backyard was not much fun. Hobson was spotted by a lone myna bird, whose piercing squawks soon drew five more birds and they all swooped down on him in formation, Hitchcock-style, and scared him indoors. The lone myna bird had instigated an impressive and clever coordinated attack.
Herding cows
These more concrete and objective benefits underlying self-interested herding run alongside unconscious influences encouraging us to join others in groups. We have seen that there are many sensible reasons for humans and other animals to gather together in groups and herds. These motivations for herding clearly help each selfish individual animal to survive, and so can be explained as a considered choice, consistent with Daniel Kahneman’s analysis of slow System 2 thinking styles.
Other forms of herding are not so easy to explain directly in terms of either System 2 thinking or survival chances for the individual. This brings us to collective herding, which, as we explored in the previous chapter, seems to be more consistent with Kahneman’s System 1 thinking, driven by instinct, impulse and unconscious motivations. We succumb to peer pressure, and experience intangible psychological satisfactions from our sense of belonging with others, even when we can see no clear, objective purpose to joining in a group – at least not from the perspective of our own self-interest.
If someone asked you to think of an animal herd, there is a good chance that you would think of cows. Cows are the archetypal herding animals, but they do not herd together out of blind stupidity. Cows are highly social animals with complex social hierarchies. They exhibit signs of stress when separated from their herd and they form strong bonds with other individual cows – in much the same way as humans identify single individuals as their best friends. In one study, behavioural ecologists measured the stress levels of cows by recording their heart rates and blood levels of cortisol (the ‘stress hormone’) in two scenarios: when the cows were put in a pen with an unknown cow, and when they were penned with their ‘best friend’. Cows showed much-reduced signs of stress when they were with their friends.9 What the cows experienced holds more generally, too, across most mammalian species. Like humans, many mammals feel less stress and more psychological satisfaction when they collect together with others they know.
Evolutionary influences
One of the mysteries of herding is why some individuals herd and copy others when it is not obviously in their best interest. Evolutionary biology can help to explain this anomaly because it does not focus on the individual animal, or even groups of animals. The selfish individualist is just a bit-part player when wider evolutionary imperatives are at stake. Whether herding is conscious and self-interested or unconscious and collective, it has evolved to maximise the chances of survival, not of the individual but of the species as a whole.
Charles Darwin’s 1859 magnum opus On the Origin of Species provides a starting point in understanding the evolution of social (and anti-social) instincts in the animal kingdom. Different species have evolved characteristics that give them an adaptive advantage, helping them to thrive in their natural habitats. If they survive long enough to reproduce then the whole species is more likely to survive too. If the environment changes, however, then some species will die out because they no longer have an adaptive advantage in the changed environment.
Evolutionary biologists develop Darwin’s ideas about natural selection to explore the different ways in which our outward behaviours have evolved in response to environmental constraints and obstacles. If our behaviour evolved a very long time ago, then it is not surprising that we do not always consciously understand why we behave in the ways we do. To better understand what drives us, we can make a distinction between proximate causes and distal causes. Proximate causes are the incentives and motivations that determine our day-to-day choices. We enjoy some foods more than others because the foods we prefer tap more effectively into the physiological systems that process our perception of reward. Distal causes explain the ultimate cause of our behaviour in evolutionary terms, as manifestations of our species’ evolutionary fight for survival. To explain the difference between these proximate and distal causes, we can turn to the example of sugar. Many of us eat too much of it. We buy and eat sugary foods because we find them satisfying. Sugar causes physiological changes that trigger rewarding bodily sensations within us, and if our bodies signal that something is rewarding then we are more likely to want more of it. This is the proximate cause of our tendency to overeat sugary foods. The distal causes are not about our immediate, day-to-day, visceral responses. They are much older, and link to ancient mechanisms which evolved in our species hundreds of thousands of years ago. We evolved to forage for sugary foods because this helped us to find sufficient nourishment in a primitive world where nutritious, energy-full food was hard to come by. Enjoying and effectively digesting ripe fruit motivated us to find the rich energy sources scarce in primitive environments. We also evolved to store this energy as fat because, in primitive environments, we might have had to wait a long time before we found new sources of nutritious food. Those who liked and got enjoyable sensations from sugar were more likely to eat sugary foods, lay down fat stores and, when the famines came, survive to reproduce. These ancient mechanisms are the distal cause of our love of sugar.
How does adaptive advantage manifest itself in human and animal behaviour? Both self-interested herding and collective herding can be explained in terms of evolved mechanisms that served, and perhaps still serve, important purposes in increasing our chances of survival.10 Herding is a form of adaptive advantage and it has distal causes. These distal causes reinforce the proximate causes that have implicitly formed the foundation of our analysis of herding so far.
In modern contexts, we learn to associate herding with reward and we are consciously and unconsciously motivated to join with others because we find it satisfying in some way. Self-interested herding is rewarding because it helps us to get what we want. Collective herding gives us less tangible, more unconscious psychological satisfactions, but these are just as crucial. Most of us enjoy being with our friends and family. Most of us are happier being part of some sort of group. We are more likely to join with other people and enjoy their collective support and safety. Whether motivated by self-interest or more diffuse and less conscious rewards, these are the proximate causes of self-interested and collective herding.
The distal causes reflect the value groups had in helping our ancestors survive in difficult primitive environments. Herding, whether self-interested or collective, is an inherited, innate strategy that we still use today. By observing and copying others our ancestors developed the best strategies for foraging, escaping predators and finding mates.11 Our ancestors adapted to their environment using herding as a strategy to increase survival chances. They went on to reproduce and so passed on these herding instincts to their descendants, and thus our herding instincts evolved.
This evolutionary perspective also suggests that adaptive advantage is what self-interested herding and collective herding have in common. From an evolutionary perspective, both forms of herding are as much about increasing the chances of survival for the group and species as they are about helping the individual. Reconciling collective and self-interested herding from this perspective of evolutionary advantag
e also allows us to see that, for humans, both forms of herding reflect our social instincts and inclinations. We evolved our sociability and the common (but obviously not universal) aversion to aggression because, in this way, our ancestors’ small communities had stable social structures and were better able to survive. Conformity served an important purpose in the evolution of our social instincts and herding tendencies, but in today’s social media-saturated landscape, this conformity is perverted by overconnectedness. Conformity has been magnified far beyond what used to make evolutionary sense in primitive environments.
Self-sacrificing slime moulds
In evolutionary biology, the self-sacrificing individual is dispensable to its species and does not get a chance to reproduce its genes. We might think that cooperation and self-sacrifice are phenomena seen only in sophisticated animal species, reaching their apotheosis in humans. In fact, both cooperation and self-sacrifice are observed in relatively primitive life forms too, for example in the slime mould species Dictyostelium discoideum, a form of social amoeba. Different slime mould cells will cooperate even when they have different genotypes (different combinations of genes). This is unusual because most multicellular organisms are composed of cells from the same genotype, which makes evolutionary sense. From the perspective of the survival of the fittest, cells of the same genotype do not need to compete for resources because whether the cells survive or their genetically identical clones do, either way the genotype survives. The priority is the survival of the genes, not the individual cells. Slime moulds are unusual because they cooperate even when they do not share genes. So the survival of cells with one genotype is at the expense of cells with another genotype.12
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