The wings of bats provide them with support and lift as they fly. But they are also giant sensors that tell bats about the flow of air around their bodies, helping them to execute sharp manoeuvres without crashing.
The wings’ ability to monitor airflow depends on tiny hairs that cover their surfaces. The hairs were discovered almost a century ago. Scientists suggested that they are sense organs that allow bats to fly in complete darkness. That idea fell out of favour in the 1940s when Donald Griffin and Robert Galambos showed that bats navigate by listening for the echoes of their own calls. The discovery of bat sonar solved the mystery of their night-time aerobatics, and the wing hairs fell into obscurity.
But John Zook at Ohio University had not forgotten about them. He has shown that the pre-sonar theories were partly correct. The hairs complement a bat’s echolocation and turn it into a better flier, allowing the animal to “feel” its way through the sky.
“The discovery of HIV enables us to develop a vaccine to prevent AIDS in the future… We hope to have such a vaccine ready for testing in approximately two years.” – Margaret Heckler, Secretary of Health and Human Services, April 23, 1984.
Twenty-seven years have passed since Heckler’s comment and no vaccine exists. There is a simple reason for this: HIV out-evolves us. HIV can produce around 100 billion new virus particles every day, and it does so with unusual imprecision. When most genetic material is copied with great fidelity, HIV goes for a sloppier approach. It duplicates itself with errors galore, creating a swarm of genetically variable viruses. It leaves a host looking very different to when it entered.
In the face of this rapid shape-shifting, any drug or vaccine soon becomes obsolete. Fighting HIV is like fighting a hydra – there are several heads and every time you lop one off, two more grow in its place.
If you walk by a European river on a summer’s day, you might get to hear the animal kingdom’s champion vocalist. His song sounds like a train of chirps, and from a metre away, it’s as loud as whirring power tools. The din is all the more incredible because it is produced by an insect just two millimetres in length – the lesser water boatman, Micronecta scholtzi
Micronecta means “small swimmer” and it is aptly named. It’s among the smallest of the several hundred species of water boatmen that row across the bottom of ponds and streams with paddle-shaped legs. The males are the ones that sing, and they often do so in large choruses to attract the silent females. These songs are famously loud. Even though the insect lives underwater, you can hear its call from the riverbank, several metres away.
Now, Jérôme Sueur from the Natural History Museum in Paris has measured Micronecta’s song using underwater microphones. He found that it the small swimmer is a record-breaker. On average, it reaches 79 decibels, about the level of a ringing phone or a cocktail party. But at its peak, it reaches 105 decibels – more like a car horn, a power tool or a passing subway train.
Three years ago, I started a thread asking readers to identify themselves, say something about their background, and tell me a bit about why they were reading this blog. These threads have become a bit of a yearly tradition and I find myself increasingly looking forward to them. I spend the whole year telling stories so it’s great to hear everyone else’s for a change, especially given the diversity that typically crops up.
So without further ado, let’s go again.
Tell me who you are, what your background is and what you do. What’s your interest in science and your involvement with it? How did you come to this blog, how long have you been reading, what do you think about it, and how could it be improved?
These questions are a rough guide. I’m working on the basis that what you have to say will be far more interesting than what I think you might say. Say as little or as much as you like, but do say something, even if you’ve never commented before and even if you commented on the previous ones.
(Photo by Marco Bellucci)
Spiders can tackle all manner of prey, from insects to fish to birds. But some of them specialise in killing their own kind. Palpimanus gibbulus and Palpimanus orientalis are two such spider-slayers, and they use special adaptations to tackle their dangerous prey, including ninja-like stealth, blinding-fast strikes, unbreakable grips, and heavy body armour.
Stano Pekár from Masaryk University in the Czech Republic confirmed that these two species (hereafter known as Palpimanus) are indeed specialist spider-hunters. They pounce upon a wide variety of other species and attack spiders more often than insects like flies or crickets. Using high-speed video cameras and staged battles, Pekár revealed their killer technique.
I have a piece in Nature News about the controversial claim that Mary Schweitzer has recovered proteins from the fossilised bones of two dinosaurs – Tyrannosaurus and Brachylophosaurus. These samples are 68 and 80 million years old respectively, and the discovery of proteins that ancient has been met by excited awe from some scientists and aggressive criticism from others.
Evan Ratliff wrote a fantastic piece about the debate circa mid-2009, and I blogged about the Brachylophosarus discovery that cropped up since. The new paper is an important part of the story because it addresses one of the biggest source of contention – the implausibility of proteins surviving for tens of millions of years. Here’s an excerpt, but do read the full thing:
Scientists have discovered how fragments of the protein collagen might have survived in fossilized dinosaur bones. The intertwining, rope-like structure of the molecule, a major component of bone, could have shielded parts of the protein from enzymes and the elements for tens of millions of years, they say.
The results, which are published in PLoS ONE, support the contentious claim that dinosaur proteins have been recovered and sequenced.
Collagen molecules consist of three long protein subunits that coil around each other in a triple helix. Five of these helices wind together to make up a microfibril, and thousands of microfibrils gather to form a fibril.
“It’s like a massive, multi-stranded rope,” says James San Antonio, lead author of the paper and a biochemist at Orthovita, a medical-implant manufacturer in Malvern, Philadelphia.
San Antonio’s team compared the recovered collagen fragments with models of human and rat collagen, and found that all 11 pieces came from the innermost parts of the microfibrils. Some originated in the same location in both dinosaurs. The researchers say that sites deep inside the collagen fibre would have been shielded from degrading enzymes and the environment.
From the ground, Heron Island looks like it has materialised out of a holiday brochure. It’s home to pristine beaches and lazing tourists, all surrounded by the turquoise waters of Australia’s Great Barrier Reef. But there’s an aspect to Heron Island that doesn’t fit with this idyllic vibe. It’s what Elizabeth Madin from the University of Technology, Sydney, has dubbed a “landscape of fear”. To see it, you need to take to the air.
Satellite images of Heron Island, freely available as part of Google Earth, depict the same vibrant colours. But around some of the reefs, there are distinct halos – light blue rings that encircle patches of rock and coral. These rings are caused animals such as fish and sea urchins, which munch on the algae and seaweed that cover the reef floor. These grazers hide from predators within the rocks and dart out to eat the surrounding algae, leaving behind a barren halo among an otherwise green landscape.
If you train intensively at long-distance running, you’ll find it easier to climb stairs or ride a bike. The running will boost your aerobic fitness and strengthen your leg muscles, providing benefits that transfer to other activities. Does our brain work in the same way? If we train ourselves on a specific mental task, do we become sharper across the board?
There’s a multi-million dollar industry that would like you to believe the answer is yes. Best-selling “brain training” games like Brain Age purport to give your brain a “the workout it needs” through a combination of word puzzles, number problems, Su Doku and more. Unfortunately, there is little good evidence that these games improve anything beyond performance on a specific task.
There are exceptions. Susanne Jaeggi from the University of Michigan has found that a simple exercise called an “n-back task” could increase the “fluid intelligence” of elementary and middle-school children (well, some of them; more on this later). It’s the latest of a series of studies showing that practicing at a single task can lead to a broader intellectual boost.
Fluid intelligence is a broad concept that includes abilities like abstract reasoning, solving new problems, spotting patterns and drawing inferences, rather than relying on knowledge, skills or experience. The n-back task isn’t meant to train all of these. Instead, it is meant to improve working memory – the ability to hold and manipulate pieces of information in our head. A good working memory is essential for problem-solving and reasoning, so Jaeggi reasoned that training the former would improve the latter, in the same way that building a runner’s fitness improves their cycling.