28 February 2011

Spikes without sodium, part 2

Previously, on NeuroDojo...

Most of the signals running along the neurons in your brain and spinal cord and in the tips of your fingers and the bottom of your bum are started because sodium rushes inside those neurons. The sodium gets in through voltage gated sodium channels. If your voltage gated sodium channels can’t open, neurons can’t fire, and you are done for.

Last week, I talked about a new paper that showed how a little worm, C. elegans, gets along without the sodium channels that we absolutely need. Gao and Zheng claim that the roundworm uses calcium, instead of sodium, to drive action potentials.

ResearchBlogging.orgThere’s another element of this paper that deserves inspection.

There are two ways to make a neural signaling system without using sodium. One is to use another ion, like calcium, to start an action potential. A second way is not to use action potentials at all, but to use graded signals (non-spiking neurons). Graded signals fade as they travel, so they tend not to be the norm.

Something I didn’t emphasize enough in my previous write-up was that Gao and Zheng were working on the muscles, not the neurons. Do the neurons also use calcium to make spikes?

If you were a regular reader with a phenomenal memory, you might dredge out of your memory that about a year and a half ago, I wrote about another C. elegans paper. It claimed that this worm’s motor neurons didn’t generate action potentials at all.

Gao and Zheng, in this newer paper, do several things. First, they are able to replicate the previous finding. They show that the motor neurons are stimulated by increasing amounts of light (described in more detail in the earlier post), there is a graded flow of ions into the muscle. But, these small potentials eventually hit a threshold within the muscle cell, which then triggers the calcium-driven action potentials, which cause the muscle to contract.

They’re also able to provide some evidence that there are two classes of these motor neurons: Excitatory motor neurons, which use acetylcholine as their transmitter, and; inhibitory motor neurons, which use GABA as their transmitter.

“Inhibitory motor neurons?”

I learned that some neuroscientists will blow a fuse at this point. Slip a gear. Spit the dummy.

I once gave a presentation where I mentioned inhibitory motor neurons. There were two prominent researchers in the audience who had co-authored two very successful undergraduate neuroscience textbooks. They were caught flat-footed by the idea of inhibitory motor neurons. They had no idea a nervous system could work that way. They believed that there are only excitatory motor neurons. This is true... for skeletal muscles in mammals. Inhibitory motor neurons are common in invertebrates, like arthropods and C. elegans.

It was a powerful reminder to me about how everyone has their blind spots.

Back to the paper. Here’s a little experiment showing that you can block action potentials in the muscles by putting on a little of the suspected neurotransmitter released by the motor neurons.


Gao and Zhen were also able to show that by stimulating neurons know to contain GABA, they were able to see relaxation of the muscles.

Mammals are use sodium-generated spikes in neurons, and those neurons can only excite muscles, which also use sodium to trigger contraction.

The worm has no spikes in its neurons, and those neurons both excite and inhibit the muscle, which use calcium to trigger contraction.

The physiology of the neurons in C. elegans are so different those of mammals that is is almost perverse that the worm has become a model system for neuroscience. But that it is different presents a wonderful opportunity for all neuroscientists to learn to appreciate the diversity of nervous systems.

Not everything works like a mammal.

References

Gao S, Zhen M. 2011. Action potentials drive body wall muscle contractions in Caenorhabditis elegans. Proceedings of the National Academy of Sciences 108(6), 2557-2562. DOI: 10.1073/pnas.1012346108

Liu Q, Hollopeter G, Jorgensen E. 2009. Graded synaptic transmission at the Caenorhabditis elegans neuromuscular junction Proceedings of the National Academy of Sciences 106(26): 10823-10828. DOI: 10.1073/pnas.0903570106

Photo from here.

26 February 2011

Free talk and South Padre Island Birding Center! (Take 2)

The talk I mentioned back in Janauary that was postponed has now been rescheduled for 10:00 am, 5 March 2011 at the South Padre Island World Birding Center.

The title of the talk is still:

“Signals for survival in the lives of fiddler crabs”


Ever seen fiddler crabs sitting next to their burrows, waving their claws? Have you ever wondered who they're waving to? Why are they waving? This talk delves into how these small animals send signals to survive!

The presentation will be free, non-technical, and hopefully a lot of fun for all. Please come and join me!

24 February 2011

Sharpies and sea squirts

Virginia Scofield is a colleague, co-author (Lambert et al. 2005), and friend of mine. She makes an extended appearance in this presentation by Sunni Brown, recorded at Duarte Design.



Lots of stuff to consider in this warm, personable presentation!

Reference

Lambert G, Faulkes Z, Lambert CC, Scofield VL. 2005. Ascidians of South Padre Island, Texas, with a key to species. The Texas Journal of Science 57(3): 251-262.

23 February 2011

Greyhound, over and out

I met Nicholas Courtney in 1986.

He played Brigadier Lethbridge-Stewart in Doctor Who in the 1970s all the way up to the character’s final appearance in The Sarah Jane Adventures about a year ago.

He was warm and friendly to me, and to others, even though he had reasons to be in a bad mood. The convention, for which he was one of the guests of honor, had failed to come up with their promised appearance fees. But Courtney and the other guests went on and continued to appear for the fans, who had showed up in good faith. (I learned some years later that Courtney and the other guests never saw a dime.)

I had the fun of telling him how great it was to meet the man who played Lethbridge-Stewart, because I had come to the convention from Lethbridge, Alberta.

In one of the Q&A sessions, I asked the guests what their favourite line was. His was from his favourite story (and that of many fans), The Dæmons, and is one of his most famous:

“Chap with wings there. Five rounds rapid.”

Courtney was so completely successful in the part that although the organization his character headed, UNIT, has reappeared in the show, none of his successors have been able to recapture the magic that Courtney brought. Courtney and the writers made Lethbridge-Stewart a complex, fully drawn character, who was often difficult. Part of the Brigadier’s charm was that the was not always charming.

And he was one of the few characters who routinely got the better of The Doctor.

He said in 1986 that he would relish the chance to play someone who wasn’t an English army officer. Even one of the times I saw him outside Doctor Who, in Yes, Prime Minister, he was playing a police commissioner. Another officer. I hope he got the chances he wanted to play those other parts.

I was so sad to hear he died yesterday, at 81.

He’s pictured here in The Five Doctors in 1983, and Battlefield in 1989; three years before and after our paths crossed.

