A Canadian team found several brain genes that make wild birds cleverer than others at foraging for food are linked with those making humans intelligent, which provides an insight into the evolutionary mechanisms affecting cognitive traits in a range of animals.
In the paper published on Wednesday in Science Advances, researchers caught bullfinches and their close relative black-faced grassquits in Barbados. Bullfinches are bold, opportunistic and innovative, while grassquits are shy and conservative.
In captivity, the problem-solving skills of the two species differed considerably in lab tests. Most of the bullfinches quickly figured out how to lift the lid off a jar of food, for example, while all the grassquits were stumped by the challenge.
The researchers from McGill University in Montreal compared the expression of all genes in six parts of the brain of the two bird species, finding that a family of genes stood out: glutamate neurotransmitter receptors, especially in the part of the bird brain that corresponds to humans' prefrontal cortex.
Glutamate receptors are known to be involved in a variety of cognitive traits in humans and other mammals.
In particular a receptor known as GRIN2B, when boosted in transgenic mice, makes them better learners.
Levels of that receptor were higher in the Barbados bullfinch than in the grassquit, the researchers found.
"It might be that mammals, including humans, and birds like the Barbados bullfinch use similar mechanisms to perform cognitively," said Jean-Nicolas Audet, a MacGill biologists who collaborated with researchers from Duke and Harvard universities in the U.S. in this study.
"If our results are confirmed in future studies, it would be a unique demonstration of convergent evolution of intelligence, involving the same neurotransmitter receptors despite the widely different brain structures of birds and mammals," Audet said.