Eight young ravens, put though cognitive tests often used on chimpanzees and orangutans, exhibited physical and social intelligence "very similar" to adult primates, a study published in Scientific Reports concluded Friday.

The first "large scale" study of ravens' cognitive skills helped to unravel "one of science's great mysteries," researchers said: How avian brains — different from mammals — had evolved, providing "parallel" intelligence over 300 million years.

How was the test carried out?

The common ravens (Corvidae) were hand-raised at the Max Planck Institute (MPG) for Ornithology near Munich. They were released into an outdoor aviary and put through so-called PCTB experiments — often used for Great Apes.

In one test, a raven would select one of three moving cups hiding a food treat, using its beak to peck or point at it, whereas a chimpanzee would use a finger.

Also run were tests on whether the ravens understood causality, had spatial and rotational memory, could communicate by looking and pointing, and exhibited mind capability by following the gazes of others.

Already, at four months, the young ravens demonstrated "full blown" cognitive skills in handling nine physical and six social tasks, said the project's leading cognitive scientists, Osnabruck University professor Simone Pika and MPG's Miriam Sima. 

"At four months of age young ravens are already quite independent," said Pika, adding that they aggregated together, and were "cognitively on top of things to deal with these new challenges."

"Our ravens and the great ape individuals showed considerable similarities," said the authors, referring to cognitive skills tested until the birds were 16 months old.  

How will the results be used?

In an ever-changing ecological environment, raven survival relies heavily "on successful cooperation and alliances," and their "cognitive toolkit" to rapidly deal with complex challenges, the authors said. 

For future studies, the scientists suggested comparing the cognitive skills of ravens and parrots if experimenters were involved or not involved in hand-raising.

The raven study was carried out at the Max Planck Institute for Ornithology, once the workplace of behavioral scientist and Nobel Prize winner Konrad Lorenz.

ipj/rt (Reuters, AFP, AP)