Discover Living World

Found: Dino-Munching Crocodiles Who Swam in the Sahara | 80beats

Fri, 20 Nov 2009 13:25:55 -0800

A thrilling set of ancient crocodile fossils have been unearthed in northern Africa. A “saber-toothed cat in armor” and a pancake-shaped predator are among the strange crocodile cousins whose bones have been found beneath the windswept dunes of the Sahara, archaeologists say [National Geographic News].

At a news conference organized by the National Geographic Society, which sponsored the research, scientists announced that the fossils represent 5 species; 3 new species and 2 that were previously known. These ancient croc ancestors, known as crocodilyforms, are unlike any crocodiles encountered in the Northern Hemisphere, according to the research team. Their findings are detailed in the journal ZooKeys.

The crocs were spectacularly diverse, and included a species that ate dinosaurs, two that grew up to 20 feet long, and two that had long legs for quick movement on land but also had long tails for swimming. The three new species are:

• BoarCroc (Kaprosuchus saharicus), a 20-foot meat-eater. It used its snout for ramming and three sets of dagger-shaped fangs for slicing dinosaurs it ate.

• PancakeCroc (Laganosuchus thaumastos): a 20-foot-long, squat fish-eater with a 3-foot long flat head with spike-shaped teeth.

• RatCroc (Araripesuchus rattoides), a 3-foot-long plant and grub eater with buckteeth used for digging [Chicago Sun-Times].

The two previously known species are nicknamed DuckCroc, a three-foot long, long-legged croc that feasted on fish and frogs, and DogCroc, another small and lanky croc that mostly ate plants and grubs.

“These species open a window on a croc world completely foreign to what was living on northern continents,” [researcher Paul] Sereno said of the unusual animals that lived 100 million years ago on the southern continent known as Gondwana [AP]. From the fossils, researchers believe that at least some of these crocs were equally at home on land and in the water. They roamed what is now Morocco and Niger at a time when the landscape was covered with lush plains and broad rivers. The crocs included meat eaters that could have devoured man—if any humans had existed at the time.

From studying the fossil skulls, the researchers made predictions about the crocs’ brain power. The scientists studied the animals’ brains by creating digital and physical casts from CT-scans, 3D X-rays. Both DogCroc and DuckCroc had broad, spade-shaped forebrains that looked different from those of living crocodiles [Telegraph]. Researcher Hans Larsson, who discovered the fossils of BoarCroc and PancakeCroc, said the brain models suggest these crocs had superior brain power compared to their modern ancestors, possibly because chasing after your meals on land requires more energy than milling around in the water waiting for your food to arrive.

Serano, the team leader, has a penchant for discovering the ancient crocs. He discovered SuperCroc—the largest of them all—nine years ago in the same region. His latest findings are the subject of “When Crocs Ate Dinosaurs,” which airs on the evening of Saturday, November 21, on the National Geographic Channel.

Image: Mike Hettwer, courtesy National Geographic

Answered: All Your Nagging Questions About Testicle Location | Discoblog

Fri, 20 Nov 2009 12:45:48 -0800

As you’ve probably heard, a man’s testicles hang down because sperm are hyper-sensitive to temperature and need to be a little cooler than the inside of the body. But isn’t there more to it than that?

Oh, definitely yes, says research psychologist Jesse Bering, writing for Scientific American. Bering goes on at great length in his analysis of testicular location. Sure, he argues, the temperature part makes sense. But why would natural selection, which so rewards passing on your genes, put a man’s means of passing on those genes in such a terribly exposed place on his body?

Bering’s lengthy account of gonad geography, and the studies trying to explain it, includes some real gems:

One of the more fanciful accounts–and one ultimately discarded by the authors–is that scrotal testicles evolved in the same spirit as peacock feathers. That is to say, given the enormous disadvantage of having your entire genetic potential contained in a thin satchel of unprotected, delicate flesh and swinging several millimeters away from the rest of your body, perhaps scrotal testicles evolved as a sort of ornamental display communicating the genetic quality of the male.

Oh, and this, on how a man’s cremasteric muscle works to keep his sperm at an optimal temperature by contracting and drawing the testicles up on a cold day and relaxing when it’s hot:

[That's] why it’s generally inadvisable for men to wear tight-fitting jeans or especially snug “tighty whities”–under these restrictive conditions the testicles are shoved up against the body and artificially warmed so that the cremasteric muscle cannot do its job properly. Another reason not to wear these things is that it’s no longer 1988.

In all seriousness, there’s nothing Discoblog values more than analysis of the silly… other than over-analysis of the silly. If you haven’t had your fill of scrotal hypotheses, check out the rest of Bering’s post.

