Corvids show that brain size does not determine intelligence

Researchers in Sweden have concluded from a series of tests that brain size does not directly correlate with the intelligence level of a species. Ordinarily, primate species are said to reign in the department of intellectual dominance over other animals. However, these tests have indicated that ravens and crows are just as intelligent as primates, despite having significantly smaller brains. With these new findings, the theory that primates are the most intelligent animal species remains under investigation.

Although cleverness is difficult to measure accurately, one of the main indicators of high levels of brain power is the ability to pause and attempt to do something more rationally, a tactic known as the exhibition of inhibitory control.

In order to calculate inhibitory control in primate subjects, scientists placed food in a transparent tube that was cut on each side and had the primates attempt to extract and consume the treat. The front of the tube, which faced the primates directly and acted as another layer to get through before reaching the food, sealed the food from the primates.

In order to successfully retrieve the food from the tube, the primates had to pause and re-strategize. The primates demonstrated high levels of inhibitory control when they appeared to stop to think about their next step and realized that they had to go around to the side openings in order to succeed.

This study was conclusive in determining that primates had massive intelligence levels, as predicted, and heavily normalized by previous scientific research. However, only recently were other animals besides primates tested on inhibitory control in the same manner. These tests were conducted with the intent of measuring self-control and self-regulation in animal species, but only primates had been evaluated in this regard in the past. 

Can Kabadayi, along with a team of other researchers, orchestrated the same test for corvid birds, or birds that belong to the family that includes crows and ravens. In order to conduct the study, the researchers first trained the birds to obtain a treat from an opaque cylindrical tube that was cut in the same fashion as the transparent tubes.

When the birds successfully retrieved the food from the opaque tube, the researchers switched the experiment over to the transparent tubes. The objective to retrieve the food stayed constant. The challenge that arose with the switch to transparent tubes was that this time the birds were able to see their treats in front of them, even though the treats were encased by a plastic covering on all sides except at the ends.

This shift triggered their inhibitory control. To the surprise of the researchers, results showed that corvid birds demonstrated the same intellectual abilities as primates.

Corvids were specifically chosen for the study because they have the largest brain size among birds. The irony that accompanies these studies is that birds are consistently labeled as small-brained and the common expression “birdbrain” is used to denote lack of intelligence and general silliness. The corvids, collectively, received a nearly perfect score that is easily comparable to that of the great apes. 

These studies have suggested that perhaps neuronal density is actually what accounts for varying intelligence levels among species. The neuron is the basic cell that processes and transmits information across the nervous system. Higher concentrations of neurons in relation to the volume of brain gray matter and nerve cells may indicate greater intelligence.

The studies have completely nullified the theory that brain size directly correlates to intelligence levels. Now that the studies have been released, scientists and researchers have another basis by which to measure intelligence more accurately.

Scientists are attempting to identify other potential factors that may contribute to these unexpectedly high levels of intelligence among bird species. One of these speculations highlights how corvids have a tendency to stay with their parents for longer periods of time than other birds do. Another theory is that corvids display more playful attitudes than other bird species do, which may enable them to develop certain cognitive abilities.

Young corvids have been known to play games with one another, games that incorporate manipulative tactics, passing items to one another and balancing tricks. Researchers are examining whether these games have the capacity to train the birds’ brains to adapt and develop certain survival instincts and strategic thinking abilities.

Researchers, though they have made a breakthrough in the intelligence levels of species outside of the primate zone, still have a lot to gather about how the brain works. If the brains of ravens and crows are similar to the brains of primates, our closest animal relatives, perhaps this revelation can help explain more about how the human brain functions in the future.