Great news... Decoding the Heavens has been shortlisted for this year's Royal Society Prize for Science Books - described as the world's most prestigious awards for science writing.

The judges said about it: "This is a rattling good detective story exploring a subject that we were amazed that we hadn't heard more about.  Learning about the extraordinary capabilities of the ancient civilisations was fascinating and left us all wondering what other incredible pockets of knowledge have been lost at the bottom of the sea or otherwise forgotten."

As would be expected there are some fantastic other books on the shortlist - looks like an even split between three US academics and three UK journalists and biographers. I've pasted the rest of the line-up below, in case anyone's looking for some stimulating summer reading.

What the Nose Knows: The science of scent in everyday life by Avery Gilbert (Crown Publishers).
The judges said: "One of the things you really appreciate about this book is the feeling that you are in the presence of someone who really knows the subject.  He's worked in the fragrance industry and in academic research and engagingly leads you into his fascinating world.  Since reading this book we've all thought more about the scents around us and our oft-neglected sense of smell."


Bad Science by Ben Goldacre (Harper Perennial).
The judges said: "We found this book was funny, accessible and offered much more than just a collection of Ben Goldacre's excellent columns in the Guardian.  He attacks and debunks pseudoscience, which is really vital given how much is out there and how important the issues are to our lives.  There's more to be said about some of the subjects, like the MMR vaccine scandal, and we're looking forward to the sequel."

The Age of Wonder: How the Romantic generation discovered the beauty and terror of science by Richard Holmes (HarperPress).
The judges said: "We all thought this was a fantastic, enlightening and inspiring book, taking characters from the history of science and making them come alive. Richard Holmes has managed to seamlessly merge science, social history and literary history in a wonderful narrative, putting science in a wider context and producing a truly enthralling read."

The Drunkard's Walk: How randomness rules our lives by Leonard Mlodinow (Penguin).
The judges said: "This book is well-written, enlightening and very funny at times.  We could see people reading it and finding their perspective of odds and probability being fundamentally altered - it definitely puts you off buying a lottery ticket or having a gamble on the roulette wheel!"

Your Inner Fish: The amazing discovery of our 375-million-year-old ancestor by Neil Shubin (Penguin).
The judges said: "This is a charming and delightful book; not often that a science book can be described in such terms!  The author, an expert palaeontologist with a deep understanding of anatomy and animal development, still manages to explain things clearly, gracefully and eloquently - we all felt he'd be a great person to meet in the pub for a chat and a drink!"

Could a mysterious coating on the Parthenon have come from outer space? Don't worry, I'm not about to tell you about some crazy theory of alien technology coming to Earth. Instead it's a possible solution to a problem that has stumped scholars of ancient Greek temples for a couple of centuries.

Last week I wrote about how researchers have detected the first traces of pigment on sculptures from the Parthenon in Athens. For the ancient Greeks, the temple would likely have been not plain marble, but a veritable explosion of red, white, blue and gold.

Since the 19th century however, archaeologists have been arguing about the significance of an orange-brown coating on the temple's stone (much of which has since been cleaned off). Similar colouring is also seen on other ancient temples in the Mediterranean region. Was this simply the result of natural weathering? Or had the Greeks used some kind of varnish to tone down the bright white of the stone, making the buildings a little easier on the eye in bright sunlight (the Greeks didn't have the benefit of polarising sunglasses after all).

Ian Jenkins, senior curator at the British Museum in London, with responsibility for the Parthenon sculptures that are held there, says the coating seems to have been applied once, rather than building up gradually over time. The coating itself has been subject to some weathering, and where it has been damaged in the past it doesn't seem to form again.

This has been used to support the idea that the colouring was applied by the Greeks, but Jenkins has an intriguing alternative theory. The coating must be due to a one-off event in antiquity, he says, that happened after the temple was constructed in the 5th century BC. But that doesn't mean it was man-made.

