Many households in the industrialised Western world own companion animals. The American Veterinary Medical Association (AVMA, 2012) reported that just over a third of US households kept one or more dogs in 2011, and just under a third kept one or more cats (AVMA, 2012: p. 1). Figures are similar, though somewhat lower, in the European Union (EU) where, in 2010, just over 25% of households had at least one dog, and just under 25% had at least one cat, according to the European Pet Food Industry (FEDIAF, 2010). In most Western countries, the number of households keeping dogs and cats has been steadily growing for decades.

The AVMA (2012) also gives us information on people’s attitudes to the animals in their homes. Two-thirds of US dog owners see their dogs as members of the family; most of the rest, according to the survey, view them as ‘companions’ or ‘pets’. Over half the owners see cats as family members. For both species, the younger the owners, the more likely they are to view their animals as family members (AVMA, 2012: p. 14). According to a survey prepared for a pet food company in 2000, nearly half of American dog owners have taken their dog on vacation, and a similar number have celebrated their dog’s birthday (Ralston Purina, 2000). Thus the general trend is not only to allow dogs and cats into the family home but also – in these respects, at least – to treat them as members of the family.

Many owners of companion animals put their money where their mouth is. Thus they both demand, and can access, a growing supply of expensive products and services, including organic dog and cat food, elaborate day-care facilities, special overnight hotels, and advanced veterinary care. It’s difficult to pin down the exact sums involved here, as different surveys produce different figures; but all show that animal companions are costly. According to the AVMA (2012: p. 57) in 2011, the average US dog owner spent $378 on veterinary services alone. The American Pet Products Association puts expenditure much higher: $655 on routine and surgical veterinary visits, $254 on food, $274 on kennel boarding and $359 on other products and services, in total more than $1500 per year. The amount spent by the average cat owner is smaller, but not by much according to the American Pet Products Association (APPA, n.d.). Although there may be significant local variations, it is reasonable to claim that the trend to spend increasing amounts on dogs, cats and other companion animals is representative of the industrialised Western world as a whole.

Yet this, surely, raises interesting questions. The number of animal companions is growing, while the costs of keeping them are increasing. Why would so many contemporary households – in particular, urban and suburban households in industrial societies – decide to spend their scarce resources on sharing their lives and homes with members of other species? How did our relationship with animal companions develop such that this could come about, and why? Could companion animals be some kind of substitute for the animals that people formerly lived alongside in rural, agriculturally based societies? Is keeping animal companions a symptom of changing family and household structures, and perhaps increasing loneliness? Or is it, instead, a way of expanding relations to nature that has been made possible by growing wealth? Are companion animals giving their owners tangible benefits or are they, rather, a diversion from other, more important, things?

In this chapter we will try to address these questions in two ways: first, we will sketch an outline of some key historical developments that led to current Western attitudes to animal companions. Second, from the perspective of evolutionary biology, we will consider whether animal companions do benefit their owners, and if so, in what ways and how much.

As we noted in the Introduction, the scope of this book is limited to the Western nations, in particular to Europe, Australasia and North America. Although living with animals as companions is practiced globally, the practice takes so many different forms internationally that – unfortunately – we do not have space to discuss them all in sufficient detail.

There is sound evidence to show that humans have lived alongside domesticated animals for more than 10,000 years. But there is still considerable dispute about how, when and why animal domestication first occurred (and even what we should take domestication to mean). It is widely agreed, however, that dogs were the first animals to be domesticated, though even here there is uncertainty over whether dogs as opportunistic scavengers ‘domesticated themselves’ or whether they were deliberately drawn in or captured by people (see Cassidy, 2007: p. 7).

However domestication began, it is likely that dogs soon became useful to people in a practical sense, in particular by warning of intruders, tracking down prey animals, and finding wounded animals that escaped during hunts. But we do not know whether dogs were more than this; not just helpers and guards, but also objects of human affection. There is some archaeological evidence that prehistoric humans had affectionate feelings for dogs. In 1978, at a late Paleolithic site in northern Israel, for instance, a tomb was uncovered where about 12,000 years ago a person had been buried with a dog or wolf puppy. The hand of the dead person, who was around 50 years old, was placed on the animal’s shoulder. It is likely that the dog was sacrificed when the person died in order that it could accompany the person onwards in his or her spiritual journey (Davis & Valla, 1978). There are many other cases, across the globe, where dogs appear to have been buried after death, a practice that was rarely adopted with other animals, with the exception of the mummification of cats in Egypt. In fact, the archaeologist Morey notes that, across many cultures, dead dogs seem to have been treated rather like dead people (Morey, 2006: p. 164).

The history of the emergence of cats as human companions is even less clear than that of dogs, in part because of uncertainty over whether and how cats could have been useful to people. Genetic evidence suggests that all current housecats come from Felis s. lybica wildcat populations in the Middle East, and there is some archaeological evidence to suggest that they became human companions as long as 10,000 years ago (Driscoll et al., 2009). It’s likely that certain human-tolerant cats came to live near humans to feed on small rodents and trash, that humans in turn tolerated them, and that gradually these bolder cats diverged from their wild relatives (Driscoll et al., 2009). However, it was in Egypt around 3700 years ago that cat domestication really seems to have spread, with cats living in homes, being represented in art, and being bred (Driscoll et al., 2009). From Egypt, the practice of living with domesticated cats seems to have spread across the world.

