12 January 2013 | NewScientist | 15

World’s oldest pills treated sore eyes

IN ANCIENT Rome, physicians treated sore eyes with the same active ingredients as today. So suggests an analysis of pills found on a cargo ship wrecked off the Italian coast in around 140 BC.

“To our knowledge, these are the oldest medical tablets ever analysed,” says Erika Ribechini of the University of Pisa in Italy, head of a team analysing the relics. She thinks the disc-shaped tablets, 4 centimetres across and a centimetre thick, were likely dipped in water and dabbed directly on the eyes (PNAS, DOI: 10.1073/pnas.1216776110).

The tablets were mainly made of the zinc carbonates hydrozincite and smithsonite, echoing the widespread use of zinc-based minerals in today’s eye and skin medications. Ribechini says there is evidence that Pliny the Elder, the Roman physician, prescribed zinc compounds for these uses almost 250 years after the shipwreck in his seminal medical encyclopaedia, Naturalis Historia.

The tablets were also rich in plant and animal oils. Pollen grains from an olive tree suggest that olive oil was a key ingredient, just like it is today in many medical and beauty creams, says Ribechini.

A Titan-like atmosphere helped early Earth keep warm EARTH should have been frozen in its youth, when the sun was cooler. Yet the young Earth was warm enough for liquid water. This paradox has puzzled us for decades, but now a look at one of Saturn’s moons suggests a new explanation.

For the first 2 billion years of Earth’s existence, the sun was up to 25 per cent dimmer than it is today. Our planet’s average surface temperature should have been around -10 °C, but the geological evidence is that Earth had liquid water at this time.

Titan, too, is warmer than it should be. This is because its atmosphere is so rich in hydrogen and nitrogen that the molecules keep colliding under pressure, leading to a chemical reaction that traps the sun’s energy.

To see whether something similar could have happened here, Robin Wordsworth and Raymond Pierrehumbert, both at the University of Chicago, Illinois, created a simulation of ancient Earth. They found that if hydrogen made up a tenth of the atmosphere and nitrogen was present at double

WHY do our fingers do prune impressions when soaked? It could be an adaptation that gives us better grip underwater.

Fingers and toes wrinkle in water after about 5 minutes due to the constriction of blood vessels. This reduction in volume pulls the skin inward, but as the skin’s surface area cannot change, it wrinkles. A study in 2011 showed that wrinkles form a pattern of channels that divert water away from the fingertip – akin to rain treads on tyres. The team thought that this could aid grip.

To find out, Tom Smulders and his

team at Newcastle University, UK, timed people as they transferred wet or dry objects from one box to another with and without wrinkled fingers.

With wrinkles, wet objects were transferred about 12 per cent faster than with unwrinkled fingers. The time it took to transfer dry objects was the same regardless of wrinkles (Royal Society Biology Letters, DOI: 10.1098/rsbl.2012.0999).

So why aren’t our digits always prune-like? “With wrinkles, less of your skin surface touches the object, so there may be issues of sensitivity,” Smulders suggests.

Pruney fingers useful? Get a grip…

Tobi

as

bern

ha

rd/G

eTT

y

or triple today’s level, ancient Earth’s average temperature would have been 10 to 15 °C higher – above the freezing point of water (Science, doi.org/j47). The hydrogen could have come from volcanoes, they say, and could have persisted as microbes that consume the gas may have been rare due to a lack of nutrients.

It’s a good model, says Chris McKay of the NASA Ames Research Center in Moffett Field, California, but he says strong evidence will be needed to show that the elements were once that abundant.

Silvered nano-shard lets light fly

A NANO-SIZED bar of glass encased in silver allows visible light to pass through at near-infinite speed. The technique may spur advances in optical computing.

Metamaterials are synthetic materials with properties not found in nature. Metal and glass have been combined in previous metamaterials to bend light backwards or to make invisibility cloaks. These materials achieve their bizarre effects by manipulating the refractive index, a measure of how much a substance alters light’s course and speed. In a vacuum the refractive index is 1, and normal materials have positive indices. Ordinary glass is about 1.5.

The new material contains a nanoscale structure that guides light waves through the metal-coated glass. It is the first with a refractive index below 0.1, which means that light moves through it at almost infinite speed, says Albert Polman at the FOM Institute AMOLF in Amsterdam, the Netherlands (Physical Review Letters, doi.org/j5x).

But the speed of light has not, technically, been broken. The wave is moving quickly, but its “group velocity” – the speed at which information is travelling – is near zero. Still, the material could be used to transmit light over very short distances in optical integrated circuits, says Polman.

Joh

n r

ensT

enze

fa/s

upe

rsT

ock

For new stories every day, visit newscientist.com/news

130112_N_In Brief.indd 15 8/1/13 09:47:08