Jenkins points out that oxalate minerals found in the coating suggest a biological origin, and he believes the event in question occurred in 536 AD, during what has become known as a "year without summer". Historical records say that during this year, dust filled the air and "the sun gave no more light than the moon". Crops failed to grow, and cattle died on their feet. Evidence of this awful time can still be seen today in tree rings from ancient timbers - the growth ring for 536 AD is extremely small.

Climate disruption continued for the rest of the century. Jenkins argues that during these darker, more humid conditions, microbes could have grown rampant on the surface of the stone, leaving behind the orange-brown coating as they decomposed.

The debate about what blocked out the sun is ongoing. In February 2008, Lars Berg Larsen of the University of Copenhagen and colleagues reported a big spike of sulphate in ice cores from both Greenland and Antarctica, that was laid down around 536 AD. This suggests much of the planet was covered in an acidic dust veil, which they concluded was due to gigantic volcanic eruption.

But in January 2009, Dallas Abbott of Columbia University's Lamont-Doherty Earth Observatory in New York and colleagues reported that they had found tiny balls of condensed rock vapour inside Greenland ice cores dating back to early 536 AD. They reckon these come from terrestrial debris ejected into the atmosphere when a comet (probably in several pieces) smashed into the Earth.

I don't know if Jenkins is right or not about the temple coatings - if anyone knows any more about this please let me know. Either way, to leave its mark all the way from the north pole to the south, this must have been one hell of a disaster.

Today, the Parthenon temple that watches over Athens is a pure, white building, dazzlingly bright on sunny days against the deep blue sky. But it wouldn't have looked anything like this in ancient Greek times. Researchers at the British Museum announce today that they have detected tiny traces of blue paint on the building's sculptures - suggesting that the temple's statues and friezes would have been not stark white, but a riot of colour.

I've just written a short story on the work for New Scientist, which you can read here. Although only a few hints of a pigment called Egyptian blue have been detected so far, experts think that the original paint job would have included red as well, with the original marble showing through white in places, and highlights of gold in others (see second pic below for one interpretation of what this might have looked like). Although we have the benefit of seeing the sculptures on display at eye level, for the ancient Greeks they were fixed around the top of the temple - 40 feet high. "Colouring would have hugely enhanced the visibility," says senior curator Ian Jenkins, who is responsible for the Parthenon sculptures held at the British museum.

Scholars have long known that the Greeks painted their marble buildings and statues, but they're particularly excited about this work because despite two hundred years of searching it hasn't been seen before on the Parthenon's sculptures (there used to be some visible traces on the mouldings just underneath the roof, but not on the sculptures themselves). In the end, post-doc Giovanni Verri used a clever imaging technique called photo-induced luminescence to pick up microscopic specks of pigment. When red light is shone onto the molecules of Egyptian blue, they absorb it and emit infrared light. Seen through a camera sensitive to infrared, any parts of the marble that were once blue appear to glow.

So far Verri has found the blue in a few different places - for example on the belt of the messenger goddess Iris from the temple's west pediment (see the pic below from the British Museum - there's a normal photo on the left, and an infra-red image showing Iris's glowing belt on the right). Depicted as she descends to earth, she's famous for her life-like flapping tunic. Verri also detected blue stripes on a cloak draped over the knees of the goddess Dione, from the east pediment. It's amazing to think that when in full colour, the Parthenon's sculptures showed details down to the weave pattern of a figure's clothing.

One thing that interests me, though, is why the public perception of Greek temples and sculptures is of simple white buildings, when there's so much evidence that they were actually brightly coloured. I asked Jenkins about this and he described it as "a conspiracy of collective amnesia".

"We don't want to know it," he says. "We want to believe that ancient sculpture was white and pure." He believes that instead of paying attention to how the Greeks really lived, we're judging them according to our own aesthetic standards - for example the idea that it would be abhorrent to cover up beautifully-carved quality marble with coloured paint. He thinks the delusion stems from the Renaissance - when artists producing sculptures inspired by those of ancient Greece left them white to dissociate them from the previous Gothic style.

