Archive for June, 2009

Sleeping on it – how REM sleep boosts creative problem-solving

By Ed Yong | June 10, 2009 8:30 am

Blogging on Peer-Reviewed ResearchThe German chemist Friedrich Kekule claimed to have intuited the chemical structure of the benzene ring after falling asleep in his chair and dreaming of an ouroboros (a serpent biting its own tail). He’s certainly not the only person to have discovered a flash insight after waking from a good sleep. In science alone, many breakthroughs were apparently borne of a decent snooze, including Mendeleyev’s creation of the Periodic Table and Loewi’s experiments on the transmission of nervous signals through chemical messengers.

Most of us have tried sleeping on a difficult problem before and using an elegant experiment, Denise Cai from the University of California in San Diego has shown that this old technique really does have merit to it. She found that our brains are better at integrating disparate pieces of information after a short bout of REM (rapid eye movement) sleep – a deep, dream-rich slumber that involves a rapid fluttering of the eyes.  Cai thinks that REM sleep catalyses the creative process by allowing the brain to form connections between unrelated ideas.

Cai is by no means the first person to link sleep or dreaming to creative revelations, but she is one of the few to test it directly through experiments. She asked 77 people to complete a task, where they were given a list of three words and had to find a fourth that was linked to all three. For example, ‘cookie’, ‘heart’ and ‘sixteen’ are all associated with ‘sweet’. In each example of this ‘Remote Associates Test‘ (RAT), the missing fourth word has a different relationship to each of the three targets.

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Anna's hummingbird outflies falcons and fighter pilots

By Ed Yong | June 9, 2009 8:23 pm

Blogging on Peer-Reviewed ResearchMany animals use impressive displays to seduce a mate, but few go as far as the male Anna’s hummingbird. He performs a death-defying courtship dive, plummeting to the ground at speeds and accelerations that put jet fighters to shame.

Annas_hummingbird.jpgThe tiny 7cm bird reaches a top speed of 60mph and at the fastest point of the dive, it covers 385 times its own body length every second. For its size, it’s the fastest aerial manoeuvre performed by any bird. In contrast, the famous attack dive of the peregrine falcon, while much faster in absolute terms, only covers 200 body lengths per second.

The hummingbird can even fly relatively faster than a jet fighter with afterburners ablaze, which only reaches 150 body lengths per second, or a space shuttle re-entering Earth’s atmosphere, which covers just 207 body lengths per second.

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Megaflood in English Channel separated Britain from France

By Ed Yong | June 8, 2009 8:30 am

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Blogging on Peer-Reviewed ResearchHundreds of thousands of years ago, one of the largest floods in Earth’s history turned us into an island and changed the course of our history. Britain was not always isolated from our continental neighbours. In the Pleistocene era, we were linked to France by a land ridge called the Weald-Artois anticline that extended from Dover, across what are now the Dover Straits.

This ridge of chalk separated the North Sea on one side from the English Channel on the other. For Britain to become an island, something had to have breached the ridge.

Now, Sanjeev Gupta and colleagues from Imperial College London have found firm evidence that a huge ‘megaflood‘ was responsible. They analysed a hidden series of massive valleys on the floor of the English Channel – vast gouges of bedrock 50 metres deep and tens of kilometres wide.

These valleys were first noticed by geologists in the 1970s but until now, no one really knew what caused them. Gupta decided to find out with the help of some modern technology. He used high-resolution sonar to create a contour map of the Channel floor, and found that this hidden world was remarkably well preserved.

He saw a clear picture of the huge, linear valleys, branching out in a westerly direction. In and among the valleys lay long ridges and grooves running parallel to the channel, V-shaped scours that taper upstream, and streamlined underwater islands up to 10km long.

Britain was once connected to France by a land ridge.

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CATEGORIZED UNDER: Earth sciences

Aphids defend themselves with chemical bombs

By Ed Yong | June 7, 2009 12:00 pm

Blogging on Peer-Reviewed ResearchWhere there are plants, there are almost certainly aphids feeding on them. These ubiquitous insects are banquets for many predators, and some have evolved incredible defences against them. The cabbage aphid, for example, is a walking bomb.

