A little more than two weeks after its arrival on Mars, NASA's Curiosity rover will on Wednesday make its first "test drive" before setting off on its Red Planet mission, the U.S. space agency said.

The $2.5 billion rover, which landed on Mars on August 6, has performed a battery of tests and appears ready to embark on its two-year mission to explore the Red Planet in the hunt for signs of life, NASA said Tuesday.

The Arctic ice cap is melting at a startlingly rapid rate and may shrink to its smallest-ever level within weeks as the planet's temperatures rise, U.S. scientists said Tuesday.

Researchers at the University of Colorado at Boulder said that the summer ice in the Arctic was already nearing its lowest level recorded, even though the summer melt season is not yet over.

Fossils of toothy, slug-like creatures that grazed the sea floor 500 million years ago have shed light on the origins of modern-day snails, shellfish and squid, a study said Wednesday.

The most comprehensive analysis yet of the ancient slugs' mouth parts -- multiple rows of teeth that moved in conveyor-belt fashion, showed they were related to present day molluscs, scientists wrote in the journal Proceedings of the Royal Society B.

Heatwaves, drought and floods that have struck the northern hemisphere for the third summer running are narrowing doubts that man-made warming is disrupting Earth's climate system, say some scientists.

Climate experts as a group are reluctant to ascribe a single extreme event or season to global warming.

Giving babies antibiotics before the age of six months could cause them to be chubby children, according to a study published Tuesday.

"We typically consider obesity an epidemic grounded in unhealthy diet and exercise, yet increasingly studies suggest it's more complicated," said co-author Leonardo Trasande of the New York University School of Medicine.

Global wildlife monitoring network TRAFFIC warned Tuesday that 515 rhinos could perish by the end of the year if no action is taken to stem the illicit trade in rhino horns.

In its latest report, the agency said that with a total of 281 animals killed as of July, there was a "predicted loss of 515 by year end if current poaching rates continue".

An ancient skull discovered in a cave in Laos has pushed back the clock on human migration to Southeast Asia by as much as 20,000 years, a study published Monday has found.

The skull discovered in the Annamite Mountains in northern Laos is the oldest modern human fossil found in Southeast Asia and is believed to be between 46,000 and 63,000 years old.

Just 10 days after NASA's Curiosity rover sent back its first color photos of the Martian landscape, the U.S. space agency said Monday it wants in 2016 to take a better look at what's happening beneath the Red Planet's surface.

"Does Mars have fault lines like the Earth does? How extensive are those? What kinds of 'marsquakes' are there?"

NASA's Curiosity rover has zapped its first Martian rock, aiming its laser for the sake of science.

During the target practice on Sunday. Curiosity fired 30 pulses at a nearby rock over a 10-second window, burning a small hole.

Scientists and birdwatchers have discovered 10 new owl species in the Philippines, using advanced recording equipment that can distinguish between their hoots, a conservation official said Sunday.

Eight of the new species were previously considered sub-species while two are totally new, said Lisa Paguntalan, field director of Philippines Biodiversity Conservation Program.