A short announcement.
Last Tuesday, this blog received its millionth page view (according to Sitemeter).
Today, I’ve also recruited my thousandth follower on Twitter (despite mercilessly pruning for spammers).
I am celebrating by having a day where I don’t write anything.
Except this.
CURSES!

As you read this, you are glowing – weakly, faintly, but glowing nonetheless. Chemical reactions within your body, besides liberating energy and producing heat, are also emitting small numbers of photons, elementary particles of light. The glow is strongest in the late afternoon, and around the lower part of your face.

Many living creatures, including fireflies, jellyfish, squid, glow-worms and deep-sea fish, are known for producing their own light often through the help of bacterial accomplices. But virtually all living things emit some degree of light, albeit so weakly that it’s very hard to detect. Our own biological glimmer is a thousand times less intense than the sensitivity of the human eye so our only hope of detecting it is with sophisticated instruments.

That’s exactly what Masaki Kobayashi from the Tohoku Institute of Technology has done. Searching for our inner light is usually the province of hippies and new age followers. Kobayashi is neither – he has actually managed to photograph the dim glow of humans using an incredibly sensitive camera, able to detect the dimmest of lights.

Previous cameras took more than an hour to record a decent image but Kobayashi’s camera is so sensitive that it can detect light at the level of a single photon. Even so, using it is tricky. The camera needs to be kept at -120 degrees Celsius and sealed in a completely light-tight room. The person being filmed also needs to be in complete darkness, as well as naked and very clean, lest clothing or grime obscure the photons they emit.

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It seems like an uneven match. In one corner, the unassuming California ground squirrel (Spermophilus beechyi), 30cm in length. In the other, the northern Pacific rattlesnake (Crotalus oreganos), more than twice the length of the squirrel, and armed with hinged fangs that pack a lethal venom. But thanks to a cunning adaptation, the squirrel often gets an unexpected upper hand in this bout.

Ground squirrels live in a series of burrows that keep them out of reach of most predators. Snakes, however, have exactly the right body plan for infiltrating long sinuous tunnels, and it’s not surprising that they are the squirrels’ major predators. It’s equally unsurprising that the squirrels have developed ways of defending themselves against snakes.

Adults have developed a certain degree of immunity to snake venom and their agility helps them avoid strikes. But their pups are still vulnerable and adults disguise their scents by chewing on the discarded skins of rattlers and licking them. When confronted, they harass the snake and wave about an upright tail. Among other benefits, this ‘tail-flagging’ tells the snake that it’s lost the element of surprise, alerts other squirrels and distracts the predator from vulnerable young.

But tail-flagging also has a hidden component that scientists have only just discovered. Aaron Rundus and colleagues from the University of California, Davis, found that the squirrels also heat up their upright tails, turning them into beacons of infrared light. It’s a countermeasure specifically evolved to exploit one of the rattlesnake’s deadliest abilities.

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We think of spiders as fearsome hunters, spinners of webs and treacherous mates, but construction workers? Yes, that too. Some groups of spiders – trapdoor and wolf spiders – dig tunnels that they use to ambush passing insects. But these tunnels can also provide shelter and accommodation for other animals, including one of the rarest of Australia’s lizards – the pygmy blue-tongue lizard. It seems that the lizard’s survival depends entirely on the spiders.

The pygmy blue-tongue is a native of South Australia. It’s so rare that zoologists thought it extinct for over 30 years and it re-emerged in the public eye in the most unlikely way. In 1992, a dead specimen of this supposedly extinct animal was found in the stomach of a brown snake, found dead on the side of a road. That unexpected discovery prompted intensive surveys of the surrounding area, which found several lizards living in spider burrows.

Like the spiders, the lizards use the burrows for ambush but they also act as nurseries, cooling stations and defensive forts. To understand the relationship between lizards and spiders, Michael Bull from Adelaide’s Flinders University studied the fates of both species in a single hectare of South Australian land. Over two years, his team spent bursts of two weeks, intensively searching the plot of land for signs of burrows. Each one was probed with a fibre optic camera to see who lay inside.

Earlier studies have found that lizards readily accept artificial burrows and adding these to the local area will halt the decline of the lizard populations. That’s all very good, but as Bull writes, “a sustainable supply of natural burrows would be a better option in the longer term”.

