I suspect that many people, asked where you'd find marsupials, would answer 'Australia' & leave it at that. But while we may be most familiar with Skippy & his ilk, those pouched mammals across the Tasman have close cousins half a world away - in South America.

Beery bladders... yes, OK, if you drink enough beer your bladder will fill up, but that's not the focus of a delightful post by Scicurious on Neurotic physiology. It's a tale of how doctors followed their noses to find that several seriously ill patients had yeast infections - and a decidedly beery odour. And no, they hadn't been drinking contraband after lights-out on the wards.

Lose weight by taking public transport? Sounds almost too good to be true  - but Paul Statt reports that a recent study does seem to show that taking the bus or train is good for you, as well as good for the planet.

And for the ecologists: in 'War & Fish' David Malakoff of Conservation Magazine describes the results of a study looking at the impact of World War II on fish stocks in the North Sea. Bombs, mines, torpedos, & the general call-up of fishermen to join the war effort saw an effective cessation of North Sea fishing & a big bounce-back in fish stocks. An argument for marine reseves in that part of the world?

I know I've said it before, but you really do learn something new every day :) I was browsing through my collection of Science alerts & an item about Legionella caught my eye. Legionella pneumophila is the bacterium that causes Legionnaires' disease, so named because it was first identified when several people attending a 1976 meeting of the American Legion came down with a serious form of pneumonia. But what I didn't know was that this bacterium is able to grow inside the cells of those affected with it - it's what's known as a 'facultative' intracellular pathogen (where 'facultative' means that it doesn't have to live this way & can also live outside of the host's cells). This raises a couple of interesting questions - how does it manage to avoid being digested by the cells it infects, and how does it get the various bits & pieces that it needs in order to survive & reproduce?

A week or so back, one of the weekend papers ran a story on just how many beers someone needed to drink before they'd be legally too drunk to drive. The Significant Other & I were staggered to find that the answer was, A Lot. (Around 9, as I recall.) Speaking for myself, about 2 would do it for me - after that, I wouldn't feel safe to drive. And yet, as Christian Jarrett points out in BPS Research Digest, most people are hopelessly bad at recognising the signs of inebriation in others.

Those of you preparing for Level 3 or Scholarship exams at the end of the year will (among other things) be learning about human cultural evolution. Some of the evidence for the development of culture comes in the form of carvings, including of the human form - the various 'Venus' figurines are a good example. Over at Gambler's House, teofilo presents information on another type of representation: human effigy vases.

And on Deep-Sea News,  Kevin Zelnio writes about a beautiful arthropod fossil, new to science but very old in the scale of arthropod evolution. Just occasionally palaeontologists find spots (lagerstatten) where the fossil assemblages are rich and amazingly well-preserved. From one such site in China comes Yicaris, an ancient crustacean, and one that's probably very close to the point at which crustacea diverged from the other arthropod lineages. (The late Stephen Jay Gould would have loved this one!)

I do like being on leave - it's nice to have the chance to roam the science blogs more widely :)

A while ago now I discussed how some plants are able to warn others when they're under attack by grazing animals. Now it seems that these responses and interactions are even more subtle - a new paper describes how signalling chemicals in tobacco plants can be altered by the grazers' saliva (Allmann & Baldwin, 2010).

As I described in that earlier post, plants demonstrate a number of responses to grazing. They may produce chemicals that directly harm the grazing animal in some way: poisons, maybe, or substances that inhibit the animal's digestive processes. Other, volatile, chemicals allow communication with other plants - they signal the presence of herbivores and stimulate those plants receiving the signal to produce defensive chemicals in advance of any grazing attack. And it appears that some of these volatiiles can attract predators that in turn feed on the grazers.

X-rays were discovered in 1895 by Wilhelm Roentgen, a discovery that was to bring him the first Nobel Prize for physics. (No, I'm not really going to trespass on Marcus's territory! Well, not for long.) Like many other scientists of the time, Roentgen was experimenting with electtrifying the thin gases in vacuum tubes. One night he noticed that a fluorescent screen at one end of his lab glowed each time he ran a current through his vacuum tube. The screen continued to glow when Roentgen placed sheets of card, copper, or aluminium between tube & scrreen, but stopped when these were replaced by lead. This must have been startling enough, but he must really have been blown away to see the bones of his hand show up on the screen when his hand passed through the invisible rays emitted from the electrified vacuum tube. Roentgen had discovered X-rays.

