Author: Discover Main Feed

On Facebook, the Farmville updates are impossible to avoid–someone is looking for a cow, someone else is watering their crops. People who have never played the game may not understand how addictive it is, but here’s some proof. The game can not only suck away large portions of your day, it can also, as one councilmember in Bulgaria’s second largest city found out, get you demoted.

While many distracted politicians twiddle their thumbs during meetings or frantically jab at their Blackberries, city councilors in Plovdiv were apparently playing Farmville during budgetary debates.

The Escapist writes:

Council Chair Ilko Iliev “strongly scolded the eager internet farmers,” who nonetheless continued to spend time on their farms while attending council meetings.

Finally, during a meeting last Thursday, in order to send a message to the rest of the Farmville-playing community, one councilmember was given the boot. Councilor Dimitar Kerin was voted off the budget committee, said fellow councilor Todot Hristov, because “he needed more time for his virtual farm.”

The Escapist added:

But he’s not leaving without a fight. “The troubled councilor has defended himself by saying he was not the only one in the City Hall watering virtual egg plants,” according to a report by Novinte.com. “He said he had reached only Level 40, whereas Daniela Zhelyazkova, a councilor from the rightist Democrats for Strong Bulgaria party, was already at Level 46.”

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Image: Farmville

The wave of high-profile seismic activity so far in 2010 has been another reminder that we humans could use all the help we can get in predicting earthquakes. This week in the Journal of Zoology, biologist Rachel Grant suggests a new way: Watch the toads.

Taking cues from the animal kingdom is not itself a new idea (not by a long shot): Reports of animal earthquake prediction are legion and they date back to at least 373 BCE, when historians record that animals including rats, snakes and weasels flocked out of Helice just days before a quake devastated the Greek city. More recently there have been reports of catfish moving violently, bees leaving their hive in a panic, and fish, rodents, wolves and snakes exhibiting strange behaviour before earthquakes [Nature]. While these anecdotes grab the imagination, the scatter-shot nature of earthquakes previously prevented anyone from documenting such animal behavior before, during, and after a quake.

But Grant did, and by sheer luck. Her team was studying common toads in Italy in April 2009 when the amphibians began to disappear from the study site. This didn’t make much sense to her, the toads abandoning a breeding site in the midst of breeding season. So the researchers tracked them. They found that 96 percent of males — who vastly outnumber females at breeding spots — abandoned the site, 46 miles (74 kilometers) from the quake’s epicenter, five days before it struck on April 6, 2009. The number of toads at the site fell to zero three days before the quake [Washington Post]. Grant says her initial reaction to the mass toad dispersal was annoyance—their flight was holding up her research. However, when they began to return the day after the earthquake, things began to make more sense.

Even in this study, where scientists happened to be in the right place at the right time to catalog this long-rumored animal activity, one can’t know for sure that seismic activity is the direct cause of the toads packing up and taking off. In an evolutionary sense, though, it seems logical: If the toads can pick up environmental clues that a quake is imminent they could flee to higher ground, someplace safer from rock falls and other hazards. Says Grant, “Our findings suggest that toads are able to detect pre-seismic cues such as the release of gases and charged particles, and use these as a form of earthquake early warning system” [BBC News].

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Image: Wikimedia Commons / Gang65

Today President Obama and Interior Secretary Salazar will announce plans to end the moratorium on oil exploration. An expanse for lease would become available from Delaware to central Florida and also include parts of the Chukchi Sea and Beaufort Sea north of Alaska. From the NYTimes:
But while Mr. Obama has staked out middle ground on other environmental matters — supporting nuclear power, for example — the sheer breadth of the offshore drilling decision will take some of his supporters aback. And it is no sure thing that it will win support for a climate bill from undecided senators close to the oil industry, like Lisa Murkowski, Republican of Alaska, or Mary L. Landrieu, Democrat of Louisiana. The Senate is expected to take up a climate bill in the next few weeks — the last chance to enact such legislation before midterm election concerns take over. Mr. Obama and his allies in the Senate have already made significant concessions on coal and nuclear power to try to win votes from Republicans and moderate Democrats. The new plan now grants one of the biggest items on the oil industry’s wish list — access to vast areas of the Outer Continental Shelf for drilling.
My …

I’ve already posted some beautiful closeups of Phobos, a moon of Mars, taken by the Mars Express space probe, after the European Space Agency aimed the spacecraft at the tiny moon. The closeups are beautiful, but now the ESA has posted a stunning full-body shot of Phobos:

[As usual, click the pix to embiggen.]

The resolution is an amazing 9 meters (30 feet!) per pixel. Clearly, Phobos has been through a lot. Mars orbits near the inner edge of the asteroid belt, which may explain how battered its surface is. The grooves were once thought to be ripples from a big impact that created the whopping crater Stickney (not seen in this view, but you can see it really well here), but are now thought to be from boulders rolling around in the low gravity of the moon, perhaps ejected rocks from various impacts landing back down in the feeble gravity.

Note the one winding path going from the upper left to lower right: that looks very much like a boulder bounced its way across the surface! The curvy path is an indication of the changing gravity field of Phobos: it’s not a smooth sphere, but a lumpy potato, so the surface gravity — what you’d think of as “down” if you were standing there — changes greatly depending on position.

They also put together this stunning 3D anaglyph. You can really see the depth of the craters and grooves on the surface. Run, don’t walk, to get a pair of red/green glasses for this one! Phobos really pops out of the screen. The depth and clarity of the 3D is amazing!