Jenkins also told me of his intriguing theory that the Parthenon's colour was affected by a severe climate disruption which caused a "year without summer" in the sixth century AD. I'll write about that in the next post...

Ever wondered what it's like to fly around inside a digital camera? OK maybe not, but in case the question catches your interest here's a video made by engineers at X-Tek (now owned by Metris), using the same 3D X-ray technology that they used to image the Antikythera mechanism in 2005. Andrew Ramsey of X-Tek showed me this fly-through on his laptop when we were in Oxford for a conference on the Antikythera mechanism last month and I found it quite mesmerising, like being transplanted into an alien world of giant floating springs and screws. This youtube version is a bit fuzzier but it's still a fascinating (and technically impressive) insight into what really goes on inside your camera. Andrew has posted a second video too, which flies around inside a lizard skull.

By the way I won't be posting again for a while as I'm off to India for a few weeks. I'll be travelling with my friend Gaia Vince, a science journalist who is documenting the effects of climate change on the planet - you can keep up with our progress at her wonderful blog, www.wanderinggaia.com. 

One of the scientists I met at the annual meeting of the American Association for the Advancement of Science in Chicago last month was Paul Tafforeau, a physicist at the European Synchrotron Radiation Facility in Grenoble, France. He was speaking about various ways in which he's using the synchrotron's powerful X-rays to get more out of fossils than has ever been possible before, from identifying new species of insects preserved in amber, to checking the microscopic structure of early hominid teeth.

So I was interested to see a paper with his name on it out this week, reporting the first fossil brain ever discovered (the brain's soft tissue generally degrades shortly after death). The brain in question belongs to a 300-million-year-old fish called Sibyrhynchus denisoni, and I've written a story on it for New Scientist, which you can read here.

Tafforeau X-rayed four iniopterygian fish fossils from the Carboniferous period for Alan Pradel and colleagues from the National Natural History Museum in Paris, who were hoping to work out the size and shape of the fish's brains from the structure of their skulls. The fossils were found twenty years ago in Lawrence, Kansas.

Tafforeau's imaging allows a 3D computer reconstruction to be made of each fossil, and when Pradel checked through the virtual skulls he saw something "like a ghost" inside one of the brain cases. So Tafforeau scanned it again, using a new technique called holotomography. This takes a conventional X-ray image but then combines it with a technique called phase contrast imaging, which analyses interference patterns created when X-rays are slowed down by areas of varying density within the object being studied.

This time the mystery structure showed up clearly (see video above). I called Pradel and his supervisor Philippe Janvier in Paris last week to ask them about their find, and Pradel told me that at first he was convinced it was just an artefact, because for the brain to survive would be so "surprising and exceptional". But then he recognised various brain areas, including the cerebellum, spinal cord and optic lobes and realised he had come across something very special. The clincher was the fact that even various nerves that protrude from the brain, including the optic nerves, were visible in exactly the right locations. "It was really staggering," says Janvier. 

The most important thing about this find, though, isn't this particular brain but that now researchers know it's possible for the structure of ancient brains to be preserved - and in incredible detail. It isn't clear why this brain didn't degrade as has happened in every other fossil found, but it's probably something to do with a film of bacteria that coated the brain after death. Palaeontologists studying fossils from similar sites (black shale, from what was once a coastal sea bed) will now be licking their lips in anticipation for similar finds - the ultimate prize would be a brain from a creature with no living relatives, such as the huge armoured fishes of the Devonian period (400 million years ago), or Tiktaalik, the fish that first crawled onto land. I was quite shocked to find from Janvier that a Walmart now stands on the site in Kansas where the fossils from this study were found, so there's no chance of looking for more fossils there. But there are other similar locations, for example in Oklahoma.

We're all celebrating the 200th anniversary of Darwin's birth this month, but what isn't so well known is that centuries before he published his theory of evolution by natural selection, scientists in the Islamic world were discussing similar ideas. The earliest known example is from a science writer called al-Jahiz, who worked in Baghdad in the 9th century.

