Not Exactly Rocket Science

Human gut bacteria linked to obesity

Mon, 06 Oct 2008 10:00:26 -0500

There is a widespread belief, that being overweight or obese is a question of failing willpower, fuelled in no small part by food, fitness and beauty industries. But if we look at the issue of obesity through a scientific spyglass, a very different picture emerges. Genes, for example, exert a large influence on our tendency to become obese often by influencing behaviour - a case of nature via nurture. But it's not just our own genes that are important.

In terms of processing food, humans are hardly self-sufficient. Our guts are the home of trillions of bacteria that help to break down foodstuffs that our own cells cannot cope with. Together the genes expressed by these intestinal comrades outnumber our own by thousands of times, and yet we are still largely in the dark what they do.

Over 90% of these bacteria, collectively known as the microbiota, come from just two groups - the Bacteroidetes and the Firmicutes. Now, new research suggests that the proportion of these groups is linked to the risk of becoming obese.

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Toxoplasma - the brain parasite that influences human culture

Sun, 05 Oct 2008 10:00:24 -0500

We like to think that we are masters of our own fates. The thought that others might be instead controlling our actions makes us uneasy. We rail against nanny states, we react badly to media hype and we are appalled at the idea of brainwashing. But words and images are not the only things that can affect our brains and thoughts. Other animals - parasites - can do this too. According to research by Kevin Lafferty from the University of California, Santa Barbara, a common brain parasite, Toxoplasma gondii, could be influencing human culture across the globe.

Toxoplasma gondii is a single-celled brain parasite spread by cats. Our feline companions are its preferred home and only in their bodies can it mature and reproduce. So like most parasites, T.gondii has a complex life cycle designed to get it into its final host. If it finds itself in another animal, it travels to the brain and changes the host's behaviour to maximise its chances of ending up in a cat. For rodents, this means being eaten and infected individuals are less fearful of cats and more active, making them easier prey.

Humans can also contract the parasite, through contact with soil contaminated by the faeces of carriers or through eating infected meat. But since cats are very unlikely to eat humans, T.gondii reaches a cul-de-sac in our bodies. Still, there is nothing to stop the parasite, evolutionarily speaking, from trying out the strategies that work so well in other hosts. In rare cases, T.gondii infection causes a disease called toxoplasmosis that produces mild flu-like symptoms and only really threatens foetuses and those with weak immune systems. But in most instances, the parasite acts more subtly.

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Learn to smell underwater with the star-nosed mole

Sat, 04 Oct 2008 10:00:18 -0500

Sniffing brings molecules in the air around us into our nose, where they are detected and manifested in our brains as smells. But try the same trick underwater and you would rapidly choke or drown. Nonetheless, smell is a tremendously important sense for most mammals and at least two species have found a way to safely sniff in water.

The star-nosed mole (Condylura cristata) is one of them and it has one of nature's most unusual noses. Its snout ends in a ring of 22 fleshy tentacles that are loaded with touch sensors. With this nasal star, the mole rapidly touches and assesses its world, searching for worms to eat. The mole is not limited to underground tunnels, but it's also a capable swimmer and will forage for food in lakes and streams. There, it uses its nose in a different way.

Kenneth Catania from Vanderbilt University, Tennessee, took high-speed video recordings of a swimming mole. As it hunted, the animal continuously blew bubbles from its nose, which it quickly re-inhaled. Catania believed that this technique was a form of underwater sniffing, allowing the mole to detect air-borne odours while submerged.

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Virgin birth by Komodo dragons

Fri, 03 Oct 2008 10:00:42 -0500

According to Christian lore, Mary gave birth to baby Jesus without ever having had sex with Joseph. A biologist might describe this as 'parthenogenesis', the Greek version of the more familiar phrase 'virgin birth'('parthenos' means virgin, and 'genesis' means birth). The New Testament aside, shunning fertilisation and giving birth to young through parthenogenesis is rare among higher animals, occurring in only one in every thousand species. Nonetheless, two Christmases ago, eight virgin births took place in the English town of Chester. The mother's name was Flora and she was a komodo dragon.

Komodo dragons are an endangered species in their island homes of >Indonesia. Fifty-two zoos around the world co-operate in a dedicated breeding programme that aims to boost the natural populations of these largest of lizards. In Europe, only two female dragons, both living in England, are sexually mature. One of these, Flora, lives at Chester Zoo where she has laid a clutch of 25 eggs despite never having been kept with a male.

