The world’s soil is in trouble, even in the fertile Midwest. Some experts warn that if degradation continues unchecked, topsoil could be gone in 60 years. That has implications for agriculture and the broader environment.
If you want to protect rare species, first you have to find them. In the past few years, biologists have developed a powerful new tool to do that. They've discovered that they can often find traces of animal DNA in streams, ponds — even oceans.
The idea took root just five years ago, when biologists in France found they could detect invasive American bullfrogs simply by sampling pond water and looking for an exact genetic match to the frogs' DNA.