This pass of the moon was designed to obtain as much scientific data as possible before the launch of the Russian mission called Phobos-Grunt, which will land on the moon and send a sample of its surface back to Earth for study. Phobos looks an awful lot like an asteroid itself, and its origin is still something of a mystery. More data like these — and obtaining a sample of its surface material! — may clear up its story once and for all.

Credits: ESA/DLR/FU Berlin (G. Neukum)

Ever prodded at an injury despite the fact you know it will hurt? Ever cook an incredibly spicy dish even though you know your digestive tract will suffer for it? If the answers are yes, you’re not alone. Pain is ostensibly a negative thing but we’re often drawn to it. Why?

According to Marta Andreatta from the University of Wurzburg, it’s a question of timing. After we experience pain, the lack of it is a relief. Andreatta thinks that if something happens during this pleasurable window immediately after a burst of pain, we come to associate it with the positive experience of pain relief rather than the negative feeling of the pain itself. The catch is that we don’t realise this has happened. We believe that the event, which occurred so closely to a flash of pain, must be a negative one. But our reflexes betray us.

Andreatta’s work builds on previous research with flies and mice. If flies smell a distinctive aroma just before feeling an electric shock, they’ll learn to avoid that smell. However, if the smell is released immediately after the shock, they’re actually drawn to it. Rather than danger, the smell was linked with safety. The same trick works in mice. But what about humans?

To find out, Andreatta recruited 101 volunteers and split them into three groups, all of whom saw coloured shapes. The first group received a moderately painful electric shock six seconds before the shapes flashed up. The second group were shocked eight seconds after the shapes appeared and the third group were shocked fourteen seconds afterwards. This last time gap should have been long enough to stop the recruits from forming a link between shock and shape.

Later, everyone saw the shapes without any accompanying shocks. When asked to rate their feelings, most people felt negatively towards the shapes, particularly those who had been shocked just afterwards. That seems fairly predictable, but Andreatta wanted to find out what they really thought.

To do that, she flashed the shapes up again, paired them with a loud burst of noise, and measured how strongly they blinked in response. This is called the startle reflex; it’s an automatic response to fear or danger, and it’s very hard to fake. The strength of the blink reflects how fearful the recruits were feeling.

Sure enough, those who saw the shapes before they were electrocuted showed a stronger startle reflex than usual. To them, the images meant that something bad was about to happen so when the noise went off, they reacted particularly strongly. But the recruits who were shocked before the shapes appeared actually showed a weaker startle reflex. It seems that despite their ratings, the lesson they had taken away was that the presence of the shapes was a positive omen.

Other studies have found that rewarding experiences can soothe the startle reflex – in flies, a sugary liquid works and in humans, news of a monetary windfall will do the trick. Andreatta thinks that some of her volunteers behaved in the same way because they had come to associate the coloured shapes with the rewarding feeling of pain relief.

For the moment, despite my introductory paragraph, it’s not immediately obvious how this relates to our daily lives. Andreatta suggests that the pleasant after-effects of otherwise scary or painful affairs might explain why we’re so drawn to dangerous or terrifying pursuits like rollercoaster rides or bungee jumping. More importantly, it could affect the way we think about mental disorders like addiction or anxiety.

Reference: Proc Roy Soc B http://dx.doi.org/10.1098/rspb.2010.0103

More on pain:

• The placebo effect affects pain signalling in the spine
• Doctors repress their responses to their patients’ pain
• Rowing as a group increases pain thresholds
• Itch-specific neurons discovered in mice
• Thinking about money soothes sting of social rejection and physical pain

Below I note that sex matters when it comes to evolution, specifically in the case of how sexual reproduction forces the bits of the genome to be passed back and forth across sexes. In fact, the origin of sex is arguably the most important evolutionary question after the origin of species, and it remains one of the most active areas of research in evolutionary genetics. More specifically the existence of males, who do not bear offspring themselves but seem to be transient gene carriers is a major conundrum. But that’s not the main issue in this post. Let’s take the existence of males as a given. How do sex differences play out in evolutionary terms shaping other phenotypes? Consider Bateman’s principle:

Bateman’s principle is the theory that females almost always invest more energy into producing offspring than males, and therefore in most species females are a limiting resource over which the other sex will compete.

Female ova are energetically more expensive, and scarcer, than male sperm. Additionally, in mammals and other live-bearing species the female invests more time and energy after the point of fertilization but before the young exhibit any modicum of organismic independence (the seahorse being the exception). And, often the female is the “primary caregiver” in the case of species where the offspring require more care after birth. The logic of Bateman’s principle is so obvious when its premises are stated that it easily leads to a proliferation of numerous inferences, and many data are “explained” by its operation (in Mother Nature: Maternal Instincts and How They Shape the Human Species the biological anthroplogist Sarah Hrdy moots the complaint that the principle is applied rather too generously in the context of an important operationally monogamous primate, humans).

But the general behavioral point is rooted in realities of anatomy and life-history; in many dioecious species males and females exhibit a great deal of biological and behavioral dimorphism. But the direction and nature of dimorphism varies. Male gorillas and elephant seals are far larger than females of their kind, but among raptors females are larger. If evolution operated like Newtonian mechanics I assume we wouldn’t be theorizing about why species or sex existed at all, we’d all long ago have evolved toward perfectly adapted spherical cows floating in our own effluvium, a species which is a biosphere.

