The Pantheon in Rome is one of the most stunning and well-preserved buildings that survives from antiquity. But could it have been more than just a temple? In today's issue of New Scientist I've written a news story about the idea that this domed building was actually a colossal sundial. An opening in the roof of the dome lets through a dramatic shaft of sunlight. During the six months of summer the noon sun falls on the walls and floor of the temple, and in winter (when the sun is lower in the sky) it falls onto the inside of the roof itself. But at the exact moment of the two equinoxes, in March and September, the sun falls at the junction between the roof and the walls, directly above the northern doorway, and shines through a grill there onto the porch floor beyond. The idea that the building was purposely designed to mark the equinoxes was suggested in the 1970s, but no one really picked up on it. Now an expert in timekeeping called Robert Hannah, who's based at the University of Otago in New Zealand, has discussed the idea in detail in his latest book, Time in Antiquity. Equinoxes occur when the Sun is on the celestial equator, and Hannah reckons that the Romans may have seen the equinox as a sacred time, when the Emperor could be raised up to dwell there with the gods.

Hannah now plans to look for other buildings and landscapes from the ancient Greek and Roman worlds that could have similar celestial significance. For example, he points out that if you stand at the Pnyx, which was the ancient political assembly area of Athens, to the west of the Acropolis, the midsummer sunrise appears directly behind the peak of Mount Lykabettos, a prominent hill to the northeast. The summer solstice was the point in time from which the Athenians measured the start of their calendar year. Hannah argues that ancient civilisations were much more aware then we are of how natural events signalled the passing of time, and he thinks they could well have used the sunrise behind Mount Lykabettos to mark the arrival of the new year.

I've written a short review of Time in Antiquity in the same issue of New Scientist. It's a lovely book about how the ancient Greeks and Romans marked the passing of the seasons and told the time. Among other things, Hannah gives a detailed analysis of the various calendars used on the Antikythera mechanism. But what makes it for me are the anecdotes from plays and poems, which give you a vivid taste of daily life in these societies. One play has a character who is a prostitute, nicknamed Clepsydra, which was the name for a type of water clock, because she used one to time her sessions with clients. Another features a guest invited to dinner when his shadow measures twenty feet long, but he's so eager for food that he measures it at dawn instead of dusk, and arrives hours early. But my favourite is probably a poem written by a Roman disgruntled that he can no longer eat when he wants because meal times are being set by new-fangled sundials. I used it in Decoding the Heavens too, here's that version:

The gods confound the man who first found out

How to distinguish hours! Confound them too,

Who in this place set up a sundial,

To cut and hack my days so wretchedly

Into small portions! 

After letting you know about the upcoming conference featuring members of the Antikythera Mechanism Research Project, today I can update you about Michael Wright, who has been working on the Antikythera mechanism since the early 1980s. He made the first working model of the mechanism (I've previously posted a video of it on youtube). Now he's working on a second model.

The first version was made out of packing crate wood and recycled brass plates from a pub door. Michael built it bit by bit, reworking and replacing different sections over the years as he studied his X-rays of the original Antikythera fragments, and worked out how the machine was put together.

Now that the structure of the mechanism is generally agreed upon (the surviving parts at least), Michael is making a smarter display version, and he has kindly sent me some photos of it. The case is made of maple, with wood panels above and below the front dial instead of the old brass strips. The dials are pretty similar to the older model, but the new ones are neater, and Michael says he has worked out how the calendar ring was held into the front dial, which he wasn't sure about before.

The top two photos show the mechanism from the front - the pointers show the Sun, Moon and the five planets that the Greeks knew about, as they circle through the sky. The inner dial is a zodiac scale, while the outer dial shows the days of the year. In the close up you can see the engravings better - look for the Sun pointer (second from left, labelled "Helios"). On the zodiac scale you should also be able to recognise Parthenon on the left (the Greek name for the sign Virgo) and Chelai on the right (meaning "claws", this is what the Greeks called the sign of Libra).

The third picture is a close up of part of the upper back dial - it was a spiral calendar inscribed with local month names, with a tiny 4-year dial inside it showing the timing of the Panhellenic Games, including the Olympic Games. Below this is a second spiral (not shown) which displayed the details of upcoming lunar and solar eclipses.

What a wonderful piece of machinery. I've had quite a few emails from people asking where they can buy an Antikythera mechanism for themselves, but as far as I know there are no plans to make them commercially.