Image: iStockphoto

Big Picture: The Banks That Prevent—Rather Than Cause—Global Crises

Fri, 20 Nov 2009 11:45:00 -0800

Every year farmers in flood-prone areas of Southeast Asia lose millions of tons of rice to high water that kills their crops. That colossal waste may soon be a thing of the past: SUB1A, a gene discovered by researchers with the International Rice Research Institute (IRRI) and the University of California, allows rice plants carrying the gene to live completely submerged for two weeks. Flood-resistant rice turned up among the 110,000 types of seed stored at the institute. It produced disappointingly low yields, but scientists were able to transfer the gene into more bountiful varieties. These have shown promising results in tests by growers in India and Bangladesh over the past two years.

This rice success story would not have been possible without the trove of genetic diversity tucked away in the IRRI’s vaults. As the world faces new agricultural challenges—shifting climate, bugs and diseases that have developed resistance to old defenses—such genetic resources are likely to become increasingly valuable. Fortunately, the IRRI is one of more than 1,000 organizations around the world (including the USDA, the International Potato Center in Peru, the Millennium Seed Bank in the U.K., and the Svalbard Global Seed Vault in Norway) cataloging and preserving crop genes. Most plant species grown for food have an associated bank that stores thousands of samples: seeds of landraces, wild relatives, and varieties that are rare, old, or adapted to very specific environments. The banks ensure that it will be possible to develop new varieties in the future.

Star Trek-Style “Phaser” Paralyzes Worms With a UV Blast | 80beats

Fri, 20 Nov 2009 10:09:34 -0800

Feel like teaching a lesson to that pinhead-sized worm that’s been bothering you? According to a study in the Journal of the American Chemical Society, a material called dithienylethene plus a blast of UV light can stop a worm in the midst of its worming, rendering it temporarily paralyzed.

The researchers fed a light-sensitive material — a “photoswitch” known as dithienylethene — to the transparent worms. When exposed to ultraviolet rays, the molecule turned blue and the worms became paralyzed. Using visible light instead made the chemical turn colorless and the paralysis ended [LiveScience]. Scientists aren’t sure why the transparent nematodes became paralyzed, but they know dithienylethene changes shapes and suspect it interferes with the worm’s energy-producing metabolic pathways. Repeated cycles of UV-induced paralysis actually killed some of the worms.

Unsurprisingly, news of this worm stun-gun led to longing for Star Trek-style phasers, and the scientists, though skeptical, were good sports about it. As lead researcher Neil Branda said tactfully: “I’m not convinced there’s a legitimate use of turning organisms on and off in terms of paralysis, but until somebody tells me otherwise, I’m not going to say that there isn’t an application” [BBC News].

But while phasers remain a fantasy, light-activated materials certainly have a future in medical research. Light-activated drugs could be used to activate tumour-killing drugs once they reach a particular location in the body. Similar chemicals have been used before, but have required a steady supply of light – often harmful UV bandwidths – to stay active. The new compounds, known as diarylethenes, could be more useful because they can be switched on and off with a single light pulse, Branda says [New Scientist].

Image: Wiki Commons / Yonatanh

Spores in Mastodon Dung Suggest Humans Didn’t Kill Off Ancient Mammals | 80beats

Fri, 20 Nov 2009 04:00:53 -0800

A fungus found within ancient mammoth dung is providing scientists with clues about how the large ancient mammals collectively known as megafauna went extinct. The fungus, Sporormiella, produces spores in the dung of large herbivores. These are then preserved in the layers of mud and can provide an index of the number of these animals, or megafauna, that roamed the environment at a particular time [BBC News]. For a new study, researcher Jacquelyn Gill collected and analyzed spores in sediment samples from an Indiana lake and several sites in New York.

From Gill’s analysis, published in the journal Science, she concluded that North American megafauna began a slow decline around 15,000 years ago and vanished about 1,000 years later. The data suggests megafauna started going extinct much earlier than previously though, which basically wipes out two theories of their extinction.

There are several theories surrounding the extinction of North American megafuana, but there are a lot more questions than answers. Much of the uncertainty surrounding the extinction of the North American megafauna, which includes mastadons, saber-tooth tigers and giant ground sloths, is due to a scarcity of evidence and difficulty pinning down the timing of events. Several major events occurred around the same time the animals disappeared: Major environmental upheaval associated with the end of the Ice Age; an asteroid explosion over North America; and the arrival of man [Wired.com]. But the new data points to an extinction culprit other than an asteroid or comet impact, because the impact is believed to have occurred long after the megafauna began their decline.

If humans were responsible for the extinction, it would have to be settlers that came along before the Clovis people, which is another debate in itself. The Clovis culture is thought to have been the first civilization to take hold in North America around 13,300 years ago–after the bulk of the megafauna extinctions, according to the new analysis. But some researchers believe that earlier settlers walked the land before the Clovis people, and could have hunted the mastodons and mammoths. The new study adds crucial info to the fossil record, but it is likely to kindle, rather than quench, the debate over megafauna extinction.

