London: A genetic analysis has revealed that the tiger began evolving 3.2 million years ago, along with the snow leopard, which means it is more ancient and distinct than previously believed.
Despite the popularity and endangered status of tigers, much remains to be discovered about them, including how they evolved.
It has long been known that the five species of big cat, the tiger, lion, leopard, jaguar and snow leopard, which belong to the Panthera genus, and the two species of clouded leopard, are more closely related to each other than to other smaller cats.
But, it has been difficult to pin down the exact relationships between them.
So, according to BBC News, to find out more, scientists Brian Davis, Dr Gang Li and Professor William Murphy conducted an analysis of the DNA of all these species.
By looking at similarities in DNA held in mitochondria and within the sex chromosomes among other places, the researchers found that the five big cat species are related to each other in a different way to previously thought.
Their data strongly suggests that lions, leopards and jaguars are most closely related to each other.
Their ancestor split from other cats around 4.3 to 3.8 million years ago.
About 3.6 to 2.5 million years ago, the jaguar began to evolve, while lions and leopards split from one other about 3.1 to 1.95 million years ago.
But the tiger had already emerged by this point.
The ancestor of tigers and snow leopards also branched off around 3.9 million years ago.
The tiger then began to evolve into a unique species toward the end of the Pliocene epoch, about 3.2 million years ago.
That makes the tiger and snow leopard “sister species”, according to the researchers.