Researchers have found cave art created by Neanderthals in a dolomite stone. The art work dates back to more than 39,000 years and was found in a seaside Gibraltar cave. 

The research shows that the ancient cousins of humans weren't dumb and were capable of higher cognitive abilities.

"It is the last nail in the coffin for the hypothesis that Neanderthals were cognitively inferior to modern humans," said Paul Tacon, an expert in rock art at Australia's Griffith University, according to the Associated Press.

Tacon wasn't involved in the study. He said that research shows that Neanderthals probably made the art work for ritual purposes or to communicate with each other.

Neanderthal groups, living in Eurasia, completely disappeared from the world about 30,000 years ago. Other studies have shown that Neanderthals might have lived near the Arctic Circle around 31,000 to 34,000 years ago. Other researches have shown that the species lived in parts of Europe till much later than previously assumed and that they might have interbred with humans.

The researchers from 11 European countries participated in the study. The team found the ancient criss-cross lines in Gorham's Cave in Gibraltar.

"This engraving represents a deliberate design conceived to be seen by its Neanderthal maker and, considering its size and location, by others in the cave as well," anthropologist Clive Finlayson, director of the Gibraltar Museum, and his colleagues wrote, according to "It follows that the ability for abstract thought was not exclusive" to modern humans, the researchers said.

Not everyone is convinced though. Recent studies have suggested that humans and Neanderthals were living together at one point in time. So, these ancient artworks could be created by humans and not their ancient cousins.

The study is published in the journal Proceedings of the National Academy of Sciences.