Image: Barry Roal Carlsen, University of Wisconsin-Madison

So Long, Colostomy Bag: British Man Gets Remote-Controlled Sphincter | Discoblog

Thu, 19 Nov 2009 13:15:40 -0800

Briton Ged Galvin survived that vicious car wreck that nearly took his life. Unfortunately, the accident crushed some of his organs and left him needing a colostomy bag to go to the bathroom.

That was until his doctors created his cyborg sphincter. Yes, you read that correctly. Doctors removed muscle from above Galvin’s knee, wrapped it around his damaged sphincter, and attached electrodes to the nerves. Now, when Galvin goes to the bathroom he simply presses a button on a remote control.

From The Telegraph:

Mr Galvin, who had previously endured the indignity of carrying a colostomy bag, added: “I thought that in these days of modern medicine surely there was something they could do. They’d mended everything else – why not this? Anything was better than a colostomy bag.

“The operation changed my life and gave me back my pride and confidence. Because of the remote control I can lead a normal life again.”

Outstanding. Though hopefully Galvin’s remote has a lock that prevents him from accidentally triggering it while it’s in his pocket.

Image: Anna Lythgoe/SWNS.COM

Starfish Prepare for Hot Conditions by Taking a Long, Cold Drink | 80beats

Thu, 19 Nov 2009 03:22:15 -0800

Like humans, sea stars enjoy lounging on the shore during the hot summer months. But when they get too hot, they can’t run for shade, so they have a back-up plan—fattening themselves with cold ocean water before the tide recedes, according to new research published in the journal The American Naturalist. This finding shows that sea stars, or ochre starfish, aren’t as helpless as previously thought. The sea stars are likely cued during low tide that it’s a hot day, the researchers say, and that signals them to soak up more water during the next high tide. “It would be as if humans were able to look at a weather forecast, decide it was going to be hot tomorrow, and then in preparation suck up 15 or more pounds of water into our bodies,” said study researcher Brian Helmuth [LiveScience]. Talk about staying hydrated.

The researchers first studied starfish in an aquarium using heat lamps to simulate a scorching summer day, an infrared camera to measure their internal temperatures, and a scale to weigh the sea stars and determine how much water they had absorbed. The researchers say the amount of water a starfish absorbs can decrease its body temperature by almost 4 degrees Celsius. But researcher Sylvain Pincebourde is concerned that this novel strategy may have limitations in a rapidly changing world…. As oceans warm together with air temperature the thermoregulatory mechanism used by the starfish will cease to work, he warns. “The colder the sea water, the more it is able to lower its body temperature. The efficiency of this thermoregulation strategy therefore might be annihilated by ocean warming” [BBC News]. Yet another reason to get a handle on global carbon emissions.

Image: flickr / laszio-photo

What Is This?: What Is This... A Hi-Tech Pin Cushion?

Wed, 18 Nov 2009 10:25:00 -0800

Hint: There are a lot fewer of them now than there were a few years ago.

Nanosilver Puts the Hurt on Microbes—and Maybe Fish, Too | 80beats

Wed, 18 Nov 2009 09:56:46 -0800

Toys, refrigerators, washing machines, socks—more and more products contain silver nanoparticles. It’s no wonder: These particles, which measure less 100 nanometers (smaller than a single HIV virus), can kill microbes on contact. But, researcher Darin Furgeson says, nanosilver can also escape into ecosystems and cause serious damage to fish embryos. Furgeson’s team published its results in the journal Small.

In one new experiment, Furgeson, a professor of pharmaceutical sciences, exposed zebrafish embryos to silver nanoparticles in a laboratory, and found that some died and others were left with dramatic mutations. “Some of the fish became extremely distorted, almost making a number nine or a comma instead of a linear fish,” he said [Scientific American]. Eyes, tails, and other body parts turned out malformed in the fish that survived.

Just how much nanosilver gets into the environment? A separate study from Environmental Science & Technology washed nine kinds of nanosilver-containing textiles, including some “anti-bacterial and anti-odor socks” that are already on the market. The researchers found that anywhere from less than 1 percent to as high as 45 percent of the silver came out in the first wash. Most of the silver was in the form of coarse particles of greater than 450 nanometers, suggesting that mechanical stress in the washing machine was responsible for most of the release [The New York Times], and that the nanoparticles might have aggregated to reach that size.

Those nanoparticles flushed out by a washing machine can end up in both fish habitats and drinking water supplies. Furgeson says his fish experiments could help show whether nanosilver is a health concern for humans, too. “Zebrafish have similar tissues and organs to us,” Furgeson said. “They don’t have lungs, but they do have a liver, kidneys and heart – though it is only two chambered – and they have a blood-brain barrier” [Scientific American].

Image: Wiki Commons / Kristof vt

In Galapagos Finches, Biologists Catch Evolution in the Act | 80beats

Tue, 17 Nov 2009 14:15:47 -0800

On the Galapagos Islands, where Charles Darwin’s observations led to his evolutionary theory, scientists are now reporting that they’re witnessing a single species splitting into two, according to a new paper in the Proceedings of the National Academy of Sciences.