Related pages

Tom Baker, the fourth Doctor, on Nick Courtney
Doctor Who website

Spikes without sodium

ResearchBlogging.orgNeuroscience is concerned with human, mammals, and vertebrates, in that order. The one example of an invertebrate that appears in many narratives for students learning the field is the squid giant axon, which was used to work out the mechanism underlying action potentials.

From the squid axon, we learned that the action potential, in a nutshell, was:

Sodium in, potassium out.

The electrical signal of a neuron was made possible because charged atoms passed into and out of the cell through channels. These channels opened due to the internal electrical state of the neuron, specifically the voltage. In most species, anything that blocks these voltage-gated sodium channels is nasty stuff indeed. Tetrodotoxin is just one of these toxins, and can be found in many animals, but is most famous as pufferfish poison.

“Sodium in, potassium out” was so common and widespread that you could be forgiven that every animal on Earth does things this way. You’d still be wrong, mind you... but forgiven.

Because one of the most studied organisms on the planet can’t get sodium into its neurons.

Caenorhabditis elegans is a little worm that has two big advantages as model nervous system. It was the first animal in which the connections between every neuron in the body was worked out; it was one of the first organisms to have its genome sequenced.

And when the genome was sequenced, people noticed that there were no genes for voltage gated sodium channels.

Gao and Zhen have a new paper that shows how these worms are managing to run their nervous system without voltage-gated sodium channels. They were focusing on the muscles, which also work with sodium in many critters.

They did several experiments, and the bottom line to them all is that in this worm, it’s calcium in, potassium out. The experiment that’s easiest to explain is that when the calcium concentration surrounding the cell was messed up (no calcium), the spikes were messed up (they stopped).

There are several reasons that this is not a huge surprise. Calcium spikes have been found in other animals. And when channels open, calcium tends to do the same thing, electrically speaking, as sodium: it makes the inside of the neuron more positive. In fact, if anything, it’s a surprise that more cells don’t make calcium spikes, because every calcium ion packs twice the electrical “punch” of a sodium atom.

Alas, examples like this rarely seem to get into neuroscience textbooks.

There’s another piece of this paper that is a nice demonstration of the diversity of nervous systems, but I’ll save that for another post.

Reference

Gao S, Zhen M. 2011. Action potentials drive body wall muscle contractions in Caenorhabditis elegans. Proceedings of the National Academy of Sciences 108(6), 2557-2562. DOI: 10.1073/pnas.1012346108

Photo by derPlau on Flickr; used under a Creative Commons license.

22 February 2011

Local storm in a teacup over evolution, continued

Previously, around Darwin Day, I learned about a local exhibition that attracted controversy in part because it featured evolution. Now, the local paper, The Monitor, is reporting more details about the exhibit.

It turns out that one local orthodontist was very much in the lead of buying this display. And it’s a nice little example of how civic projects can unfold (slightly condensed).

“I was the impetus for this thing. I pulled the levers to make it happen,” said John Gerling, a McAllen orthodontist and member of the museum’s board. For the last decade, Gerling said he’s worked with the museum to bring science exhibits to McAllen.Gerling said he stumbled across “A Walk Through Time: From Stardust to Us,” the now-controversial outdoor science exhibit tentatively planned for display along the hike-and-bike trail.

Gerling said he pitched the project to city leaders, including Mayor Richard Cortez.

The city commission approved the exhibit, and gave money to the museum, which purchased the exhibit, Gerling said, adding it was his project, and that he didn’t consult the museum’s board.

Funding came from the federal stimulus package, formally called the American Recovery and Reinvestment Act of 2009, Gerling said.

Gerling said he only intended to improve local science education, and didn’t want to cause problems or irritate people with strong religious beliefs. After hearing the complaints, Gerling said he was considering how to “retask” the exhibit.

“If there’s one person who’s been educated by this exhibit, it’s me,” Gerling said.

There’s even an online version of the exhibit. It is, in my estimation, surprisingly sophisticated in the information in presents.

Tuesday Crustie: Kaiju

Continuing with the theme of oversized pop culture crustaceans, here’s a favourite giant monster from Toho Studios:


Ebirah was introduced in Godzilla Vs. The Sea Monster, where the two participated in some slightly surreal soccer action with boulders.


“Ebi,” if I’m not mistaken, means shrimp in Japanese, so the name means something like monster shrimp.

I preferred Ebirah’s brief but tightly choreographed, energetic action scene in Godzilla: Final Wars. (even if Ebirah didn’t get a rematch with Big G). Here’s some conceptual art:




And here’s the final version in the film:

 
You can watch both movies on Crackle.

21 February 2011

We haven’t seen this in a mammal! Rewrite the textbooks!

ResearchBlogging.orgTextbooks have a lot to answer for.

Textbooks are not the compilation of all knowledge in a field. They are simplified summaries created to teach students new to a field the general lay of the land.

People forget this. Cranks get obsessed with advancing their pet theories by attacking “textbook examples,” because they think the textbook example is all the evidence we have. “If I can show there’s something wrong with the peppered moth example of natural selection, I’ll prove evolution is fake!”

Admittedly, legitimate researchers say, “One day, this will be in all the textbooks!” sometimes, too. It can look self-aggrandizing and egotistical, though.

So this press release titled

Rewrite the textbooks

Findings challenge conventional wisdom of how neurons operate


annoyed me and set off my bullshit filter. My annoyance got worse with the first sentence, and continued increasing as I read the press release.

The good news is that the paper is nowhere near as bombastic as the press release. It is a very good paper. It acknowledges the state of the art in the field and does not present itself as revolutionary. The experiments are technically proficient. And the findings are intriguing.

Let’s compare what the press release says and what the paper says.

Press release:

(T)he basic functional concept is that synapses transmit electrical signals to the dendrites and cell body (input), and axons carry signals away (output).

Paper (my emphasis):

There are exceptions to this, including neurons that lack dendrites or an axon, as well as action potentials propagating from the axon into dendrite. In invertebrates, action potentials can originate in multiple sites, including axon terminals.

What the press release is putting first as the big new finding is not new. It. Just. Is. Not. And the paper’s authors know this and say so in the paper.

In the press release, though, one of the authors, Nelson Spruston, changes his tune:

“Signals can travel from the end of the axon toward the cell body, when it typically is the other way around. We were amazed to see this.”

