A revolution has recently taken place in behavioural biology. Its consequences are far-reaching, both for our self-image as humans and for our relationship with animals. Just a few decades ago, behavioural science was guided by two key dogmas: animals cannot think, and no scientific statements can be made about their emotions. Today, the same discipline holds both ideas to be false and posits the very opposite: animals of some species are capable of insight – they can recognise themselves in a mirror and exhibit at least a basic sense of self-awareness – and they have rich emotional lives that seem to be startlingly similar to those of humans. Situations that lead to strong emotional responses in humans, whether positive or negative – for example, when we fall in love or lose a partner – seem to have the same effect on our animal relatives.
Indeed, the transformation of the concept of the animal in modern behavioural biology has been so fundamental that it amounts to a paradigm shift. And since it has long since become untenable to distinguish between Homo sapiens as driven by reason and animals as driven by instinct, the question arises: what actually differentiates humans from animals? How much of ourselves is present in them?
The general perception of these differences has also changed in parallel to developments in the life sciences. A few decades ago, if biology students had been presented with photos of a goldfish, a chimpanzee, and a human, and asked to sort them into two categories of their own devising, more than 90 per cent would have put the human in the first category and the ‘animals’ in the second. If biology students today are asked the same question in their first semester, the result is completely different: over 50 per cent group humans and chimpanzees into one category and the goldfish into another. Apparently, humans and animals have grown closer to one another in the public imagination, too.
This has been confirmed by the death of a third dogma: for decades, it was taught that animals behave for the good of their species, generally never killing members of their own – known as ‘conspecifics’ – and often helping them to the point of self-sacrifice. Today we know that this is not the case. Rather, animals do everything to ensure that copies of their own genes are passed to the next generation with maximum efficiency and, when necessary, they will also kill conspecifics. Clearly, they are not, as Jane Goodall had once famously hoped, ‘like us, but better’.
The border between humans and animals is also beginning to blur in other areas. Certain aspects of the social environment can cause stress for both humans and animals, while other similar factors can alleviate it. Both have their thinking, feelings, and behaviour shaped by similar interactions between genetics and environment. Indeed, animal behaviour does not develop in a fixed manner: environmental influences, socialisation, and learning can alter an animal from the prenatal phase through adulthood. Like humans, animals ultimately appear individualised upon closer inspection, which is why behavioural biology now takes animal personalities into account.
This book will demonstrate how and why the scientific understanding of animal behaviour has changed so fundamentally. It will focus on a group of animals to which, biologically speaking, we also belong: mammals, whose approximately 5500 species populate the most diverse range of habitats on our planet. Lions and zebras inhabit the savannah, gorillas and orangutans inhabit the tropical rainforests, fennecs live in deserts, polar bears live in the arctic, moles live underground, bats have taken to the skies, and whales and seals have taken to the water.
Humans have much in common with all these creatures. For one, our genes: we share about 99 per cent of them with our closest relatives, bonobos and chimpanzees. Brain structure is also nearly identical across all mammals: the so-called ‘ancient’ parts of the brain in particular – like the limbic system – show similarities down to the last detail. A human’s fear response at the sight of a snake, for instance, may likely be controlled by the exact same neuronal process as in a chimpanzee or a squirrel monkey. Our physiological regulatory systems, too, are strikingly similar. The same hormones enable all mammals to cope with stressful situations, adapt to changing environments, or reproduce. In fact, the production of the sex hormones testosterone and oestradiol, the stress hormones adrenaline and cortisol, or the ‘love’ hormone oxytocin is not unique to humans; rather, these hormones occur in the same form in a wide variety of species, from bats to rhinoceroses to dolphins.
However, such similarities across genes, brain structure, and the endocrine system do not automatically imply similarities concerning thoughts, feelings, and behaviour. To better understand these traits, we need to look at specific studies in both animals and humans. In the case of animals, such studies take place within the field of behavioural biology, which was aptly defined by one of the fathers of the discipline, the Nobel Prize winner Nikolaas Tinbergen, as ‘the study of behaviour by biological methods’.
