Serge Wich, a scientist at the Great Ape Trust of Iowa, thinks orangutan whistling could provide clues about the evolution of human speech.

Fish and snakes don't have eyelids. Some lizards have 2! Why we need eyelids ...

Within the U.S., the most pervasive problems with regards to air quality are in the area of ozone and particle pollution, says Jim Szykman.

Earth's Arctic and the Antarctic are very different kinds of places - but if these polar animals switched habitats, penguins might struggle, and polar bears might thrive.

Water is unusual in that it can occur naturally in three distinct forms - gas, liquid and solid - at the same time.

"Our water supply systems are dependent on how much water resources we've got, we don't know what the condition of our water system is," says David Maidment.

Stephan Schuster and his team compared genes from 18 different mammoths. He discovered mammoths became less genetically diverse the got closer to extinction.

Do animals laugh? If you tickle a chimp, it'll make a panting noise that sounds like a handsaw cutting wood. When dogs play, they wag their tails.

California's future as a food producer for the rest of the U.S. is tied to its water, particularly to the fresh water supply in the Sacramento-San Joaquin Delta, says Jeff Mount. Mount said over time, the levees have weakened and the ecosystem has declined - and the state will have to make difficult choices to restore the delta.

Dee Boersma said penguins can't find food as easily because of the effects of warm water on the fish they eat. Warming ocean temperatures, she said, have altered sex ratios in some populations of the fish they eat, creating more males.