Bird (and human) brains wired for duet

JOHNS HOPKINS (US) — The brain is built to collaborate, whether it’s humans working together to build a bridge or birds singing a lively duet on a South American mountainside, a new study suggests.

“What we learned is that when it comes to the brain and cooperation, the whole is definitely greater than the sum of its parts,” says Eric Fortune, associate professor of psychological and brain sciences at Johns Hopkins University. “We found that the brain of each individual participant prefers the combined activity over his or her own part.”

Fortune’s research, published in the journal Science, was conducted in the cloud forests of Ecuador, on the slopes of the active Antisana Volcano. It’s one of the only places in the world where you can find plain-tailed wrens.


These chubby-breasted rust-and-gray birds, who don’t fly so much as hop and flit through the area’s bamboo thickets, are famous for their unusual duets.

Their songs—sung by one male and one female—take an ABCD form, with the male singing the A and C phrases and the female (who seems to be the song leader) singing B and D.

“What’s happening is that the male and female are alternating syllables, though it often sounds like one bird singing alone, very sharply, shrilly and loudly,” explains Fortune.

“The wrens made an ideal subject to study cooperation,” he says, “because we were easily able to tape record their singing and then make detailed measurements of the timing and sequences of syllables, and of errors and variability in singing performances.”

Fortune and his collaborators then captured some of the wrens and monitored activity in the area of their brains that control singing. They expected to find that brain cells responded most to an animal’s own singing. But that’s not what happened.

“In both males and females, we found that neurons reacted more strongly to the duet song—with both the male and female birds singing—over singing their own parts alone. In fact, the brain’s responses to duet songs were stronger than were responses to any other sound,” he said. “It looked like the brains of wrens are wired to cooperate.”

So it’s clear that nature has equipped the brains of plain-tailed wrens in the Andes of Ecuador to work cooperatively and to prefer “team” activities to solo ones. But what does that have to do with people?

“Brains among vertebrate animals—frogs, cats, fish, bears, and even humans—are more similar than most people realize,” Fortune says. “The neurotransmitter systems that control brain activity at the molecular level are nearly identical among all vertebrates and the layout of the brain structures is the same.

“Thus, the kinds of phenomena that we have described in these wrens are very relevant to the brains of most, if not all, vertebrate species, including us humans.”

Study co-authors include researchers at Pontificia Universidad Catolica del Ecuador and Claremont McKenna College. The work was supported by the National Science Foundation.

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