The Study of Behaviour by Biological Methods
This definition can very simply be illustrated by the relationship between a general knowledge of animals and a knowledge of behavioural biology: a knowledge of animals is certainly required to study behavioural biology, but it is not in itself sufficient to draw scientific conclusions about animal behaviour. Thus, the terms are by no means synonymous. Not everyone who interacts with animals and makes statements about their behaviour is a behavioural biologist, although people who have close contact with animals may have an excellent knowledge of their behaviour. My grandmother, for example, was always right about our dog – if she warned he was about to bite, one did well to take it seriously. But this was not knowledge in a scientific sense: it was intuition acquired through experience, and, if I had asked her how she knew these things, she would have answered, ‘I can just tell.’ Experiential or intuitive knowledge can, of course, be just as true as scientific knowledge. But it does not have to be, so it is very hard to decide when it is valid and when it is not. Take, for example, the characteristics of certain animals that have made their way into the vernacular: we speak of the thieving magpie or the silly goose; we compare a clumsy person to a bull in a china shop, or a person stuck in their habits to an old dog who cannot learn new tricks. Whether these attributes are accurate to these animals or not can ultimately only be clarified through behavioural studies, which have indeed frequently shown them to be prejudices.
How, then, is knowledge characterised in behavioural biology? As with any type of scientific knowledge, it must be possible to convey the methods and procedures by which it was acquired. This was not the case with my grandmother’s knowledge of our dog – it is not enough for someone to sit in front of a group of animals, be affected by their behaviour, and describe his or her subjective impressions of it. In a legitimate behavioural study, the researcher must first list and define the specific behaviours of the animal species under study in what is known as an ethogram. Then, data is collected on these behaviours using an appropriate method: if the researcher were studying animal social life, for instance, he or she would record how often and for how long each animal exhibited socio-positive behaviour (that is, friendly behaviour towards other members of the group), how often each animal initiated or was the target of aggressive behaviour, how often each animal positioned itself next to certain others in the group, and which males paired with which females. These observations used to be collected by hand, but behavioural data is now recorded and analysed with sophisticated software, as is the statistical evaluation of the results.
Let’s stay with the topic of mammalian social life for a little while longer. The history of research in this area also shows how crucial it is to use the right method of data collection. A few decades ago, when the first of such studies were being conducted in animals’ natural habitats, scientists often used the ad libitum method: they observed all the animals in a group simultaneously and recorded all behaviours that they noticed. However, this method introduced a huge problem that has long been known to perceptual psychology: humans tend to focus their attention on what is loud and distinctive, neglecting events that occur quietly and unobtrusively. In many mammalian societies, male behaviour – especially in interactions with conspecifics – is more expressive and louder than female behaviour, as confrontations with other males are often marked by conspicuous vocalisation. If researchers apply the ad libitum method to these interactions, they will inevitably collect significantly more data on males than females. This perceptual bias may have contributed to the fact that males have long been described as dominant and tone-setting in many mammalian societies, while females have been characterised as passive and inferior.
After this procedural error was recognised, researchers began to replace the ad libitum method with what is known as focal-animal sampling, in which each animal in the group is observed for the same amount of time regardless of what it is doing, thus ensuring that all are given the same amount of attention. The data collected using this method has contributed significantly to the revision of our concept of the female role in mammalian societies: we know today that females are by no means passive, but rather tend to interact in subtler yet no-less-influential ways. Recent behavioural biology textbooks reflect this insight, teaching that it is often the females in primate societies who make the most important decisions for the group.
While animal societies like those of primates are organised into fixed groups of several adult males and females, there is a great diversity in the social life of mammals: many species, like tigers, live solitary lives, while others, like certain zebras, organise themselves into harems, and elephants, who constitute the strongest matriarchy in the animal kingdom, present close, sometimes lifelong, bonds between the females of a group. Such long-term bonds between males are found in a few species, such as the cheetah. In the saddle-back tamarin, a small South American species of monkey, harems of one female and two males regularly occur. Interestingly, the favoured lifestyle of humans – monogamy – rarely occurs in non-human mammals: no more than 3–5 per cent of species organise themselves into pairs. (One that does is the North American prairie vole.) None of our closest biological relatives – bonobos, chimpanzees, gorillas, or orangutans – live monogamous lives.
Given this great variety of species, habitats, and lifestyles, studies in behavioural biology must not only be conducted using a sound methodology but the results must also be reproducible. If a research group in Berlin shows that bees can orient themselves to the position of the sun, for example, then this result must also be obtainable by researchers in London or Tokyo.
