In a manner similar to what happens with humans, sperm whales in different social groups or clans develop regional dialects, evidence that a form of culture — something considered exclusively human — may exist in the animal kingdom, researchers say.
Sperm whales live in tight social networks, often in numbers of thousands of animals, and communicate with each other through click sounds.
Separate networks, or clans, have been shown to use a sequence of clicks unique to them, the researchers report in the journal Nature Communications.
That suggests the whales are exhibiting behavior that resembles, in some ways, similarly to human cultures, they argue.
"Animal culture is a highly-debated topic among experts," says Mauricio Cantor, a biologist at Dalhousie University in Nova Scotia, Canada. "Our findings provide evidence that key features of human culture — which we think makes us so different from everything else in nature — might be at play in populations of other animals."
The dialects are not innate, the researchers emphasize, but must be "culturally learned" by each whale following the example of family members and peers.
The researchers following sperm whales in the eastern Pacific Ocean water near the Galapagos Islands found two clans whose click patterns were distinct from each other.
One, dubbed the "regular" clan, used clicks that were spaced regularly, while the other, which researchers called the "plus-ones," made a prolonged pause before the final click in their conversations.
The respective clans, with their separate dialects, did not mix, says Dalhousie researcher Hal Whitehead.
"They behave differently; they move around differently; they babysit their babies differently," he says. "And so while a family unit from the regular clan will get together with another family unit from the same clan, sometimes for days — and the same for the plus-ones — we've never seen a regular unit associate with a plus-one unit."
Developing a dialect — a repertoire of communication sounds used in one group that cannot be understood by another — is rare in nature, Cantor points out, but is common in human populations as a result of evolving culture.
The study findings confirm that sperm whales are social creatures, perhaps as much or more than humans, Whitehead says.
"They have little permanent in their environment except each other," he says. "They depend on each other for all kinds of things. You can see it — they touch each other a lot; they nuzzle."
As vocal creatures, their sounds — and dialects — serve a primary function of social bonding, he says, and the way that they're learned suggests something akin to cultural transmission, formerly thought an exclusive quality of humans.