In The Book of Animals he wrote: "Animals engage in a struggle for existence [and] for resources, to avoid being eaten and to breed.... Environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming into new species. Animals that survive to breed can pass on their successful characteristics to [their] offspring."

And in the 10th century, an Ismaili scholar called Muhammad al-Nakhshabi wrote: "While man has sprung from sentient creatures [animals], these have sprung from vegetal beings [plants] and these, in turn, from combined substance, these from elementary qualities, and these [in turn] from celestial bodies." 

Sounds familiar. Of course, coming up with the general idea of evolution is very different from the huge body of work that Darwin did to observe and test the mechanism of natural selection, but still, I think it's amazing just how long ago Islamic scholars were discussing such ideas. 

These quotes are given in Ehsan Masood's excellent book, Science and Islam, which I have reviewed for this week's New Scientist along with The House of Wisdom by Jonathan Lyons (you can read the review here). Both are well worth reading, and turn the all-too-common Western view that Islam is an "anti-science" religion on its head. A thousand years ago, it was Christianity that forbade its followers from enquiring into the natural world. For those in Europe, the idea that species could change and develop over time would have been unthinkable.

It's the last day of the AAAS meeting today, and one of the most fascinating themes has been the sessions on various weird and wonderful types of life. All kinds of fundamental questions in biology -how likely is life to arise, does it have to be based on DNA, how you define life in the first place - are difficult to answer with a sample size of one, ie the life we know that has originated on Earth. So for biologists trying to answer these questions, the dream would be to have a second sample, an alternative kind of life to compare to the life we already know.

Many of them are working to make this a reality, by trying to synthesise different types of artificial life, and they're making good progress. For example, Tony Forster of Vanderbilt University and his colleagues started with a normal bacterial cell and worked out what would be the minimal components needed for it to survive. They reckon the least they can get away with is 151 genes, which is just one fifth the size of the smallest known natural genome (belonging to a bacterium called Mycoplasma). The plan now is to build all these components from scratch, and compile them into a working cell. That's a fair way off of course, but Foster is confident that it will be possible.

Meanwhile others are taking a more stripped down approach. Sheref Mansy of the University of Denver makes cell-like structures out of fatty acid molecules. Under the right conditions the fatty acids form a double membrane a bit like a cell membrane, and coalesce into spherical vesicles. The vesicles can grow in size, and Mansy has even managed to replicate short snatches of DNA inside them. Next he hopes to coax them to divide.

A key requirement in many definitions of life, however, is the ability to evolve by natural selection. And this is something that Steven Benner of the Foundation of Applied Molecular Evolution has been able to achieve. He and his colleagues synthesised RNA-like molecules using an alphabet of six different genetic letters (the four used by normal life, plus two artificial ones). They were able to get these molecules to replicate in a test tube. What's more, when errors arose in the replication, those errors were passed on to the next generation of molecules - just as occurs in Darwinian evolution.

Is this life? It meets nearly all of the requirements in NASA's formal definition of life: "A self-sustaining chemical system capable of Darwinian evolution." But it falls down on the "self-sustaining" part. Benner has to continually add a soup of raw materials and enzymes to keep the reaction going. Next he hopes to create a system in which the genetic template can catalyse its own replication. Then biologists could have an argument over whether the result should count as life. Even though it's not included in the NASA definition, many may feel that the system would also need to be enclosed inside cells, like Mansy's, before they hail it as living. I think this is a bar that will keep moving as the research advances.

But perhaps all we need to do to find new forms of life is to look around us. Physicist and astrobiologist Paul Davies pointed out that alternative creatures might exist on Earth already, right under our noses. If life originated on Earth once, he said, perhaps it originated several times, leading to two or more unrelated lineages. If so, this "other" life might have died out early on, or it might have integrated with the early organisms from which we are descended. But in his talk he focused on a third, more exciting possibility, that it might still be living alongside us today. He calls the idea a "shadow biosphere".