Cabbage aphids defend themselves with chemical weaponsIts body carries two reactive chemicals that only mix when a predator attacks it. The injured aphid dies. But in the process, the chemicals in its body react and trigger an explosion that delivers lethal amounts of poison to the predator, saving the rest of the colony.

The aphids’ chemical weapons are stolen from the plants they eat. Far from being sitting ducks, plants defend themselves from herbivores with a wide range of poisons. Cruciferous vegetables, for example, such as mustard, watercress and wasabi, use a group of chemicals called glucosinolates.

These are harmless on their own, but when they come into contact with an enzyme called myrosinase, the result is a violent chemical reaction that produces several toxic products. Among these is allyl isothiocyanate, the substance that gives mustard and horseradish their strong, pungent flavour.

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Skinks set their sex in three ways – genes, temperature and egg size

By Ed Yong | June 5, 2009 8:30 am

Blogging on Peer-Reviewed ResearchFor humans, sex is a simple matter of chromosomes: two Xs and we become female; one X and a Y and we develop into males. But things aren’t so straightforward for many lizards – many studies have found that the temperature of the nest also has a say, even overriding the influence of the chromosomes. But the full story of how the lizard got its sex is even more complicated. For at least one species, the size of its egg also plays a role, with larger eggs producing females, and smaller ones yielding males.

The discovery comes from Richard Shine’s group at the University of Sydney. In earlier work, they showed that if the Eastern three-lined skink (Bassiana duperreyi) incubates its eggs at low nest temperatures, XX carriers develop into males regardless of their chromosomes.

Now, Rajkumar Radder, a former member of Shine’s team, has shown that the amount of yolk also determines the sex of a skink, but only at low temperatures. By deliberately adding and removing yolk from eggs using a syringe, he managed to alter the sex of the hatchlings. This degree of complexity is totally unprecedented – it means that for the skink, sex is a question of its chromosomes, the temperature it was reared under and the amount of yolk it had.

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Scientists tickle apes to reveal evolutionary origins of human laughter

By Ed Yong | June 4, 2009 12:00 pm

If you tickle a young chimp, gorilla or orang-utan, it will hoot, holler and pant in a way that would strongly remind you of human laughter. The sounds are very different. Chimp laughter, for example, is breathier than ours, faster and bereft of vowel sounds (“ha” or “hee”). Listen to a recording and you wouldn’t identify it as laughter – it’s more like a handsaw cutting wood. But in context, the resemblance to human laughter is uncanny.

Apes make these noises during play or when tickled, and they’re accompanied by distinctive open-mouthed “play faces”. Darwin himself noted the laugh-like noises of tickled chimps way back in 1872. Now, over a century later, Marina Davila Ross of the University of Portsmouth has used these noises to explore the evolutionary origins of our own laughter.

Davila Ross tickled youngsters of all of the great apes and recorded the calls they make (listen to MP3s of a tickled chimp, gorilla, bonobo and orang-utan). She used these recordings to build an acoustic family tree, showing the relationships between the calls. Scientists regularly construct such trees to illustrate the relationships between species based on the features of their bodies or the sequences of their genes. But this is the first time that anyone has applied the same technique to an emotional expression.

The tree linked the great apes in exactly the way you would expect based on genes and bodies. To Ross, this clearly shows that even though human laughter sounds uniquely different, it shares a common origin with the vocals of great apes. It didn’t arise out of nowhere, but gradually developed over 10-16 million years of evolution by exaggerating the acoustics of our ancestors. At the very least, we should now be happy to describe the noises made by tickled apes as laughter without accusations of anthropomorphism, and to consider “laughter” as a trait that applies to primates and other animals

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Spiders gather in groups to impersonate ants

By Ed Yong | June 3, 2009 8:30 am

Blogging on Peer-Reviewed ResearchThe animal world is full of harmless liars, who mimic species more dangerous than themselves in order to avoid the attention of predators. But none do it quite like the dark-footed ant-spider Myrmarachne melanotarsa.

As its name suggests, this small species of jumping spider, discovered just nine years ago, impersonates ants. In itself, that’s nothing special – ants are so aggressive that many predators give them a wide berth and lots of species do well by imitating them. The list includes over 100 spiders but among them, M.melanotarsa‘s impression is unusually strong. It doesn’t just mimic the bodies of ants, but their large groups too.

