No Moon, no life on Earth, suggests theory
Four billion years ago, when life began, the Moon orbited much closer to us than it does now, causing massive tides to ebb and flow every few hours. These tides caused dramatic fluctuations in salinity around coastlines which could have driven the evolution of early DNA-like biomolecules.
This hypothesis, which is the work of Richard Lathe, a molecular biologist at Pieta Research in Edinburgh, UK, also suggests that life could not have begun on Mars.
According to one theory for the origin of life, self-replicating molecules such as DNA or RNA emerged when small precursor molecules in the primordial "soup" polymerised into long strands. These strands served as templates for more precursor molecules to attach along the templates, creating double-stranded polymers similar to DNA.
But the whole theory fails without some way of breaking apart the double strands to keep the process going, says Lathe. It would take some external force to dissociate the two strands, he says.
Lathe believes that thanks to the Moon, something similar happened during Earth's early years. Most researchers agree that the Moon formed five billion years ago from debris blasted off Earth in a giant impact.
A billion years later when life is thought to have arisen, the Moon was still much closer to us than it is now. That, plus the Earth's much more rapid rotation, led to tidal cycles every two to six hours, with tides extending several hundred kilometres inland, says Lathe. Coastal areas therefore saw dramatic cyclical changes in salinity, and Lathe believes this led to repeated association and dissociation of double-stranded molecules similar to DNA. …
If the theory is right, life could not have evolved on Mars, says Lathe. Phobos, the larger of Mars's two Moons, is so small that the tidal forces it generates are just one per cent of those generated by our Moon. "Even if there was water on Mars, life could not have evolved there because these polymers could not have replicated," he says.
Sedna
Whatever his peers ultimately decide about Lathe’s theory concerning our closest planetary neighbor, astronomers were agog this week about the discovery of the most distant planet in the Solar System, No. 10. Not everybody thinks it’s such a big deal. Chinese scientists
sniffed that this ice ball with a 10,500-year orbit around the sun is only a planet
oid. Merely, they say, one of many bodies in the Kuiper Belt. At any rate, the new discovery has been named “Sedna,” after the Inuit
goddess of the Arctic Ocean. Appropriate choice since the surface temperature of the disputed object comes in at around minus 240º C.
Although Sedna wasn’t another of the Hubble's spectacular discoveries, the space telescope's future has been on a lot of minds lately since NASA has decided not to repair or upgrade it again out of alleged safety concerns related to the Columbia disaster. Among those upset by the decision are many astronauts who have been lobbying for NASA to
reverse itself.
“I just think it’s a huge, huge mistake,” says Greg Harbaugh, who performed Hubble repairs during a pair of spacewalks in 1997. “It is probably the greatest instrument or tool for astronomical and astrophysical research since Galileo invented the telescope, and I think it is a tragedy that we would consider not keeping the Hubble alive and operational as long as possible.”
That’s Harbaugh in the photo below, on the left, working with Joseph Tanner during a 1997 servicing mission.
Although many have disputed NASA’s safety claims and argued that the decision has more to do with abandoning various space projects in order to fund President Bush’s
space initiative, the agency hasn’t
yielded. However, it is considering an alternative: sending a robot to replace the telescope's failing gyroscopes and batteries.
Speaking of robots, it turns out that Mel Gibson spent $350,000 for an
animatronic Jesus stand-in for the Crucifixion scenes in
The Passion. Apparently, it was too cold for actor Jim Caviezel to be filmed in just a loincloth. Blood-drenched robot photo
here is oddly reminiscent of Lance Henriksen as Bishop in
Aliens.
TGIF Happy Hour Division: Even though 18th Dynasty Pharoah Tutankhamun died (or was murdered) and hastily buried in a less than royal tomb in Western Thebes, he was well supplied with all the needs for a healthy afterlife, including
jars of red wine. Spanish experts have for the first time provided evidence of the color of wine in an archaeological sample.
The inscription on one jar reads: "Year 5. Wine of the House-of-Tutankhamun Ruler-of-the-Southern-On, l.p.h.[in] the Western River. By the chief vintner Khaa."
A 3400-year-old vintage. Robust, with a bouquet of embalming fluid.
Bureau of I Wish You Hadn’t Told Me That:
Insect deaths add to extinction fears
A survey of British wildlife suggests that insects - thought to be among the most resilient species - are suffering similar extinction rates to larger, better-studied animals.
If the same is happening worldwide, we may be witnessing the largest die-off since the mass extinction that killed the dinosaurs, says Jeremy Thomas of the
Centre for Ecology and Hydrology in Dorset, UK, who led the study in this week's
Science.
Thomas's team analysed surveys of British birds, plants and butterflies stretching back 40 years. The statistics, collected by 20,000 amateur naturalists, form an unprecedented census of insects. "No dataset approaches this detail and scale anywhere in the world," Thomas says.
The researchers divided Britain into 10-kilometre squares and counted the number of squares occupied by each species. Of 58 butterfly species, 71% have declined or disappeared over the past 20 years, alongside 54% of birds. The past 40 years has seen declines in 28% of plants studied.
Experts had assumed that the sheer number of insects would safeguard them against mass extinction. "The gloomy result is that this group has declined massively," says Thomas. As insects comprise more than 50% of the planet's species, a large die-off would be bad news for global diversity, he adds.
"This study provides further evidence that the world is facing another major extinction crisis," warns Michael Rands, director of UK conservation group
BirdLife International.
There have been five such events since the birth of multicellular life 600 million years ago. In each, 65-95% of the world's species died out. No one is claiming that current species loss has reached this rate, Thomas concedes. "But it's accelerating," he warns. "If nothing is done, we're going lose a lot more species."