History
The genus Panthera, which includes all the big cats, has a very crowded family tree. It includes lions, leopards, jaguars, and, of course, tigers. But at the roots of that family tree there should be a common ancestor, and scientists have worked hard to find it. DNA mapping shows that the big cats share a common ancestor from about 6 million years ago, so when researchers discovered a big cat skull in Asia that dated to 5.8 million years, they were ecstatic. The rest is speculation of course, but it’s thought that a big cat species that lived in the cool climates of the Tibetan plateau would have been well adapted to cold, and could therefore spread throughout Asia as global temperatures dropped during the ice ages. The species would then adapt to its various settings, leading to the prevalence of big cats like Tigers over a wide range, each adapted extremely well to its surroundings.