The death toll from the Dec. 26 tsunami has reached between 160,000 and 230,000 people. As aid workers clean up the devastated areas, they notice something odd-while human corpses are everywhere, animal carcasses are rarely found. This observation has rekindled debates as to whether animals possess an innate sixth sense that enables them to foretell impending natural disasters and flee before the calamity strikes.
There are no firm numbers on animal deaths from the tsunami because rescue efforts are still focused on treating human survivors. Anecdotally, most animals that perished seem to be those that were tied to trees or penned, unable to escape. But some researchers are still hesitant to ascribe too much extrasensory ability to animals.
\I'm skeptically open-minded,"" said Patricia McConnell, UW-Madison associate adjunct professor of zoology. ""A lot of places where the tsunami hit were fishing villages, where there's not much livestock. A few cattle, goats, pigs, chickens maybe, but the villagers' main protein source is fish."" In other words, maybe there weren't many animals there to begin with.
Let's consider one animal we know was there, a species which local witnesses reported seeing running away shortly before the tsunami struck: elephants. Elephants have a keen ability to sense vibrations, and they can also detect very low-frequency sounds.
""Maybe they sensed very, very small vibrations in the ground,"" said Jim Hubing, director of the Henry Vilas Zoo in Madison. Elephants probably evolved that sensitivity to detect the movement of predators, Hubing speculated, and the fact that elephants might use it to detect earthquakes would be an evolutionary bonus.
McConnell agreed that some animals are more attuned to ground vibrations. Hoofed animals in particular have many vibration sensors in their feet, she said, many times more than humans do. Perhaps humans, as descendants of tree-dwelling primates, had less need to sense ground vibrations, she conjectured.
Other theories abound. Sandi Sawchuk, clinical instructor at the UW-Madison School of Veterinary Medicine, suggested animals might not be relying on a unique sense.
""Animals have many capabilities-olfactory, vision, hearing-that are better developed than humans'. That doesn't mean they have an extra sense,"" she said.
U.S. government scientists share Sawchuk's skepticism. According to Andy Michael, a geophysicist with the United States Geological Survey, the only evidence that animals have an extra sense is anecdotal, not supported by rigorous scientific inquiry.
""It's a big leap to go from 'animals didn't die in the tsunami' to 'they physically sensed the earthquake,'"" Michael said. ""After every U.S. earthquake, we get calls from people: 'Right before the quake struck, my dog did this, my cat did that. They predicted the earthquake.' But it's always a small percentage of calls-not every pet owner reports noticing a reaction. If there really were some evolutionary basis, you'd expect a wider percentage of animals to react.""
He said the anecdotes about elephants fleeing surprise him.
""Why would an elephant care about an earthquake?"" he asked. ""They're not at particular risk."" In addition, while Michael acknowledged elephants can sense tiny vibrations, he said our own instruments are more sensitive to vibration than an elephant is. If our instruments didn't pick up any vibrations, the elephants didn't either.
The USGS said no scientific study has ever linked animal behavior to an ability to predict natural disasters.
""Animals react to so many things-being hungry, defending their territories, mating, predators-so it's hard to have a controlled study,"" Michael said.
Dinesh Ramde is a graduate student in journalism. You can contact him at dramde@wisc.edu.
