The Social Lives of Animals

INTRODUCTION

Man is by nature a social animal; an individual who is unsocial naturally and not accidentally is either beneath our notice or more than human. Society is something that precedes the individual. Anyone who either cannot lead the common life or is so self-sufficient as not to need to, and therefore does not partake of society, is either a beast or a god.

—Aristotle

In the rainforest of northern Trinidad, an abandoned house is gradually being reclaimed by nature. Lianas wrap themselves about its walls, while saplings venture through broken windows and push their roots through crumbling masonry. Animals, too, have seized the opportunity and have moved in. At the heart of the house, beneath a sagging staircase, a musty space provides refuge for an animal with a chilling reputation: the vampire bat. During the heat of the tropical day, the bats huddle in the cool seclusion of their lair, resting and gathering strength for the coming hunt. As night falls, they stir into wakefulness. Their hunger sharpened by the daytime fast, they take wing to scour the forest in search of blood. They’re seeking sleeping mammals, those that have dropped their guard. Any mammal might be targeted, from forest deer or peccaries to domestic livestock or even an unwary person.

In a forest clearing, a vampire circles cautiously above a tethered goat. The goat is unaware of the bat’s presence, the faint noise of fluttering wings lost amid the many sounds of the Trinidadian night. Stealthily, the bat alights on the ground and scurries in its ungainly fashion toward its victim. It makes an incision in the goat’s flank, cutting through the skin into flesh with scalpel-like teeth. As the blood begins to flow, the vampire drinks greedily, consuming as much as a third of its own weight before the meal is finished. Once satiated, it leaves as silently as it arrived—and with its prey none the wiser, despite a wound that continues to flow because of the anticoagulants in the bat’s saliva.

Back in the safety of their dilapidated shelter, the bats who have had a fruitful night can begin to digest their meal. But not all the returning hunters have been successful. The large mammals they seek as prey are few and far between, and many of those that can be found are alert to the threat posed by the bats. For these hungry individuals, time is running short: failure to feed on just three consecutive nights can mean starvation and death. Yet this is where the vampire bat’s behavior belies its sinister reputation. Should one of its roostmates go without a meal, a well-fed bat will step in. Almost like a parent bird tending its chicks at a nest, the successful hunter provides for its less fortunate companions by regurgitating some of its blood bounty. And the next time tonight’s lucky bat goes without, it can count on its companions to return the favor. In their struggle for survival, the bats have each other’s backs, a strategy that works well for all in uncertain times.

Cooperation such as this is a hallmark of social animals. Though the extent to which vampire bats engage in each other’s welfare is by no means universal, almost all animals that live in groups provide some degree of support to one another. At the most basic level, this might manifest in the form of what’s known as social buffering. Essentially, this means that social animals, from tiny krill to humans, gain a clear and measurable benefit simply from being near their own kind and being able to interact with them. They are buoyed by the presence of others, supported by the collective. For our own species, this has never been more important. The recent experience of lockdowns and social distancing prompted by the COVID-19 pandemic disrupted our connections and enforced solitude upon many. Little wonder, then, that a mental health crisis has emerged in the wake of the pandemic. Alongside this, the march of technology is gradually disposing of many of the day-to-day interactions that were once part of normal life. Self-service checkouts, automated tellers, metro ticket machines: all of them replace face-to-face encounters, while headphones lock us out of everyday discourse and the web replaces real-time connections with virtual ones.

The question is: Does this matter? I argue that it does. We humans are intensely social organisms. Our lives are interconnected with networks of friends and loved ones, and each of us plays a role in broader societies that define and shape our patterns of behavior. This social tendency has enabled us to achieve far more than could ever have been possible if we were solitary creatures. Moreover, the far-reaching effects of living alongside one another include everything from the development of spoken language to the ways that we interact with one another in daily life. It even provided the basis for the evolution of the intelligence that is the hallmark of our species. Ultimately, our instinct for cooperation has provided the foundation for human civilization. But this instinct didn’t begin with the first people; rather, it was something intrinsic to us, a legacy inherited through our shared ancestry with the animals that we live among.

Countless other animals have adopted sociality to solve the problems that life poses. Living in groups provides the platform for the success of species throughout the animal kingdom. What’s more, we can trace direct and important parallels between our own societies and those of the animals with whom we share the planet. These parallels, echoes of our own evolutionary journey, help us to appreciate how sociality shapes our lives so fundamentally. By understanding animals on their own terms, we can understand ourselves, and our societies, so much the better.

Watching animals and studying their behavior has always been my greatest passion. I’ve spent countless hours at it. Once, as a child, I lay on my front and peered into a tiny stream for so long that a stoat mistook me for a log and decided to come for a drink on the opposite bank, within just inches of my prone figure. When I looked up and came face to face with it, the astonished stoat leapt so high in the air that even its fleas applauded.

But being enraptured by creatures is one thing. Turning it into my life’s work seemed impossible. Lacking the confidence to pursue my animal ambitions, and leaving school with a motley assortment of underwhelming qualifications, I drifted into an underwhelming office job. There I stayed for five years, stuck in a rut of my own making. I might have continued much in that vein were it not for the intervention of my manager. It took him a long while to realize the extent of my ineptitude, but once he did, he sacked me.

Forced to find a new direction in life, I pondered what to do next. Could I put my meager skills to use looking after the exhibits at Scarborough Sea Life Centre? It wasn’t my dream job, perhaps, but the idea of working with animals, in whatever way, conjured happy memories of afternoons mucking about in rock pools or turning over logs to look for bugs. The Sea Life Centre needed someone to tend to assorted urchins, prawns, and starfish. I reached out to them (the management, not the animals). They reached right back to flick my ears. “You need a biology degree to scrub algae off an old lobster” was the gist of their reply.

