Cats are among the most popular pets in the United States. Statistics estimate that more than 18 million cats live in the United States. These cats range in size, but most are under one inch in length. Most live in large cities where their population numbers increase along with the population of humans. In many cities there are areas of high human density such as around town areas, hospitals, airports, nursing homes, schools, and other places where cats live and breed. They are also a natural element in rural areas because they live in houses and alleys.
The domestication of cats was a long process involving centuries of hunting, catching prey, and evolving into a more refined animal. Domestic cats are the descendants of wild cats that left the territory of their birth and later survived and bred with feral domestic cats. The first cat to be domesticated was the Old World hunting cat, the African Wild Cat or Felis silvestris, which was probably brought as a feral by the Romans. It was later on the fate of these cats that their domestic counterparts became known as the cat, thanks to Christopher Columbus who took them from Africa and brought them back to Europe.
The main ancestor of the domestic cat was the Old World lynx, the cats most likely to be reintroduced to North America from Africa and Asia in recent times. They are thought to have originated in the Himalayas, but were driven to the near-desert wastes of Nepal and Arct Rica by climate changes and habitat encroachment. Thereafter they were able to adapt to warmer weathers, a diet of mice and rats, and the natural conditions of their respective countries and regions. Some of these cats went on to live in arid forests and became prey to big game animals such as lions and hyenas. A few managed to adapt to new climatic conditions in the New World and colonized parts of what is now the USA, while some went further south and to the warmer regions of Australia and South America.