circa 12,000 BC: The Asian wolf is domesticated for use in tracking game, creating the first known 'dog,' though it bore little resemblance to today's household dogs.

circa 7,300 -- 7,000 BC: The trend continues almost five thousand years later when tribes in the British Isles, and later the Greeks, begin to keep dogs.

circa 3,500 BC: The domestication of animals, including goats, sheep, asses, cattle, pigs, horses, and dogs -- combined with the invention of the wheel and the development of irrigation -- has streamlined food production enough to allow a few people to engage in scholarly, spiritual, aesthetic, and economic pursuits.

circa 3,000 BC: Following the invention of granaries in Egypt, wild cats are allowed indoors to hunt mice, beginning the evolution of the large, ferocious feline into our much smaller, yet ever willful, houseguests.

circa 2,850 BC: The Great Sphinx is created.

circa 2,000 BC: Egyptian hieroglyphics depicting exotic menageries of birds -- including doves, parrots, and ducks -- chronicle the beginnings of birdkeeping.

circa 0 AD: Jesus Christ is, reportedly, born in a manger, surrounded by humble animals.

circa AD 500 -- AD 1800: Pets were not uncommon in Europe during the Middle Ages and the Renaissance, but they were kept for the most part by courtiers, members of privileged religious orders, and the upper classes.

circa 1500 AD: The word pet, which is probably related to petty (small), is introduced into English as a reference to 'an animal kept as a favorite.'

19th century: As human dependence on animals decreases, Victorians become increasingly sentimental about horses and dogs. Intelligence, character, and even human forms of morality are attributed to them.

1851: The word 'doggone' first appears in print in the novel Scalp Hunt. It is generally taken as a deformation of the profanity 'God damn,' though its original form is thought to be 'dog on it,' to be used like 'pox on it.'

1865: Lewis Carroll publishes Alice's Adventures in Wonderland, and no one ever again looks at cats, mice, and rabbits without a touch of uneasiness.