A neuroscientist amazed by this is either playing to the microphone, or is admitting that he started the project with an ignorance of the diversity of neurobiology. There is certainly no shame in the latter; many neuroscientists concentrate so deeply on one system, they aren’t aware of what else is out there. But playing up, “The signal! It goes backwards! Up the axon!” as something amazing, new, and borderline revolutionary after you’ve admitted in the paper that it happens in other systems is overdoing it.

If I were to rewrite textbooks on this point, it would be to add, “Invertebrates have nervous systems that often work differently than mammals.” Most neuroscience textbooks are far too fixated on humans, mammals, and vertebrates, in that order. If it weren’t for Hodgkin and Huxley’s work on action potentials in squid giant axon, you might have no idea that invertebrates existed.

Press release:

A deeper understanding of how a normal neuron works is critical to scientists who study neurological diseases, such as epilepsy, autism, Alzheimer’s disease and schizophrenia. ...

This unique neuronal function might be relevant to normal process, such as memory, but it also could be relevant to disease.

Paper:

Consolidating these results suggests the existence of a previously unknown operational mode for some mammalian neurons. ... The mechanisms responsible for all aspects of this new operational mode are unknown and elucidating them will require extensive work.

These guys care about how cells work. There’s no mention of medical applications anywhere. (They do mention epilepsy, because neurons in animals with epileptic-like conditions do odd things.)

The press release is making empty promises. “What are the practical applications of this?” is a science journalism cliché ranking up there close to “He said, she said.”

Press release:

“It”s very unusual to think that a neuron could fire continually without stimuli,” Spruston said.

My first reaction was, “Hello! Spruston! They’re called pacemaker potentials and plateau potentials! Both well described in lots of neural circuits!” A pacemaker potential occurs in a neuron that fires over and over again, spontaneously. A plateau potential occurs when a short input causes sustained firing that is much longer than the input; input less than a second could trigger firing for tens of seconds or even minutes.

Paper:

What Sheffield, Spruston and company have found is something that resembles plateau potentials, but is operating on a different timescale. Plateau potentials are triggered by very distinct, short inputs that depolarize the neuron. The neurons in this paper are getting “set off” by long trains of many events. You need hundreds of potentials (small bottom trace) over many seconds to “set off” these long sets of spikes in response in the downstream cell.


That is different and noteworthy and something I haven’t see quite seen before.

And it’s happening in the axon. Potentials starting in the axon isn’t new, and long periods of firing without stimuli isn’t new, but the combination of those two, plus the long time frame of the trigger (the most truly new and interesting thing in the paper, in my estimation) makes for intriguing combination.

Press release:

Their studies of individual neurons (from the hippocampus and neocortex of mice) led to experiments with multiple neurons, which resulted in perhaps the biggest surprise of all. The researchers found that one axon can talk to another.

“But... but... but... Axons interacting with axons isn’t new. I learned the term ‘axoaxonic synapse’ from a diagram in a textbook showing two axons connected to each other. Presynaptic inhibition is two axons talking to each other, and Dudel and Kuffler described that in the 1960s.”

Paper: All of the experiments I described above have involved single cells responding to the experimenter. When they were recording from two neurons, they found that occasionally (3 of 19 pairs), when one cell was “set off” into a bout of sustained firing, the partner cell would also go into a long set of sustained firing. This suggests this phenomenon could be a substantial part of the network in this region of the brain (hippocampus).

Finally, Sheffield and colleagues admit they don’t know how these cells are able to generate persistent firing. (This will probably keep this finding out of textbooks until they get the mechanism down. Phenomena without mechanisms are curiosities. Textbooks thrive on neat, complete stories.) Putting on chemical that block gap junctions prevents this sustained firing. But it’s still up in the air as to what gap junctions, where, between what cell, might be involved.

Press release:

Spruston credits the discovery of the persistent firing in normal individual neurons to the astute observation of Mark Sheffield, a graduate student in his lab.

I say this seriously, with no irony intended: That was a classy thing to say, Dr. Spruston, and good on you. Grad students do not get anywhere near enough credit for being the drivers of discovery that we know they are.

Recently, John Rennie asked science journalists to image what would happen if they didn’t write about papers the same week they were released. This press release was written two months after the pre-print of the paper was published online.

So a cooling off period did not appear to help in this case. The press release is breathless and hyped and oversells a paper that is very admirable and interesting. This paper is like a top notch remix of a song: there’s more old stuff than new material, but the combination is cool and worth listening to.

References

Sheffield M, Best T, Mensh B, Kath W, Spruston N (2010). Slow integration leads to persistent action potential firing in distal axons of coupled interneurons. Nature Neuroscience 14(2): 200-207. DOI: 10.1038/nn.2728

Dudel J, Kuffler SW. 1961. Presynaptic inhibition at the crayfish neuromuscular junction. Journal of Physiology 155(3): 543–562. PDF

Hat tip to GertyZ for finding me a PDF of the paper so I could compare it to the press release!

Photo by punkrockscience on Flickr; used under a Creative Commons license,

18 February 2011

What PubMed thinks I do


I’m glad that “neurons” is the largest word in the cloud. I was hired as a neurobiologist. But not all the research I’ve been doing lately have neurons in it.

Visualized with PubMed2Worldle. Hat tip to Steven Kembel.

17 February 2011

Songs and size in sabrewings: evolution across an isthmus

ResearchBlogging.orgThe wedge-tailed sabrewing.

The name sounds like a super top secret stealth fighter jet. The kind that make deep swooshing noises as it flies by that you can barely hear but feel in your bones.

But it’s even cooler than that. The wedge-tailed sabrewing is a tropical American hummingbird. And we know how cool hummingbirds are.

This particular hummingbird species has a couple of extra cool features, though, mostly revolving around mating. The males form leks, loose groups of males that show off for females. They also have elaborate songs, which is quite variable.

We know hummingbirds are quick, but are they quick evolving birds, too? Clementina González and colleagues wanted to find out. They were particularly interested because this bird’s distribution straddles the Isthmus of Tehuantepec in southern Mexico, which is the narrowest point between the Gulf of Mexico and the Pacific Ocean. The isthmus divides two mountain ranges.

The hummingbird populations are not restricted to the high mountain ranges, but they are somewhat separated in the isthmus. For evolutionary biologists, variation of the species and disconnected populations virtually screams, “Allopatric speciation!” Heck, the conditions for these hummingbirds are virtually the definition of allopatric speciation.

When they looked at the DNA of the three subspecies, bird, they were able to cluster them neatly into one eastern and two western populations, on either side of the isthmus. The three different subspecies could also be distinguished by their the songs.

