February 9, 2010
Category: Animal behaviour • Animal defences • Animals • Insects • Invertebrates
Mothers can teach their children much about the world, but some mothers can do it without ever meeting their young. Take the field cricket Gryllus pennsylvanicus. A female cricket isn't exactly a caring mother. Once she lays her eggs, she abandons them to their fate. But amazingly, she can also forewarn her young of the dangers they might face. If a pregnant female is exposed to a wolf spider, her experiences affect her unborn young. When they hatch, the baby crickets are more likely to freeze when they smell wolf spiders nearby.
If mothers sense a threat in their environment, there are clear advantages in being able to prepare her young to face those threats. Over the last decade or so, scientists have discovered that many animal and plant mothers do exactly this, even before their young are born. If pregnant water fleas are exposed to the smell of a predatory midge, they produce young that are armed with larger "crowns-of-thorn", defensive spiky helmets that make them difficult mouthfuls. In the same way, aphids produce more winged offspring if they sense danger. Even the humble radish can generate a generation with sharp, spiky hairs.
In all of these examples, the adaptations are physical ones. The case of the crickets, documented by Jonathan Storm and Steven Lima at Indiana State University, is the clearest example yet of mothers preparing their young for life by influencing their behaviour. Physical defences wouldn't do much good here, for even the largest of crickets are easy pickings for spiders.
Storm and Lima bred crickets that had never seen a wolf spider before. They placed pregnant females in cages with wolf spiders whose killing fangs had been disabled with wax. After a while, the females were removed and allowed to lay their eggs. Storm and Lima collected the hatchlings and placed them in plastic arenas lined in paper saturated with the faeces and silk lines of wolf spiders.
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Posted by Ed Yong at 9:30 AM • 3 Comments • 0 TrackBacks
February 8, 2010
Category: Fairness • Morality • Psychology
The English language is full of metaphors linking moral purity to both physical cleanliness and brightness. We speak of "clean consciences", "pure thoughts" and "dirty thieves". We're suspicious of "shady behaviour" and we use light and darkness to symbolise good and evil. But there is more to these metaphors than we might imagine. The mere scent of a clean-smelling room can take people down a virtuous road, compelling them to choose generosity over greed and charity over apathy. Meanwhile, the darkness of a dimmed room or a pair of sunglasses can compel people towards selfishness and cheating.
These new results are the latest from psychologist Chen-Bo Zhong. Back in 2006, he showed that people who brought back memories of past wrong-doings were more likely to think of words related to cleaning, or to physically crave cleaning products. He called this the "Lady Macbeth effect". Subsequently, another group found that it works the other way too. People judge moral transgressions more leniently if they had previously washed their hands or if they had been primed with words related to cleanliness, like 'pure' or 'immaculate'.
Now, Zhong, together with Katie Liljenquist and Adam Galinsky, have expanded on these studies by showing that clean smells can make people behave more virtuously. They ushered 28 volunteers into a room that was either unscented or that had been lightly sprayed with a citrus air freshener. In either case, they had to play a trust game, where a "sender" has a pot of money and chooses how much they want to invest with a "receiver". The investment is tripled and the receiver decides how much to give back.
The volunteers were all told that they had been randomly chosen as receivers. Their anonymous partner had invested their entire $4 pot with them, which had been tripled to $12. Their job was to decide how much to give back. On average, they returned a measly $2.81in the unscented rooms but a more equitable $5.33 in the scented ones. The single spray of citrus nearly doubled their tendency to reciprocate.
In a second experiment, the trio again ushered 99 students into either a scented or unscented room. They were given a pack of miscellaneous tasks, including a flyer requesting volunteers for a charity called Habitat for Humanity. Those in the citrus-scented rooms were more likely to be interested in volunteering, and almost four times more willing to donate money to the cause.
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Posted by Ed Yong at 9:05 AM • 11 Comments • 0 TrackBacks
February 7, 2010
Category: Animals • Mammals • South African wildlife
These are rock hyraxes or dassies. They may look like guinea pigs, but they're in an entirely different order of mammals. It's sometimes said that they are the closest living relatives of elephants. However, some scientists would dispute that sirenians - the manatees and dugongs - are more closely related still, with the hyraxes as a more distant outgroup.
They're nimble animals, scuttling comfortably across rocky terrain and even climbing trees with relative ease. They can often be spotted basking in the sun to raise their body temperature, not unlike a reptile would. We found this pair in Tsitsikamma National Park.
Posted by Ed Yong at 11:57 AM • 4 Comments • 0 TrackBacks
February 5, 2010
Category: Amphibians • Animal behaviour • Animals • Evolution • Speciation
Toads are an evolutionary success story. In a relatively short span of time, they diversified into around 500 species and spread to every continent except Antarctica. Now, Ines van Bocxlaer from Vrije University has uncovered the secrets of their success. By comparing the most home-bound toads with the most invasive ones, she has outlined seven qualities that enabled these amphibians to conquer the world. In a common ancestor, these seven traits came together to create an eighth - a pioneer's skill are colonising new habitats.