At least now I knew what was needed. I enrolled at University of Leeds, where I tried to find meaning in rote learning amino-acid structures. Two years in, just when I was reaching a crisis point in my quest for the degree, I met a kindred spirit in the shape of Jens Krause, one of the academics at Leeds. Here was someone whose curiosity for the living world was as great as my own. Not only that, he was making a wonderful career of studying the behavior of animals. All of a sudden there was a point to it all. I saw for the first time what I wanted to do. Everything was laid out before me, even if the path wasn’t always easy. I like to think that the animals of Scarborough’s fourth-busiest attraction wished me well, and have found it in their tiny hearts to forgive me for abandoning them.

The point of these reminiscences isn’t just to show you, dear reader, how daunting I found it to be to admit to myself that I wanted to be a scientist. The point is how the purpose of my life became clearer just by virtue of coming into contact with another human being who shared my interests. The realization that you need other people in order to help you understand your own mind and what you want from life is a common experience for many. Unfortunately, what is also common is the human tendency to undervalue this very need, and not to appreciate that community and collaboration are frequently the bedrock of progress and a meaningful existence.

The one aspect of human behavior that has contributed more than anything else to our remarkable success story has been sociability—the ability to live and work alongside one another in groups, to cooperate. It has allowed us to find solutions to problems from prehistory to the modern day, to safeguard ourselves from predators and to hunt our own prey, to share information and learn from one another, to explore the globe and overcome a multitude of challenges. Since the first modern humans appeared in Africa around 300,000 years ago, society has changed and evolved with us. For perhaps the first 290,000 of these years, we lived as hunter-gatherers in small, nomadic bands. Then, as the world emerged from the most recent ice age, the warming climate and human ingenuity ushered in the Neolithic Revolution, and we began to live for the first time in small settlements as agriculturalists. From there, human civilization developed apace, and as it did so, we had other species accompanying us, such as cattle, goats, and dogs, that were all social animals like ourselves.

Modern human society is a mix of culture and relationships, of law and conflict, and is composed of families, communities, cities, and nations. We might imagine that in this regard we stand distinct from other animals. Yet while our society is certainly different in character from theirs, in many ways it is not unique. Many social animals organize themselves in similar ways. Moreover, they were doing so for millions of years before we appeared. Our social instinct, our society, has an ancient lineage, and we have much in common with other social animals. In a world seemingly full of individuals navigating cityscapes and isolation, we arguably need to understand these parallels now more than ever. Why? Because they are a reminder of the fundamentals that shape behavior. Studying the social behavior of animals not only provides insights that are valuable in their own right, but also sheds light on the evolutionary basis of human sociality.

Take language, for example. Communication is an essential facet of living in groups and interacting within a social milieu. The more complex the web of relationships, the more important language becomes. It allows us to navigate our communities, to negotiate, to foster and develop relationships, to teach and instruct. In addition, it has enabled us to assemble into coherent, cooperative teams, from the hunting parties of our ancestors to the organizations and institutions of the modern day. Our cultures, our social behavior and social norms, the rules by which we interact, and the moral frameworks in which we operate developed alongside language. And while human language and culture may not look exactly like any language or culture found among other group-living animals, many animals do communicate with each other, whether it’s bees with pheromones or whales with clicks and whistles. By learning something about how other animals live together and communicate, we can understand ourselves a little better.

In another example, think of how we feel about our closest personal friendships. These feelings not only operate at the level of consciousness, but also permeate our physiology, via hormones that cushion us from the worst effects of stress. Those who engage in an active social life and feel close to friends and family members tend to live longer than those who do not. It should come as no surprise, then, to learn that the same may be said for other gregarious creatures. While the assistance that vampire bats offer to their roostmates provides a compelling example, it is the intangible, enduring support garnered simply through interacting with a community that provides the most powerful aid to social animals. Here again, we can appreciate the common links between humanity and the rest of the animal kingdom.

This appreciation has been slow in coming, but scientific research over the past half century has forced a reappraisal of our understanding of animal sociality and cooperation. In recent years, technology has afforded us remarkable insights into the behavior of animals in swarms, schools, flocks, herds, and even our own crowds. These insights have shown us that there are often striking similarities between ourselves and our animal cousins. Simultaneously, they have allowed us to better appreciate the complexity of animals while recasting our own sociality as a fundamental animal impulse. Some balk at such notions, believing humans to be separate and exceptional from other animals. Yet the differences between us and the rest of the animal kingdom is, as Charles Darwin said, of a degree rather than of a kind.

Almost a quarter of a century on from my first fumbling attempts to work out my course in life, I can look back on a dream fulfilled and at a series of adventures. It’s been an incredible privilege to study at close hand some of the world’s amazing creatures and to grapple with the hows and whys of their social behavior. In the following chapters, I consider a succession of animals, beginning with Antarctic krill and working through to our closest relatives, chimpanzees and bonobos. What all these animals have in common is that they are social.

The word social means many different things to many different people, but for the purposes of this book, I define a social animal as one that is drawn to its own kind, that lives and interacts in groups. It’s been my life’s work to study these interactions between animals: how they relate to one another; how they connive and compete, on the one hand, and unite and cooperate, on the other. In this book I’ve attempted to distill the wonder that I still feel in the company of animals.