Three of Flora's eggs tragically collapsed while they were being incubated, but this provided Phillip Watts and colleagues from the University of Liverpool with a chance to trace their origins. They analysed the genetic make-up of the lost eggs using genetic fingerprinting and found that their genomes matched those of their mothers.Children born through sex have two copies of every gene, one inherited from their father and one from their mother but the genomes of Flora's babies had two identical copies of every gene, a sign that every copy came from Flora alone.

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Taking the new out of neurons

Thu, 02 Oct 2008 10:00:21 -0500

You are not the person you used to be. Two weeks ago, the surface of your skin was covered with a completely different set of cells, which have since died and flaked off. Four month ago, you had a wholly different set of red blood cells. Since birth, your body has grown tremendously in size and much of it is constantly regenerating, replacing old cells with new ones.

But your brain is different. At birth, the part of your brain that controls your most human abilities - the neocortex - came fully equipped with 100 billion neurons. These same neurons have lasted throughout the years and still power your thoughts today.

The neocortex makes up most of the brain. Its relatively large size is unique to humans, and with good reason. In addition to controlling our bodies, its collection of neurons house our most characteristic qualities - our experiences, and our powers of language, reasoning and creativity. For this reason, the development of these neurons has fascinated scientists for decades.

Throughout our lives, the neocortex needs to change at an incredible pace as we accrue new memories and skills. One of the most hotly contested questions in neuroscience is how it copes - does it constantly grow new neurons (a process called neurogenesis), or do we have the same set from birth? For years, the question has had no hard answers because of inaccurate and easily misinterpreted research techniques. A reported sighting of newly-made neurons in primate brains fanned the flames of debate but could not be confirmed. Clearly, a new breakthrough was needed. It came from the most unlikely of techniques - carbon-dating.

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How to turn cotton into a food crop

Wed, 01 Oct 2008 10:00:26 -0500

The world is currently home to 6.5 billion people and over the next 50 years, this number is set to grow by 50%. With this massive planetary overcrowding, Band Aid's plea to feed the world seems increasingly unlikely. Current food crops seem unequal to the task, but scientists at Texas University may have developed a solution, a secret ace up our sleeves - cotton.

Cotton is famed for its use in clothes-making and has been grown for this purpose for over seven millennia. We do not think of it as a potential source of food, and for good reason. The seeds of the cotton plant are rife with a potent poison called gossypol that attacks both the heart and liver. Only the multi-chambered stomachs of cattle and other hooved animals can cope with this poison, relegating cottonseed to a role as animal feed.

Getting rid of gossypol could contribute towards reducing the world's hunger crisis. A fifth of a cottonseed's weight is made up of oil, and a quarter of high-quality protein, and for every kilogram of fibre, each cotton plant produces 1.65 kg of seed. The plant is a worldwide crop, grown in over 80 countries by some 20 million farmers, the majority of whom live in the poorest parts of the world where starvation is an ever-looming threat. If only the seeds could be made edible.

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Robo-starfish learns about itself and adapts to injuries

Tue, 30 Sep 2008 10:00:20 -0500

I am walking strangely. About a week ago, I pulled something to my left ankle, which now hurts during the part of each step just before the foot leaves the ground. As a result, my other muscles are compensating for this to minimise the pain and my gait has shifted to something subtly different from the norm. In similar ways, all animal brains can compensate for injuries by computing new ways of moving that are often very different. This isn't a conscious process and as such, we often take it for granted.

But we can get a sense of how hard it actually is by trying to program a robot to do the same thing. It's far from straightforward. Robots have been used for years to perform structured, repetitive tasks and as engineering has advanced, their movements have become more life-like and more stable. But they still have severe limitations, not the least of which is inflexibility in the face of injury or changes to their body shape. If a robot's leg falls off, it becomes as useful as so much scrap metal.

So for robots, adaptiveness is a desirable virtue, especially if they are to be used in the field. Modern bots can independently develop complex behaviours without any previous programming but usually, this requires trial and error and lots of time. But not always. Josh Bongard and colleagues at Cornell University have developed an adaptable bot that's programmed to continuously assesses its body structure and develop new ways of moving if anything changes.

It differs from other models in that it has no built-in redundancy plans, no strategies for dealing with anticipated problems. It's simply programmed to examine itself and adapt accordingly. The concept of a robot that can adapt to new situations is often the precursor to nightmare scenarios in many a science-fiction film. So it is fortunate that Bongard's robot isn't armed or threatening, but instead looks more like a four-armed starfish.

