This Week

Tiny specks of carbon discovered in 3.85-billion-year-old rocks indicate that life on Earth arose far earlier than previously thought and in a period of asteroid bombardment.

On Mars

A British team announced that the abundance of organic compounds in a young Martian meteorite, as well as their isotopic ratio of carbon-13 to carbon-12, suggests bacteria may have thrived on Mars as recently as 600,000 years ago.

Boning up on postmenopausal hormones

Lens gets X rays to a point

An aluminum lens focuses high-energy X rays to a spot only a few micrometers wide.

Deadly Ebola virus seen to thrive in bats

By inoculating jungle-dwelling animals and plants with lethal Ebola virus, researchers have shown that healthy bats may harbor the virus, whose source in nature remains a mystery.

Depression fails to scar personality

A long-term study finds that people who suffer an initial episode of major depression do not experience lasting personality changes, such as becoming more introverted or dependent on others.

Gene variations sway prostate cancer risk

An enzyme that converts testosterone to a more potent hormone comes in two versions; which one a man has may partially determine his risk of prostate cancer.

Ant life: It's a sister-eat-brother world.

To increase the chances of passing their genes on to future generations, some female ants seem to kill off male siblings.

Research Notes:

Astronomy:

Hailing Hale-Bopp

After a fallow period this spring, in which it looked like Comet Hale-Bopp might prove a fizzle, the icy body has become more active, so it still may be the most dramatic comet of the century when it nears Earth next March.

Biology:

Does parenting or prolactin hit first?

The hormone prolactin appears to direct some birds to take on parenting responsibilities for their relatives' offspring.

Birds keep close track of seed business

Chickadees replace missing seeds from their winter food caches on almost a one-for-one basis.

Behavior:

Out-of-order memories

The act of trying not to think about an episode, such as a traumatic experience, makes it difficult to remember the sequence in which events occurred and may lead to a repression-like memory loss.

Anatomy of apprehension

The amygdala, an almond-shaped brain structure, appears to specialize in picking up signs of threat and danger in the social world, according to a new brain-scan investigation.

Biochemistry:

Molasses recruit bacteria for cleanup

Mixing molasses with TNT-contaminated soil spurs bacteria to break down the explosive into harmless molecules.

Magnetic bacteria probe for proteins

Scientists have hitched antibodies to tiny magnetic particles made by bacteria in order to pull proteins out of a solution.

Articles:

The Mother Lode of Natural Gas

Methane hydrates stir tales of hope and hazard

Vast deposits of frozen methane beneath the seafloor could be the fuel of the future.

Gastrointestinal Blues

Research finds bugs that inflame the human gut

Microbes may cause gastrointestinal inflammation in people who are genetically susceptible.

Departments:

Our Weekly Listing of New Publications

Letters:

A Selection from Letters to the Editor