In a fascinating paper published last year in Science, a team led by Andreas Nieder of the University of Tübingen in Germany showed that crows—already known to be among the most intelligent of animals—are even more impressive than we knew. In fact, the evidence suggests that they are self-aware and, in an important sense, conscious.
The corvid family of birds, which includes crows, ravens, jays and magpies, had been observed previously to use tools, as well as remember the faces of people they like or don’t like, or drop nuts on the road so that passing cars will crack them open. At a train station once, I watched a pair of crows team up at a water fountain. While one pushed the button with its beak, the other drank from the water that started to flow.
Nieder’s experiment showed that the birds were actively evaluating how to solve a particular problem they were confronted with. In effect, they were thinking it over. This ability to consciously assess a problem is associated with the cerebral cortex in the brains of humans. But birds have no cerebral cortex. Nieder found that in crows, thinking occurs in the pallium—the layers of gray and white matter covering the upper surface of the cerebrum in vertebrates.
Other studies support the notion that the bird brain can, in principle, support the development of higher intelligence. This idea had been dismissed in the past due to the small size of birds’ brains. But recent research has shown that in birds, the neurons are smaller and more tightly packed, which makes sense to reduce weight and make it easier to fly. The total number of neurons in crows (about 1.5 billion) is about the same as in some monkey species. But because they are more tightly packed, communication between the neurons seems to be better, and the overall intelligence of crows may be closer to that of Great Apes such as the gorilla.
The brains of dinosaurs—the ancestors of today’s birds—have been found to be astonishingly small. But if they had the same brain anatomy as birds, dinosaurs could have been much smarter than previously thought. As I speculated in my book about the Cosmic Zoo hypothesis, some of those who had a relatively large brain compared to their body size, such as the Troodons, could have been quite advanced.
This research has important consequences for our understanding of the evolution of higher intelligence. First, a cerebral cortex is not needed, and there are other anatomical means to achieve the same outcome. Second, either the evolution of consciousness is very ancient, tracing back to the last common ancestor of mammals and birds about 320 million years ago, or, equally intriguing, consciousness arose at least twice later on, independently in mammals and birds. Both options raise the likelihood, in my view, that higher intelligence on other planets may not necessarily be mammal or human-like, but could very well be birdlike.