Going beyond what is skin deep, in humans it is often stated that males are less immunologically robust than females. Some argue that this is due to higher testosterone levels, which produce a weakened immune system. Amtoz Zahavi might argue that this is an illustration of the ‘handicap principle’. Only very robust males who are genetically superior can ‘afford’ the weakened immune system which high testosterone produces, in addition to the various secondary sexual characteristics beloved of film goers. Others would naturally suggest that male behavior is to blame. For example, perhaps males forage or wander about more, all the better to catch bugs, and they pay less attention to cleanliness.

But could there be a deeper evolutionary dynamic rooted in the differential behaviors implied from Bateman’s principle? A new paper in The Proceedings of the Royal Society explores this question with a mathematical model, The evolution of sex-specific immune defences:

Why do males and females often differ in their ability to cope with infection? Beyond physiological mechanisms, it has recently been proposed that life-history theory could explain immune differences from an adaptive point of view in relation to sex-specific reproductive strategies. However, a point often overlooked is that the benefits of immunity, and possibly the costs, depend not only on the host genotype but also on the presence and the phenotype of pathogens. To address this issue we developed an adaptive dynamic model that includes host–pathogen population dynamics and host sexual reproduction. Our model predicts that, although different reproductive strategies, following Bateman’s principle, are not enough to select for different levels of immunity, males and females respond differently to further changes in the characteristics of either sex. For example, if males are more exposed to infection than females (e.g. for behavioural reasons), it is possible to see them evolve lower immunocompetence than females. This and other counterintuitive results highlight the importance of ecological feedbacks in the evolution of immune defences. While this study focuses on sex-specific natural selection, it could easily be extended to include sexual selection and thus help to understand the interplay between the two processes.

The paper is Open Access, so you can read it for yourself. The formalism is heavy going, and the text makes it clear that they stuffed a lot of it into the supplements. You can basically “hum” through the formalism, but I thought I’d lay it out real quick, or at least major aspects.

This shows the birth rate of a given genotype contingent upon population density & proportions of males & females infected with a pathogen

These equations takes the first and nests them into an epidemiological framework which illustrates pathogen transmission (look at the first right hand term in the first two)

And these are the three models that they ran computations with

There are many symbols in those equations which aren’t obvious, and very difficult to keep track of. Here’s the table which shows what the symbols mean….

If you really want to understand the methods and derivations, as well how the details of how they computae evolutionarily stable strategies, you’ll have to go into the supplements. Let’s just assume that their findings are valid based on their premises.

Note:

– They assume no sexual selection
– They assume unlimited male gametes, so total reproductive skew where one male fertilizes all females is possible
– Fecundity is inversely correlated with population density
– Total population growth is ultimately dependent on females, they are the “rate limiting” sex
– Total population growth is proportional to density
– There is no acquired immunity
– There is no evolution of the pathogen in this model

Basically the model is exploring a quantitative trait which exhibits characteristics in relation to resistance of acquiring the pathogen and tolerance of it once the pathogen is acquired. In terms of the “three models,” the first is one where there is resistance to the pathogen, individuals recover from infection and decrease pathogen fitness. The second is one of tolerance, individuals are infected, but may still reproduce while infected. Note that the ability to resist or tolerate infection has a trade off, reduced lifespan (consider some forms of malaria resistance). The third model shows the trade off of tolerance and resistance.

The “pay off” of the paper is that they show that the male evolutionarily stable strategy (ESS), that is, a morph which can not be “invaded” by a mutation, may be one of reduced immune resistance in certain circumstances of high rates of infection. There is an exploration of varying rates of virulence, but there was no counterintuitive finding so I won’t cover that. In any case, here’s the figure:

The text is small, so to clarify:

1) The two panels on the top left are for model 1, and show variation in male and female recovery from infection left to right (resistance)

2) The two panels on the bottom left are for model 2, and show variation in male and female fecundity when infected left to right (tolerance)

3) The four panels on the right are for model 3, and show variation in recovery in the top two panels and fecundity in the bottom two, with male parameters varied on the left and female on the right

The vertical axis on all of the panels are male infection rate, the horizontal the female infection rate. Circled crosses (⊕) indicate regions (delimited by solid lines) where females evolve higher immunocompetence than males. The lighter shading indicates a higher value of the trait at ESS (recovery or fecundity). Note that the two top left panels show a peculiar pattern for males, the sort of counterintuitive finding which the model promises: when infection rates among males are very high their resistance levels drop. Why? The model is constructed so that resistance has a cost, and if they keep getting infected the cost is constant and there’s no benefit as they keep getting sick. In short it is better to breed actively for a short time and die than attempt to fight a losing battle against infection (I can think of possible explanations of behavior and biological resistance in high disease human societies right now). It is at medium levels of infection rates that males develop strong immune systems so that they recover. The bottom right portion of panel which shows variation in male resistance illustrates a trend where high female infection results in reduced immune state in males. Why? The argument is simple; female population drops due to disease result in a massive overall population drop and the epidemiological model is such that lower densities hinder pathogen transmission. So the cost for resistance becomes higher than the upside toward short-term promiscuous breeding in hopes of not catching the disease. Another point that is notable from the panels is that males seem to be more sensitive to variation in infection rates. This makes sense insofar as males exhibit a higher potential variance in reproductive outcomes because of the difference in behavior baked into the model (males have higher intrasexual competition).

