Is a dog better or a cat? Why do cats and dogs hate each other? Questions that have been pondered, giving rise to endless debates, ever since man and his four-legged companions have been around.

Now scientists have confirmed that cats are better than dogs — at least from an evolutionary perspective.

A groundbreaking study of 2,000 ancient fossils by researchers from the University of Gothenburg in Sweden, the University of São Paulo in Brazil and the University of Lausanne in Switzerland revealed that felids (members of the cat family) have historically been much better at surviving than the canid (members of the dog family).

The study has also shown that about 40 species of dogs became extinct due to the ancestors of cats. Reason enough to hate each other, one would say.

About 40 million years ago, the dog family, including wolves from which today's domesticated dogs are descended, originated in North America. They reached a point when there were more than 30 species on the continent. It was at this juncture that the cat family arrived from Asia.

A period of dramatic decline was seen among the dog clan with the influx of cats. Today, North America has just nine species of wild dog, comprising different variations of wolves and foxes, according to the fossil analysis published in the Proceedings of the National Academy of Sciences journal PNAS.

"The arrival of cats to North America had a deadly impact on the diversity of the dog family. We usually expect changes in climate to play the overwhelming role in the evolution of species. Instead, competition among different carnivore species proved to be even more important for the dogs," said the report's lead author, Dr. Daniele Silvestro, of the University of Lausanne in Switzerland, according to the Independant.

Size and natural prowess of the cats are seen as massive contributors to their supremacy over man's best friend.

"The cats have retractable claws, which they only pull out when they catch their prey. This means they don't wear them out and they can keep them sharp. But the dogs can't do this, so they are at a disadvantage to the cats in an ambush situation," elaborated Silvestro, according to RT.

Despite the fact that cats had a significantly negative impact on dogs, the same is not true regarding the effects of dogs on the survival of ancient cats. The study showed that compared to other extinct species included in the family of dogs, felids could have been more adept predators, reported Tech Times.