Richard Harris

Many of the drugs we take aren't actually digested — they pass through our bodies, and down through the sewer pipes. Traces of those drugs end up in the bodies of fish and other wildlife. Nobody's sure what effect they have.

Now, a paper being published in Science magazine finds that drugs for anxiety drugs — even at these very low levels — can affect the behavior of fish.

North Korea's latest nuclear weapons test is much more powerful than the previous two, according to estimates made by instruments that measure seismic waves from the blast. It's about the size of the bomb that devastated Hiroshima in World War II.

But it's not so easy to verify the claim that the nuclear explosive has also been miniaturized. That's a critical claim because a small warhead would be essential if the rogue regime chose to threaten the United States with a nuclear-tipped missile.

Big bombs are easier to make, but they aren't all that useful as a threat.

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From NPR News, this is ALL THINGS CONSIDERED. I'm Audie Cornish.

MELISSA BLOCK, HOST:

And I'm Melissa Block.

It's official, federal scientists say 2012 was the hottest year on record for the Lower 48 States. In fact, the average shattered the previous record set in 1998.

Here's NPR science correspondent Richard Harris.

A Shell Oil drilling rig has been pulled of the rocks, where it washed up a week ago during a storm. It has been towed to a bay where divers will inspect it for damage. The incident raises questions about the oil company's controversial plans to continue exploring for oil in the Arctic Ocean this summer.

It's a year-end tradition to cobble together a list of the most important advances in science. But, truth be told, many ideas that change the world don't tend to spring from these flashy moments of discovery. Our view of nature — and our technology — often evolve from a sequence of more subtle advances.

Even so, chances are good that this year's list-makers will choose the discovery of the Higgs boson as the most important discovery of 2012.

Cartoonists have found many clever ways to depict the conventional wisdom that complex life evolved in the sea and then crawled up onto land. But a provocative new study suggests that the procession might be drawn in the wrong direction. The earliest large life forms may have appeared on land long before the oceans filled with creatures that swam and crawled and burrowed in the mud.

United Nations climate talks ran into overtime on Friday night, as diplomats pressed for whatever small advantage they could achieve.

As usual, the talks, which are being held in Doha, Qatar, involve closely interwoven issues. They include the usual wrangling over money, as well as early efforts in a multiyear process that is supposed to result in a new climate treaty.

Part of that involves finding a graceful way to phase out the Kyoto treaty, which has not proved to be a successful strategy for dealing with a warming planet.