Thursday, December 08, 2005

Bottlenose dolphin proves the importance of language

AS EVERY dolphin knows, it's good to talk. But what their human admirers are only now realising is how fast, sophisticated and essential for survival dolphin lingo is.

New scientific research has pinpointed how the much-loved mammals speedily relay complex messages between many members of their own "school" in a bid to find food or avoid predators - often across many miles of water.

The research was carried out among the 130-strong bottlenose dolphin colony living in the Moray Firth on the east coast of Scotland by a team from Aberdeen University.

They believe that despite the distances involved when dolphins split up to forage for food, highly developed communications networks mean it only takes an average of 3.9 "contacts" for any two animals to form a link over danger or where to find a meal. This "small world" network in the Moray Firth means information about new food sources and any predators can be quickly spread, helping the animals to survive and prosper.

The research team believes the findings help to explain why language has developed in other species, including humans, who also had to split up from their core group for hunting expeditions.
The scientists, whose work is published in the current edition of the Journal of Animal Ecology, discovered that all dolphins have preferred companions, although they spend long periods surrounded mainly by what appear to be more casual acquaintances.

Survival of those preferred companions depends on constant networking and rapid communications between separated groups.

Research team spokesman Dr David Lusseau said: "Three-quarters of the members of a school will not spend much time together - typically less than a day at a time.

"Therefore individual dolphins will often join others that come from other schools. This means knowledge about food location could quickly spread throughout the whole population just by 'word-of-mouth'."

Bottlenose dolphins are one of the most vocal animals in the world, producing two types of sound, whistles and very short- duration clicks at varying rates. The clicks are used for both communication and echo location, and the whistles mainly for communication alone.

Research on captive mammals has found that more than 90% of whistles are individual and specific to certain situations. When food is involved, speed of communication is vital, as competitors are not likely to be far away.

"Competition is going to put a premium on communication," Lusseau said. "Networking and language go hand in hand. This highly effective system where one can be first with the news is essential to survival."

Lusseau believes the small-world nature of dolphin society may come from evolution, which favours the efficient transfer of information. He contends his dolphin research can help explain the evolution of language among other species.

His next step is to lead a study into 10 animal populations worldwideto establish the roots of speech.

Quick "Facts about Dolphins"