One can say much more, as is said in the paper. Since you can read it yourself, I commend you to do so if you are curious. Rather, I would like a step back and ask: what does this “prove?” It does not prove anything, rather, this is a model with many assumptions which still manages to be quite gnarly on a first run through. It is though suggestive in joint consideration with empirical trends which have long been observed. Those empirical trends emerge out of particular dynamics and background parameters, and models can help us formalize and project abstractly around real concrete biological problems. The authors admit their model is simple, but they also assert that they’ve added layers of complexity which is necessary to understand the dynamics in the real world with any level of clarity. In the future they promise to add sexual selection, which I suspect will make a much bigger splash than this.

I’ll let them finish. From their conclusion:

We assessed the selective pressures on a subset of sex-specific traits (recovery rate, reproductive success during infection and lifespan) caused by arbitrary differences between males and females in infection rate or virulence (i.e. disease-induced death rate). In so doing, we covered a range of scenarios whereby sex-specific reproductive traits such as hormones and behaviour could plausibly affect the exposure to infection…r the severity of disease…First, we showed that changes in the traits of either sex affect the selective pressures on both sexes, either in the same or in opposite directions, depending on the ecological feedbacks. For example, an increase in male susceptibility (or exposure) to infection favours the spread of the pathogen in the whole population and therefore tends to select for higher resistance or tolerance in both sexes if the cost of immunity is constitutive. However, above a certain level of exposure, the benefit of rapid recovery in males decreases owing to constant reinfection (we assume no acquired immunity). This selects for lower resistance in males, ultimately leading to the counterintuitive situation where males with higher susceptibility or exposure to infection than females evolve lower immunocompetence…A similar pattern arises if the cost of immunity is facultative, in the form of a trade-off between rate of recovery and relative fecundity during infection (model (iii)): if males happen to be more susceptible (or exposed) to infection than females, they are predicted to evolve a longer infectious period balanced by higher sexual activity during infection than females.

Restif, O., & Amos, W. (2010). The evolution of sex-specific immune defences Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2010.0188

Fascinating post by Bayes, Phylogenetics, cultural evolution and horizontal transmission:

For some time now, evolutionary biologists have used phylogenetics. It is a well-established, powerful set of tools that allow us to test evolutionary hypotheses. More recently, however, these methods are being imported to analyse linguistic and cultural phenomena. For instance, the use of phylogenetics has led to observations that languages evolve in punctuational bursts, explored the role of population movements, and investigated the descent of Acheulean handaxes. I’ve followed the developments in linguistics with particular interest; after all, tracing the ephemeral nature of language is a daunting task. The first obvious road block is that prior to the invention of writing, the uptake of which is limited in geography and history, language leaves no archaeological record for linguists to examine. One particular note I’d like to make is that when Charles Darwin first formulated his theory of natural selection, he took inspiration from linguistic family trees as the basis for his sketch on the evolutionary tree of life. So it seems rather appropriate that phylogenetic approaches are now being used to inform our knowledge regarding linguistic evolution.

Like many other attempts applying evolutionary thinking in culture, phylogenetic approaches are, at times, met with contempt. This stems from assertions that cultural evolution and biological evolution differ greatly in regards to the relative importance of horizontal transmission….

…

I guess the general points to take away from this post are: 1) Do not necessarily assume horizontal transmission is dominant in shaping culture; and, 2) Even with certain levels of reticulation, it does not necessarily invalidate a phylogenetic approach in investigating cultural and linguistic evolution.

I think the point that horizontal transmission may be less important relative to vertical transmission than we’d previously thought in regards to the spread and diffusion of cultures may explain some of the recent findings from DNA extractions which suggest that hunter-gatherers were replaced in Europe by farmers. The standard model before the recent wave of extractions was that farming spread through cultural diffusion, with a minority view championed by L. L. Cavalli-Sforza of “demic diffusion” whereby demographic growth from the point of origination spread a culture, though the initial distinctive genetic signal became progressively weaker through dilution via admixture. But if cultural practices such as agriculture were much more vertically transmitted, from parent to child, rather than horizontally across societies, the genetic pattern of replacement becomes more comprehensible.

Of course, the main caveat is that intermarriage has been very common between neighboring groups. The rape of the Sabine women may reflect a common practice on the part of migratory males; the Greek colonization of the western Mediterranean was almost all male, so the subsequent generations were biologically the products of Greek men and native women (though culturally they were fully Greek, as evidenced by the term “Magna Graecia” to refer to Sicily and southern Italy). It is not atypical for vertical transmission of culture to occur from one parent, and in particular one sex. More recently the descendants of the pairings of Iberian men and indigenous women in Latin America tend to speak Spanish and avow the Christian faith. Though aspects of local identity, such as cuisine and clothing, may retain an indigenous stamp it is no coincidence that these populations are labelled “Latin American” despite their mixed genetic provenance.

Note: In the United States children have traditionally been more often raised in the denomination of their mother than father, so there isn’t always a male-bias in vertical transmission when the parents are not concordant for a cultural trait.

Earlier I pointed to the possibility of biophysical constraints and parameters in terms of inheritance shaping the local trajectory of evolution. Today Olivia Judson has a nice post [link fixed] on how the existence of two sexes in many species results in a strange metastable tug-of-war in terms of phenotypic evolution:

In sum, the traits that make a “good” male are often different from those that make a “good” female. (Note: I’m only talking about “good” in evolutionary terms. That means a trait that improves your chance of having surviving offspring.) Since many of these traits have a genetic underpinning, male and female genes are thus being sculpted by different forces.