Today X-rays are used in a wide range of applications. The structure of DNA was elucidated through X-ray diffraction photographs. Airport security systems use them to detect various proscribed items in travellers' baggage. (Recent developments in this area have led to concerns that customs officers might see more of a traveller than modesty might permit.) And of course there are the medical applications of X-rays, along with their more sophisticated spin-off, the CT (or computerised tomography) scan. CT scans are a signifcant medical tool, but they've also allowed scientists to examine some truly ancient indiviuals: CT scans of a Homo  floresiensis cranium have been used to build a 'virtual endocast' that models the indivdiual's brain & has been used to attempt to determine its affinities.

And where is this heading? Well, I now have a lovely X-ray of my left foot that shows very clearly what happens when your little toe connects at speed with a door jamb. The proximal phalanx of my little toe (that's the toe bone closest to the bones of the foot itself) is in 2 quite distinct parts. Ouchy ouch ouch! I must wear a moon shoe for the next few weeks,and the dog is Not Pleased. Not pleased at all.

Your immune system is a wonderful, complex, multipartite mechanism that usually allows you to fight off the attentions of the various pathogenic organisms (bacterial, fungal, and viral) that you'll meet during your life. I say 'usually' because it's not always successful on its own, and even where it is, you can be laid low for quite some time - think of flu, but also think of measles, mumps, smallpox, polio... This is where vaccination comes in: this 'primes' your immune system so that it can react far more rapidly when it encounters the actual pathogens themselves. NB for a taste of some 'alternative' thinking on this concept, try this thread over on SciBlogsNZ.

I have a dog. As a result, papers to do with dogs tend to catch my eye :) On his blog Neuroanthropology, Greg Downey reviews an upcoming book by Pat Shipman and discusses humanity's long relationship with canines. Beginning with the point that "the first animals domesticated were not food sources, but a fellow predator and scavenger: the wolf (dogs being descendants of wolves, even a subspecies by some reckoning). Clearly, domestication wasn’t first about eating the animal..." Our current relationship may have begun as a commensal one, with wolves following nomadic human hunter-gatherers - unfortunately this sort of thing doesn't exactly leave traces in the fossil record. A long post, but well worth reading (especially for those of you currently studying human cultural evolution as part of your NCEA L3 biology).

Jason Goldman writes The thoughtful animal.He's just discussed a paper looking at some intriguing behaviour in the Galapagos marine iguana. These reptiles are non-vocal, communicating among themselves through visual & olfactory signals. But - they appear to respond appropriately to alarm calls by mockingbirds, becoming more vigilant when the birds' calls indicate that a predator's on the prowl. This sort of interspecific eavesdropping's not unknown, but it's a first in a species that doesn't itself use sounds to communicate.

And at Tetrapod zoology, Darren Naish has a fascinating article about the strikingly ugly turtle, the matamata. Its weird looks are matched by its unusual feeding behaviour, for it catches prey not by snatching & biting but by inhaling it, expanding its throat to rapidly draw in large volumes of water along with whatever happens to be swimming in it at the time. How neat is that?

Parasites are ubiquitous. I remember watching a video (years ago, while I was teaching at secondary school) about parasites that make humans their home. Lice, eyelash mites (yes, really!), various intestinal worms... I tell you, I had psychosomatic itching for days after seeing that! Then I got my hands on Carl Zimmer's wonderful book, Parasite Rex - as well as learning all sorts of stuff about parasites & how they live, I also had it brought home to me that parasites aren't just some sort of passive, undesirable house guest - in many cases they actively influence the host's behaviour in ways that enhance the parasites' ability to complete their life cycles.

I was alerted to a recent paper in this area by a blog post from another Kiwi blogger: his sub-header was 'zombie ants controlled by parasitic fungus for 48 million years', which reall y took my fancy (the link will take you to a story in the Guardian, of which more later in this post). The authors of this paper (Pontoppidan et al. 2010) point out that it's not just a case of the parasite affecting individual ants - they can structure the entire host population in terms of its distribution in time and space & thus influence their own distribuiton: the parasite's 'extended phenotype', if you will.

On Thursday I was privileged to spend several hours (actually, a lot of the day as we didn't finish until about 8.45pm) judging the Waikato regional science fair. I always enjoy doing this as you get to speak with some wonderful young people who are doing some really good science. (It acts as something of an antidote, especially this year as I'd just written a few posts on pseudoscience -that MMS one among them - and was being to worry about the state of science understanding out there.) These young scientists are passionate about what they are doing and every year I learn something new. F'r instance, I overheard Marcus discussing the finer points of trebuchets with the builder of a modern-day form, & now I know why they were on wheels...