Why some birds learn new tricks while others sing the same old song

One of the mysteries of birdsong has been solved by scientists trying to understand why some birds are able to learn new songs while others are stuck with the sounds they are born with.

One of the mysteries of birdsong has been solved by scientists trying to understand why some birds are able to learn new songs while others are stuck with the sounds they are born with.

Three of the 23 major groups of birds are able to learn to sing - or even "talk" in the case of the hummingbirds, parrots and songbirds. They have all been found to possess seven brain structures that enables them to perform and remember complex vocalisation, scientists have found.

The seven individuated brain facets appear to have evolved independently in each of the three groups, while they have not evolved at all in the remaining 20 orders of birds for which calls - such as the cock's crow - are genetically "hardwired" from birth rather than learned.

A team of American and Brazilian zoologists, led by Erich Jarvis of Duke University, North Carolina, discovered that hummingbirds have the same seven neurological structures in their forebrains as the songbirds and parrots.

The scientists, who report their findings in the journal Nature, say that the three groups are not closely related, which means that the seven structures might have evolved independently as a result of common constraints on being able to learn how to sing.

Dr Jarvis added that a similar phenomenon mostly likely informed the independent evolution of the wing, which occurred at least three times in vertebrate animals when the forelimbs of pterosaurs (flying dinosaurs), bats and birds became adapted for flight.

"The reason why wings evolved in a similar way is because there is an environmental constraint - the centre of gravity - placed on how animals can fly," he said.

He added: "Here, I think there is an interaction between the environment and the brain, and mother nature has a basic constraint, even instructions, on how you can develop brain structures for a complex behaviour such as vocal learning."

The fundamental requirement for seven specialised regions of the brain may shed some light on how mammals, including humans, are able to learn vocalisations. Besides human beings, only whales, dolphins and bats can learn how to "sing".

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