The importance of reproducibility is wonderfully illustrated by a certain well-known historical case study. Shortly before the First World War, a man named Wilhelm von Osten caused quite a stir with his horse, Clever Hans. Hans could seemingly do basic arithmetic – addition, subtraction, and division – and indicate the correct answers to problems by stomping on the ground or nodding his head. The public was amazed, but scientists quickly began to doubt that a horse was capable of such a mental feat. Wilhelm von Osten agreed to an investigation, and indeed, the first study showed that Clever Hans was able to solve basic equations even if they were given to him by strangers. However, as the study continued, it was revealed that Clever Hans could no longer solve a problem if no one present knew the solution. The horse, it turned out, was able to pick up on the smallest nuances in the body tension of the person who gave him the mathematical problem to deduce when he should stop stomping or nodding. Clever Hans had extraordinary sensory perception – but he could not do arithmetic.
Nevertheless, he has had a lasting impact on research. Today it is generally accepted that displays of animal cognition can only be scientifically verified through so-called blind studies, during which the experimenter does not know the solution to the task given to the animal. Unconscious assistance, which must be eliminated in any legitimate study, is known as the ‘Clever Hans effect’. Wilhelm von Osten was certainly no charlatan – he was firmly convinced of his horse’s cognitive abilities. Even today, many pet owners attribute outstanding cognitive abilities to their dogs or cats, claiming things like: ‘My dog understands every word I say.’ Whether this is really the case, however, cannot be judged from everyday experience alone. Clever Hans has certainly taught us that.
The basic behavioural biological method is therefore known as the process of objectively and reproducibly recording animal behaviour. Depending on the study, however, techniques from neighbouring disciplines may also be used. Researchers rely on state-of-the-art satellite technology to determine the position of birds during migration, for example; they divine the stress state of animals by measuring their hormone levels; they determine paternity or kinship with the help of molecular genetics. Such techniques allow scientists to gain insights that would not be possible through behavioural observation alone, which can often be misleading. For example, songbirds have long been considered in the public imagination as the epitome of fidelity. But paternity verification through genetic fingerprinting has revealed a very different picture: a large part of the offspring found in these birds’ nests often do not come from the males who occupy them and feed the young there. Evidently, songbirds are not as monogamous as humans might like to believe.
A Short History of Behavioural Biology
Since their earliest days of existence, humans have taken an interest in the animals that surround them: in how to escape them, hunt them, or even just enjoy their presence. The cave paintings at Altamira and Lascaux, which are among the oldest works of art in human history, are a Stone Age testimony to the human–animal relationships of this early period. Through breeding, we have been domesticating what were once wild animals for thousands of years: sheep, pigs, cattle, and goats have lived among us for about 10 000 years, while dogs may have been man’s faithful companions for as long as 30 000 years.
Greek philosophers began to contemplate the nature of humans vis-à-vis animals about 2500 years ago. Aristotle famously saw the animal’s lack of reason as a fundamental difference between the two, and this distinction is still anchored in much of society’s consciousness today: many still believe that humans alone possess reason while animals can only follow their instincts.
The first examples of empirical scientific and experienced-based observation of animal behaviour can be found in the Middle Ages. In the thirteenth century, Emperor Frederick II, known to his contemporaries as stupor mundi, ‘the wonder of the world’, wrote De Arte Venandi cum Avibus/The Art of Hunting with Birds, which can be considered the first scientific book of western ornithology – or, some may argue, of behavioural biology. As early as the sixteenth century, naturalists such as Konrad Gesner, Carl von Linné, and Jean-Baptiste de Lamarck were describing and systematising animals and plants, including many species from the parts of the world only recently visited by Europeans. These writings include numerous descriptions and contemplations of animal behaviour, but general consensus does not consider behavioural biology to have truly emerged as a discipline until the middle of the nineteenth century.
The father of behavioural biology (and many other related disciplines) is the British naturalist Charles Darwin. In On the Origin of Species, first published in 1859, Darwin lays out the basic features of his theory of evolution, which we still hold to be true today. He understood evolution to be two things: first, the process by which species change over time, based on the premise that they do not exist in a static state but rather are altering their appearance and behaviour constantly. The second feature is the descent from common ancestors. Eight to ten million years ago, for example, there were no humans or chimpanzees on our planet. There did exist, however, a certain species of ape, now extinct, from which both humans and the chimpanzee derive. Through his studies, Darwin not only proved that evolution exists, but also recognised the major driving force behind evolutionary change: natural selection.