But — and this is the source of the tension I mentioned — males and females are formed from the same underlying set of genes. After all, in humans, whether you’re a boy or a girl comes down to whether you have a Y chromosome or not: boys do, girls don’t. The rest of the genes occur in both sexes.

The X choromosome in mammals spends about 2/3 of its time in females and 1/3 in males.* And obviously the Y is found only in males. But the rest of the genome is found in both males and females. Judson notes that traits which may be attractive in males may not in females, and which may be attractive in females may not in males. There’s a fair amount of evolutionary psychological work in humans in this vein in regards to the heritability of testosterone and estrogen levels in females and males and how it effects the same and opposite sex (in short, there is suggestive data that “sexy” individuals of one sex, those who exhibit strong secondary sexual characteristics, may be prone to having less sexy offspring of the opposite sex).

Of course you can overcome the balancing tug of war; that’s why you have sexual dimorphism in things like size or facial proportion. But these sorts of traits emerge very slowly because of the equilibrium described above, modifier genes and sex-specific gene expression have to slowly engineer around the overwhelming problem that males and females are genetically no different on a sequence level aside from the Y chromosome. Some estimates put the rate of evolutionary change of sexual dimorphism, that is, trait differences between sexes, between 1 and 2 orders of magnitude slower than conventional population level evolution. Ergo, one would expect that sexual dimorphism differences varying across populations have great time depth, and are probably more interspecific than intraspecific (for example, gorillas vs. humans).

There is naturally a whole field devoted to the study of the origin of sex. But whatever its ultimate rationale and utility an evolutionary context, its existence as a background condition in many taxa may result in a constraint of the exploration of phenotype space, as species divided into two sexes characterized by strong phenotypic differences dance between two sex-specific phenotypic optima.

* Sex determination varies by taxon.

“The authors report a field experiment with skateboarders that demonstrates that physical risk taking by young men increases in the presence of an attractive female. This increased risk taking leads to more successes but also more crash landings in front of a female observer. Mediational analyses suggest that this increase in risk taking is caused in part by elevated testosterone levels of men who performed in front of the attractive female. In addition, skateboarders’ risk taking was predicted by their performance on a reversal-learning task, reversal-learning performance was disrupted by the presence of the attractive female, and the female’s presence moderated the observed relationship between risk taking and reversal learning. These results suggest that men use physical risk taking as a sexual display strategy, and they provide suggestive evidence regarding possible hormonal and neural mechanisms.”

Thanks to Anne for today’s ROFL!

Image: flickr/fotologic

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In autumn, as green hues give way to yellows and oranges, some leaves develop mysterious green islands, where life apparently holds fast against the usual seasonal decay. These defiant patches still continue the business of photosynthesis long after the rest of the leaf has withered. They aren’t the tree’s doing. They are the work of tiny larval insects that live inside it – leaf-miners.

The larvae were laid within the leaf’s delicate layers by their mother. They depend on it for shelter and sustenance, and they can’t move away. If their home dies, they die, so they have a vested interest in keeping at least part of the leaf alive. These are the miniature landscape architects that create the green islands, and they don’t do it alone – to manipulate the plant, they wield bacteria.

Wilfried Kaiser and scientists from Rabelais University discovered this partnership after realising that some bacteria and fungi can also cause green islands. He reasoned that microbes might be helping insects to achieve the same ends. So he searched for them in one particular species, a tiny moth called the spotted tentiform leaf-miner, Phyllonorycter blancardella. Its larva makes its home in the leaves of apple trees.

Kaiser found that the leaf-miners are host to just one detectable type of bacteria – Wolbachia. That’s hardly surprising. Wolbachia infects around 60% of the world’s insect species, making it a strong candidate for the title of world’s most successful parasite. Without exception, every leaf-miner that Kaiser tested, from all over the Loire Valley, carried Wolbachia in their tissues.

The bacteria were the true agents behind the green islands. When Kaiser cured the leaf-miners of their infections using antibiotics, they seemed perfectly healthy. But they completely lost the ability to stem the yellowing of leaves. As a result, 85% perished before adulthood; for comparion, the typical mortality rate of Wolbachia-carrying larvae is just 10%. Worst of all, since Wolbachia is passed down from mother to offspring, later generations also suffered the same lack of beneficial bacteria, the same inability to produce green islands and the same high odds of an early death.

The bacteria manipulate the leaves using their own signalling chemicals – a group of plant hormones called cytokinins. These substances perform many tasks in a leaf: they maintain the supply of chlorophyll; they prevent the leaf from dying; and they control the flow and storage of nutrients. They’re the barrier that stands between a living leaf and a rotting one. Stick cut plants in cytokinin solution and they’ll stay green for longer. What better tool for a bacterium or an insect looking to prolong the life of its leafy home?

Inside a typical mine, levels of cytokinins are much higher than usual. But when Kaiser cured the leaf-miners of Wolbachia, he found that the levels of cytokinins in the mine plummeted to levels typically seen in yellow leaves. Without these hormones, the insects failed to protect their homes. And if Kaiser injected cytokinins into leaves directly, he could create green islands on his own, without the need for either Wolbachia or a leaf-miner.