When looking at the bodies of the sabrewings, one of the western subspecies stood out from either of the other two by being larger. The other two were a little more difficult to distinguish based on their body shape, although bill size could pick apart the remaining two subspecies.

With all these different groups of data, they then tried to figure out what caused the differences in these populations. For the differences in morphology, genetic drift alone – random mutations accumulating in one population because they don’t mate with the others – seemed to explain the differences.

The songs, however... they seemed to be not randomly wafting apart as time went on. The changes were such that the authors suggested that selection was occurring to shape the songs of the different populations.

Songs can be shaped over evolutionary time by many different selective pressures. Physics is one. If you move into different habitats with different acoustical properties, different sounds are advantageous. González and colleagues didn’t find any evidence for that, though.

González and colleagues suggest that song evolution is being driven by female preferences for particular songs. This seems plausible on the face of it, but the authors also note that hummingbirds are like humans, songbirds, and parrots: they can learn their vocalizations.

Differences in songs might be better described as changes in learned behaviour (cultural drift, if you will) than evolutionary selection. It’s not clear to me at this instant how you might distinguish between the two alternatives experimentally.

The largest of these three subspecies is also the one in the most danger. It tends to live more in the lowlands, which is being logged for timber.

Reference

Gonzalez C., Ornelas J., & Gutierrez-Rodriguez C. (2011). Selection and geographic isolation influence hummingbird speciation: genetic, acoustic and morphological divergence in the wedge-tailed sabrewing (Campylopterus curvipennis) BMC Evolutionary Biology, 11 (1) DOI: 10.1186/1471-2148-11-38

Related post

Come on, let me hear you sing with tailfeathers

Hummingbird photo by jerryoldenettel on Flickr; used under a Creative Commons license.

16 February 2011

Are cows magnetic sensors? Re-examining northern alignment

ResearchBlogging.orgA couple of years ago, a paper by Begall and colleagues made a big splash by claiming that cows could detect, and align to, earth’s magnetic field. This report took on a life of its own. I heard it within the last week on one of the science podcasts I listen to (though I can’t remember which one).

This paper got attention not only because this was an unusual claim, but for the way that they determined this. Instead of generating their own data, they looked at pictures of cows in Google Earth.

We know that some animals have a magnetic sense; this is pretty much beyond question at this point (for birds, see Ed Yong’s posts here; here; here). But particularly in mammals, we’re not quite sure how they do it.

It’s very unsatisfying when you don’t have a mechanism for a phenomenon. This is why “And how does that work?” is such an incredibly powerful question to ask people selling expensive water that they claim benefits health, holographic bracelets that improve strength, and so on. If you can’t find a plausible mechanism, you don’t have a good understanding of what’s going on.

Hert and colleagues set out to try to replicate the earlier findings, again using Google Earth images.

They found cows were oriented randomly with respect to direction.

And I should add that they also had two sets of data, that were analyzed separately. So it’s not as though this is a one off fluke; maybe a two-off fluke, but not one time happenstance.

Nature abhors a contradiction. How can these two dramatically different results be reconciled?

One possibility is that this study measured the directions of individual cows. The earlier project measured the direction of herds. Begall and colleagues argued:

Cattle of the same heard might not orient independently of each other, and we therefore calculated a single mean vector per pasture that was used in further analysis(.)

There are other subtle differences between the two studies. Begall and company measure to the nearest 5°. Hert and company apparently measured more precisely, but added 4° random “jitter” to the measurements “to account for imprecision in the measurements”.

It’s also important to note that this study doesn’t mean the earlier one was completely wrong. It presented data from three species, and the cows actually showed the weakest trend to northern orientation of the three. The apparent preferences for a northern orientation in deer were much stronger.

The good news in all this is that because these data are fairly easy to get (you don’t have to take all those aerial photos yourself!), the fact of the matter should come clear fairly quickly as more people try to find the effect.

The bad news is that if it turns out that there’s nothing to it, unfortunately, there will be a lot of “Did you know cows orient to the north?” out there for a long time...

References

Begall S, Cerveny J, Neef J, Vojtech O, Burda H. 2008. Magnetic alignment in grazing and resting cattle and deer Proceedings of the National Academy of Sciences 105(36): 13451-13455. DOI: 10.1073/pnas.0803650105

Hert J, Jelinek L, Pekarek L, Pavlicek A. 2011. No alignment of cattle along geomagnetic field lines found Journal of Comparative Physiology A. DOI: 10.1007/s00359-011-0628-7

Photo by clarissa~ on Flickr; used under a Creative Commons license.

Are magicians master mimes?

Research on magic has been getting a lot of attention recently, but most of the focus has been on the psychology of the audience.

But what can we learn by studying the performer?


One of the things you need to be a magician, particularly a close-up magician who works with cards or coins, is dexterity. I tried to learn some basic card tricks once, and failed. It requires some very fine motor control, and I didn’t put in enough work to master it.

ResearchBlogging.orgMany illusions rely on the magician imitating a movement they would make as if they had an object in hand. For instance, some tricks might revolve around pretending to toss a coin from hand to hand, when there is no coin. Peoples’ expectations can be so strong that they will often swear to seeing a coin moving from hand to hand, even when there was no coin.

Are magicians better at this than untrained people? Cavina-Pratesi and colleagues decided to find out.

They recruited experienced magicians and people who were not, and gave them some simple tasks.

See a block on a table, grab it, and move it, or;

See a block on the table, pretend to grab it, and move it.

This was a bit more complicated than it sounds, because the experimenters threw in a twist: you couldn’t see what you were doing.

They used some funky liquid crystal glasses that can switch from transparent to opaque in an instant by applying a little electrical current. This is the same technology used in some new 3D video systems.

People got to see the table, the object they had to pick up and move, but as soon as they started to move their hands, it all went dark, and they had to remember the rest of the move.

When they did this, there were consistent differences across the board between the movements made when people actually picked up and moved an object compared to when they pretended to move the object. Everyone was slower moving their hands when miming, so it isn’t the case that magicians can perfectly mimic their make-believe movements.

On some other factors, the two groups were distinct. Non-magicians tended to hold their fingers together more closely when miming than when they held the real object. Magicians kept their fingers about the same distance apart with both the real and imagined objects.

In a second experiment, people had to do the same sort of task, except in some conditions, there was no object for them to on the table. Instead, they had to imagine moving some familiar object, like a battery.

