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In the 16th century, during its conquest of South America, the Spanish Empire forced countless Incas to work extracting silver from the mountaintop mines of Potosí, in what is now Bolivia—then the largest source of silver in the world. The Inca already knew how to refine silver, but in 1572 the Spanish introduced a new technology that boosted production many times over and sent thick clouds of lead dust rising over the Andes for the first time in history. Winds carried some of that pollution 500 miles northwest into Peru, where tiny remnants of it settled on the Quelccaya Ice Cap. There it stayed—buried under hundreds of years of snow and ice—until researchers from The Ohio State University found it in 2003.

For more than 30 years, the 1,000-mile Yukon Quest International Sled Dog race, which begins Saturday, has followed the Yukon River between Whitehorse, Canada, and Fairbanks, Alaska.

A little open water along the Yukon Quest trail is nothing new, but in recent years, long unfrozen stretches of the Yukon River have shaken even the toughest mushers.

Last year, musher Hank DeBruin of Ontario had stopped along the Yukon River to rest his dog team in the middle of the night, when the ice started to break up.

The world’s biggest bivalves are the aptly named giant clams. Inhabiting the warm waters of the Indo-Pacific, the largest of these species, the eponymous giant clam (Tridacna squamosal), can reach up to 1.2 meters (4 feet) in length and wiegh over 230 kilograms (500 pounds). Historically known as the killer clam for its supposed ability to trap careless divers, these harmless and colorful bivalves are favorite animals for divers and snorkelers to spot, but they may also be big players in the ecosystem. 

The health benefits of active outdoor pursuits over sedentary indoor pastimes are well known and increasingly highlighted in the battle against childhood obesity and its long-term consequences. 

People of all ages extol the virtues of getting some fresh air, particularly for a generation of children in which, according to a Mothercare survey last year, more than a quarter play outside for less than half an hour a week.

Don't go chomping on a handful of chili peppers just yet, but there may be help for hopeful dieters in those fiery little Native American fruits.

A large percentage of the world's population -- fully one third, by the World Health Organization's estimates -- is currently overweight or obese. This staggering statistics has made finding ways to address obesity a top priority for many scientists around the globe, and now a group of researchers at the University of Wyoming has found promise in the potential of capsaicin -- the chief ingredient in chili peppers -- as a diet-based supplement.