Jon Hamilton

Scientists say they have finally figured out how smoking helps people keep off extra pounds.

It turns out that nicotine activates a pathway in the brain that suppresses appetite, according to a study in the journal Science. This discovery should lead to better diet drugs, the researchers say.

The finding comes after decades of research showing that smokers tend to be a bit thinner than nonsmokers, and that smokers who quit tend to put on weight.

A technology that monitors electrical activity in the brain could help identify infants who will go on to develop autism, scientists say.

The technology, known as electroencephalography, or EEG, is also providing hints about precisely how autism affects the brain and which therapies are likely to help children with autism spectrum disorders.

A group of scientists has formally challenged the conclusions of a highly publicized report describing a mysterious microbe that seemed to thrive on a diet of arsenic.

The report, published in December by the journal Science, suggested that a bacterium found in California's Mono Lake was able to substitute arsenic for phosphorous, one of several elements considered essential for life.

There have been nearly 1,200 tornadoes in the U.S. so far this year. That's nearly twice the usual number of twisters, and it comes as something of a surprise to the scientists who study them. It turns out there is still no good way to predict tornado outbreaks more than a couple of days ahead of time.

Every year, government meteorologists tell the public about how many hurricanes to expect during the Atlantic season. But the government doesn't do that with tornadoes.

So far this year, there have been nearly 1,200 tornadoes in the U.S. That's close to twice the usual number — and it comes as something of a surprise to the scientists who study them.