What does this key concept mean? Darwin recognised that all organisms have a nearly unlimited ability to reproduce – many more offspring can be created in a single generation than there are parents. But this enormous potential is not realised; rather, the size of a population remains more or less constant, meaning that the majority of offspring perish. Only a few survive to sexual maturity, and even fewer subsequently reproduce. Therefore, Darwin posits, there must be steep competition for survival and scarce resources such as food, habitats, and mates: what he termed the struggle for existence. Which animals survive is by no means left to chance. Individuals who are better adapted to their environment through hereditary advantages – for example, they find food or mates more easily or are more likely to escape predators – are more likely to survive and successfully reproduce than their less-capable conspecifics. The genetic makeup that allowed certain individuals to survive is then successfully passed on to the offspring, while the genetic makeup that caused others to perish is lost. Through this process of natural selection, animal species become constantly better adapted to their environment.
One chapter of On the Origin of Species is devoted exclusively to animal behaviour. In it, Darwin states that instincts and the behaviours they control, just like all other characteristics of an organism, are modified through natural selection and therefore continually adapted to the environment. He thus anticipates a central theme of behavioural ecology, an important discipline of contemporary behavioural research: the adaptation of behaviour to ecological conditions. He further describes the similarities that appear between the instincts of closely related species that are present even when they live in separate parts of the world. Both South American and European species of thrushes, for example, line their nests with mud. That closely related species share more common behaviours in their ethogram than distantly related ones would become a central dogma of comparative behavioural research decades later.
In 1872, Darwin published another book: The Expression of the Emotions in Man and Animals. In it, he argues that certain facial expressions – especially those that reflect basal emotions such as joy, sadness, or anger – exist independently of culture and are thus innate. Furthermore, he says, some animal species may possess emotions comparable to those of humans, which they express using similar faces. The book became a bestseller shortly after it was published, although it did not catch on in the scientific community and, for a long time after, was virtually forgotten. Then, in the 1960s, the biologist Irenäus Eibl-Eibesfeldt revisited Darwin’s theses and founded human ethology, a sub-discipline of behavioural biology that attempts to comprehend emotions as innate features of human behaviour. Indeed, Eibl-Eibesfeldt was able to identify universal similarities in human facial expressions when he compared feelings such as joy, sadness, or disgust among different ethnic groups across Africa, South America, and Asia.
At the time, animal emotions had not been a topic in behavioural biology for well over a century – the idea that humans and animals shared certain emotions had long been considered politically incorrect. But in the last decade or so this has changed dramatically. Today, emotions are a central field of research in behavioural biology, and perhaps in this context we will see a Renaissance of Darwin’s long-forgotten work.
For about half a century after Darwin, the majority of biologists were not specifically interested in animal behaviour: research tended to focus on systematics, physiology, and developmental biology. Only then did the field we now call behavioural biology begin to emerge through the writings of the researchers Konrad Lorenz, Nikolaas Tinbergen, and Karl von Frisch.
Karl von Frisch studied sense perception: how animals calibrate themselves to their environment and communicate with one another. He was the first to prove that fish can hear and bees can see colour, and that they orientate themselves with the help of a solar compass. von Frisch became known primarily through his investigations into animal communication, in which he discovered the so-called ‘waggle dance’ used by individual bees to tell hive-mates the direction and distance of a food source. von Frisch was also the first scientist to study animal behaviour through a logical sequence of related experiments.
While von Frisch is a key figure in behavioural biology (or ethology or animal psychology, as it was also called in its early days), the emergence of the discipline was even more influenced by the researchers Konrad Lorenz and Nikolaas Tinbergen. Through their work, it was first accepted that behaviour can be studied in the same way that anatomy, morphology, or physiology can, and observation of animal behaviour was established as a serious scientific method. In a series of classic studies, Lorenz described the behaviour of various duck species down to the smallest possible units, which were termed ‘fixed action patterns’. These relatively stereotyped behaviour patterns are exhibited by all members of the same species, at least those of the same age and sex: one could say that the courtship behaviour of a mallard in Berlin is the same as that of one in Beijing. Lorenz’s comparison of fixed action patterns across different species such as mallards, Meller’s ducks, pintails, shovelers, teals, wigeons, or mandarin ducks in turn showed that the more closely certain species were related, the more fixed action patterns they shared. Thus, comparative ethology was born.
