The evolution of the domestic house cat is not as straightforward as you might expect. Twenty-first century science has illuminated some aspects of domestication, but lineages remain murky. In short, all cats probably evolved from the prehistoric proailurus, which was either the last cat precursor or the first cat.
Family Trees and Common Scratching Posts
All cats are in the Felidae family. It's not wrong to call them felids. Within the felidae family are two living subfamilies: Pantherinae (which includes jaguars, lions, leapards and tigers) and Felinae (which includes cougars, cheetahs, lynxes, ocelots and house cats). There was a third Felidae subfamily -- Machairodontinae, which included the smilodon, aka the saber-toothed tiger -- but they died off. The most recent common ancestor of all three families, extant and extinct, is the pseudaelurus. Its predecessor, the proailurus, may have been the first true felid.
The First Cats
Pseudaelurus was a prehistoric cat that lived in Eurasia and North America roughly 20 million years ago. The pseudaelurus had slender proportions and short legs, not unlike a weasel. It died out about 8 million years ago. In scientific literature it's sometimes cited as the basal stock of the Felidae family. Its predecessor was the proailurus, which lived in Eurasia roughly 25 million years ago.
The proailurus was slightly bigger than a domestic cat. It had a long tail and probably hung out in trees. Some scientists posit it as the basal stock of the Feliformia superfamily -- this includes Felidae and similar animals -- but other scientists dub it the first true felid.
All Cats, Large and Small
All cats -- that is, all felids -- share common traits. This might seem counter-intuitive if you're comparing your house cat with a tiger. Remember, though, the term "big cats" carries no biological significance apart from size distinction. It may help to keep in mind that the similarities found in ancient cat remains have made tracing their genealogy quite difficult.
In any case, all cats are obligate carnivores (they have to eat meat), many are social, and they're often nocturnal. No members of the Felidae family have taste receptors for sweetness.
Cats traveled from Eurasia to North America and back again multiple times through the course of prehistory, spreading throughout the world by millions of years ago according to 21st century scientific studies.
The domestication of the house cat came much more recently. Scientists used to think the Egyptians were the first people to domesticate cats, roughly 3,600 years ago; but new evidence puts domestic cats in the Fertile Crescent perhaps as long as 10,000 years ago.
Warren E. Johnson and Stephen J. O'Brien, both of the National Cancer Institute, and other scientists have used DNA evidence to chart lineages of all cats, big and small. They've identified 37 species, all of which evolved from pseudaelurus and, by extension, proailurus.