For every young American under the age of 18, there are about two cats or dogs receiving free food and lodgings in US homes and that pattern is replicated in many other countries. So why do so many of us keep pets? Why do we name them, consider them part of the family? Companionship, pleasure, status symbol and kinship with all life have been offered as explanations but it's easy to forget that mass keeping of pets - as opposed to working animals - is a recent development of the last two centuries or so. Iszi Lawrence talks about our evolving relationship with pets with Dr. Anindita Bhadra from the Dog Lab at the Indian Institutes of Science Education and Research in Kolkata; Dr. Erin Hecht, evolutionary biologist from Harvard; Dr. Margo DeMello, anthrozoologist from Carroll College in Montana; writer and cultural commentator from Japan Manami Okazaki; Durham University historian Professor Julie-Marie Strange; and Rachel Williams, neuroscientist at UCL and comedian. We also sift through the dozens of comments and pet stories sent in by Forum listeners. (Photo: A young woman with her pet dog. Credit: Luis Alvarez/Getty Images)