To find this weird life, he suggested looking in environments where normal life can't survive, such as extremes of temperature, salt, or radiation. Or you could run an experiment with conditions that would kill off normal organisms, for example by disrupting the normal genetic code, and see if anything grows.

Davies thinks these shadows would have to be microbes, or we'd have noticed them already. He points out that only a fraction of microbial species have ever been cultured in the lab, in fact many of them seem impossible to grow, no matter what conditions researchers try - so maybe some of them are living by different rules. I used to be a microbiologist, and I'd get very frustrated when my cultures didn't grow. It never occurred to me that I might be dealing with aliens.

The ancient Greeks had some pretty sophisticated astronomy, but as far as I know they never speculated about the possibility of life on other planets (apart from the general idea that the cosmos as a whole could be seen as a divine, living organism).

Now astronomers are going to the other extreme, and seeing the potential for life literally everywhere. I just went to a press conference at the AAAS meeting here in Chicago where planet expert Alan Boss gave his latest views on how many habitable planets may be out there (that means rocky planets roughly the size of Earth, orbiting at the right distance from their star to have liquid water). The numbers were quite astounding - he reckons there could be one habitable Earth for every Sun-like star in the universe, an incredible 100 thousand billion billion of them, and 100 billion in our galaxy alone. Boss also thinks there's a high chance of life evolving on such planets. "Life is so tenacious and hard to stop," he told the press conference. He reiterated the point Anthony Remijan made here yesterday, that comets continually carry rich mixtures of prebiotic organic molecules onto the surface of planets. "If a habitable planet is sitting around a star for billions of years - something is going to come up."

Of course, many astronomers aren't nearly as optimistic about the chances for life elsewhere. So far it's hard to settle the argument as it hasn't been possible to detect directly any Earth-sized planets orbiting other stars, but Boss is basing his estimate on the 300 or so larger planets that have been detected, as well as computer simulations of how planets form. We know that bigger hotter "super-Earths" seem to form around a third of stars like our Sun, and Boss reckons that normal-size Earths should form much more easily. There are some kinds of solar system in which it would be very difficult to image a habitable Earth-like planet forming - for example when there is a huge gas giant, like Jupiter, orbiting close to the star. But so far this type of system has only been seen in around 15 per cent of solar systems, leaving 85 per cent in which an Earth (or several) could form.

He was speaking just 3 weeks in advance of the launch of NASA's Kepler mission, which aims to detect Earth-like planets for the first time. Three or four years from now, we should have enough results to give us a much more solid estimate of the number out there. Boss said he'll be "absolutely astounded" if the mission doesn't find any.

Once we find some planets that look habitable, the next step will be to build better telescopes so that rather than simply detecting their presence, astronomers can get more detailed images. Even a picture just ten pixels across would enable us to look for the presence of oceans and continents. And directly detecting light from these systems should tell us something about the different chemicals in the planets' atmospheres - the presence of oxygen, for example, would be good evidence that life has already evolved.

If we do see signs of life, Boss thinks we should send a small (unmanned) spacecraft to check it out. Even if the planet was relatively close, say 30 light years away, it would take a couple of thousand years for the spacecraft to arrive. But once it was there it could beam back detailed images - if there's anyone still here to receive them.

Boss has just written a book all about the search for habitable planets, called The Crowded Universe.

Last Friday I caught the train to snowy Cambridge for a half-day conference on the Antikythera mechanism, organised by the Whipple Museum of the History of Science. Several of the researchers from the Antikythera Mechanism Research Project spoke about their work on the device, so it was a good opportunity to catch up with them and find out where things have got to.

First, Mike Edmunds of Cardiff University and his London-based colleague Tony Freeth summarised the project so far. They didn't add much to what has been said before, however, and it was Alexander Jones, over from the Institute for the Study of the Ancient World in New York, who gave the most interesting talk of the day. He has been collaborating with Tony Freeth and others to decipher the inscriptions on the mechanism, particularly those letters hidden beneath the surface of the surviving fragments and revealed only recently by 3D X-ray imaging.