Without that short-term visual cue and working only from their long-term memory of object size, the magicians did no better than the non-magicians.

There is something different in how magicians are pretending to move things, but what is it? It seems like the magicians are able to use visual information in a different way than non-magicians. The authors put it this way:

(T)he pantomimed actions made by magicians may be indistinguishable from real ones because they have learnt that the best way to fake an action is by performing it “for real”. The talent of magicians therefore lies in their ability to
use visual input from real objects to calibrate a grasping action toward a separate spatial location (that of the imagined object).

Is this skill unique to magicians? Not clear. A follow-up might be to see if other people with lots of motor training perform like the magicians do. Trained mimes or other actors, for instance. Or maybe pianists, who also have highly developed motor control of their fingers, but don’t use use it in creating illusions.

The next logical step in figuring out how magicians are pulling this off is to get a bunch of untalented amateurs, and teach them magic. Then, see what happens as they get better and better. Maybe even throw in a few physiological measurements. Some recordings of muscle activity, or maybe even some brain scans.

That would be an experiment that I totally sign up for. It would be a great excuse to try to learn magic again – for science!

Reference

Cavina-Pratesi C, Kuhn G, Ietswaart M, Milner A. 2011. The magic grasp: motor expertise in deception. PLoS ONE 6(2): e16568. DOI: 10.1371/journal.pone.0016568

Related post

Magic for dogs

Photo by Christophe Verdier on Flickr; used under a Creative Commons license.

15 February 2011

Tuesday Crustie: Macho


Following on last week, here’s more proof that crustaceans can be terrifying. For some people.

For more “They don’t make ‘em like that any more” men’s magazine covers, go visit this gallery in The Art of Manliness. Besides crabs, men in the 1950s also fought flying rodents, monkeys, weasels, giant turtles, and giant otters.

Comments for first half of February 2011

JL Vernon thinks science blogging is going to turn us all into Carl Sagan. I’ve heard this song before.

PF Anderson documents a conversation about Prezi she had with many on Twitter that included me.

14 February 2011

Promises versus trust

If you’re reading this, chances are you have more than a passing interest in science. You’re probably convinced that science is, on the whole, a good thing.

Two entries on the web on Friday were both about convincing people of the worth of basic science.

Holly Bik wrote a post on the Scientific American Guest blog:

Marine sponges are practically a gold mine. The mere mention of this phylum elicits Pavlovian salivation from pharmaceutical companies—in addition to malaria, sponge chemicals are leading the fight against tumors, cancer, bacteria, inflammation, and arthritis. Even sponge skeletons have been tested as ‘bioscaffolds’ to help heal bone and cartilage injuries.

Holly and I had a conversation on Twitter about this. I worry that in trying to advocate for basic research, we make two mistakes:

  1. We define “benefits” very narrowly, usually medicine.
  2. We oversell those potential benefits.

Holly replied:

Unfortunately a lot of people only relate ‘benefits’ to human medicine. I was playing the game to get the msg across & open eyes.

It was reminiscent of this cartoon:


Hannah Walters chipped in that she thought “because it’s awesome” is an honest way to talk about research, but it’s hard to put that into a sound bite.

Coincidentally, Randy Olson wrote an editorial on this the same day:

But research scientists are in a different situation. And yet, they too need the public’s support. So how can they achieve this?

The answer is trust. People support institutions they trust. Scientists have a long record of success. They have brought us technology, cured diseases, and improved the standard of living for humanity. Rather than pointing to the future and asking the public to hope for their continued success, scientists can draw on their past record to win public trust.

And this is one reason why I am always telling scientists that one of our biggest advantages is our lack of pretense, our honesty, and authenticity.

(S)upport for science will come not from the promise of future solutions but from telling stories about solutions achieved in the past.

With that in mind, I reread Holly’s blog. What stories are there about solutions achieved in the past?

In parasitology we learned that Artemisinins, some of the most potent and effective anti-malaria drugs, were originally discovered in an unremarkable pan-Eurasian herb, Artemisia annua (annual wormwood).

There is a potentially great story... but it’s just one sentence! You could do a whole post – at least! – just telling that story.

Plus, one of the great things about stories and building trust is that it can take the long view. James Burke’s epic television series Connections come to mind as a model for telling great stories about science that show how one discovery can simmer for a long time before triggering some other finding.

Promises are most effective when they’re made and fulfilled in the short-term. A promise to do something in 50 years isn’t much of a promise. Science is horrible at keeping promises.

Stories can span decades and generations. That’s the time frame that science operates at, and excels at.


12 February 2011

In which I celebrate Darwin Day with a local storm in a teacup over evolution

Our local newspaper, The Monitor reports that a potential science exhibit got people riled up. The reason? It features evolution.

“We’re very offended by it because it’s a theory that’s being presented as fact,” said Ruth Ann Jones, president of the Westway Avenue Neighborhood Association.

Together, the panels would explain the scientific history of the universe, starting with the big bang and ending with the evolution of man.

Sigh.

Aside to the reporter: people evolved, not just men.

Public displays and statues and exhibits are always a source of controversy in communities. I bet that you can go to any moderately sized town, and you’ll find some statue that someone will point to and gripe, “Can you believe our town paid thousands of dollars for that ugly thing?”

I have not seen this particular exhibit. I might agree that it is an eyesore. I might agree that it should not be put up in that location. I might agree that the city shouldn’t have bought it.

A collaboration between McAllen and the International Museum of Art and Science, the exhibit cost about $100,000, said Sally Gavlik, McAllen’s director of parks and recreation. Her department has been tasked with finding a home for the exhibit, which McAllen acquired several years ago.

That is quite a bit of cash.

While most people who spoke registered their opposition to any city-endorsed exhibit explaining evolution, they also criticized the project’s aesthetic appeal and said the money could be better used improving lighting on the trail and planting vegetation.

Since the exhibit was bought years ago, saying that the money could be used for something else is almost moot point.

The price you pay for living in a tolerant, pluralistic society is that you will be presented with ideas you don’t agree with. One local politician appears to understand this:

“The city has events like La Posada and the mayor’s prayer luncheon. We start our city commission meetings with a prayer. I think to go down this path, it’s dangerous — because it’s a slippery slope,” Ingram said. “If these individuals oppose these sorts of exhibits, they’re opening the door for others to oppose La Posada, starting our meetings with a prayer and the mayor's prayer luncheon. I think that’s unfortunate because that would hurt our sense of community.”