Through observing ducks and geese, Lorenz also recognised that these animals have no innate knowledge of their species’ appearance – rather, they only learn to recognise each other through what is known as imprinting. In a specific window of time shortly after hatching, chicks will become fixated on whatever moves and makes noise in their vicinity. In their natural habitat this is usually the mother, whom the chicks then learn to follow. But if, during this phase, Lorenz moved the chicks around and called to them instead, the chicks would irrevocably imprint on him. If they later had a choice to follow him or their mother, the chicks would choose Lorenz.
Lorenz also developed important models for behavioural control. According to these, key environmental stimuli activate releasing mechanisms, which results in an associated innate behavioural response. Tinbergen was then able to experimentally prove that these models held true for many animal species. For example, if a rival invades a stickleback’s territory, the stickleback will instinctually react with threatening behaviour. What causes this aggression? The red underside of the intruder’s belly is the key stimulus: a lifelike stickleback model without a red underbelly does not trigger any aggression in the creature, but the stickleback will begin to violently attack a piece of wood whose lower half has been painted red, even though the wood does not remotely resemble a conspecific rival.
Tinbergen also conducted simple but ingenious experiments in the natural habitats of certain animals to understand the function of their behaviour. In one classic experiment, for example, he asked himself: Why do black-headed gull parents remove the broken eggshells from their nests after a chick hatches? To answer this question, he fashioned artificial nests with gull eggs, laying broken eggshells near some of the nests and leaving others without. After a while he noticed that the presence of an eggshell increased predation of a nest. Thus, parents apparently remove the eggshells to avoid predation. By studying the adaptive value of behaviour, Tinbergen laid the foundations for behavioural ecology, an important discipline of behavioural biology that emerged in the 1970s.
In these early days of behavioural biology, Lorenz, Tinbergen, von Frisch, and their ever-growing number of students studied many different species – birds, fish, and insects especially. The scientists were particularly fascinated by the fact that these animals seem to have an innate knowledge of how to behave and were thus perfectly adapted to their habitat. A digger wasp, for instance, knows how to seek the right kind of prey and build the right kind of nest without ever having had contact with its parents or learned from any conspecific. Like Darwin, the early behavioural biologists named the source of this knowledge ‘instinct’, and, like Darwin, they assumed that such instincts formed in the course of evolution through natural selection.
The importance of this topic is clear from the title of the first-ever textbook in behavioural biology: Tinbergen’s The Study of Instinct, which first appeared in 1951. Indeed, the central goal of this early phase of behavioural biology was to study instinctive (that is, innate) behaviour. Several of the models developed at that time are no longer considered correct, such as the hierarchy of instincts, or the role of the interaction between environmental stimuli and internal factors in triggering instinctive behaviour. Nonetheless, the achievements of Lorenz, Tinbergen, and von Frisch cannot be understated: through their work, behavioural biology became an independent scientific discipline that has fundamentally changed the concept of animal behaviour. They were awarded the Nobel Prize in 1973.
Tinbergen in particular also pointed this fledging field in the direction that it has taken up to the present day. In his article, ‘On aims and methods of ethology’, nearly 60 years ago, he provides the theoretical framework which is still the basis of behavioural biology: that explanations can and should be given for every behavioural phenomenon – from insect social organisation to chimpanzee tool use to bird song – on four different levels: mechanism, ontogeny, function, and phylogeny.
What does this mean? The reason why a male chaffinch sings, for example, can be explained in four different ways. The first is that the increasing length of the days in spring acts as an environmental stimulus that the male birds perceive, triggering the production of the sex hormone testosterone in their testes. This testosterone is then transported through the bloodstream to the brain, where it activates certain nerve impulses that direct the necessary muscles for singing. This is the causal explanation, which clarifies the mechanism of the behaviour.
A second explanation follows that a male chaffinch sings because he learned to from his father during a prescribed period when he was particularly able to do so. This is the life-historical explanation, which focuses on the ontogeny of the behaviour. (Ontogeny is understood as the period of time between the fertilisation of an egg and the death of an individual.)
A third explanation is that the male chaffinch sings to attract females and drive away potential rivals. This is the functional reason, which indicates what sort of adaptive value the behaviour has – why an animal who engages in this behaviour is better adapted to his or her environment and more successful in passing on his or her genes than a conspecific who does not.
