2009 06 25 Hidden Whale Culture Could Be Critical to Species Survival Print E-mail
Written by Andrew Stevenson   


Though it sounds at first like a marine biologist’s take on political correctness, respecting the cultural diversity of whales may be essential to saving them.

Scientists are accustomed to thinking of whale populations in terms of genetic diversity. But even when they share the same genes, groups of whales can live in very different ways, raising the possibility that species might be saved even while individual cultures vanish. The tragedy of cultural extinction aside, cultural diversity may sustain the long-term health of Earth’s cetaceans.

“We have no idea what’s going on. As we mess up the world, it goes off in all kinds of weird directions,” said biologist Hal Whitehead of Dalhousie University in Nova Scotia. ”The more diversity that’s out there, both genetic and cultural, the more whales can deal with it.”

That whales could even have culture is a relatively new scientific proposition. It was not unil the late 1960s that recordings of humpback whale songs provided a glimpse of the unexpectedly complicated and beautiful world of cetacean communication. The songs don’t appear — for now — to reach the level of language, but they’re clearly a form of learned communicative behavior common across the cetacean realm. And as researchers spend more time with whales, they’re realizing just how much their learned behaviors differ.

One of the best-known example of marine culture comes from killer whales (which, technically, are dolphins, but they’re mentioned in the same breath as whales by biologists). Pods of killer whales have highly varied dialects and ways of life, even while sharing the same habitat — the aquatic equivalent of a neighborhood populated by two different ethnic groups.

Over the last decade, two pods found off North America’s west coast and known to researchers as the Northern and Southern residents became the focus of an international conservation battle. Scientists showed that the pods had different dialects and feeding habits. The Southern Residents, their numbers at a fraction of historical levels, often ranged south through Puget Sound and into waters off the California coast. They’re more threatened than their Northern counterparts by shipping collisions and depleted salmon populations.

In 2004, Canada’s environmental officials declared the Southern Residents both distinct and endangered, but U.S. officials insisted on treating the two pods as a single, genetically similar and unendangered group. The next year, following outrage among scientists and environmentalists, the United States acknowledged the Southern Residents as unique and endangered.

Their decision was promising, but cultural considerations are otherwise absent from U.S. government conservation plans and the agenda of the International Whaling Commission. To some extent, the absence reflects the state of cetacean science. Most species have not been extensively studied at the cultural level. But with pollution, noise, global warming, overfishing and intermittent hunting threatening the recovery of creatures nearly hunted to extinction by the early 20th century, it might be time to expand the focus.

“If I take all the sperm whales in the North Atlantic, can I consider them as one population? If I can, I can apply all kinds of theoretical results to it. But if there are factors that might break the population apart, that’s going to impact the way I can use the models to manage the populations,” said Luke  Rendell, a postdoc biologist at Scotland’s University of St. Andrews. “Once you realize that these sorts of things are going on, that has to be taken into account.”

Rendell is a specialist in sperm-whale vocalization and learning patterns of sperm whales. Over the last decade, he and Whitehead and other researchers have painstakingly analyzed acoustic recordings of the whales, linking them to observations and biological samples, ultimately cobbling together an unexpectedly complex picture.

Sperm whales live in small social units linked by maternal lineage, and form larger groups only with other units from the same clan. In the Pacific, these groups are large and tightly linked. In the Atlantic, they’re small and loosely distributed. Vocalizations vary widely between groups, as do their habits, from hunting patterns to babysitting. Yet their genes are extremely similar.

In the Pacific, warming waters produced by El Niño fluctuations appear to affect clans differently, said Whitehead. “In normal temperatures, one of the clans does better,” he said. “And when El Niño strikes, the clan that was doing worse does better than the other clan. The clan that was doing well is in trouble. That has implications for global warming, because it’s going to make conditions more like El Niño. You can see how maintaining the diversity of clans in sperm whales makes it more likely that they’ll survive.”

Whether other cetacean species possess equally rich cultures is largely unknown, but mostly because so little research has been conducted. “It’s notoriously difficult to collect hard evidence about what’s going on,” said Rendell. “It’s not like a bird or a bat or a chimpanzee that you can bring into the lab and investigate how they behave.”

But given the abilities seen in the cetaceans that have been studied, and the socialization patterns obvious in other species even when they haven’t been rigorously studied, researchers say cultural diversity is likely common.

“My guess is that there are all kinds of complicated social conventions. We know some from the killer whales, but I bet they’re in lots of other whale species as well,” said Whitehead.

New research is “giving us a window into really complicated societies,” said Rendell. “You get a much better appreciation of the complexity. Ten or 20 years ago, it was just, ‘There’s a bunch of whales over here.’”

  • By Brandon Keim, Wired Science
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