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Camouflaged communication - the secret signals of squid

Mon, 29 Sep 2008 10:00:35 -0500

Two strangers are having a normal conversation in the middle of a large crowd. No one else can see them. No one else can listen in. Thanks to advanced gadgetry, they are talking in coded messages that only they can decipher. These invisible conversationalists sound like they've walked out of a Bond film. But they are entirely real, and their skill at secrecy is biological, not technological. They are squid.

Squid and their relatives, the octopus and cuttlefish, are masters of concealment. They have the most sophisticated camouflage abilities in the animal kingdom and use them to avoid predators who would gladly feast on their soft shell-less bodies. Their remarkable abilities also allow individuals to communicate with each other through a rich vocabulary of colour-changes and body postures. But in doing so, they face a problem - how can they signal to each other without compromising their finely crafted camouflage?

Lydia Mathger and Roger Hanlon at the Marine Biological Laboratory, Massachusetts, have the answer and it lies in the squid's dual-layered skin. The animals use these two layers to communicate with one another using polarised light, without ever compromising their perfect disguises.

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Elephants recognise themselves in mirror

Sun, 28 Sep 2008 10:00:46 -0500

You are on a date and by all accounts, it's going well. Midway through dinner, you excuse yourself and head to the bathroom where, to your chagrin, the mirror reveals that you have a streak of sauce on the side of your face. Embarrassed, you wipe it away and rejoin your date.

It's a fairly innocuous scene but it requires an ability that only the most intelligent of animals possess - self-awareness. It's the understanding that you exist as an individual, separate from others. Having it is a vital step to understanding that others are similarly aware and have their own thoughts and desires. As such, it is intimately linked to mental qualities like empathy and selflessness. This may seem obvious to us but even human children only become self-aware in their second year of life.

In the animal kingdom, the skill is even rarer and has only been found in the most intelligent of species - humans, apes, dolphins and more recently, magpies. In 2006, Joshua Plotnik of Emory University added elephants to that list.

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Carbon nanotechnology in an 17th century Damascus sword

Sat, 27 Sep 2008 10:00:52 -0500

In medieval times, crusading Christian knights cut a swathe through the Middle East in an attempt to reclaim Jerusalem from the Muslims. The Muslims in turn cut through the invaders using a very special type of sword, which quickly gained a mythical reputation among the Europeans. These 'Damascus blades' were extraordinarily strong, but still flexible enough to bend from hilt to tip. And they were reputedly so sharp that they could cleave a silk scarf floating to the ground, just as readily as a knight's body.

They were superlative weapons that gave the Muslims a great advantage, and their blacksmiths carefully guarded the secret to their manufacture. The secret eventually died out in the eighteenth century and no European smith was able to fully reproduce their method.

Two years ago, Marianne Reibold and colleagues from the University of Dresden uncovered the extraordinary secret of Damascus steel - carbon nanotubes. The smiths of old were inadvertently using nanotechnology.

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Ad Placement FAIL

Thu, 25 Sep 2008 17:59:04 -0500

Heh. Roffle.

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Why do people overbid in auctions?

Thu, 25 Sep 2008 14:00:17 -0500

The art of auctioning is an ancient one. The concept of competitively bidding for goods has lasted from Roman times, when spoils of war were divvied up around a planted spear, to the 21st century, when the spoils of the loft are sold through eBay. But despite society's familiarity with the concept, people who take part in auctions still behave in a strange way - they tend to overbid, offering more money than what they actually think an object is worth.

Some economists have suggested that people overbid because they are averse to risk. They would rather make spend more money to be sure of a win than to risk making a steal by gambling with a low bid. Others have suggested that it's the element of competition that drives people to overbid - the joy of winning is what they're after. Now, Mauricio Delgado and colleagues from Rutgers University have provided new evidence to show that neither theory is right.

With a combination of brain-scanning and psychological games, they have found that economists who suggested a social competition angle were moving along the right lines. But it's not the joy of winning that's important - it's the fear of losing. People cough up too much because of simple social competition.

Delgado's team (which included Elizabeth Phelps, whose work I have blogged about before) used a brain-scanning technique called functional resonance magnetic imaging (fMRI) to study the brains of 17 volunteers as they played two games - a two-player auction or a single-player lottery.