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Bats view the world in echoes, timing the reflections of their own ultrasonic calls to navigate and hunt. This biological sonar, or echolocation, has made them masters of the night sky; it’s so sensitive that some species take moths and other insects on the wing, while others pluck spiders from their webs without entangling themselves in silk. But with such an efficient technology, it was only a matter of time before their quarry developed countermeasures.

Some insects gained ears; others simply rely on outmanoeuvring their attackers. But one group, the tiger moths, play bats at their own game. When attacked, they unleash ultrasonic clicks of their own to jam the calls of their pursuers, disrupting their ability to accurately gauge distances or even feigning echoes off non-existent objects.

This technique has been suggested ever since moths were first discovered to click several decades ago, but Aaron Corcoran from Wake Forest University has found the first conclusive evidence that moths actually do this. They pitted moths of the species Bertholdia trigon) against four big brown bats (Eptesicus fuscus) against each other over the course of three days, in gladiatorial arenas surveyed by high-speed infrared cameras and ultrasonic microphones.

When the three bats were pitted against moths in flight, they only managed to snag B.trigona on around one in five attempts. Even if the moths were tethered onto a stump, the bats still fumbled their approach at the last minute. A related moth species that doesn’t click fared much worse and almost always succumbed to the bats.

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In the world of horse-racing, the horses understandably get all the attention but much of the thrill of today’s races depends on the jockeys. Their modern riding posture – the so-called Martini glass – has led to a dramatic improvement in race times, by making things much easier on their horses.

Modern horse-racing has been going on for over two centuries, but in its earliest days, jockeys would ride vertically. The modern, crouched style was only developed in the late 19^th century in the US. By 1897, it has been adopted in the UK and by 1910, it was a global phenomenon. The new posture clearly had benefits for the horses for in the few decades after its introduction, race times improved by 5-7%, more than they did in the subsequent century.

You might think that crouching down speeds up races simply by reducing drag on the horse, but not so. Jockeys may be bent over but they still sit fairly high on their mounts, much higher than, say, a track cyclist does on theirs. This high posture means that from the front, the total area of horse and rider doesn’t change very much between the upright and modern riding styles. Less than 2% of the total work done by the horse’s muscles is spent on overcoming this extra drag.

Instead, Thilo Pfau at London’s Royal Veterinary College has found that the uncomfortable stance greatly reduces the burden on the horse by uncoupling its movements from those of its rider.

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Compare the elegant grace of a running wolf with the comical shuffle of a waddling dachshund, and you begin to understand what millennia of domestication and artificial selection can do to an animal. As dachshunds develop, the growing tips of their limb bones harden early, stunting their growth and leading to a type of dwarfism called chondrodysplasia. The same applies to at least 19 modern breeds including corgis, Pekingese and basset hounds, all of which have very short, curved legs.

These breeds highlight the domestic dog’s status as the most physically diverse of mammals. Now, a team of scientists led by Heidi Parker from the National Human Genome Research Institute have found the genetic culprit behind the stumpy limbs of all these breeds, and its one with surprising relevance for dwarfism in humans. 

All cases of stunted legs in domestic dogs are the result of a single genetic event that took place early on in their evolution. Some time ago, a gene called FGF4 (short for fibroblast growth factor 4), which plays an important role in bone growth, was copied and reinserted into a new site in the dog genome. It’s this extra errant copy – a retrogene – that has retarded the growth of so many domestic breeds.

Parker’s team sequenced genes from over 835 dogs across 76 different breeds, including 95 short-legged individuals, and found a genetic signature unique to these stunted animals. This included a handful of genetic variants – each consisting of a single altered base pair or “DNA letter” – that were overrepresented in the short-legged breeds and that clustered in the same site. One of these variants was 30 times more common in the short-legged breeds than their long-limbed peers.

The team found that this mystery region exactly matched a gene called fibroblast growth factor (FGF4). That was puzzling, for FGF4 normally sits at a very different location, some distance away on the dog genome. In fact, Parker found that the short-legged breeds have two copies and the one associated with their abnormal growth has been inserted in an unusual site. Not only did all the stunted animals have this errant FGF4 gene, but 96% of them had two identical copies of it.

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To me, and I suspect many readers, the quest for information can be an intensely rewarding experience. Discovering a previously elusive fact or soaking up a finely crafted argument can be as pleasurable as eating a fine meal when hungry or dousing a thirst with drink. This isn’t just a fanciful analogy – a new study suggests that the same neurons that process the primitive physical rewards of food and water also signal the more abstract mental rewards of information.

