Crows display impressive math prowess, using brain regions entirely different from those of mammals.
Counting crows. I’m Bob Hirshon and this is Science Update.
People are experts at tallying up how many objects there are in a group. In the Proceedings of the National Academy of Sciences, University of Tübingen animal physiologist Andreas Nieder and his colleagues have shown that crows are also expert at it. He says the family trees of mammals and birds diverged three-hundred million years ago, from small-brained reptilian ancestors.
But surprisingly, birds and mammals then independently developed higher endbrain centers that are now anatomically very distinct and different. Still, they are able to give rise to these very intelligent, high-level cognitive capabilities like numerical competences.
He points out that sizing up how many items are in a group is helpful when evaluating food resources, and especially useful for social animals navigating coalitions of friends and foes. I’m Bob Hirshon, for AAAS, the science society.
Making Sense of the Research
Could the hunter's fable about crows' ability to count be true? According to this fable, three hunters go into a blind situated near a field where watchful crows roam. They wait, but the crows refuse to move into shooting range. One hunter leaves the blind, but the crows won't appear. The second hunter leaves the blind, but the crows still won't budge. It's only when the third hunter leaves that the crows resume their normal feeding activity.
This recent research by Dr. Nieder and Dr. Helen Ditz at the University of Tübingen seems to imply that crows can indeed count. For this research, the scientists worked with carrion crows. They trained the crows to distinguish between groups of dots. 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 rewarded. If they were different, they got rewarded for not pecking.
As the crows were being tested, the team recorded the responses of individual neurons in an integrative area of the crow endbrain. (The endbrain is the front section of the forebrain (the forward-most portion of the brain), making up the cerebrum and related structures.) This region of the brain also happens to process visual information. The researchers discovered that the activity of these neurons suggests the crows 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. "When a crow looks at three dots, grains, or hunters, single neurons recognize the groups' 'threeness,'" said Helen Ditz. "This discovery shows that the ability to deal with abstract numerical concepts can be traced back to individual nerve cells in corvids [the family of birds that includes crows, jays, and ravens]."
This is a classic case of covergent evolution of intelligence. (Convergent evolution is the independent evolution of similar features in species of different lineages.) Though crows and humans are only distantly related in terms of evolution, they both seem to have developed this neural basis of number recognition. It seems that even abstract behavior, which we think of as sophisticated mental feats common to humans, ultimately has biological roots.
Now try and answer these questions:
- What is the hunter's fable about crows being able to count?
- What kind of crows were involved in this study?
- How did the researchers set up the study?
- What did the crows have to do in order to get rewarded?
- What is the endbrain? What does the activity detected in the crows' endbrain suggest about their ability to count?
- What is covergent evolution?
You can follow up this Science Update by hearing more about birds and learning in the Parrot Learning Science Update.
The whole area of human learning and learning in other animals can be a fascinating one for your students to study. You can use this Science Update plus several other ones to capitalize on that interest. For example, the Word Associations Science Update looks at researchers who are studying exactly what happens in the brain when it learns and remembers information. In the Human Language Science Update, researchers look at how language is not only universal among humans, but also has universal properties that are unique to the language of human beings.