A husband and wife team, Peter and Rosemary Grant of Princeton University, have spent the past 36 years studying Darwin’s finches, technically know as tanagers. Darwin’s observations of the birds during his voyage to the Galapagos on the HMS Beagle helped him arrive at the idea of evolutionary divergence: when different populations of a single species become geographically isolated, and evolve in different directions. The Grants have pushed that work further, with decades of painstaking observations providing a real-time record of evolution in action. In the PNAS paper, they describe something Darwin could only have dreamed of watching: the birth of a new species [Wired.com]. The process has been taking place with the help of a little bit of chance and a special song.

The split began in 1981 when an unusually large male finch from Santa Cruz island arrived on the island where the Grants were based, Daphne Major. The biologists tagged the bird number 5110, and followed him and his offspring through seven generations total. In the fourth generation a drought killed off all the descendants except one male and one female. These offspring became isolated because they have the avian equivalent of a strange accent. These finches learn their songs from their father, and the Grants suggest that 5110 sang the songs from his birth home of Santa Cruz then modified his come-hither ballad by roughly copying the Daphne Major birds’. This imperfect copying, they suggest, has over time acted as a barrier to interbreeding [Nature News]. So the immigrant bird’s descendants have bred only with each other for three generations.

The Grants say there’s no clear rule for when to declare a reproductively isolated population a new species, and also note that the birds descended from 5110 could still die out. But whatever happens, their legacy will remain: New species can emerge very quickly — and sometimes all it takes is a song [Wired.com].

The Grant’s are currently in Japan accepting the Kyoto Prize in basic science for their life’s work.

Image: flickr / putneymark

Vancouver BC: Infection Commences Tomorrow | The Loom

Tue, 17 Nov 2009 13:39:27 -0800

I’m waiting to board my Air Canada flight to the rain-drenched city of Vancouver. Residents of that fair city are invited to come to the Beaty Biodiversity Museum, dry off for a spell, and hear my talk tomorrow at 7 about Darwin, the flu, and evolution . It’s free, but you have to register here. See you tomorrow.

How to Build a Whizbang Chicken Plucker From a Washing Machine | Discoblog

Tue, 17 Nov 2009 09:26:38 -0800

With Turkey Day right around the corner, you don’t want to be caught with an unplucked bird. And who has the money to buy a plucker?

The solution? Build a chicken plucker out of your washing machine!

From the Annals of Improbable Research:

A Whizbang plucker will pick the feathers off chickens, ducks, turkeys and geese in a matter of seconds. Every component needed to make the machine is thoroughly discussed and the construction process is carefully detailed, step by step. There are 62 clear drawings…. Commercial tub pluckers cost $2,000+ but this book tells the reader how to build a comparable unit for $500 or less.

A bizarre trend of DIY chicken plucker videos has emerged on YouTube. Must be the tough economy. WARNING: If you’ve never seen a chicken plucked, it may seem a little disturbing. The chicken is already dead, but still…

Image: Whizbang Books

Extinct Goat Tried out Reptilian, Cold-Blooded Living (It Didn’t Work) | 80beats

Tue, 17 Nov 2009 07:55:56 -0800

Say you’re a goat stuck on a Mediterranean island with scarce food and no way to leave. How do you survive? The strange species Myotragus answered that question by getting small, and, most unusually, adopting the cold-bloodedness normally seen in reptiles.

In a paper in this week’s Proceedings of the National Academy of Sciences, researchers say that the now-extinct dwarf goat managed to survive thousands of years of resource scarcity by adjusting its metabolism to match how much food was available. The discovery marks the first time scientists have seen this cold-blooded survival strategy in mammals. The surprising skill likely allowed the goats to endure potentially fatal periods of scarcity on what is now the Spanish island of Majorca [National Geographic News].

Paleontologists figured out this oddball habit of Myotragus by analyzing its bones, as well as those of reptiles that lived in the same time and place. The bones of cold-blooded reptiles, such as the crocodiles, have parallel growth lines that cyclically come to a halt before starting up again…. Similar to tree rings, these lines match the growth cycles of animals. Warm-blooded species, on the other hand, exhibit uninterrupted, fast bone growth [Discovery News].

Taking on cold-blooded characteristics allowed Myotragus to survive, but it came at a price. The goats were born only as big as a large rat, and spent years growing to adult size, which was just more than a foot and a half in height. They probably had small brains and small eyes, and moved about sluggishly to save energy.

Coauthor Meike Köhler says those factors spelled doom when a new threat reached the island: people. “The postcranial skeleton indicates that this animal was not able to run, jump, or move fast around, and [would have been] easy prey,” [National Geographic News], Köhler says.