Just a quick note today to let you know about a conference that's coming up on the Antikythera mechanism. It's open to the public and it's being held in Cambridge on 6 February (more details here). The speakers include Mike Edmunds and Tony Freeth, who headed the latest team to image the fragments of the Antikythera mechanism, as well as Yanis Bitsakis and Alexander Jones, who both helped to read the inscriptions that were revealed. Because it's a public meeting I don't know if they'll be giving away any as-yet unpublished secrets, but it should be a wonderful opportunity to hear about the latest work on this fascinating device, from the researchers who carried it out. I'll certainly be there, so I'll post about it afterwards, but I imagine they'll be focusing on their most recent paper, published in Nature last July. In it they reported that the mechanism had a 4-year dial on it that showed the timing of the Panhellenic Games, including the Olympic Games, as well as a local calendar which hinted that the mechanism might have come from Syracuse, on the island of Sicily in the western Mediterranean. This was a huge surprise because all the indications from the shipwreck on which the mechanism was found suggested that it came from somewhere much further east, perhaps Rhodes. (See this news story I wrote about it at the time for New Scientist, or my more recent feature.)

If you can't make it on the day, there's also an associated exhibition dedicated to the Antikythera mechanism, at Cambridge's Whipple Museum of the History of Science until spring 2009. The mechanism itself is on display in the National Archaeological Museum in Athens, but the exhibition has information about the latest research by Tony Freeth's team, as well as this beautifully-made video.

There's a story doing the rounds at the moment that Italian scientists are seeking permission to exhume Galileo's body to see if they can extract DNA from it. Galileo was known to have suffered from a degenerative eye disease that left him blind before he died, so they want to look for evidence in his DNA of what the disease was, and exactly how it might have affected what he saw through his telescope. Paolo Galluzzi, director of the Institute and Museum of the History of Science in Florence, says this might help to explain certain mistakes Galileo made, such as why he described Saturn as having "lateral ears" rather than rings. But really, this project has to be an incredible longshot, even if the researchers do get permission to open Galileo's grave. As one expert in ancient DNA comments in ABC's version of the story: "If you put a human corpse in a coffin and seal it inside a slab of granite, which appears what happened to Galileo's body, there is going to be a huge amount of purification [I assume this is meant to say putrefaction] and decomposition," he says. DNA was recently used to identify 16th-century human remains buried in Poland as belonging to the astronomer Copernicus, but simply checking for a match between two sequences isn't as challenging as trying to identify specific mutations within the genes associated with blindness. Still, it's all great publicity for International Year of Astronomy, organised this year by the International Astronomical Union and UNESCO to celebrate the 400th anniversary of Galileo's first use of an astronomical telescope.

Back in November, I posted about an initiative to allow astronomy sites to be recognised on the World Heritage List. I think this is a long overdue project (and part of a broader need to recognise scientific heritage more generally) so I invited Clive Ruggles, an archaeoastronomer and chair of the working group that will decide how these astronomy sites should be chosen, to write a comment piece for New Scientist about why he thinks ancient astronomy is so important for our cultural heritage. You can now read the result here, as well as view a photo gallery showing some of the world's most striking astronomical sites, as chosen by leading archaeoastronomy experts. Old favourites such as Stonehenge in the UK and Chichen Itza in Mexico are covered, but also lesser known sites like the Big Horn Medicine Wheel in Wyoming (an oval arrangement of stones aligned to the summer solstice) and a 7th-century observing tower in Cheomseongdae, South Korea. 

One thing I found particularly interesting about Ruggle's article was the idea that rather than simply preserving ancient sites in isolation, we should try to look after the environments in which they were placed. For astronomical sites that of course includes the sky - an ancient observatory can't be truly appreciated without the starry sky to go with it, yet today an undimmed view of the stars is distressingly rare. The last time I saw a properly dark sky was several years ago, sitting on the beach of a tiny island in Fiji, far from any artificial lights. It was one of the most beautiful things I've ever experienced; far from being dark the sky seemed alive and pulsating, an awesome (and colourful!) display of shimmering, bursting light - it's easy to see why ancient people thought they saw gods up there. "To those of us in the modern, lit-up world, the first time that we see a truly dark night sky can be breathtaking," says Ruggles. "But until relatively recently, most people experienced this spectacle every clear night, wherever they lived. If we want to appreciate the beliefs and practices reflected in the architecture of ancient temples and tombs, we cannot ignore their relationship to the sky."

This obsession with the sky was also what drove the development of much ancient technology including the first scientific instruments, from sundials to astrolabes, and of course the Antikythera mechanism.

A few sources over the past week have picked up a story about DNA being extracted from very old parchment. Made from dried animal skin, parchment was a popular writing material in the ancient world and through Medieval times. The story reported last week was that researchers from North Carolina State University in Raleigh tested five pages from a 15th-century French manuscript and found genetic material from two closely related calves. Tim Stinson will be presenting the results of the research at the annual meeting of the Bibliographic Society of America on Friday. The hope is that identifying DNA from manuscripts of known origin could shed light on ancient trade routes or herding practices. Alternatively, comparing the DNA of manuscripts for which the date or source isn't known with others for which it is, might help provide clues as to their origin.

