They Don't Have a Word for It

Does language sometimes define the content of thought? Are there people who cannot entertain certain ideas because their language does not have the words to express them? Are there concepts that cannot be translated into some languages?

These questions have vexed linguists and neuroscientists for years. The general feeling has been that language does not limit cognition. However, a new study in the online version of Science suggests that the prevailing notion may not be correct.

Peter Gordon, a behavioral scientist at Columbia University, conducted an unusual set of experiments with seven adults of the 200-member Piraha tribe of Amazonian Indians in Brazil.

The tribe's counting system consists of three words -- one that means "roughly one," one that means "a small quantity" and one that means "many."

Gordon asked the Piraha subjects to perform various tasks in which performance would be greatly enhanced by the ability to count. These included laying out the same number of nuts or sticks that he had laid out; distinguishing two boxes whose only difference was the number of fish drawn on their tops; and knowing when a tin can was empty after watching the researcher put nuts into the can and then withdraw them one by one.

Gordon found that the Piraha were essentially incapable of following or accounting for more than three objects. When a task involved larger numbers -- even five or six -- the subjects' answers were little more than guesses, even though they clearly understood the tests and were working hard on them.

He attributed this surprising finding to the fact the Piraha "have no privileged name for the singular quantity" -- in other words, no one, no notion of an integer.

"The present study represents a rare and perhaps unique case for strong linguistic determinism" -- the idea that language determines thought -- Gordon wrote.

-- David Brown

Chimps Hint at Malaria Drug

By studying the behavior of wild chimps, French and Ugandan scientists have discovered a new compound that may be useful for fighting malaria.

Thierry Sevenet of France's Centre National de la Recherche Scientifique, and colleagues were observing a community of 50 wild chimps in the Kibale National Park in western Uganda when they noted some odd behavior:

A few animals would occasionally nibble on leaves from a shrub called Trichilia rubescens. The chimps would eat only some of the leaves, and the leftovers would remain untouched by the other animals.

"The other chimpanzees from the party did not even try to feed on the shrub after the consumer left it," the researchers wrote in reporting their findings in the August issue of the journal Antimicrobial Agents and Chemotherapy.

When the scientists tested extracts from the shrub's leaves in the laboratory, they discovered certain compounds that appeared to show significant activity against the malaria parasite, suggesting that the chimps might be self-medicating.

"New evidence has been provided to support the previous hypothesis that chimpanzee diet contains secondary metabolites" that may be useful to health maintenance, the researchers wrote. "The study of self-medication in apes based in veterinary and behavioral survey might provide a novel approach to the discovery of new bioactive natural products useful in human therapy."

-- Rob Stein

Runners' Lore Questioned

It is common wisdom among runners and other sports enthusiasts that lactic acid is the enemy of endurance. The chemical is a byproduct of metabolism during periods of intense exercise, when oxygen supplies cannot keep up with energy output. Its accumulation in work-stressed muscles has long been considered a major cause of achiness, exhaustion and failure.

Now, in an Olympian reversal, scientists have found that lactic acid actually enhances a tired muscle's ability to keep on twitching.

The biochemistry and physiology that propel leaping legs and barbell-boosting arms start with a nerve impulse that delivers the mental demand for action and ends with a rush of electrically charged sodium, potassium, chloride and calcium atoms into and out of cells in synchronized succession.

George Stephenson of La Trobe University in Australia and his colleagues studied those molecular changes in individual rat muscle fibers made to twitch repeatedly, and tallied the effects of those changes on the fibers' ability to keep contracting.

They found that the increasing acidity that comes with lactic acid buildup lowered the threshold that a muscle fiber must overcome to contract. Specifically, a chloride ion-based mechanism that normally keeps resting muscles from contracting was more easily overcome under acid conditions, in seeming recognition that a tired muscle should not have to work so hard to generate the next twitch.

In the words of Science magazine, in whose Friday issue the new work appeared, lactic acid may be "the latest performance-enhancing drug."

The new work does not prove that various strategies for reducing lactic acid buildup -- such as drinking bicarbonate of soda or "warming down" muscles -- are of no value to athletes, researchers said. But it may mean they work for reasons other than what was thought.

-- Rick Weiss