Humans generally don’t like being held in suspense when a big prize is on the horizon. If we get wind of a raise or a new job, we like to get advance information about what’s in store. It turns out that monkeys feel the same way and like us, they find that information about a reward is rewarding in itself.

Ethan Bromberg-Martin and Okihide Hikosaka trained two thirsty rhesus monkeys to choose between two targets on a screen with a flick of their eyes; in return, they randomly received either a large drink or a small one after a few seconds. Their choice of target didn’t affect which drink they received, but it did affect whether they got prior information about the size of their reward. One target brought up another symbol that told them how much water they would get, while the other brought up a random symbol.

After a few days of training, the monkeys almost always looked at the target that would give them advance intel, even though it never actually affected how much water they were given. They wanted knowledge for its own sake. What’s more, even though the gap between picking a target and sipping some water was very small, the monkeys still wanted to know what was in store for them mere seconds later. To them, ignorance is far from bliss.

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In a world where the temptation to lie, deceive and cheat is both strong and profitable, what compels some people to choose the straight and narrow path? According to a new brain-scanning study, honest moral decisions depend more on the absence of temptation in the first place than on people wilfully resisting these lures.

Joshua Greene and Joseph Paxton and Harvard University came to this conclusion by using a technique called functional magnetic resonance imaging (fMRI) to study the brain activity of people who were given a chance to lie. The volunteers were trying to predict the outcomes of coin-flips for money and they could walk away with more cash by lying about their accuracy.

The task allowed Greene and Paxton to test two competing (and wonderfully named) explanations for honest behaviour. The first -the “Will” hypothesis – suggests that we behave morally by exerting control over the desire to cheat. The second – the “Grace” hypothesis – says that honesty is more a passive process than an active one, fuelled by an absence of temptation rather than the presence of willpower. It follows on from a growing body of psychological studies, which suggest that much of our behaviour is governed by unconscious, automatic processes.

Many studies (and several awful popular science articles) have tried to place brain-scanning technology in the role of fancy lie detectors but in almost all of these cases, people are told to lie rather than doing so spontaneously. Greene and Paxton were much more interested in what happens in a person’s brain when they make the choice to lie.

They recruited 35 people and asked them to predict the result of computerised coin-flips while sitting in an fMRI scanner. They were paid in proportion to their accuracy. In some ‘No-Opportunity trials’, they had to make their predictions beforehand, giving them no room for cheating. In other ‘Opportunity trials’, they simply had say whether they had guessed correctly after the fact, opening the door to dishonesty.

To cover up the somewhat transparent nature of the experiment, Greene and Paxton fibbed themselves. They told the recruits that they were taking part in a study of psychic ability, where the idea was that people were more clairvoyant if their predictions were private and motivated by money. Under this ruse, the very nature of the “study” meant that people had the opportunity to lie, but were expected not to.

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While dogs can often be taught new tricks, cat-owners will be all too aware that it can be very difficult to persuade them to do something they don’t want to do. Eddie Izzard summed it up best in his legendary Pavlov’s cat sketch, where felines are quite capable of outfoxing (outcatting?) eminent Welsh-Russian psychologists. Real cats may be less devious, but only just – new research suggests that they are very skilled at getting their human owners to do their bidding.

When they want food, domestic cats will often purr in a strangely plaintive way that their owners find difficult to ignore. By analysing the structure of these calls, Karen McComb from the University of Sussex has found out why. On the surface, the “solicitation purrs” are based on the same low-pitched sounds that contented moggies make, but embedded within them is a high-pitched signal that sounds like a cry or a meow. It’s this hidden signal that makes the purr of a hungry cat so irresistible to humans.

McComb has a long history of research into animal communication and she has studied the calls of African elephants, red deer, lions and macaques. But it was her own cat, Pepo (pictured above), who provided the inspiration for this study.

“He consistently woke me up in the mornings with very insistent purring,” she said. ”I wondered why this purring sounded so annoying and was so difficult to ignore.  Talking with other cat owners, I found that some of them also had cats who showed strikingly similar behaviour.  As I was an academic who actually worked on vocal communication [in mammals], I had the right background, tools and collaborators to tackle this question directly.”

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