Tuesday, December 22, 2009

Science Top Ten

In some respects the past ten years haven’t been great, as far as science is concerned. George W. Bush announced an ambitious plan to send a manned mission to Mars, but provided no money. In 2003 the space shuttle Columbia disintegrated over Texas during reentry into Earth’s atmosphere. Using intelligent design, anti-evolutionary forces tried to smuggle their untruths in school curricula. There was a popular and sometimes hysterical campaign against the MMR vaccine, based on a single discredited study, that resulted in outbreaks of measles in the US and UK as herd immunity declined. Despite an overwhelming amount of scientific evidence, climate-change skeptics claimed that there was no link between anthropogenically-generated carbon dioxide and global warming or denied that any warming was taking place, and mounted ad hominem attacks on climate scientists. Although their case is largely supported by myths and untruths rebutted by many sources, rather than papers in peer-reviewed journals, millions chose to believe them and 2009 was dubbed 'the year of the skeptic'. And just this month the UK government announced swingeing cuts in the funding of scientific research.

But to counterbalance all this gloom, there was a plethora of fantastic scientific discoveries and advances, too. Here’s my personal top ten.

10. Research into medical use of stem cells, which can renew themselves through division and differentiate into all kinds of specialised cells, was attacked by prolife groups in the US because although it promised to be the basis of many new medical treatments, it depended in part on harvesting cells from aborted fetuses. However, recent research has shown that cells taken from adults can be deprogrammed and returned to a primal state from which they can be encouraged to develop into muscle, skin or brain cells and used in research or to replace damaged or diseased tissues.

9. Pluto lost its planetary status after many objects similar to it were discovered in the Kuiper Belt, some sharing the region through which it orbits. Despite its debased status, Earth-based observations suggest that Pluto is more active than previously believed: it possesses a thin, transitory atmosphere replenished during the summer by geysers of nitrogen gas, and unlike Earth's atmosphere temperatures rise with altitude.

8. The BioBricks Foundation has developed a catalogue of standardised biological parts that treats the genetically-based properties of organisms as plug-and-play features. Researchers, many of them citizen scientists, can order off-the-shelf modules and insert them into their organism of choice, offering the potential of fast, cheap, open-wetware genetic engineering.

7. Paleontologists discovered in late Devonian rocks a fossil that bridges the transition between fish and amphibians, and underscores the predictive powers of evolutionary science. Named Tiktaalik roseae, it possesses fins whose bone patterns share features with tetrapod limbs - the basis of animal life on land, an incredibly important part in the jigsaw of the evolution of life on Earth.

6. After a long hiatus, the Large Hadron Collider is now up and running, and smashing protons together at energies not seen in the universe since the Big Bang. I'd put it higher up the list if I was as interested in fundamental particles and the deepest laws of nature as I should be, but it's definitely a impressive example of international cooperation.

5. The first exoplanets were discovered towards the end of the twentieth century, but in the past few years the first images of planets around other stars have been captured. One, roughly the size of Jupiter, orbits Fomalhaut (pictured); three more orbit the star HR 8799; another orbits the young star Beta Pictoris. Astronomers have even predicted the weather on two hot gas giants - since they are tidally locked to their stars but display even temperatures across their day- and night-sides, they must be racked by roaring winds that drive all the way around their circumferences and redistribute heat from their day-sides.

4. The two rovers Spirit and Opportunity landed on Mars and quickly discovered unequivocal evidence that there had once been liquid water on the surface. High-resolution images taken by the HiRISE instrument of the Mars Reconnaissance Orbiter revealed deposits on the beds of ancient dry lakes, and the shoreline of an ancient ocean that capped the northern hemisphere. And the Phoenix surveyor landed near the north pole and tasted Martian ice, and imaged what may have been blobs of liquid water on its legs (pictured). Phoenix succumbed to the Martian winter but the MRO is still working in orbit, and the two rovers are still active on the surface, although Spirit has become stuck in a sand trap and may not be able to escape. The Moon’s soil, previously thought to be bone-dry, was found to contain traces of water, thought to be produced by interaction of hydrogen ions in the solar wind and oxygen in minerals. And last month the LCROSS mission crashed a rocket stage and a probe into a permanently shadowed crater at the Moon’s south pole and produced a plume of material that contained water; there’s an unknown amount of water ice trapped in those shadows, and at -240 degrees centigrade they're the coldest known places in the Solar System.

3. New research on an ancient hominin species, Ardipithecus ramidus, discovered in 1994, has suggested that it may be the last common ancestor shared by humans and chimpanzees. And the hominin family tree had been extended by the discovery, in caves in a small and remote island in Java, the bones of a new species, Homo floresiensi, that was just a metre high, and lived as recently as 8000 years ago. A draft genome of our extinct near cousins Homo neanderthalensis has been produced, and shows that they shared with us the FOXP2 gene, implicated in language skills.

2. The Cassini-Huygens probe entered into orbit around Saturn and began to send thousands of stunning images and reams of data back to Earth. The Huygens probe successfully landed on Saturn’s largest moon, Titan, and revealed that it was surprisingly Earthlike, with riverine valleys and pebbles of ice scattered across what may have been a dry lake bed. Later, Cassini mapped Titan’s previously hidden surface and discovered lakes of liquid methane and ethane, and a hydrological cycle, including rain and fog, much like Earth’s, albeit based on liquid hydrocarbons rather than water. And Cassini also discovered that Enceladus, a moon just 500 kilometres across, was spewing jets of water ice and vapour from cracks in its south pole (pictured), hinting that liquid water lay beneath the tiny moon’s frozen surface.

1. In 2001, academic researchers in the International Human Genome Sequencing Consortium and Craig Venter’s biomedical research company, Celera, put aside their
differences and published the first drafts of the complete human genome. One surprise was the paltry number of protein coding genes; another was the amount of so-called junk DNA, and the fact it wasn’t randomly distributed across the genome but tended to cluster around functional genes, suggesting some as yet unknown function; yet another was more than 100 genes seem to be bacterial in origin, acquired by some kind of horizontal transfer. The first drafts also showed that humans are 99.9% identical, and there is no scientific basis for precise racial categorisation. Since then, refinements have filled in gaps, and all kinds of functions have been to assigned to genes, ushering in a new biomedical era.


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