A scrap of bone found in a cave in Siberia has shed light on the genetic odyssey of an enigmatic group of humans called the Denisovans, scientists reported on Thursday.

The existence of the Denisovans only emerged in 2010, through a piece of finger bone and two molars unearthed at the Denisova Cave in southern Siberia's Altai Mountains and dated to around 80,000 years ago.

Twin satellites rocketed into orbit Thursday on a quest to explore Earth's treacherous radiation belts and protect the planet from solar outbursts.

NASA launched the science probes before dawn, sending them skyward aboard an unmanned rocket. Within 1½ hours, the two satellites were flying free. "We're all thrilled, just as excited as can be," said launch director Tim Dunn.

Australian scientists said Thursday they had successfully implanted a "world first" bionic eye prototype, describing it as a major breakthrough for the visually impaired.

Bionic Vision Australia (BVA), a government-funded science consortium, said it had surgically installed an "early prototype" robotic eye in a woman with hereditary sight loss caused by degenerative retinitis pigmentosa.

Scientists said on Wednesday they had identified a genetic variant that influences gait in horses, a potential boon for breeders but also for the quest to fix human spine injuries.

A patented DNA test will become available from Thursday, enabling horse buyers to spot an animal with a higher genetic chance of success at harness racing, they said.

Astronomers using a powerful radio telescope in Chile said Wednesday that they had discovered sugar molecules, one of the building blocks of life, orbiting a young star similar to the Sun.

"This is the first time sugar been found in space around such a star," the European Southern Observatory (ESO), which is administering the project, said Wednesday.

Polonium, the poison suspected of being used to kill Palestinian leader Yasser Arafat in 2004, is a highly radioactive material rarely found outside military and scientific circles.

Also known as Radium F, it is a rare but naturally occurring metalloid found in uranium ores that emits highly hazardous alpha, or positively charged, particles.

NASA transmitted the first song to be broadcast from Mars on Tuesday, by Grammy-winning U.S. musician will.i.am, as part of efforts to inspire young people to get interested in science.

"Reach for the Stars" was then beamed back by the Curiosity rover, which landed on the surface of the Red Planet earlier this month, to NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

Having a smaller family is a springboard for giving future generations the chance of greater prosperity, according to a Swedish study published on Wednesday.

Providing scientific support to what is anecdotal evidence, it says that in an advanced industrialized society, having fewer offspring means children benefit from greater parental investment and from inherited capital.

Thousands of Morocco's unemployed slum-dwellers head to the Atlantic coast every morning to scrape a living as illegal mussel pickers. But experts say they threaten the health of the marine ecosystem.

The stretch of coast between Rabat and Casablanca, Morocco's economic capital renowned for its sprawling slums, or "bidonvilles," is the most popular destination for these unlicensed fishermen, who flock to the area at low tide.

Scientists have found three well preserved ancient insects frozen in amber — and time — in what is Earth's oldest bug trap.

The discoveries of amber-encased insects in Italy may sound like something out of "Jurassic Park" but these bugs are even older than that. They are about 230 million years old, which puts them in the Triassic time period, and about 100 million years older than what had been the previously known oldest critters trapped in fossilized tree resin, or amber.