Most recently the research group has been studying the text on the front of the mechanism, and they have a paper planned on this very soon. Unfortunately Jones didn't pass on any juicy advance details and instead focused on the back of the mechanism, which was the subject of a Nature paper published in July last year.

In that paper, the team reported that the month names used on a 19-year calendar on the back of the mechanism came from a civil calendar, not an astronomical one as assumed, and that a smaller dial didn't show a 76-year calendar as previously thought, but a 4-year cycle marking the timing of the Olympic and other Greek games.

In his talk, Jones told us how surprised he had been to learn that this civil calendar was tightly regulated to lunar and solar cycles. Previously it had been thought that only astronomers used such sophisticated calendars, whereas the calendars used by ordinary people were much more ad hoc. But that clearly wasn't the case. Among other things, the mechanism's dial explained which months should have 29 days and which should have 30 days, and exactly which days to skip.

Jones also talked about the month names used on the calendar, including Phoinikaios, Kraneios, Lanotropios and Machaneus. Different month names were used in different regions of Greece, so in theory these should help pin down where the mechanism was made. Unfortunately knowledge of exactly what months were used where is very patchy, but the closest matches to the ones on the Antikythera mechanism are with regions colonised from the city of Corinth - candidates include Corfu, Illyria and Epirus in northwest Greece, and Syracuse in Sicily. Syracuse is a particularly exciting prospect because this is where Archimedes lived - and ancient writings suggest he once made a device similar to the Antikythera mechanism. But Jones revealed a hint that may implicate northwest Greece instead.

It's on the 4-year Olympiad dial. The different games listed on the dial are Isthmia, Olympia, Nemea, Pythia and Naa (plus one other that hasn't been deciphered). Isthmia, Olympia, Nemea and Pythia were all major games, of importance across the Greek world. But the Naa games, held in Dodona, were a much smaller affair, of only local interest. So Jones speculates that the dial might have been designed for someone who lived nearby. Dodona was in Epirus, one of the regions also implicated by the month names on the calendar, so perhaps the device was made in Epirus. Deciphering the final name on the list might help to confirm or rule out this theory.

Jones said he thinks the Antikythera mechanism wasn't so much a computer, designed for making specific calculations, as a simulator, intended to demonstrate the workings of the universe to a broad intellectual audience. He also revealed that it may be even older than thought, perhaps from the early second century BC. The inscriptions have been dated to around 100 BC. But because we don't know where the device is from, that's only a very rough estimate. Jones pointed out that many of the Corinthian colonies were devastated or taken over by the Romans well before 100 BC: Syracuse in 212 BC, Epirus in 167 BC, Corinth in 146 BC. After Roman conquest the inhabitants would presumably have stopped using their Greek calendar, suggesting that the Antikythera mechanism was built earlier than this. I think he's right when it comes to northwest Greece, but Syracuse was still Greek-speaking and relatively prosperous into the first century BC so its inhabitants could have carried on using this calendar for quite a while.

Also still unanswered is the question of how the mechanism ended up on the ship on which it was found.This was a Roman ship sailing from Asia minor in the eastern Mediterranean, carrying valuable goods (probably war booty) back to Rome. Yet the Corinthian colonies were all in the western Mediterranean. This caused a bit of discussion after the talks between Jones and Edmunds, who believes that devices like this, if not the Antikythera mechanism itself, were being made at the time in Rhodes in the east. I think he's probably right, and that the tradition of these devices spread across the Greek world.

Paul Cartledge, professor of Greek classics at the University of Cambridge, wrapped up proceedings with some entertaining comments about the wider significance of the Antikythera mechanism. In particular, he's interested in what the device tells us about the culture and mindset of the ancient Greeks. His main point was that although historians have often viewed the Greeks as not very technologically minded, the Antikythera mechanism shows that science and technology were central to their world. What's more, it suggests they were moving away from belief in superstition and omens towards a much more modern mindset in which the universe is explainable, and operates according to predictable rules.

I still find that astounding. More than two thousand years ago, you could say that the Greeks were having their own Scientific Revolution.