Finally, the singing can be explained by the fact that a chaffinch is a songbird, descending from ancestors who sang. This is the phylogenetic explanation, which clarifies the behaviour based on its evolutionary history, or phylogeny. Tinbergen’s point in laying out these four types of explanation was clear: we cannot understand a particular behaviour until we understand it on the level of its mechanism, function, ontogeny, and phylogeny, as well as the relationship of all four to each other. This message has never been more relevant to behavioural biology than it is today.
Indeed, in the past few decades, the questions Tinbergen posed about animal behaviour have been researched on a large number of species. But in the process behavioural biology has splintered into several disciplines that are unfortunately hardly related to each other: behavioural ecology and sociobiology, for instance, both focus on the functions of behaviour, its adaptive value, and its evolution, primarily asking: What are the advantages of certain behaviours? This line of research answers these questions wonderfully but neglects the ontogeny and mechanisms of the behaviour in doing so. These aspects are the focus of disciplines such as behavioural endocrinology, behavioural neurobiology, and behavioural genetics, which examine the relationship between behaviour and hormones, neurons, and genes, respectively. These disciplines mainly ask how a certain behaviour arises, but they are hardly concerned with its functions and evolution. Each of these disciplines has produced spectacular findings on animal behaviour, but there is very little unification of the results and the subsequent ways they have, taken together, changed our concept of the animal.
The Common Thread
So, here is where this book comes in: using these fundamental findings from different disciplines of behavioural biology, we can see how much the scientific concept of the animal has changed over the past decades. This shift has undoubtedly been helped along by new emphasis on certain questions that were not addressed in the early days of the field: Can animals think? Do they have emotions? What about distinctive personalities? What does it really mean to be ‘animal friendly?’
Furthermore, new methods have enabled us to re-examine old questions. For example, decoding the genomes of humans and certain animals has given us a much better understanding of the interplay between genes and environment in the execution of behaviour. Mammals, including many species of primates, have also increasingly become the subject of study, which has further contributed to our fundamentally altered view of animal behaviour. In summary, the findings of these various disciplines show that animals exhibit many characteristics, abilities, and behavioural patterns that we until recently regarded as unquestionably human.
In the following six chapters, this book presents the findings that have most notably contributed to this shift in understanding. The conclusion then summarises the new scientific concept of the animal and discusses how much of ourselves we might really see in it.
First, Chapter 2 deals with the relationship between behaviour and stress. The same characteristics of the social environment, it seems, lead to stress in humans and animals, while very similar factors can also reduce stress in both.
Chapter 3 addresses animal emotions and well-being, asking: What scientific methods can we use to determine whether animals are thriving? Under which conditions do they do well, and under which ones do they struggle? How do animals see the world? What do we know about their emotions? What exactly does an ‘animal-friendly’ life mean?
Chapter 4 looks at a question that has preoccupied science and society alike for many years: How much is behaviour determined by genes, and how much by environment? It traces how methods and perspectives on this problem have changed dramatically over the last few decades and shows how modern behavioural genetics provides new answers to old questions, culminating in the revolutionary realisation that genes not only influence behaviour but behaviour can also influence genes.
Chapter 5 deals with findings from cognitive biology, which address: How and what can animals learn? Can they think? Do some have self-awareness? And is it really true that great apes, our closest relatives, are more intelligent than other species?
Chapter 6 lays out mammalian behavioural development as an open process whose course is not predetermined at conception, birth, or even the end of childhood. A mammal’s behaviour is already influenced by the environment in which its mother lives during the period of gestation, and the experiences the animal has throughout childhood and adolescence continually shape its behaviour. This is how animal personalities are formed, a subject of one of the newest areas of research in behavioural biology.
Chapter 7 addresses the central finding of sociobiology: animals apparently do not behave for the good of their species, but rather according to what are known as ‘selfish genes’. If acting cooperatively helps them pass on their individual genetic material, then they will do it, but if their goal is better achieved through coercion or aggression – even to the point of killing conspecifics – then animals will exhibit such behaviour.
Chapter 8 concludes by reiterating the central point of this book: we, as humans, have moved much closer to animals than we have ever thought possible. Indeed, there is much more of us in them than we could have even a few years ago envisioned.