Unlike all of its relatives, the spider lives in silken apartment complexes, consisting of many individual nests connected by silk. These blocks can house hundreds of individuals and while moving about them, the spiders usually travel in groups. Now, Ximena Nelson and Robert Jackson from the University of Canterbury have found evidence that this social streak is all part of the spiders’ deception.

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Glowing squid use bacterial flashlights that double as an extra pair of "eyes"

By Ed Yong | June 2, 2009 8:30 am

Blogging on Peer-Reviewed ResearchIn the darkness of the deep ocean, some animals create their own light. Among these is the Hawaiian bobtail squid Euprymna scolopes, which forms a partnership with the luminous bacterium Vibrio fischeri. The squid houses colonies of these bacteria in special light organs, and it can control the brightness and direction of their illuminations. But these organs do much more than produce light – they detect it too.

Deyan Tong from the University of Wisconsin has discovered that the organs generate nervous signals when they sense light and they’re loaded with proteins responsible for detecting it. The light organs are effectively an extra set of primitive eyes, each equipped with its own “iris” and “lens”.  The squid comes equipped with a pair of living, ‘seeing’ flashlights.

Scientists have studied the light organ of E.scolopes for over 20 years and its similarity to an actual eye hasn’t gone unnoticed. The core of the organ where the bacteria live is surrounded by a reflective layer of tissue and part of the squid’s ink sac. These can expand and contract like an iris to control how much light escapes the core. The entire package is covered by a thick, transparent tissue – a “lens” – which diffuses the light produced by the bacteria.

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Gender gap in maths driven by social factors, not biological differences

By Ed Yong | June 1, 2009 4:51 pm

Blogging on Peer-Reviewed ResearchHistory has had no shortage of outstanding female mathematicians, from Hypatia of Alexandria to Ada Lovelace, and yet no woman has ever won the Fields medal – the Nobel prize of the maths world. The fact that men outnumber women in the highest echelons of mathematics (as in science, technology and  engineering) has always been controversial, particularly for the persistent notion that this disparity is down to an innate biological advantage.

Now, two professors from the University of Wisconsin – Janet Hyde and Janet Mertz – have reviewed the strong evidence that at least in maths, the gender gap is down to social and cultural factors that can help or hinder women from pursuing the skills needed to master mathematics.

The duo of Janets have published a review that tackles the issue from three different angles. They considered the presence of outstanding female mathematicians. Looking beyond individuals, they found that gender differences in maths performance don’t really exist in the general population, with girls now performing as well as boys in standardised tests. Among the mathematically talented, a gender gap is more apparent but it is closing fast in many countries and non-existent in others. And tellingly, the size of the gap strongly depends on how equally the two sexes are treated.

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Chimps use Swiss army toolkit to rob beehives

By Ed Yong | June 1, 2009 8:30 am

Blogging on Peer-Reviewed ResearchChimps are known to make a variety of tools to aid their quest for food, including fishing sticks to probe for termites, hammers to crack nuts and even spears to impale bushbabies. But a taste for honey has driven one group of chimps in Gabon’s Loango National Park to take tool-making to a new level.

Chimps_beehives.jpgTo fulfil their sweet tooth, the chimps need to infiltrate and steal from bee nests, either in trees or underground. To do that, they use a toolkit of up to five different implements: thin perforators to probe for the nests; blunt, heavy pounders to break inside; lever-like enlargers to widen the holes and access the different chambers; collectors with frayed ends to dip into the honey; and swabbers (elongated strips of bark) to scoop it out.

Some of the tools are even fit for the Swiss army, combining multiple functions into the same stick. For example, some were obviously modified at both ends, but one was blunt while the other was frayed, suggesting that they doubled as enlargers and collectors.

These observations were made by Christophe Boesch from the Max Planck Institute for Evolutionary Anthropology and they emphasise yet again the extraordinary brainpower of chimpanzees. It takes an uncommon intellect to be able to design and manufacture a suite of tools and use them in sequence to extract a foodstuff that’s hidden from sight.

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MORE ABOUT: Bees, chimp, chimpanzee, honey, tools
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