We know that the bacteria are necessary for the cytokinin flood that maintains the mine, but the exact source of these chemicals is unclear. It’s possible that the bacteria secrete them directly, or allow the leaf-miner to do so. Indeed, Wolbachia has a gene that’s important for the creation of cytokinins, and a paper published four decades ago found large amounts of these hormones in the salivary glands of a leaf-miner. The other alternative is that the bacteria encourage the plant to over-produce its own hormones. Of course, all of these possibilities could be working together.

Of course, many insects have their own beneficial resident bacteria, or symbionts. These tenants provide them with valuable nutrients that they can’t make themselves, and they can even offer protection against enemies and environmental challenges. But this is the only known example of an insect using a bacterial symbiont to directly manipulate a plant, and it seems to be a successful strategy.

By all accounts, leaf-mining is an evolutionary success story, and hundreds of species have adopted this lifestyle. Their partnership with bacteria might be the secret of their success but Kaiser will only know that for sure once he works out how widespread the use of bacteria is, and what these microbes actually do to the plant.

Reference: Proc Roy Soc B http://dx.doi.org/10.1098/rspb.2010.0214

Images: by Kaiser

More on insects and bacteria

• Life-shortening bacteria vs. dengue mosquitoes
• Butterflies evolve resistance to male-killing bacteria in record time
• An entire bacterial genome discovered inside that of a fruit fly
• Virus and bacteria team up to save aphid from parasitic wasp
• Museum butterfly collections chronicle evolutionary war against male-killers
• Leafcutter ants rely on bacteria to fertilise their fungus gardens

Beauty may lie in the eyes of the beholder, but morality, apparently, lies just behind your right ear–in an area scientists call the right temporoparietal junction (RTPJ).

In a study that helps explain the mechanics of morality, neuroscientist Liane Young and her colleagues found that activity in the RTPJ is linked to the types of moral judgments we make–and those judgments can easily be tinkered with using a mere magnet. The researchers found that by delivering magnetic pulses to the RTPJ they were able to impact moral judgments; the magnetic pulses made people less likely to condemn others for attempting but failing to inflict harm [Nature]. The findings were published in journal Proceedings of the National Academy of Sciences.

Says Young: “You think of morality as being a really high-level behavior. To be able to apply a magnetic field to a specific brain region and change people’s moral judgments is really astonishing” [BBC].

Most of us make moral judgments based on not just what the consequences of an action were, but also on what the person’s intentions were. So little children and people with mental illness aren’t judged as harshly for their actions, because their intentions usually aren’t bad. It’s not just a matter of what they did, but how much they understood what they were doing [Nature].

The process of figuring out how much blame to attribute to a person involves the RTPJ. So for this study, scientists used a non-invasive technique called transcranial magnetic stimulation (TMS) to deliver small magnetic pulses to the RTPJ; the pulses temporarily stop brain cells from working normally. Then the researchers asked their subjects questions based on different scenarios while monitoring brain activity with functional magnetic resonance imaging (fMRI).

In one test, participants were asked how acceptable it was for a man to let his girlfriend walk across a bridge he knew as unsafe. After receiving a 500 millisecond magnetic pulse to the scalp, the volunteers delivered verdicts based on outcome rather than moral principle [BBC]. If she safely made it across the bridge, the subjects said, the boyfriend didn’t do anything wrong.

In the second test, researchers delivered shorter magnetic pulses and found that the subjects continued to make moral judgments based on outcome and not intention. This type of thinking is reminiscent of how little children often make moral judgments–thinking, for example, that a kid who broke 5 teacups accidentally is naughtier than the kid who broke one teacup on purpose. Researchers say that children under the age of 5 haven’t yet developed a full understanding of intentions.

Some experts say the study helps dispel the notion that morality is a lofty, intangible thing, and argue that it has been hardwired into our brains by evolution. Joshua Greene, psychologist at Harvard University explained: “Moral judgment is just a brain process…. That’s precisely why it’s possible for these researchers to influence it using electromagnetic pulses on the surface of the brain.” If something as complex as morality has a mechanical explanation, Green says, it will be hard to argue that people have, or need, a soul [NPR].

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Image: iStockphoto

Two decades ago, neurosurgeon Itzhak Fried of UCLA was stimulating a woman’s brain with electrodes that had been implanted before surgery to treat her epilepsy. He realized his patient was trying to tell him something, and as he bent down to listen, she mumbled that she had a sudden urge to shift her hand. Apparently an electrode had activated the part of the brain’s motor cortex that controlled the woman’s will to move. Fried realized that medical procedures like this one presented a rare scientific opportunity: Patients being examined for neurosurgery allow researchers to investigate the human brain in action, exploring the functions of different regions in precise detail and in real time.

These days, surgeons like Fried are increasingly partnering with brain researchers to take advantage of this access. About 30 such collaborations are currently under way. Although noninvasive imaging methods such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) can track activity in the brain, they provide limited resolution. As Caltech neuroscientist Ueli Rutishauser puts it: “fMRI is like viewing a city from space. You can see the brightness of the lights and the number of inhabitants, but not what they’re doing or who is talking to whom. For that, you have to walk the streets yourself.”

The 147th Carnival of Space is now online at Weird Sciences. If you read that blog with underwear on your head and a doll attached to electrodes, Kelly LeBrock will walk out of your bathroom. I saw it in a movie, so it must be true.

Also, the Skeptics Circle has been posted on The Digital Cuttlefish, too.

Over the next few days, get yourself outside at sunset and look west. As the sky darkens, Venus will be obvious and easy to spot above the horizon, a brilliant beacon hovering in the sky. But for a few days, the elusive Mercury will also be popping in for a visit!