Some, like the harlequin toads, are restricted to such narrow tracts of land that they are vulnerable to extinction. Others, like the infamous cane toads, are highly invasive and notoriously resistant to extinction despite the best efforts of Australians and their sporting equipment. This diversity of lifestyles allowed Bocxlaer to search for characteristics shared by the most pioneering of toad species.
She compared over 228 species, representing just under half of all the known toads, and constructed a family tree that charts their relationships. She showed, as others before have suggested, that the family's fortunes kicked off in South America, around 35-40 million years ago. This was the start of their global invasion.
Seven qualities make for wide-ranging toads. For a start, the adults don't have the typical amphibian dependency on constant water or humidity. They have skins that can cope with the drier side of life, giving them a chance to seek out new habitats away from the safety net of moist environments. Secondly, they tend to have fat deposits near their groin, which act as a back-up energy source when food is scarce. Thirdly, they tend to be larger (meaning at least 5 centimetres in length), which also helps to conserve water. Larger animals have larger bladders so they retain more water, and they lose less of it because they have small surface areas for their size.
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Posted by Ed Yong at 9:21 AM • 5 Comments • 0 TrackBacks
February 4, 2010
Category: Dinosaurs • Palaeontology
National Geographic should have a 3-D animation up soon
The pursuit of accurate dinosaur colours just turned into a race, and a heated one at that. Just last week, I wrote about a group of scientists who claimed to have accurately identified the colours of some feathered dinosaurs by microscopically analysing three fossils. According to that study, Sinosauropteryx had a tail covered in ginger stripes. Now, another group have revealed the palette of an entire dinosaur, Anchiornis. This tiny predator had a dark grey body and the limbs bore long, white feathers tipped with black spangles. Its head was mostly grey with reddish-orange and black specks, and an extravagant reddish-orange crown.
Both reconstructions are based on microscopic structures called melanosomes. They're partly responsible for the brilliant colours of modern bird feathers, they're packed with pigments, and they happen to fossilise well. There are two major types. Spherical 'phaemelanosomes' contain a reddish-brown or yellow pigment while the rod-like 'eumelanosomes' have black-grey tints.
The technique of inferring colours from fossil melanosomes was pioneered by Jakob Vinther at Yale University. He used it to show that a Cretaceous bird feather probably had black and white stripes and, later, that another fossil feather had an iridescent starling-like sheen. But these were analyses of single papers and even last week's paper coloured Sinosauropteryx by looking at just one part of a single individual.
Vinther isn't impressed with his rivals. "They are in the Stone Age when it comes to understanding melanosome fossilization and interpretation of original colors," he says. To him, it's simply not enough predict colours based on the presence of one type of melanosome. Even the hues of single feathers can depend on a mix of the two melanosome types with different concentrations of pigments. So you need to know the distribution of melanosomes across an animal and even then, you still need to work out how that translates to different colours.
And that's exactly what he's done. When I spoke to Vinther last week, he said, "We are still far from putting colours on dinosaurs [but] the future is promising. Eventually we will have dinosaurs in technicolour. We are working seriously on that currently." He wasn't kidding!
He had been working on a new specimen of Anchiornis with the catchy name of BMNHC PH828. The tail is missing but the rest of the skeleton is beautifully preserved, including the skull and both sets of limbs with their elegant plumes. Rather than looking at individual body parts, Vinther took 29 samples from the specimen, representing every type of feather types across different body parts. In each one, he thoroughly analysed the size, shape, density and distribution of melanosomes.
To interpret this goldmine of data, he worked with his colleague Matt Shawkey to catalogue the melanosomes from a wide variety of living birds, from ravens to finches to mallards. This modern data set was a cross between a paint catalogue and a Rosetta stone. It told Vinther how different combinations of melanosomes led to different colours and allowed him to correctly paint his Anchiornis.
Read on »
Posted by Ed Yong at 2:00 PM • 31 Comments • 0 TrackBacks
February 3, 2010
Category:
[It's probable that only British readers will understand the joke in the headline. Everyone else: just pretend it's an uproariously funny pop-culture reference and we can move on.]
This morning, the Times published a list of its 30 best science blogs and I'm incredibly honoured to be on it. Twice. Once for Not Exactly Rocket Science, and again for my efforts at Cancer Research UK's Science Update blog.
A bit of background - the Times recently launched a monthly science supplement called Eureka and every issue, one of its writers selects their favourite science blogs. This list is a compilation of the past however many selections.
And what a list - I'm doubly proud to be listed among some of my favourites, including such illustrious bloggers as Carl Zimmer, Vaughan Bell, David Dobbs, Bora Zivkovic, Brian Switek, SciCurious, Martin Robbins, Dan MacArthur, Revere, Gimpy, Jack of Kent, Chris Mooney, Sheril Kirshenbaum, Frank Swain and Orac.
This is also a good opportunity to give Mark Henderson, the Times's Science Editor, a hearty round of applause for his work in getting Eureka off the ground. In a climate where specialist science journalism is allegedly imploding, the fact that a major national newspaper has increased its science output is very heartening indeed. Mark also just gets the value of blogs and online reporting - hence the monthly shout-outs. So, cheers. Long may Eureka continue.
