Sloth-like isn't such a bad way to be

OK, they barely move, but they often skip meals

March 11, 2004|By Jonathan Pitts | Jonathan Pitts,SUN STAFF

We are becoming, Uncle Sam says, a nation of sloths.

We eat too much, exercise too little, and now a grotesque 64 percent of us, the Centers for Disease Control reports, are overweight and possibly on our way to an early grave.

There's no denying that's bad. But truly sloth-like?

Not at all, says Carey Rowsom, head curator of the rainforest exhibit at the National Aquarium - home to a pair of two-toed sloths, Rapunzel and Slo-Mo, whose inborn lethargy makes the most dedicated TV addicts and chip eaters seem hyperactive.

"Our animals aren't pets, and we don't like to anthropomorphize them," she says with a laugh, "but these two are very charming, for sloths, and what they prove is that sloths are actually very good at being sloths."

Unlike humans, sloths have diffidence layered into their biology. A 15- to 20-pound member of the anteater family, they have long, sharp claws and fur Rowsom compares, reluctantly, to that of Cousin Itt on The Addams Family. Its low body temperature (between 93 degrees and 94 degrees) is but one indicator of nature's most molasses-like metabolism.

"Sloths are vegetarians," says Rowsom, "and that helps. To them, fruit, like grapes, mangoes and papayas, or vegetables, like Romaine lettuce, are a feast. They don't have to break down proteins, so they don't need a lot of energy. They have all the energy they need."

It's almost unfair for this animal's name to suggest the dissolute. Rowsom has never seen or heard of an overweight sloth. Like their kin in the wild, Rapunzel and Slo-Mo dwell in the "canopy" of their rainforest - the highest branches they can find - where they blend in visually, masked in part by the green tint of the algae that settles into their lengthy fur. (On this day, in fact, Rapunzel is nowhere to be seen.) They make a lifestyle of snuggling into crooks, ball up their bodies to resemble termite nests, and spend the better part of their days sound asleep.

So it's not exercise that makes them trim. It's a matter of balance, says Rowsom, something modernity has bred out of human existence. Unlike people, who "don't generally seem to have that innate, self-regulating mechanism," sloths regularly pass on their food. Rowsom's crew fills their bowls each evening, but the chow is often untouched by the next morning.

"Slow as their metabolism is, they don't need or want a whole lot," she says. "We could learn from that."

As we could, perhaps, from a lifestyle that might best be termed sluggish.

The average sloth lives into its 30s, and the healthy maturity of Rapunzel (28) and Slo-Mo (17) isn't solely due to their upbringing in captivity. Sloths stay off the radar of other creatures, especially that of the dreaded harpy eagle. They descend from the trees only once a week to defecate, and the activity can take them all day. When they do decide to move - mostly when they sense "something happening," says the curator - it can take them an hour to cover 40 feet.

"They're not a blur," says Rowsom in something like admiration.

Nor are they a bore. Rapunzel and Slo-Mo have long been friendly, but an unexplained falling-out has sundered them; after several spats, the male now inhabits his own enclosure, giving his ex the run of the place. Tooth marks in Rowsom's arm prove that even the most lethargic animals act when provoked. "I was holding him in a net," she says, "and brushed him unexpectedly. My friends kid me. `You couldn't avoid a sloth?' But it's a badge of honor."

If humans had the sloth's instinct for living within their limits, she says, studies like the one published yesterday might not be necessary.

"No need to make fun of them," she says. "They teach us something: It's OK to be mellow, if you do it right."

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