Mercury orbits much closer to the Sun than Earth does, and so from our vantage point never seems to stray far from our nearest star. It’s always lurking in the twilight, and most people can go their whole lives without seeing it. It’s rumored (though by no means established fact) that Copernicus himself never saw Mercury. But this week will provide you with an excellent chance to spot it. It will stay near Venus for several days, and with no other bright stars nearby it will be fairly easy to pick out.

Both Mercury and Venus move faster in their orbits than Earth does, so if you go out every night you’ll see them change positions slightly in the sky. From our perspective, Venus is on the far side of the Sun, and Mercury to the side. After about April 10, Mercury will start to fade rapidly, so get out there and take a look! More info and diagrams to help you spot the planetary duo can be found at the Sky and Telescope website.

And I’ll add that if you have a digital camera, try to get some photos! The planets are bright enough to show up in images easily, and if you get an interesting foreground object (a tree, a bridge, etc.) you can get some very nice shots.

Makani Power is a San Francisco Bay Area based alternative energy start-up that seeks to provide renewable energy from high-altitude wind. In this compilation image, a computer-controlled, high-performance wing prototype is tethered to a flexible cable, attached here to a re-purposed aerial ladder truck. This test shows how the wing can access wind energy with a small footprint, and without the supporting material required by wind turbines.

Makani Power staff photographer Andrea Dunlap reflects: “I spend a lot of time sitting in fields waiting for the wind to be right for the engineers to fly things. Airtime can be anywhere from a minute to thirty hours. I love that we are sharing this testing space with so many other users of the land—farmers, cattle, birds, kite surfers and an entire energy infrastructure of traditional wind turbines and transmission lines. I go to each test site in eager anticipation of a day spent watching wind, clouds, sky and surf. As the sun sets and the wind dies down for the night we pack up and tuck our kites away until next time.”

Courtesy Andrea Dunlap/Makani Power

Welcome to this week’s installment of the From Eternity to Here book club. Part Four opens with Chapter Twelve, “Black Holes: The Ends of Time.”

Excerpt:

Unlike boxes full of atoms, we can’t make black holes with the same size but different masses. The size of a black hole is characterized by the “Schwarzschild radius,” which is precisely proportional to its mass. If you know the mass, you know the size; contrariwise, if you have a box of fixed size, there is a maximum mass black hole you can possibly fit into it. But if the entropy of the black hole is proportional to the area of its event horizon, that means there is a maximum amount of entropy you can possibly fit into a region of some fixed size, which is achieved by a black hole of that size.

That’s a remarkable fact. It represents a dramatic difference in the behavior of entropy once gravity becomes important. In a hypothetical world in which there was no such thing as gravity, we could squeeze as much entropy as we wanted into any given region; but gravity stops us from doing that.

It’s not surprising to find a chapter about black holes in a book that talks about relativity and cosmology and all that. But the point here is obviously a slightly different one than usual: we care about the entropy of the black hole, not the gruesome story of what happens if you fall into the singularity.

Black holes are important to our story for a couple of reasons. One is that gravity is certainly important to our story, because we care about the entropy of the universe and gravity plays a crucial role in how the universe evolves. But that raises a problem that people love to bring up: because we don’t understand quantum gravity (and in particular we don’t have a complete understanding of the space of microstates), we’re not really able to calculate the entropy of a system when gravity is important. The one shining counterexample to this is when the system is a black hole; Bekenstein and Hawking gave us a formula that allows us to calculate the entropy with confidence. It’s a slightly weird situation — we know how to calculate the entropy of a system when gravity is completely irrelevant, and we also know how to calculate the entropy when gravity is completely dominant and you have a black hole. It’s only the messy in-between situations that give us trouble.

The other reason black holes are important, of course, is that the answer that Bekenstein and Hawking derive is somewhat surprising, and ultimately game-changing. The entropy is not proportional to the volume inside the black hole (whatever that might have meant, anyway) — it’s proportional to the area of the event horizon. That’s the origin of the holographic principle, which is perhaps the most intriguing result yet to come out of the thought-experiment-driven world of quantum gravity.

The holographic principle is undoubtedly going to have important consequences for our ultimate understanding of spacetime and entropy, but how it will all play out is somewhat unclear right now. I felt it was important to cover this stuff in the book, although it doesn’t really lead to any neat resolutions of the problems we are tackling. Still, hopefully it was somewhat comprehensible.

The smashing has started. Now the science can commence.

Last week we reported that the Large Hadron Collider’s operators at CERN targeted today to attempt the highest energy particle collisions ever. And to show the world that yes, in fact, the LHC can meet a deadline, today they slammed together the two proton beams, each carrying 3.5 trillion electron volts, to produce 7 TeV collisions. As the first data from the impacts were announced, physicists who had gathered at CERN applauded, jumped up and down, and clutched laptops displaying images of the collisions to their chests as if the computers were newborn babes [National Geographic].

While the physicists enjoy their moment of euphoria, they caution that it will be some time before the LHC’s collisions translate into new data that could reveal deeper secrets of the universe. “Major discoveries will happen only when we are able to collect billions of events and identify among them the very rare events that could present a new state of matter or new particles,” said Guido Tonelli, a spokesman for the CMS detector at the LHC. “This is not going to happen tomorrow. It will require months and years of patient work” [BBC News]. This round of collisions should last a year and a half or so. After a planned shutdown, the physicists plant to crank up the collider to its full power of 14 TeV.