Related Content:
DISCOVER: The Biggest Dwarf Ever (For island living, size does matter.)
Discoblog: Are Wind Turbines Killing Innocent Goats?
80beats: How Did Dinosaurs Get So Big? Maybe Because They Were Couch Potatoes

Image: Wiki Commons / Xavier Vázquez

World Famous Sex Blogger’s Day Job? Research Scientist. | Discoblog

Tue, 17 Nov 2009 06:25:00 -0800

Belle de Jour, the best-selling author who penned books about her life as a call girl, revealed her true identity over the weekend. Her name is Brooke Magnanti.

Dr. Brooke Magnanti to be exact. It turns out she’s a cancer researcher who began turning tricks while in grad school.

Via the London Times:

Magnanti is a respected specialist in developmental neurotoxicology and cancer epidemiology in a hospital research group in Bristol. Six years ago, in the final stages of her PhD thesis, she ran out of money and turned to prostitution through a London escort agency, charging £300 an hour. Already an experienced science blogger, she began writing about her experiences in a web diary that was adapted into books and a television drama starring Billie Piper.

It’s not like she didn’t try to find honest work. She told the Times that at one point during her double life she had a job as a computer programmer, “but I kept up with my other work because it was so much more enjoyable.”

So what do you think readers? Is this a commentary on how poorly grad students, and scientists in general, are compensated?

More reactions over at The Great Beyond.

Image: flickr / keepwaddling1

Science Cabaret | The Loom

Mon, 16 Nov 2009 16:51:59 -0800

Here’s a fun talk I had Saturday on Science Cabaret, a radio show on WICB in Ithaca. The host, Jennifer Nelson, is a graduate student at Cornell and has only been interviewing people about science for two months, but she’s clearly a natural at this. At the Science Cabaret site, you can listen to her earlier talks, too. Check them out.

Worst Science Article of the Week: io9’s Unspeakable Genetic Error | Discoblog

Fri, 13 Nov 2009 15:04:18 -0800

In a new study in yesterday’s edition of the journal Nature, researchers analyze the speech-connected gene called FOXP2—both in the variant found in we talkative humans and that found in our close relatives the chimpanzees, who despite great genetic similarity to us are not a linguistic bunch. The team notes that only two amino acids separate the human and chimp versions. So a post over at io9 came out with the headline, “One Gene Tweak Could Make Chimps Talk.”

It has a nice poetic ring to it, and we can understand why a sci-fi blog would theorize that tinkering with this important gene could turn our fair home into Planet of the Apes. But we have to play the fun police on this one: The headline is just so wrong.

FOXP2 certainly is important. The scientists say in the Nature study that “so far, the transcription factor FOXP2 (forkhead box P2) is the only gene implicated in Mendelian forms of human speech and language dysfunction.” They say that scientists don’t know for sure whether this two-amino-acid change in human FOXP2 occurred around the same time we developed language and is connected us beginning to talk, but their study teases the idea: “These data provide experimental support for the functional relevance of changes in FOXP2 that occur on the human lineage, highlighting specific pathways with direct consequences for human brain development and disease in the central nervous system (CNS).”

But the fact that FOXP2 is connected with human language, and that chimps have a slightly different version of the gene, doesn’t mean chips would start reciting Shakespeare if we swapped our version for theirs. For one thing, there are unavoidable physical differences in the voicebox and the size (and non-speech functions) of the brain. And FOXP2 isn’t “The Speech Gene.” Rather, it exerts some control over a series of other genes that all work in concert—at least 116 of them in humans.

The New York Times reports:

Several of the genes under FOXP2’s thumb show signs of having faced recent evolutionary pressure, meaning they were favored by natural selection. This suggests that the whole network of genes has evolved together in making language and speech a human faculty.

So talking chimps aren’t coming just because of one genetic tweak. But maybe I’ll move Planet of the Apes up to the top of my Netflix queue—original version, of course.

Image: flickr / King Chimp

Thanksgiving for Fish: Food Chemicals Go Through People & Back Into Water Supply | Discoblog

Fri, 13 Nov 2009 09:06:16 -0800

Pulses of certain Turkey Day food ingredients are detected in the water supply in the days after the holiday, according to researchers. But as reported in National Geographic News, it doesn’t stop there:

For instance, thyme and sage spike during Thanksgiving, cinnamon surges all winter, chocolate and vanilla show up during weekends (presumably from party-related goodies), and waffle-cone and caramel-corn remnants skyrocket around the Fourth of July.

A research team from the University of Washington tracked pulses of food ingredients that enter Washington’s Puget sound to learn more about how our actions on land affect the water supply, and to determine what slips through sewage treatment plants. Similar monitoring is underway worldwide, and scientists have turned up things such as flu vaccines, cocaine, heroine, rocket fuel, and birth control in waterways.

Click on over to team leader Rick Keil’s lab Web site to learn more about the Puget Sound research. But Keil told National Geographic News that the no one knows yet whether the subtle seasoning of the water is having an impact.

For now, there’s no evidence that a sweeter and spicier sound is a bad thing—salmon, which can smell such flavors, could be enjoying their vanilla-enhanced habitat, Keil said.