Happy Darwin Day, everyone.


Statue photo by bastiman on Flickr; used under a Creative Commons license.

11 February 2011

Deserving cheap degrees

Texas, like every other state in the U.S., is having a hard time making ends meet. And this has big implications for state institutions like the one I’m at. So the governor’s recent comments on higher education in the state of the state address were interesting.

One idea that emerged from that process is called “Outcomes-Based Funding” in which a significant percent of undergraduate funding, would be based on the number of degrees awarded. Texans deserve college graduation for their hard-earned tax dollars, not just college enrollment.

Ah, that word again: “Deserve.” If we were in ancient Greece, I might say that only the gods know what people deserve. Maybe everyone deserves to be a millionaire. And you can make that happen. But then a loaf of bread will set you back $500,000.

I just can’t see how changing the funding incentive to graduation can lead to anything but pressure to lower standards. And what will happen when Perry’s revered employers start to realize that they’ve hired incompetent screw-ups?

This also ignores that people don’t complete degrees for all sorts of personal reasons, not just because the university fails somehow to provide a service. People drop out to start businesses, families, find they are uninterested. These are not factors that an institution can control, short of kidnapping, bribery, and other nefarious deeds.

I’m challenging our institutions of higher education to develop bachelor's degrees that cost no more than $10,000, including textbooks.

Let’s leverage web-based instruction, innovative teaching techniques and aggressive efficiency measures to reach that goal.

Interesting. I looked at my own university’s costs. We have one of the lowest costs in the state of Texas. Cost for our resident students are way over Perry’s $10,000 mark in one year. I have no idea how Perry can suggest cutting costs to less than 25% of what they are now as an achievable goal.

Perry’s challenge has about as much chance of happening as challenging automobile makers to create a car that gets 120 miles to the gallon. You can do it, but the transformation you’d have to undergo would be so radical that you might end up losing a lot of value.

You can make a vehicle that gets over a hundred miles per gallon. It’s called a bicycle (estimates of mileage here and here; regardless of the exact numbers, bicycles are mighty efficient). But I don’t know if the governor would appreciate getting a bicycle in place of a car.

Additional: The College Guide blog reaches similar conclusions.

10 February 2011

What big eyes you have!

“My goodness, Gammarus, what big eyes you have!”

ResearchBlogging.orgThere are a lot of possible answers to Red Riding Hoods question. You might have big eyes to help you navigate in the world, to find resources, mates, and all sorts of things. If you see variation in eye size in populations, it will be tricky to figure out what the selection pressure on eye size is, because eyes do so many different jobs.

In the case of one amphipod crustacean, the answer to Red’s question seems to be:

“All the better to see predators with, m’dear.”

Gammarus minus is a small, freshwater crustacean. Douglas Glazier and Travis Deptola were lucky enough to find five springs where this little bug lives. Two of them were nearly predator free. Amphipod paradise! Three other springs, though, were also home to a fish predator with the suspicious-sounding name of the slimy sculpin. With a name like that, you know that’s a fish up to no good. Two of the springs have quite large numbers of sculpins, and one had sculpins, but far fewer. The sculpins appear to be the major predators in these springs, though the authors note that the two with the highest number of sculpins also had the occasional trout.

Glazier and Deptola went through all five springs in one day, catching sculpins. They standardized the area and time spent looking for the fish. Not only did they count all the sculpins they found, they took and weighed them all in the lab.

They also caught amphipods from each stream, took them back to the lab, and measured the size of their eyes and their body length.

The authors show that the eyes are smaller in the spring without sculpins, and in the one with the smallest number of sculpins, than in the two springs with lots of sculpins.

It’s tricky to interpret this result. It would be cleaner if eye size fell right along a “sculpins / no sculpins” dividing line. Instead, you have to start thinking about what the threshold of selection pressure is, how many fish prey upon how many amphipods, etc.

The authors don’t detail any relevant behaviour here, either of the crustacean or the fish. It’s reasonable to think that the amphipods avoid the fish by visual cues, but the authors do say that this sculpin is “relatively inactive benthic fish.” I could imagine some fish would have predation strategies that slightly larger eyes would not help to avoid. A little more detail on how this fish feeds might help persuade that bigger eyes can help the amphipod.

This set of springs is a lovely little natural experiment, but I hope that follow-ups start to bring some more lab experiments to bear on relationship of predation and eye size.

Reference

Glazier D, Deptola T. 2011. The amphipod Gammarus minus has larger eyes in freshwater springs with numerous fish predators. Invertebrate Biology. DOI: 10.1111/j.1744-7410.2010.00220.x

Gammarus photo from here. Sculpin photo by Noel Burkhead on Flickr; used under a Creative Commons license.

09 February 2011

Are prizes good for science?

Last Friday’s post on Nobel prizes got a lot of attention. This may be because I promoted the post with a provocative title on Twitter: “Why Nobel prizes are the enemy of science.” (Hey, at one point I was thinking of using the title, “Why the Nobel prizes are evil.” I scaled back.)

Given the argument that Nobel prizes and other “status symbols” have bad effects, it was fair comment to point out that here on this very blog, I promote my own successes. I’m not shy about pointing out that I’ve had posts in Open Lab, or putting links to some of my new papers. This made me think more about awards, and whether they have good effects.

Do you do science to win awards?

The more people answer that question, “Yes,” the bigger the problem of awards becomes.

It’s nice to get an award. Having hard work and achievement recognized is undeniably pleasant. But is that why you do what you do? For most people, according to Dan Pink, the big three reasons people are fulfilled by doing something is autonomy, mastery, and purpose. The further you get away from those and towards external incentives (like awards, money, and other secondary reinforcers), the outcomes, Pink argues, typically get worse, not better.

That is, while I’m proud that I’ve had posts in Open Lab, I don’t blog to get something in Open Lab.

You might also ask why I picked on the Nobel prizes in particular. There are plenty of prizes, so if it wasn’t the Nobel, wouldn’t it just be something else? Probably. But as of right now, the Nobels aren’t a prize. They’re the prize. And for whatever strange set of reasons, that main event has gained more and bigger sideshows (some welcome, some not) than any other award.

