Nell Greenfieldboyce

More than 13,000 years ago, hairy elephant-like creatures with giant tusks roamed North America. These mastodons were hunted by some of the earliest people to live here, and scientists recently learned a bit more about those mysterious cultures by taking a new look at an old mastodon bone.

Federal officials continue to probe allegations of misconduct related to a famous report on dead polar bears that raised concerns about climate change. Later this month, officials plan to re-interview one of the two government scientists who wrote that report.

The new development suggests that scientific integrity remains a focus of the investigation, which recently detoured into allegations that the other researcher under scrutiny broke rules related to federal funding of research. Both scientists work for agencies of the Department of the Interior (DOI).

Lists of the world's most ugly animals sometimes include the naked mole rat. But scientists who have just analyzed its entire genetic code say this bizarre little creature has an inner beauty — unique traits that could aid research on cancer and aging.

Naked mole rats are not moles and are not rats, although they are naked. They have tiny eyes and piggy noses, and have been described as looking like sausages with teeth.

Scientists have used DNA lurking inside the teeth of medieval Black Death victims to figure out the entire genetic code of the deadly bacterium that swept across Europe more than 600 years ago, killing an estimated half of the population.

The researchers didn't find any genetic feature that could explain why the plague was so virulent, according to a report just published in the journal Nature.

Our planet's risk of being hit by a dangerous outer space rock may be smaller than scientists previously thought. That's according to a survey of the sky that NASA is calling the most accurate census yet of near-Earth asteroids.

A NASA space telescope called the Wide-field Infrared Survey Explorer, or WISE, recently went searching for asteroids lurking nearby — and found far fewer than astronomers had expected.