Image: flickr / Lana_aka_BADGIRL

Sea Section: Shark Bites Shark & 4 Babies Pop Out | Discoblog

Thu, 12 Nov 2009 14:25:36 -0800

Some sharks have a nasty habit of taking bites out of each other, but in an aquarium in New Zealand one aggressive shark ended up doing its tank-mate a favor when it tore out a piece of the second shark’s belly. Visitors at Kelly Tarlton’s Underwater World watched in shock as four baby sharks popped out of the gaping wound. The visitors ran to notify the aquarium staff, who quickly removed the babies.

Via the New Zealand Herald:

[Aquarium staff member Fiona] Davies said the unusual delivery had probably saved the baby sharks’ lives.

Staff did not know the mother was pregnant and, had she given birth naturally, most likely at night, the babies would have been eaten by adult sharks and stingrays before staff could rescue them.

When the mom was removed from the communal tank to get her wound stitched up, vets found four more babies inside her. All are reportedly doing well, despite the spontaneous C-section.

Image: flickr / snickclunk

Warning Label | The Loom

Thu, 12 Nov 2009 08:59:05 -0800

This is definitely going into the swine flu talk! From Colin Purrington’s The Axis of Evo.

Indian Villagers to Rare Turtle: Stay With Us, Mighty God | Discoblog

Thu, 12 Nov 2009 04:00:06 -0800

If your God was going to drop down from the heavens for a stroll around your town, what form do you think he or she would choose? A turtle, perhaps?

According to Reuters:

Hundreds of poor Hindu villagers in eastern India have refused to hand over a rare turtle to authorities, saying it is an incarnation of God, officials said on Tuesday. Villagers chanting hymns and carrying garlands, bowls of rice and fruits are pouring in from remote villages to a temple in Kendrapara, a coastal district in eastern Orissa state.

Police have been trying to take the animal from the villagers since it’s actually illegal to harbor this rare turtle. (Note: That’s not a picture of the turtle to the left. The exact species isn’t clear from news reports.) The villagers are saying the turtle has holy symbols on its shell and is really an incarnation of Lord Jagannath, a popular Hindu deity.

Let us all pray to Jagannath that this doesn’t devolve into an Elian Gonzalez-type situation, with Indian authorities barging in to grab a confused reptile…

Image: flickr / Rennett Stowe

T. Rex May Have Been a Hot-Blooded, Sweaty Beast | 80beats

Thu, 12 Nov 2009 03:32:32 -0800

The world domination achieved by such fearsome bipedal dinosaurs as the T. rex may have been a result of their warm-blooded biology, according to new research. For decades, scientists assumed that because dinosaurs resembled lizards, they were cold-blooded as well, their internal temperature rising and falling with the outside world. However, birds are warm-blooded, and the fact that birds seem to be descended from dinosaurs raises the question of whether their ancestors were as well [LiveScience]. The new study, published in the journal PLoS ONE, examined the anatomy of 14 species of bipedal dinosaurs, and argues that many of them needed more energy to power their massive leg muscles than a cold-blooded metabolism could provide.

Lead researcher Herman Pontzer based his findings on the estimated amount of energy dinosaurs must have expended moving about. Recent research by Dr Pontzer has shown that the energy cost of walking and running is strongly associated with leg length. Hip height – the distance from the hip joint to the ground – can predict the observed cost of locomotion with 98 per cent accuracy for a wide range of land animals [Telegraph]. The research team also used measurements of fossilized leg bones to determine the leg muscle mass of each species, and found that the muscles would have required a great deal of energy during walking and running.

The dinosaurs would have benefited from a warm-blooded metabolism, Pontzer says, because they could have been agile and active even when the temperature dipped, and could have therefore spread through areas with colder climates. But there would also have been a downside: Maintaining a stable internal temperature … costs a lot of energy and requires the animals to feed more regularly [The Guardian]. At any rate, the new results aren’t likely to convince paleontologists who aren’t in the warm-blooded camp, and you can expect the debate to continue.

Image: PLoS ONE / Herman Pontzer, et al.

Elephant Seals Take Naps During Slow Dives Through the Sea | 80beats

Wed, 11 Nov 2009 13:39:05 -0800

For elephant seals, at least, there is some rest for the weary.

These marine mammals undertake epics migrations of thousands of miles, in which they might not return to land for as long at eight months. But elephant seals don’t have the same talent as whales and dolphins, which can have one hemisphere of their brains sleep while the other stays awake, so marine biologists weren’t sure how the seals managed to doze off while at sea. A new study in Biology Letters, however, suggests the seals might sleep as they drift slowly downward.

Past research had identified certain types of dives that include a period of slow descent that might be a siesta of sorts, for resting or digesting [The New York Times]. So scientists tagged a half-dozen young northern elephant seals off the California coast with instruments that tracked the seals’ positions and modeled their dives in three dimensions.

