U.S.

Researchers modeled noise levels in nearly 500 wilderness and park locations and found that more than half of them were twice as loud as the environment would be without human-generated sounds. This cacophony could inhibit animals' hunting, mating and other survival behaviors.

CHINA

Some caterpillar pests have grown resistant to genetically modified (GM) crops designed to be toxic to them. But researchers have developed a hybrid of GM and nonmodified cotton that keeps one species of caterpillar susceptible to the plant's deadly proteins.

SOUTH AFRICA

Newly discovered weapon remnants suggest humans were using a delicate, skillful stone-sharpening technique called pressure flaking to finely shape points for spears and other hunting tools as early as 77,000 years ago.

RUSSIA

A study of animal bones collected from the Berelyokh site in the Siberian republic of Sakha indicates that mammoths may have suffered from human diseases, including osteoporosis, a possible factor in their extinction. A lack of minerals in their diet may have made the animals susceptible.

INDIA

Analyses of scat, blood and tissue show that two populations of endangered Bengal tigers in the Himalaya foothills are not breeding enough to maintain genetic diversity. Researchers say that relocating villages and halting mining could encourage more mingling between those groups.