Dolphin Mums Teach Daughters How to Use Tools
Date: 08-Jun-05
Country: USA
Their finding also seems to show a true animal case of culture -- a behavior that is passed along socially and not hard-wired into the genes, they said.
The animals that used the sponges all seemed to be related, but the researchers could not find any genes associated with the behavior, they report in this week's issue of the Proceedings of the National Academy of Sciences.
Michael Kruetzen of the Anthropological Institute and Museum at the University of Zurich in Switzerland and colleagues watched the dolphins at work in Shark Bay in Western Australia.
For years researchers have seen the dolphins pick up sponges with their beaks and then use them as they poked along the sea beds, evidently to protect their delicate snouts from spiny fish.
Kruetzen's team analyzed DNA from 13 "spongers" and 172 dolphins that did not display this behavior. While the sponging animals all seemed related along the female line, there was no genetic link.
Only one sponging male was studied. The researchers noted that this is a solitary behavior -- not suited to the sociable lives of males. Male dolphins make complex alliances with one another and often move in packs -- frequently in pursuit of females.
"Experimental evidence from captive dolphins demonstrates that bottlenose dolphins are capable of social learning," the researchers wrote.
They may be even better at imitating their peers than primates are, the researchers added.
"Hence, among all marine mammals, bottlenose dolphins are prime candidates for a social transmission of a behavioral trait in the wild," they wrote.
Monkeys, birds and chimpanzees have all demonstrated behaviors that could be described both as tool use and as culture.