The monitors revealed that the seals periodically flip onto their backs and slip into slow, spiraling dives. The seals wobble as they drift down, and most of the time their bodies follow circular paths toward the bottom of the sea, said study co-author Russel Andrews…. “[They] resemble a leaf that has dropped from a tree branch and is falling toward the ground, fluttering from side to side,” he said [National Geographic]. It seems likely, the scientists say, that the seals catch a quick nap during these long drifts; in fact, once in a while they strike bottom without even noticing.

Related Content:
DISCOVER: 20 Things You Didn’t Know About… Sleep
DISCOVER: Portrait in Blubber reveals surprising details of the elephant seal’s private life
DISCOVER: How to Pinpoint a Pinniped describes a tracking technology for seals
80beats: Attempt to Control Invasive Species Backfires Spectacularly on an Antarctic Island
80beats: Otter-like Fossil is a Missing Link in Otter Evolution

Image: flickr / Mikebaird

Are Gross, Whalebone-Eating Worms Actually Older than Whales? | Discoblog

Wed, 11 Nov 2009 11:23:39 -0800

If ever a species got the disgusting name it deserved, bone-eating worms would be the one. Robert Vrijenhoek’s team discovered them five years ago eating the bones of a dead gray whale off California, and since then they’ve shown up in whalebones around the world. The worms don’t have mouths or anuses—instead, they rely on their bacteria to handle nutrient uptake and waste disposal. And according to a new study by Vrijenhoek in BMC Biology, there’s more to these strange sea-dwelling scavengers: They might have been around since before whales even existed, and are probably more numerous than we thought.

Back in 2004, Vrijenhoek’s first analysis of the bone-eating worms, which carry the scientific name Osedax, found five different species. However, according to the genetic analysis he carried out in the new study, there could be as many as 17 distinct evolutionary lineages.

Osedax is old, too. Using a molecular clock taken from shallow-water invertebrates, the researchers calculated that the bone worms could have split off from their nearest relatives 45 million years ago, about the time whales arose (and became meals for Osedax upon dying and sinking to the bottom). But if Vrijenhoek used a different clock, one designed for deep-sea worms, he found that the bone-eaters could date back 20 million years further, to a time before whales even existed.

Scientists will have to look at fossils of ancient whales and their predecessors to figure out the history of bone-eating worms. But they already know these oddball sea creatures have a taste for more than whales. Vrijenhoek told Wired.com that he has offered cow, sea lion, and pig bones to Osedax, and the worms like them just fine.

Image: MBARI

Feathers That Sing: What A Little Sexual Selection Can Do | The Loom

Wed, 11 Nov 2009 05:51:56 -0800

If you ever find yourself in the forests of Ecuador, you may have the good fortune of spotting a club-winged manakin. The closest the rest of us will probably ever get will be to watch this video. But don’t just watch it. Listen.

If you said to yourself, “Hold on, is that bird singing with its wings?” the answer is yes.

As I wrote in this 2005 article in the New York Times, ornithologists have long known that a few species of manakins can make sounds with their wings. The sounds are produced by the males, as part of their courtship displays. Some make firecracker pops, and some make whooshing sounds. Darwin pointed to the sounds of manakin wings as evidence of just how much sexual selection could transform male animals as females were attracted to some mates over others.

But no one had any idea how manakins could make noises with feathers until Kimberly Bostwick of Cornell and her colleagues tackled the question. Bostwick took a high-speed camera into the jungle to film club-winged manakins. It turns out the birds flap their wings 100 times a second, far faster than typical birds. Later, she closely examined museum specimens. Club-winged manakins have one peculiar wing feather with a stiff, curved tip, right next to one with a series of ridges. Bostwick and her colleagues proposed that curved tips raked across the ridges on the neighboring feather like a spoon pulled across a washboard, producing the bird’s 1500-cycle-per-second sound.

Biologists are quite familiar with this way of making sound–but in crickets and other insects. Typically, they draw their legs across ridges on their exoskeleton, making their bodies resonate in a process called stridulation. Bostwick and her colleagues were proposing, for the first time, that a vertebrate could stridulate, too.

Since Bostwick published her first paper on the birds, she’s continued to study them to test her hypothesis. In a paper just published in the Proceedings of the Royal Society B, she and her colleagues report a new experiment in which they looked at the physics of the manakin feathers. They clamped the feathers in a device known as a vibration mini-shaker, and then–well, as you can guess–shook them. The scientists bounded lasers off the feathers to track their wiggles as the mini-shaker vibrated faster and faster. They used the device first to measure the special spoon-and-washboard pair of feathers. Then they measured how other feathers responded, and then, finally, they studied a set of ordinary and spoon-and-washboard feathers joined together on a ligament.

