The origin and spread of these adorably nasty little creatures are still not well understood. A recent study has sequenced DNA from more than 200 cats that lived between 200 to 15,000 years ago, from more than 30 archaeological sites across Europe, the Middle East and Africa. The researchers found that the cat population appear to have grown in 2 waves: a wave in which wild cats expanded with early farming from Middle Eastern to eastern Mediterranean, followed by another wave from Egypt to Eurasia and Africa a few thousand years later (and this lineage is also found in a Viking burial site a few centuries later). The researcher on the study suggests that the cat lineage that spread with early farming may be associated with grain stockpiles attracting rodents, which in turn attract wild cats, and the second wave of expansion might due to sea-faring people keeping cats on the boat to keep rodents in check.
Now cats have expanded their spread to the Internet, I wonder where they will go next!
Further reading:
http://www.nature.com/news/how-cats-conquered-the-world-and-a-few-viking-ships-1.20643
the Runaway Lab Book 