For more about the long road to now and the future of LHC physics, follow DISCOVER blog Cosmic Variance.

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Image: CERN

It’s rainy and drab outside and the only thing making us feel better is watching videos in which Applegirl shows off her amazing abilities with the iPhone. This YouTube sensation performs hit songs using a collection of apps on several different iPhones. Yesterday it was a three-phone version of Beyonce’s “Irreplaceable,” and today she’s taken a stab at Lady Gaga’s “Pokerface” using four phones.

She seems to use a mix of looping drum beat apps, guitar chord apps, and, for Pokerface, the T-Pain autotune app for that modern vocal sound. Here’s a look at both videos. However, here’s a heads up–Applegirl doesn’t get into the swing of things with Irreplaceable till 1:34 into the video and the cat making the rounds in Poker Face is very distracting.

Enjoy.

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In a far-reaching judgment that could have major implications for the biotech industry, a federal judge in Manhattan has struck down patents related to two human genes linked to hereditary breast and ovarian cancers, BRCA1 and BRCA2.

Myriad Genetics held the patents, and women who want to find out if they have a high genetic risk for these cancers have to get a test sold by Myriad, which costs more than $3,000. Plaintiffs in the case had said Myriad’s monopoly on the test, conferred by the gene patents, kept prices high and prevented women from getting a confirmatory test from another laboratory [The New York Times]. In his decision, United States District Court Judge Robert W. Sweet found that the company’s patents were invalid because the genes are “found in nature,” and products of nature can’t be patented. In essence, he agreed with the plaintiffs’ argument that the genetic code contained in each human being’s cells shouldn’t be private property.

Tuesday’s decision, if upheld, could have wide repercussions for the multi-billion dollar biotech industry, which is built on more than 40,000 gene patents. Already, about 20 percent of the human genes have been patented. The decision, however, is not binding on other federal courts and other judges may or may not abide by it. But it does the set the stage for years of litigation over other gene patents. Myriad Genetics plans to appeal the judgment.

As DISCOVER reported earlier this year, the case was brought to court by the American Civil Liberties Union (ACLU) on behalf of 20 plaintiffs, including the American College of Medical Genetics, the Association for Molecular Pathology, and various individuals. The lawsuit charged that the BRCA patents—and gene patents in general—violate established laws that prohibit the patenting of products and laws of nature. According to the ACLU, “Human genes, even when removed from the body, are still products of nature” [DISCOVER]. The plaintiffs alleged that the company’s patents also prevented research on the genes and their link to cancer, and was ultimately harmful in the long run.

However, Myriad Genetics, the company that holds the patents with the University of Utah Research Foundation argued that the case held no merit as the work of isolating the DNA from the body transforms it and makes it patentable [The New York Times]. Patents like this, the company maintained, had been granted for decades. Judge Sweet however, shot down that argument and maintained that the previous patents were “improperly granted.” He said that many critics of gene patents considered the idea that isolating a gene made it patentable “a ‘lawyer’s trick’ that circumvents the prohibition on the direct patenting of the DNA in our bodies but which, in practice, reaches the same result” [The New York Times].

Calling the decision a “victory for the free flow of ideas in scientific research,” the ACLU said the human genome “was discovered, not created. There is an endless amount of information on genes that begs for further discovery, and gene patents put up unacceptable barriers to the free exchange of ideas” [Newsweek]. However, experts who sided with Myriad said that if the decision was upheld, it would have a significantly hold back medical research, as new companies would have trouble raising money from investors for their research.

Here’s what the other biotech companies who have been watching the case closely need to know: The decision won’t affect their patents at this point, and experts say the U.S. Patent and Trademark Office isn’t likely to change its rules on gene patenting because of this decision. But the lawsuits have no doubt just begun.

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Image: iStockphoto

After more than a decade of triumph, setbacks, and much sturm and drang, the Large Hadron Collider made history last night by taking two beams of protons and smashing them head on at just a whisper under the speed of light.

Yay!

The LHC is the world’s largest physics experiment, and is attempting to recreate conditions in the Universe when it was only a fraction of a second old. At that point, pressures and temperatures were so high that the laws of physics were somewhat different than we’re used to. These conditions are extremely difficult to duplicate, which is why it’s taken so long to get the LHC running. The collider uses extremely powerful magnets to guide and accelerate two beams of protons to nearly the speed of light. They go around the collider in opposite directions, then are tweaked to smack into each other. The huge energies of the collision create particles and conditions that can be detected and used to test theories of how the Universe behaves.

There were some minor glitches before the protons could be injected into the main collider last night, but once things got going, the beams were sent at each other at full power. The energies were ramped up to 3 TeV, or three trillion electron volts (a unit of energy).

Now, 3 TeV is not much energy in human terms. It’s roughly the amount of energy of a single mosquito in flight. But for a single proton, 3 TeV is huge, vast, incredible, brobdingnagian, ginormous! When the two proton beams are at full power, they contain the same kinetic energy as a battleship moving at several kph! So we’re talking about powerful events, indeed.

I visited CERN and the LHC a couple of years ago, and wrote up my thoughts. I was of the opinion then, and still am now, that this will be a revolution in physics.

I made a video of that tour, too.

My congratulations to the hordes of people who made this moment possible. It has been a long, difficult journey indeed, but now the real voyage is underway. May the wild physics rumpus begin!