^ Wood, Lisa; Martin, Karen; Christian, Hayley; Nathan, Andrea; Lauritsen, Claire; Houghton, Steve; Kawachi, Ichiro; McCune, Sandra (2015). "The Pet Factor – Companion Animals as a Conduit for Getting to Know People, Friendship Formation and Social Support". PLoS ONE. 10 (4): e0122085. Bibcode:2015PLoSO..1022085W. doi:10.1371/journal.pone.0122085. PMC 4414420. PMID 25924013.
The genetic divergence between dogs and wolves occurred between 40,000–20,000 years ago, just before or during the Last Glacial Maximum. This timespan represents the upper time-limit for the commencement of domestication because it is the time of divergence and not the time of domestication, which occurred later. The domestication of animals commenced over 15,000 years ago, beginning with the grey wolf (Canis lupus) by nomadic hunter-gatherers. The archaeological record and genetic analysis show the remains of the Bonn–Oberkassel dog buried beside humans 14,200 years ago to be the first undisputed dog, with disputed remains occurring 36,000 years ago. It was not until 11,000 years ago that people living in the Near East entered into relationships with wild populations of aurochs, boar, sheep, and goats.
According to the Humane Society of the United States, 3–4 million dogs and cats are euthanized each year in the United States and many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or castrating dogs helps keep overpopulation down. Local humane societies, SPCAs, and other animal protection organizations urge people to neuter their pets and to adopt animals from shelters instead of purchasing them.
Domestic dogs have been selectively bred for millennia for various behaviors, sensory capabilities, and physical attributes. Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal. Dogs are predators and scavengers, and like many other predatory mammals, the dog has powerful muscles, fused wrist bones, a cardiovascular system that supports both sprinting and endurance, and teeth for catching and tearing.
A 2005 paper states "recent research has failed to support earlier findings that pet ownership is associated with a reduced risk of cardiovascular disease, a reduced use of general practitioner services, or any psychological or physical benefits on health for community dwelling older people. Research has, however, pointed to significantly less absenteeism from school through sickness among children who live with pets." In one study, new guardians reported a highly significant reduction in minor health problems during the first month following pet acquisition, and this effect was sustained in those with dogs through to the end of the study.
Amongst apprenticeship programs and other hands-on training activities, Petco pet stylists who are trained from within the company are required to attend and pass Petco's comprehensive 12-week Pet Stylist Apprentice & Certification academy program. In addition to hands-on grooming training with a Petco-certified pet stylist mentor or instructor, all participants receive instruction in health, safety protocols and grooming salon operations. At the end of the program, candidates must pass a technical skills assessment in order to become a Petco Certified Pet Stylist.