Finally, the Times wants to compile a definitive Top 100 list, so there's all to play for in the remaining 70 spots. Feel free to email your favourite blogs to them at eureka@thetimes.co.uk, with "Best blogs" in the subject line. Check out the blogroll on the left for some inspiration.
Posted by Ed Yong at 12:22 PM • 9 Comments • 0 TrackBacks
Category:
Nominations for the Research Blogging Awards 2010 are now open. These awards are designed to recognise "the best of the best" when it comes to posts about peer-reviewed journal articles.
Any blog that discusses peer-reviewed research is eligible for nomination, and the winners will be determined by votes from their peers in the Research Blogging community. All finalists will be highlighted on ResearchBlogging.org, and winners will receive cash prizes totaling $2000. Anyone can nominate blogs to be considered for the awards and nominations close February 11, 2010. Click here to nominate your favorites.
A panel of expert judges will select 5 to 10 finalists in each category, who will be announced February 25, 2010. Registered users of ResearchBlogging.org can then vote for the winners between February 25 to March 11, 2010. The winners will be announced on March 23, 2010.
Do vote for your favourite blogs and obviously, I will be grateful for any of you wanted to nominate Not Exactly Rocket Science in any of the available categories. I think I'm probably out of the running for Best Blog - German Language, but Best Blog - Biology and Best Lay-Level Blog are possibilities, as are Blog Post of the Year and Research Twitterer of the Year. All nominated blogs are automatically considered for the big prize of Research Blog of the Year
Posted by Ed Yong at 12:00 PM • 0 Comments • 0 TrackBacks
Category: Animals
"That is Shadowfax. He is chief of the Maeras, lords of all horses, and not even Theoden, King of Rohan, has ever looked on a better. Does he not shine like silver, and run as smoothly as a swift stream?" - Gandalf
In the Lord of the Rings, Gandalf rides upon a magnificent white stallion called Shadowfax. White horses have been greatly prized in human societies as a sign of wealth and dignity, largely because their bright coats are both pretty and rare. There are reasons for that. In the wild, the same conspicuousness that inspires legendary tales also makes white horses vulnerable to predators and sensitive to skin cancer. But they have an unexpected benefit - they make horses less attractive to horseflies.
Anyone who has been bitten by a horsefly (formally, a tabanid) knows that they're much more irritating than your average midge or mosquito. Rather than puncturing skin, their mandibles are designed to rip and shear. As a result, their bites hurt and they can drive grazing animals to distraction. They can also transfer serious diseases, including Equine Infectious Anaemia, parasitic worms, and even anthrax.
Now, Gabor Horvath from Eotvos University, Hungary, has found that white coats are more horsefly-proof than darker ones. They reflect very little polarised light - light vibrating on a single plane - and it's this light that horseflies use to track down their next blood meal.
On a sunny June day, Horvath watched two horses - one brown and one white - as they grazed in a local field. Both were almost continuously attacked by horseflies and had to defend themselves by tail-swishing, kicking, shuddering, head-swinging, biting, licking and even rolling on the group. But the white horse had the better time of it - photographs revealed that, on average, the brown horse had 3.7 times more horseflies on or near it. Eventually, the attacks were so irritating that the horses were driven into a nearby shady forest, where they gained a temporary respite. Again, the brown horse was always the first to cave and spent longer in the shade.
Read on »
Posted by Ed Yong at 9:30 AM • 6 Comments • 0 TrackBacks
February 2, 2010
Category: Neuroscience • Psychology
In Western films, the gunslinger that draws first always gets shot. This seems like a standard Hollywood trope but it diverted the attention of no less a scientist that Niels Bohr, one of history's greatest physicists. Taking time off from solving the structure of the atom, Bohr suggested that it takes more time to initiate a movement than to react to the same movement. Perversely, the second gunslinger wins because they're responding to their opponent's draw.
Now, Andrew Welchman from the University of Birmingham has found that there's something to Bohr's explanation. People do indeed have a "reactive advantage", where they execute a movement about 10% more quickly if they're reacting to an opponent. Of course, ethics committees might frown on scientists duelling with the pistols in the name of discovery, even if the people in question were graduate students. So Welchman designed a laboratory gunfight, played out using buttons rather than guns.
Two opponents faced each other and had to press a series of three buttons as quickly as possible. To begin with, they held a central "home key" with their trigger fingers and they had to wait for a short spell before before starting the round. The point where they were allowed to begin varied from trial to trial and the players weren't told how long it would be. There was no starting pistol or countdown. Either player could start the race but if they went too soon, an alarm would sound to signal a false-start.
These button-mashing duels revealed that, on average, the players completed their sequence 21 milliseconds faster if they reacted than if they initiated. That's an improvement of around 9%, and most of this advantage came at the very beginning, when they pressed the first button. It's an interesting result and like all good scientists, Welchman systematically considered and ruled out several possible explanations for it.
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Posted by Ed Yong at 7:00 PM • 24 Comments • 0 TrackBacks
