Parallel Great Apes

By 4 months of age, the cognitive performance of common ravens (Corvus corax) in experimental tasks is similar to those of two great ape species, chimpanzees (Pan troglodytes) and orangutans (Pongo pygmaeus).

Pika et al. conducted the first systematic, quantitative large-scale assessment of physical and social cognitive performance of common ravens (Corvus corax) with a special focus on development. Image credit: Ralph Capri23auto.

“Human children show unique cognitive skills for dealing with the social world but their cognitive performance is paralleled by great apes in many tasks dealing with the physical world,” said lead author Dr. Simone Pika, a researcher at the University of Osnabrück and the Max Planck Institute for Ornithology, and colleagues.

“Recent studies suggested that members of a songbird family — corvids — also evolved complex cognitive skills but a detailed understanding of the full scope of their cognition was, until now, not existent.”

In the study, the scientists tested the cognitive skills of eight hand-raised ravens at 4, 8, 12 and 16 months of age using a series of tests.

They investigated the following skills: spatial memory, object permanence (understanding that an object still exists when it is out of sight), understanding relative numbers and addition, and the ability to communicate with and learn from a human experimenter.

They found that the cognitive performance of ravens was similar from 4 to 16 months of age, suggesting that the speed at which the ravens’ cognitive skills develop is relatively rapid and near-to-complete by 4 months of age.

At this age ravens become more and more independent from their parents and start to discover their ecological and social environments.

Although task performance varied between individuals, ravens generally performed best in tasks testing addition and understanding of relative numbers and worst in tasks testing spatial memory.

Comparing the cognitive performance of the ravens with those of 106 chimpanzees and 32 orangutans who completed similar tasks in a previous study, the authors found that with the exception of spatial memory, the cognitive performance of the ravens was very similar to those of the great apes.

The findings provide evidence that ravens, similarly to great apes, may have evolved general, sophisticated cognitive skills.

“We propose that ravens developed these skills in response to living in a constantly changing environment where survival and reproduction are reliant on cooperation and alliances between ravens,” the researchers said.

“However, the performance of the ravens studied may not be representative of the species in general.”

The results were published in the journal Scientific Reports.

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S. Pika et al. 2020. Ravens parallel great apes in physical and social cognitive skills. Sci Rep 10, 20617; doi: 10.1038/s41598-020-77060-8