From ancient times it has also been common to keep other animals, not least birds, as companions. For example, there is ample evidence from ancient Greece that people kept a number of bird species in cages for company, and according to Kitchell (2011: p. 19) next to dogs, birds ‘may have been the second most common type of pet in ancient Greece’.

Christian theology shaped Europe’s cultural and political climate from medieval times, and its influence was persistent. Prior to 1600, at least, a dominant view held within Christian orthodoxy was that close relations between humans and animals were theologically and morally troubling, and were best avoided. Of course, different theological traditions had somewhat divergent approaches here, and there were some notable exceptions. The best known of these is St Francis of Assisi, who famously called animals his brothers and sisters, and as Hughes (1996: p. 313) notes, friendships with animals were not unusual among religious ascetics.

A key idea that strongly influenced the dominant Christian tradition of keeping animals at a distance was the belief that humans had a unique status in nature. This idea was supported in multiple ways. One of the most influential was Aristotle’s argument that humans, like other animals, have a nutritive and sensitive soul, but that they differ from animals by also having an intellectual or a rational soul. Medieval theologians linked this idea with a second powerful concept of separation, drawn from the Judaeo-Christian tradition, that man is created in God’s image:

Let us make mankind in our image, in our likeness, so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground.

(Genesis 1: 26)

This idea of separation was reflected and revitalised in early modern philosophy in the work of René Descartes (1596–1650). Descartes divided the world into souled and soulless beings, arguing that animals lacked souls while humans possessed them. Since Descartes equated the soul with the mind and consciousness, his view entailed the conclusion that animals lack consciousness and rational thought, and that their actions and responses were purely the result of mechanistic processes. Although Descartes’ work is open to more subtle interpretation (see Cottingham, 1978) the claim that animals are essentially mechanisms, lacking both agency and feelings (including the capacity to feel pain) was influential not only in terms of reinforcing the existing view of human supremacy, but also serving as a licence to deny that animals could have morally relevant needs.

That humans have a unique status vis-à-vis the animals does not, by itself, imply anything about whether or not humans should enjoy their company – just as the assumption that flowers lack sentience should not debar us from enjoying their beauty. The claim that humans ought to maintain a clear boundary between themselves and other animals follows from a different aspect of a Christian view of human nature: the idea that to get close to God, humans should suppress and forsake the animal sides of their natures. The historian Keith Thomas maintains that humans were taught ‘to regard their bodily impulses as “animal” ones, needing to be subdued’ (Thomas, 1984: p. 38). Lust, in particular, was seen as belonging to human’s problematic nature; and one of Thomas’s sixteenth-century sources is quoted as saying that lust made men ‘like … swine, goats, dogs and the most savage and brutish beasts in the world’ (Thomas, 1984: p. 38). A tacit premise here seems to be that by enjoying the company of animals, a human being will excite his or her ‘animal side’. Bestiality therefore was a particularly heinous sin, since it ‘was the sin of confusion; it was immoral to mix the categories’ (Thomas, 1984: p. 39).

However, the idea of ‘mixing the categories’ of human and animal was regarded as more broadly problematic, beyond having sex with them. According to Thomas ‘in early modern England even animal pets were morally suspect, especially if admitted to the table and fed better than the servants’; and he quotes a moralist from the early seventeenth century as saying: ‘Over-familiar usage of any brute creature is to be abhorred’ (Thomas, 1984: p. 40).

Thomas reproduces the following story of a pious woman from the sixteenth century who on her deathbed regrets the way she and her husband have privileged their female dog:

She … said “Good husband, you and I have offended God grievously in receiving many a time this bitch into our bed; we would have been loathe to have received a Christian soul … into our bed, and to have nourished him in our bosoms, and to have fed him at our table, as we have done this filthy cur many times. The Lord give us grace to repent it” … and afterwards she could not abide to look upon the bitch any more.

(Thomas, 1984: p. 40)

Being too close to dogs, or treating them better than some people, was seen as problematic. Occasionally, dogs were even demonised, although in this respect, the dog’s situation during the Middle Ages seems to have been better than that of cats.

There is considerable uncertainty as to the roles cats played in medieval Europe. We have evidence that they were skinned, though this may not mean that they all were kept for their skins; many may have led essentially feral lives, while others were kept as companions (O’Connor, 1992). It is clear, though, that cats were sometimes portrayed as the personification of the devil, and this served as a justification for their persecution. Serpell notes that on feast days, cats were tortured and killed in violent ways as a way of symbolically driving out the Devil:

By associating cats with the Devil and misfortune, the medieval Church seems to have provided the superstitious masses of Europe with a sort of universal scapegoat; something to blame and punish for all of life’s numerous perils and hardships.

(Serpell, 2000: p. 12)