In Western societies, domesticated animals have increasingly been subjected to extreme genetic manipulation in order to manufacture ever more novel and attractive pet animals. In Europe, the earliest kennel clubs, designed to develop and maintain breeds and record pedigrees, began as dog show societies in England in 1859 and were later established as governing bodies and official institutions, starting in 1873. Although dog breeds now come from all over the world and continue to be developed—a recent addition to the list of breeds recognized by the American Kennel Club (AKC) is the Biewer terrier, first recognized in January 2021—the majority of modern pet breeds were first developed in Victorian England, where pet keeping flourished and was adopted by all social classes. Sometimes, this selective breeding of pets is detrimental to the health of the animal breed. In the English bulldog, for example, 86 percent of litters must be delivered by cesarian section because the pups’ large heads and mothers’ narrow pelvises have made live, natural births very challenging (Evans and Adams 2010). In addition, as dog breeders create more and more specialized pets, the gene pool becomes narrowed and less diverse, producing animals that are more prone to conditions such as cancer, hip dysplasia, deafness, hereditary epilepsy, and allergies. In pedigreed cats, which are subject to the same selective pressures in breeding, there are both heart and kidney problems that are thought to be accelerated by selective breeding. One of the most commonly sought set of characteristics by people selectively breeding animals for pets is the appearance of a permanent juvenile state. Neotony, the tendency for an animal to maintain both physical and behavioral juvenile characteristics into adulthood, has been highly sought after in many domesticated animals. Some of the most commonly desired juvenile physical traits are larger and wider-set eyes, a smaller snout (or nose), a more globular (or rounded) skull, and fewer and smaller teeth (which leaves many dogs with crowded teeth and dental problems). Social neotony involves a cluster of traits relating to a strong and submissive attachment to humans and increased attentiveness to human behavior. The overall size of animals is also a consideration when breeding pets. Consider the range of miniature animals we have selected for today: miniature horses, mules, and pigs; pygmy goats and hedgehogs; and others. Of all animals kept as pets, dogs have been the most manipulated in size. Today, there is a proliferation of “teacup” breeds that can be carried in the owner’s pocket or purse. Small dogs offer many advantages to humans living in urban environments and small apartments, but there are few advantages for the dogs themselves. Most teacup versions are created by breeding the smallest animals in a litter. There are many health risks that accompany this process of extreme miniaturization, such as collapsing tracheas, digestive problems, heart defects, liver shunts, slipping kneecaps, and a host of dental challenges. Pet keeping has deep roots in human societies and has changed over time. Interestingly, it has also been documented among some animals. Nonhuman animals have been known to form cross-species friendships and alliances and to take care of each other both in the wild and in captivity. One interesting example is the gorilla Hanabiko, called “Koko,” who was trained to understand spoken English and communicate using a form of American Sign Language that her keeper called Gorilla Sign Language. Koko became interested in cats and signed that she wanted a kitten for Christmas in 1983. Her keepers at first provided her with a stuffed cat, but Koko insisted that she wanted a living one. On her birthday the following July, her keepers allowed her to choose a rescue kitten, which she named “All Ball” because he had no tail and was very fluffy. The relationship between Koko and her kitten, documented in many articles and videos, was a nurturing one in which Koko treated All Ball like her baby and her pet. Pet keeping says a great deal about the human need to reach across species for companionship, dominance, and affection. Perhaps, though, this is not solely a human need.