By four months old, the cognitive performance of ravens may be similar to that of adult great apes, a study suggests.
The birds’ performance in experimental tasks testing their understanding of the physical world and how they interact with other ravens was analysed by researchers. They tested the cognitive skills of eight hand-raised ravens at 4, 8, 12 and 16 months of age using a series of experiments.
The skills the authors investigated included spatial memory, object permanence – understanding that an object still exists when it is out of sight – understanding relative numbers and addition. Scientists also looked at the ability to communicate with and learn from a human experimenter.
“For instance, to investigate whether ravens know where food is located, we hid treats under a cup, and moved it quickly back and forth among other cups that were empty, just as one does in the ‘shell game’," said Dr Miriam Sima of the Max Planck Institute for Ornithology. "A raven selected a cup by pecking or pointing at it with its beak, while a chimpanzee would have done this with their fingers."
According to the study published in Scientific Reports the cognitive performance of ravens was similar from 4 to 16 months of age, suggesting the speed at which their cognitive skills develop is relatively quick and near-to-complete by 4 months of age.
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“This may be due to the fact, that at four months of age young ravens are already quite independent and start to be interested in non-breeding aggregations of conspecifics," explains Prof Simone Pika from the University of Osnabrück, Germany. "Hence, they need to be cognitively on top of things to deal with these new challenges."
Although task performance varied between individuals, the ravens generally performed best in tasks which tested addition and understanding of relative numbers. They performed worst in tasks testing spatial memory.
The researchers compared the cognitive performance of the ravens with those of 106 chimpanzees and 32 orangutans who completed similar tasks in a previous study. They found that with the exception of spatial memory, the cognitive performance of the ravens was very similar to those of orangutans and chimpanzees.
Pika and her colleagues say the findings suggest ravens, similarly to great apes, may have evolved general, sophisticated cognitive skills. The authors propose the birds developed these skills in response to living in a constantly changing environment where survival and reproduction are reliant on cooperation and alliances between ravens.
However, the authors caution that the performance of the ravens studied may not be representative of the species in general.
Reader Q&A: Do any other animals have religion?
Asked by: Rodney Minns, Hampshire
Although my dog may stare at me like I’m a deity, there’s no evidence to suggest that non-human animals have religion. They don’t worship, pray or believe in gods of any kind, but they do perform ritualistic behaviours, prompting some to speculate that animals could have a spiritual side.
Elephants, famously, ‘mourn’ their dead. Family members visit the bodies of deceased relatives, and smell and touch them. There are claims that magpies have been seen placing ‘wreaths’ of grass next to dead individuals. In 2018, a ‘grieving’ orca carried her dead calf through the icy waters of the Salish Sea for more than two weeks before finally letting it go.
Putting aside the use of anthropomorphic terms such as ‘mourning’ and ‘grief’, these and other incidents still hint that some animals at least have an awareness of death and the capacity to ritualise their dead.
Rituals have been perceived in other areas, too. Jane Goodall witnessed chimpanzees dancing at waterfalls, and pondered whether the animals are experiencing feelings of awe or wonder. Other scientists have watched elephants waving branches at the waxing Moon, prompting some to wonder if the Moon holds symbolic significance for them.
It’s a tough call. On the one hand, why shouldn’t intelligent, socially complex animals feel awe in response to the natural world or the night sky? Maybe ritualistic behaviour does hint at a level of spirituality. On the other hand, maybe chimps just like having a boogie, and elephants just like waving sticks. Until we can read their minds, we should keep ours open.
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