"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," explained Fortune, who spent hours hacking through the thick bamboo with a machete, trying to catch the songbirds in nets. "The wrens made an ideal subject to study cooperation 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."
The team then captured some of the wrens and monitored activity in the area of their brains that control singing. They expected to find that the brain responded most to the animal's own singing voice. 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 said. "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 is very relevant to the brains of most, if not all, vertebrate species, including us humans."
|Contact: Lisa DeNike|
Johns Hopkins University