I also mentioned money in the post. Grants are different than award in some ways. To get science done, you need money in most cases. You need a lot of money in some cases. But I’ve heard too many stories about how at some institutions, scientific worth is evaluated by the number of dollars brought in. This makes about as much sense as arguing that X-Men Origins: Wolverine was a better movie than the latest Star Trek because it had a bigger opening weekend at the box office. (Yes, I overheard someone make that argument.) Money in science should always be a way to reach the goal, not be the goal itself.

Publications also have this double edged element to them: they should be a means, but for many people, they become an end unto themselves.

All of these can become a problem when people not only aspire to them, but come to think they deserve them. Nobel laureate Gerald Edelman said in a recent interview that one of the problems with the prizes was that some people didn’t get prizes who “deserved” them. You hear arguments about this getting their “piece of the pie” in regards to grants (“Old has-been PIs are hogging too much of the money!” “Young PIs with no experience can’t judge the quality of my science!”) I find figuring out what people “deserve” to be complicated and time consuming. But I do know that a sense of entitlement is rarely appealing.

It’s a matter of means, ends, and side effects. To me, the end goal of science should be good evidence, strong predictions, and less ignorance about the world. Money is a means to the end. Awards are a side effect.

I’m still thinking on this, but I hope I’ve managed to get a little more nuance than in my previous post.

Photo by AlaskaTeacher on Flickr; used under a Creative Commons license.

08 February 2011

Tuesday Crustie: Pulp fiction

I have to say that I have a hard time finding crabs scary. But some do...


And the best part of this? There isn’t just the one book. There’s an entire series of crab-based horror novels by Guy N. Smith.

07 February 2011

Carnivals for February 2011

Encephalon #83 is at Providentia.

Carnival of Evolution #32 is available at Denim and Tweed.

Finally, Circus of the Spineless #59 is hosted at Shell and Mantle

I’ve got a brain carnival, an evolution carnival, an invert carnival... if I had an ethology carnival, I’d have a personal scientific carnival quadrafecta.

Oh, don’t forget Carnival of the Blue #45 is just a post behind this one!

Carnival of the Blue #45

The epipelagic: The sunlight zone


The surface of the ocean is the place that most of us are familiar with, since this is where the water meets the land. Humans have been driving stakes into the mud flats and beaches for generations.

The interactions of humans with the denizens of these shallow waters are not always... friendly. And well lit does not always mean “visible.” Heed well the tale of Ivan, he who stepped on a stonefish and live to tell thee the tale.

On rockier shores, we get tidal pools that house delightful animals like hermit crabs. There are more crabs than snails in some places, according to Wandering Weeta. This clearly warrants further investigation.

This top layer of the ocean is also where the fresh waters of the land mix with the salt waters of the seas. Some fish brave both environments. Salmon are born in the fresh waters of rivers and streams, the live their lives trying to find their way home again. This clearly warrant immortalization in poem.

The mangroves are often near all the interface of all three: the sea, the fresh waters, and the land. Fishpond Fever looks at the sediments and bacteria you’ll find down among the mangrove roots...

The mesopelagic: The twilight zone





Going deeper, light is slowly filtered out. But you can still make out human activity at some of these depths. Like, say, establishing an oil rig. Last year, of course, oil drilling led to an massive escape of oil in the Gulf of Mexico. Emily discusses a report about the BP oil accident and wants your take.

The bathypelagic: The midnight zone





This deeper layer probably makes up a large amount of the total volume of the world’s oceans. When Danielle Meitiv talks about how the ocean will absorb the carbon dioxide humans are putting into the atmosphere, this is probably where much of it will end up (even if we’re more focused on shallower waters where corals live). Danielle’s good news is that some chemistry might mitigate things.

Abyssopelagic: The abyss


Light doesn’t penetrate to the deep sea. The only light to be see are those of biolumiscent animals, and those we bring ourselves. It’s no wonder that Danielle calls the ocean deep the most mysterious ecosystem on earth. (Incidentally, she describes how not to preserve a giant isopod.)

Hadopelagic: The trenches


Finally, we have the deep ocean trenches. Sadly, there were no posts on the literal ocean trenches, so let me to play with the double meaning of “in the trenches”: not only can it mean being in the deep ocean, it can mean being in a difficult working environment.

When you’re being sexually harassed by a giant sea turtle during your working day, you might wish that you could escape from the workplace trenches to the actual trenches. Just for a little while.

As we ascend back to the surface, prepare for next month’s dip into the depths at Oceanographer’s Choice! And the Carnival is looking for hosts for the second half of the year.

Salmon picture by toddraden on Flickr; trench photo by drakegoodman on Flickr; used under a Creative Commons license.

04 February 2011

Texas ice 2011

Walking home last night:


I realized two things.
  1. It was probably a smart move that the university decided to close for the day.
  2. I was going to have the only windshield scraper around. Who else but a Canadian would have one in South Texas? I could make a killing lending it out the next morning!

The power went out in my apartment about 10:45 pm. Came back on briefly a while after that, but when I woke up this morning, it was out again. I was curious to see what it was like out, so I put on my winter jacket and headed outside.



The sidewalks and roads were mostly bare, but  there was ice on the grass and the trees.


The Science building was on emergency power only when I went by, so I trundled back home for a while. Power finally came back on at about 10:55 am. By noon, it had turned sunny, and the ice was starting to melt.


I’ve put up a few more selected photos on Flickr.

Of Pandas and People publisher pulls back

Texas Freedom Network reports that the the Foundation for Thought and Ethics, publishers for the “intelligent design” / creationist textbook Of Pandas and People, has changed its plan to submit educational materials for review for possible use in Texas K-12 schools.

The publisher says on their website that they intended to withdraw from consideration back in November, but that they hadn’t realized an actual hard copy signed letter on paper was necessary to do so.

Will you still love me if I don’t win the Nobel prize?


Yesterday, I posted a link to this article about a woman getting out of Science on Twitter. It got a huge number of re-Tweets. And, because the scientific community is that small, some knew this person personally and collaborated with her.

I’ll bet there are going to be a lot of blog posts in response to this article. There’s a lot going on in it.

The thing that struck me most were the repeated references to Nobel prizes and Nobel prizewinners. First, she works in a lab that has generated multiple laureates:

I got the top first in my year and applied, with a mixture of terror and chutzpah, for a Ph.D. at the Medical Research Council Laboratory of Molecular Biology (LMB) in Cambridge, which was then at the pinnacle of science in the United Kingdom; seven scientists working there during my time have gone on to win Nobel Prizes.

Then she works with someone who become a Nobel winner.

