Human domestication of other animals has shaped human history. Dogs, which have been domesticated for at least 10,000 years, have provided humans with guards, hunting aids, carrying aids, and sources of meat and fur. The domestication of sheep, goats, pigs, cows, and other animals enabled humans to live as herders. Living in close proximity to domestic animals probably stimulated the development of the human immune system. The domestication of the horse had a huge impact on human warfare.
Pets today tend to be associated with the human desire for companionship. However, the share of U.S. households with a pet actually rises with household size. For example, 38% of two person households had a dog in 2006, while 54% of households containing five or more persons had a dog. The importance persons attach to using the Internet for social communication also rises with household size. More opportunities for communications of various types seem to be positively correlated. That’s consistent with the success of online social networks for pets. More generally, despite the obvious difficulties of traditional media, communication is not a zero-sum business.
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Data: U.S. Statistical Abstract 2011, Table 1240, “Household Pet Ownership: 2006“. In the U.S. at the end of 2006, 43% of households owned dogs and 38% owned cats. Here are some additional statistics.