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Caterpillars use wormholes and early warning hairs for defence

Wed, 24 Sep 2008 10:00:47 -0500

A caterpillar is an eating machine - a mobile set of mandibles, whose sole mission is to survive long enough to munch its way to adulthood. Standing in their way are spiders, birds and predatory insects that want to eat them, and parasitic wasps that want to convert them into living incubators for their own larvae.

With so many enemies, defence is paramount for caterpillars and the various species have evolved a dazzling array of countermeasures. Some camouflage themselves, others use bright colours to advertise their toxic chemical weapons, which in at least one species is powerful enough to kill a human. They are coated with irritating hairs, throw up their digestive juices, emit foul odours, hang from silken safety lines and recruit ants as bodyguards.

But one group of caterpillars - those of the metalmark moths (Brenthia) - lack any of these. They feed on the topsides of leaves, sheltering only under a flimsy sheet of silk that they themselves spin. Out in the open, they are among the most conspicuous of caterpillars and surely would make easy target for enterprising predators or parasites. But not so; Jadranka Rota and David Wagner from the University of Connecticut found that the metalmark caterpillars use a defensive measure all their own - a wormhole.

The metalmarks chew a small hole in the leaf they feed on, directly under their silken shelter. It's an escape tunnel that allows them to flee to safety of the leaf's underside if danger threatens. The caterpillar senses the arrival of danger with extremely long hairs that protrude from its sides. Those on its rear end are so unfeasibly long that they always touch the silk that surrounds the caterpillar and often form part of the silk web itself. These hairs convert the entire silken tent into a giant sensory organ.

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Aborigines improve biodiversity by starting fires

Tue, 23 Sep 2008 08:30:25 -0500

Imagine that you have been given responsibility over a tract of land. Your goal is to maintain its precious biodiversity (increasing it if at all possible), prevent the local habitats from becoming degraded and among all that, find a way to eke out a way of life. Of the many possible ways of doing this, regularly and deliberately setting fire to the local plants might be low on the list. But that's exactly what Aborigine populations in Australia have been doing for centuries and a new study shows that this counter-intuitive strategy does indeed work.

A team of American anthropologists led by Rebecca Bird at Stanford University studied the practice of "fire-stick farming" among the Martu people of Australia's Western Desert. The Martu live mostly as hunter-gatherers and supplement their food with the odd supply bought from local outstations. Their homelands are mostly dominated by sandy plains and the ubiquitous spinifex grass (Triodia) and these are the areas that the Martu start fires in.

They have different words for land at various stages of post-fire recovery: nyurma is freshly scorched earth, waru-waru describes land where shoots have started to sprout; mukura turns up after a few years when grasses, flowering shrubs and edible plants have arrived; mangul occurs a few years later still when the growing spinifex starts to outcompete edible plants, leading to kunarka when the spinifex starts to die and leaves behind sterile hollows.

The "successional stages" follow one after another in predictable ways and the Martu only ever set fire to the last two, when spinifex is dominant. In doing so, they effectively press an ecological reset button, allowing plants to return to areas that had previously been won by the unbeatable spinifex.

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Defining Moments in Science

Mon, 22 Sep 2008 11:00:14 -0500

Well this is exciting... A year ago, I was asked to contribute to a book that would detail 1000 awesome scientific thinkers, discoveries and events over the last century, to be called the Little Black Book of Science. And after a long silence, it's finally out, albeit under the much less good title of "Defining Moments in Science".

I wrote 20 of the 1000 articles (2%, for the percentage-inclined) and in total, the book represents the combined efforts of 60 or so of the UK's finest science writers, including one of my co-bloggers at Cancer Research UK, Kat Arney. Many thanks to Hayley Birch and the good people at Null Hypothesis for editing the not-insubstantial undertaking. It was a great chance to delve into some historical aspects of scientific discovery that I don't usually get to do.

The ones I did include:

Biographies of Richard Dawkins, Niko Tinbergen and Robert Winston.
Elizabeth Blackburn's discovery of telomeres.
The creation of chemotherapy
Raup and Sepkoski's work on mass extinctions
The classic study on predator-prey relationships with lynxes and hares
The discovery of anaphylaxis (poor, poor dog...)
The discovery of paracetamol
And the international success of Viagra.

Which marks the only time in my life that I have ever deliberately done a Google search for Viagra. Therein lies a world of horror and torment.

Unlike this book. Which you should get. Because it will be brill.

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