DNA has been extracted from old parchment before. One of the key studies was published in 2007 by Greek researchers including Yanis Bitsakis and Agamemnon Tselikas at the Centre for History and Palaeography in Athens. Bitsakis and Tselikas are experts in deciphering ancient lettering - they were both involved in reading the inscriptions revealed when the mysterious Antikythera mechanism was X-rayed in 2005. I visited them at the centre when researching Decoding the Heavens, and it's a lovely place, hidden in an Athens back street and filled with piles and piles of beautiful old books and manuscripts. While I was there they told me how they had teamed up with ancient DNA expert Nikos Poulakakis from the University of Crete to extract DNA from some of the collection. They were able to identify DNA from three Greek manuscripts dating from the 13th and 16th centuries AD, which turned out to come from three different goats.

The US and Greek researchers are now in contact. Bitsakis tells me they hope to build a database of DNA sequences from manuscripts, using Tselikas's collection as a starting point.

Another top ten today - there's a fun blog post over on Beauty of Earth, with a list of the ten most famous uncracked codes. They range from Kryptos, a 1990 sculpture installed in the grounds of the CIA in Langley, Virginia, to Linear A, one of two linear scripts used in ancient Crete. (The other script, Linear B, was deciphered in 1952 by a British architect called Michael Ventris, when he showed that it was used to write Greek. Reading about Ventris's work was what inspired a young London schoolboy called Michael Wright to find a mystery of his own to solve. Decades later, he went on to decode the Antikythera mechanism.)

It's an intriguing list, although the reason that some of the codes have never been cracked may well be because they are meaningless hoaxes. Unfortunately it's impossible to know which! One entry that has been called into question recently is the Phaistos Disc. This flat disc of fired clay is stamped on both sides with an uneven spiral pattern of mysterious pictographic symbols. It was found in 1908 in the Minoan palace of Phaistos in Crete, alongside remains dating from around 1700 BC. Because of the way the symbols were stamped into the clay, it has been described as the earliest ever example of movable type.

But no one has ever been able to decipher the symbols. And last summer, Jerome Eisenberg, a specialist in faked ancient art, published an article in the magazine Minerva arguing that the disc was fired too perfectly to be authentic. He reckons that the Italian archaeologist who supposedly found it, Luigi Pernier, may have faked the disc because he was desperate to unearth something at Phaistos that would outdo the fabulous artefacts that his rival, Sir Arthur Evans, was discovering at the nearby site of Knossos.

Plenty of enthusiasts are still convinced that the disc is real, though, and I for one really hope that it is. The mystery could be solved by a technique called thermoluminescence dating, which would give a rough date for when the object was last fired. Unfortunately the authorities at the Heraklion Museum, where the disc is held, have apparently refused permission for this to be done. The test involves heating a sample of the object, so they may be concerned about damaging such a precious artefact. Or perhaps they know something we don't.

Hurray, ancient DNA is back in the headlines. When the genome sequence of the mammoth was announced in November, I talked a bit about the possibility of using cloning to resurrect extinct creatures from their DNA, and suggested that the next genomes to be published in this area maybe those of the Neanderthal and the cave bear. Clearly inspired by the same thought, New Scientist has a light-hearted feature this week listing its top ten candidates, apart from the mammoth, for species to be brought back to life.

The main issue is preservation of the DNA. This means dinosaurs are out, because they are too old - no genetic information is likely to survive for more than a million years. So ideal candidates would have lived less than 100,000 years ago, and there will be specimens preserved in permafrost. It's also helpful to have a closely-related species alive today, that can provide eggs for the cloning process, and serve as a surrogate mother. Finally, New Scientist based its selection on a made-up measure called "megafaunal charisma" (how exciting the prospect of resurrecting these animals is) which basically means it chose the candidates it thought would be most interesting to write about.

Here is the top 10, in no particular order:

Sabre-toothed tiger

Neanderthal

Short-faced bear

Tasmanian tiger

Glyptodon (a giant armadillo the size of a Volkswagen Beetle)

Dodo

Woolly rhinoceros

Giant ground sloth

Moa

Irish elk

Gorilla (not extinct yet but could be soon)

Out of those, my favourite has got to be the Glyptodon (pictured), although the lack of a suitable living surrogate (today's armadillos aren't going to be able to carry one of those to term) would be a huge challenge. In fact the hurdles for resurrecting any of these species are still enormous, but then the science is progressing dizzyingly fast. Just 55 years ago when the structure of DNA was discovered, the idea of sequencing an entire genome in just a few months, for example, or of cloning a new individual from an adult cell, would have seemed impossible. So who knows what will be doable in the next 50 years.