I graduated with a solid Ph.D. from LMB after 3 years and then went for postdoctoral work in San Francisco with J. Michael Bishop... With a pretty good curriculum vitae in hand, I came home in 1989 – the same year Mike won a Nobel Prize – to a tenure-track job, running my own research lab at a University of London institute, where I remained until the sad demise of my career.

Her estimation of her scientific worth becomes measured against Nobel winners.

My initial conviction – essential for anyone who wants to make it as a scientist – that I could really make a difference, maybe even win a few prizes and get famous, eroded when I realized that my brain was simply not wired like those of the phalanx of Nobelists I met over the years; I was never going to be original enough to be a star.

It all ends with an industrial-grade case of imposter syndrome:

My loss of belief in my own potential was the first step toward where I am today. Once I had decided I would never be shaking hands with royalty in Stockholm, I downgraded my career expectations drastically, in a way that fellow failed perfectionists may recognize.

Over and over again: the measure, the yardstick, the standard of worth is the Nobel prize.

I’ve never understood this obsession with the Nobel prize.

Back in grad school, I said over dinner with a guest speaker that I never got the mentality of people who aspired to win a Nobel prize. This generated an anecdote about Konrad Lorenz. Lorenz was heading an institute, and when time came for him to step down, someone remarked to Lorenz that it would be hard to find a replacement for.

“Well, you can’t really replace me,” Lorenz said. “I’m a genius.”

It’s not just the Nobel, of course. It’s getting papers in Science and Nature. It’s who can bring in the most grant money. It’s who can run the biggest labs with the most grad students and post-docs.

None of this is healthy. Let’s not pretend that merit is the one and only factor in scientific success. The pursuit of fame in science is subject to the same vagaries of luck and chance as in arts like acting and music.

It’s a little demeaning for people who don’t work in fields that win Nobel prizes or get published in Science, Nature or Cell or is funded by the biggest government agency. Because having yardsticks for greatness that are unattainable in some fields means that you have to spend your career getting subtle signals that you are a second class scientist.

In my classes, I often tell my students about some research that won the Nobel prize – Lorenz and Tinbergen and von Frisch, or Hodkin and Huxley – then end with, “It should have been the Nobel prize in biology. But there is no Nobel prize in biology.”

I’m glad for that. Because there seems to be something strange and corrosive about that particular prize that breeds avarice and envy.

I wonder if mathematicians feel the same way?

Picture by quinn.anya on Flickr; used under a Creative Commons license.

03 February 2011

Analysis of an extreme meterological even in South Texas

If you visit out university website, you will be informed that things are bad. Very bad. Mother Nature has it out for us and is going to try to do us all in:


It must be serious! They’ve put an exclamation point in the “A” and everything!

And look at that graphic! There are snowflakes in it!

I decided that I had to be brave and document this natural disaster. So I went outside and...


...thought it was okay.

But you can see how the freezing temperatures have... have...


...not frozen anything.

Yes, it’s chilly. This is the coldest I’ve been for a few years here. And I understand it may get worse. But I was perplexed by having a meeting this afternoon cancelled “because of the weather.” I’ve lived through severe weather. I know severe weather. This is not severe weather. Yet.

Bizarre moment this morning was seeing someone walking around campus with a scarf wrapped around her face... with her coat unbuttoned. People unclear on the concept?

(I almost sent this post to the JAYFK before I realized there was was no science to speak of.)

Ptarmigans on ptreadmills

ResearchBlogging.orgYou might not want to fly because of the pat-down, but a bird might not want to fly because it’s hard work. As the old joke goes, “I just flew in from New York, and boy are my arms tired.”

Typically, the faster you want to go, the more energy you have to burn. But it’s not a simple relationship. I can walk home from work, or I can run. But if I’m in a hurry, but not too big of a hurry, is it easier to walk fast, or run slow? Have you ever tried walking as fast as you can? It’s hard! It’s often easier to speed up a little and switch to a slow jog.

The relationship between speed and energy gets even more complicated when you start to look across other animal species. The patterns are different for large quadrupeds versus large birds. Large running birds, like ostriches, have been studied fairly well, but small running birds haven’t been. Small running birds like Lagopus muta here:


This is a ptarmigan, a wide-ranging ground-dweller of a bird. Nudds and colleagues were interested in how these small birds used energy during locomotion, so they put them in treadmills, measured how much oxygen they breathed as they ran, and filmed them so they could see when they were walking or running.

The running is a little complicated, because there are two ways that ptarmigans run. There’s grounded running, where the foot is on the ground more than 50% of the time, and aerial running, where the foot is on the ground less than 50% of the time. It’s faster than grounded running. Buried in the methods is a passing comment that aerial running is also called...


Groucho running. And people think scientists have no sense of humour.

The results are fairly simple to sum up.

The faster the ptarmigans moved, the cheaper it got for them.

Walking used more energy per distance moved than grounded running, which used more energy per distance moved than aerial running.

Ptarmigans are the first birds to show this counter-intuitive result, but they’re not the first animal to show this. Kangaroos show something similar, with the typical explanation that kangaroos are able to use their tendons like springs to store energy. The ptarmigans have some leg tendons that might contribute here, but how big a factor that is remains to be seen.

There are hints of similar patterns of increasing efficiency with increasing speed in roadrunners, but the data there aren’t conclusive. This means either:

  • Many small running birds may run more efficiently than they walk, or;
  • Ptarmigans alone can run like a boss.

Regardless of how general the ptarmigan pattern is for small birds, it’s still rather different than most other animals. Even the similarity between kangaroos isn’t very strong, because kangaroo hopping isn’t very similar in form to ptarmigan running.

Why would ptarmigans ever walk or use grounded running? It’s easy to see the advantage of moving slowly for walking. You may want to avoid rapid movement to avoid injury or to avoid drawing attention to yourself.

It’s trickier to know when the animals might prefer to use grounded running, which seems to be the worst of both worlds: slow and more costly than aerial running. An answer to that question probably won’t come from lab studies. It will probably require researchers to go into the field and watch a lot of ptarmigan locomotion.

P.S.—Yes, I wrote the entire post just because I wanted to use that silly ptitle.

Reference

Nudds R, Folkow L, Lees J, Tickle P, Stokkan K, & Codd J. 2011. Evidence for energy savings from aerial running in the Svalbard rock ptarmigan (Lagopus muta hyperborea). Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2010.2742

Photo by omarrun on Flickr; used under a Creative Commons license.