Anyone who has matched wits with crows wreaking havoc in their yard knows that these birds are clever. Their knack for breaking into garbage bins and invading gardens reveals some of their skills, but looking into their brains shows that crows are even capable of performing the sophisticated task of counting.
When researchers examined the brains of crows as they performed a task involving numbers, they found that the activity of specific neurons suggests they can count. The patterns of brain activity they observed as the crows seemed to ponder numbers was similar to that seen in the brains of primates such as humans. The work, published in the journal Proceedings of the National Academy of Sciences, could help scientists better understand how intelligence evolves.
"This is a classic case of 'convergent evolution' of intelligence," study co-author Andreas Nieder told Tech Times. "It allows us to investigate the general principles that make a brain intelligent."
Crows come in dozens of species. Each is a bit different but most, if not all, are known for being particularly intelligent birds. For this study, the researchers worked with carrion crow, Corvus corone.
"These birds are smart and are very abundant," says Nieder. "They can be nicely trained to peck on touch screens to have a computer-controlled behavioral setup."
They trained crows to discriminate between groups of dots on a screen. Some of the dots were different sizes or shapes to see if this would throw the crows off. The birds had to detect if two groups contained the same number of dots, and received rewards for correct responses. If the number in the two displays was the same, they had to peck the screen to get the reward. If they were different, they got a reward for not pecking.
While the crows performed this task, researchers recorded the activity in particular neurons in the crows' brains. They were surprised to find that despite the fact that primates and crows are only distantly related in terms of evolution, the neural basis of number recognition was similar between the two groups. This hints at how our own ability to count arose, as it suggests that the ability to distinguish between numbers relative to one another is key to developing full-blown counting skills.
"There is ample evidence that our counting abilities emerge from estimation capabilities that seem to be rooted into our brain even before we master numbers after heavy training as children," says Nieder.
The crows were good at pointing out when two groups contained the same number of dots, regardless of the dots' shape, size, or arrangement. But only humans are able to count "in a strict sense," according to Nieder. That is, a crow can determine numbers relative to one another, but would not be able to determine whether a group contains exactly 10 objects, for example.
One question that Nieder is left wondering about crows is, "Can they perform simple arithmetic calculations?" He hopes to find out in future experiments.