Of course the ethical issues surrounding bringing back any of these species, especially the Neanderthal,  are much harder to dismiss. If they wouldn't have anywhere to live - the reason many of these animals went extinct in the first place - what's the point? But then as New Scientist says, "let's not spoil the fun". Car-sized armadillos would certainly give a trip to the New Forest a whole new edge.

So what would you bring back, and why? 

How much are researchers' interpretations of tantalising ancient remains affected by their own prejudices? It has certainly been a significant factor in studies of the Antikythera mechanism. Several scholars from naval backgrounds, who studied the fragments soon after they were retrieved from a shipwreck in 1901, were convinced it must have been a navigational instrument. Later, Erich von Daniken, the Swiss author who thinks ancient civilisations got much of their technology from visiting extraterrestrials, concluded that the clockwork machine was used in alien spaceships. Even today, experts disagree over whether the device was primarily a planetarium or an eclipse predictor, depending partly on which part of the mechanism they discovered.

A story reported in the Guardian today suggests that archaeologists working on sites across ancient Greece may be suffering from a similar problem. They often find the remains of homes that contain hundreds of drinking cups, and it is generally assumed that these must have belonged to wealthy families who threw lavish parties. But Clare Kelly Blazeby of Leeds University, who is due to speak at the Archaeological Institute of America meeting in Philadelphia on Saturday, reckons a more plausible explanation is that the buildings were owned by working class residents, who earned extra money by turning their houses into drinking dens. This would also solve the mystery of why so little physical evidence has been found of Greek tavernas, even though they are so often mentioned in classical literature. Kelly Blazeby thinks that archaeologists may not have recognised the bars when they found them because the sites didn't fit with their ideas of how domestic houses should be used. "It's amazing how entrenched people in the field are," she told the Guardian. "We are trying to change archaeologists' minds by pointing out that houses could be used economically as well as being residences."

Kelly Blazeby probably has a good point. But then her specialist field is the anthropology of working class drinking, so just maybe she too is finding what she's looking for. 

[Picture credit: Gorivero] 

Sorry for the long wait between posts, I took a break over Christmas and New Year. Thought I'd catch up with a great story about Stonehenge from while I've been away - the finding by Rupert Till, an expert in acoustics and music technology at Huddersfield University, that the ancient stone monument is perfectly designed to amplify certain sounds, even producing a "repetitive trance rhythm" in some circumstances. Till thinks that the builders of Stonehenge purposely shaped and positioned the stones for the best possible acoustics. The story was covered first in the Yorkshire Post on 2 January, then made international news over the past few days, somehow morphing into the idea that Stonehenge was a "concert venue" or (according to MSNBC) a "totally awesome rave location".

Some of the more extreme headlines are rather ridiculous - archaeologists don't think that the primary purpose of Stonehenge was music. But the events going on there would certainly have involved sound, and the idea that neolithic Britons finetuned the acoustics of their monuments isn't surprising, according to Dave Batchelor, who is an archaeologist working at the Stonehenge site. He told 24 Hour Museum: "The use of music, drums and those types of instruments is well-known from archaeological records going back tens of thousands of years to Paleolithic cave art. People were making simple flutes and rums out of animal and bird longbones and things like that."

There are also lots of other examples of ancient monuments that incorporated sound. Rock art expert Steven Waller has taken sound recordings of echoes at more than 300 archaeological sites in France, Australia and the US. At many of them, including Horseshoe Canyon in Utah and Hieroglyphic Canyon in Arizona, he has found that rock paintings tend to be located where the echoes are most intense. He thinks that the artists interpreted the eerie natural sound effects as the spirits speaking to them, and that this motivated them to create the paintings.

Thomas Ault of Indiana University, Pennsylvania, thinks that an elaborate two-storey structure in Orissa, India, that dates from the third century BC (previously interpreted as a place for meditation) is actually a theatre, after measuring its acoustics and finding that a person speaking anywhere on the "stage" area (but nowhere else) can be heard clearly throughout the site. 

And then there's my favourite - acoustic expert David Lubman has studied the Mayan site at Chichen Itza in Mexico, and believes that the Mayans designed the staircase of the main pyramid (pictured) so that its echo sounded like the chirp of their sacred bird, the quetzal. Click here to listen to two quetzal chirps, followed by the echoes of two handclaps at the pyramid.

The sad news is that at many sites, these ancient sound effects aren't recognised, let alone protected, so they are being lost through erosion, vandalism, noise pollution and alterations. The amplification that Till discovered no longer works at Stonehenge, for example. He only discovered it after visiting a full-size concrete replica of the monument in Maryhill, Washington.