The scientists found that the spoon-and-washboard feathers resonated at about 1500 cycles, just as Bostwick had predicted back in 2005. The unmodified feathers on other parts of the wing, however, showed no such response when the scientists shook them one by one. But when they shook the spoon-and-washboard feathers together with seven neighboring wing feathers, the entire set resonated strongly at 1500 cycles.

As you can see in this video, the club-winged manakin moves its entire wings upward before flapping. Bostwick proposes that the spoon-and-washboard feathers create a 1500-cycle sound, which the entire wing amplifies. This special kind of stridulation is not totally unique–the Australian whistling moth whistles by clicking castanet-like organs together, causing its entire wings to resonate. What is unique, however, is the evolution of feathers into such a sophisticated sound system.

Was This Fish the Inspiration for Alien? | Discoblog

Tue, 10 Nov 2009 08:51:20 -0800

See that fish in the video below– that’s a slingjaw wrasse. Looks kind of boring, right? Well as you’ve probably guessed from the headline (or from the name slingjaw), it’s not. Just watch the video.

Via the Telegraph:

Its mouth shoots out like that of the monster in the Ridley Scott film Alien, slinging forward up to half the fish’s body length and engulfing the victim in moments.

The odd beast, found in shallow reef and lagoon waters, feeds mainly on small fish, shrimp and crabs.

The secret of the slingjaw wrasse’s remarkable mouth projection: Unlike most bony fishes, its lower jaw is not firmly attached to its skull, allowing the entire mouth to shoot outward. The foot-long fish isn’t really a threat to humans, but you might want to watch your fingers just in case.

Video: YouTube / Wainwrightlab

NASA’s Plan to Irradiate Monkeys Raises Cruelty Concerns | 80beats

Tue, 10 Nov 2009 06:30:10 -0800

If NASA ever wants to send astronauts on long-term space flights, it needs to know how radiation will affect the crew. Testing humans obviously isn’t going to happen, so NASA is funding a round of experiments to study how radiation effects monkeys, the first time monkeys have been used as test subjects by NASA in decades. The point of the experiments is to understand how the harsh radioactive environment of space affects human bodies and behavior and what countermeasures can be developed to make long-duration spaceflight safe for travelers beyond Earth’s protective magnetic shield [Discovery News]. The monkey studies will advance previous radiation experiments with rats and mice and will focus on how radiation affects the monkeys’ central nervous system.

Researchers will expose 18 to 28 squirrel monkeys with a small dose of radiation, similar to what astronauts would receive on a round trip flight to Mars. The monkeys, previously trained to perform a variety of tasks, will be tested to see how the exposure affects their performance [Telegraph] at different times after exposure to gamma rays. The monkeys will not be killed during the experiments, and after testing staff and veterinarians will look after them for the rest of their lives at Harvard Medical School’s McLean Hospital in Boston.

As you might expect, the experiment’s funding announcement is causing a stir among animal rights groups like the Physicians Committee for Responsible Medicine (PCRM) and People for the Ethical Treatment of Animals (PETA). PCRM sent an appeal to NASA urging them to halt the experiments, which they are branding as “one giant leap backward for NASA.” They are also arguing that the research is “cruel” since it violates NASA’s own guidelines for animal treatment and that it’s “unnecessary” since long-term spaceflight still seems like a pipe dream. NASA’s animal testing policy, established in 1996, asserts that “the minimization of distress, pain and suffering is a moral imperative” and emphasizes that experimenters must weigh the burdens of animal subjects against potential societal benefits [Scientific American].

In response to the criticism, NASA’s administrator Charles Bolden restated the agency’s commitment to deep space travel and the necessity of radiation testing. Jack Bergman, who will lead the research, said “there’s a long-standing commitment on the part of NASA to deep space travel and with that commitment comes a need for knowing what kinds of adverse effects deep space travel might have, what are the risks to astronauts,” Bergman said. “That’s not been well assessed” [Discovery News]. Bergman will conduct the experiments at NASA’s Space Radiation Laboratory at the Department of Energy’s Brookhaven National Laboratory in New York.

Image: flickr / suneko

What Head (and Other) Lice Tell Us About Evolution | Discoblog

Mon, 09 Nov 2009 10:51:07 -0800

The second episode of NOVA’s big evolution special “Becoming Human” premieres tomorrow night at 8 PM ET/PT on PBS. Tuesday night’s show focuses on Homo erectus, the ancestor who became “basically us” almost 2 million years ago, developing the first human societies.

Much of what we know about Homo erectus comes from “Turkana Boy,” the famous skeleton found by the Leakey team in Kenya in the early 1980’s. An important part of what we know, though, comes from the genetic study of lice. And not just head lice.

Using “paleoartists,” digital filmmaking and the work done with Turkana Boy over the past two decades, the NOVA producers are able to paint a vivid portrait of Homo erectus’s role in key innovations – like using fire and developing social bonds – that make us human.

The real action in the documentary starts about halfway through, when scientists tackle the question of how Homo erectus was able to obtain the protein necessary to support brain growth. Of course, stone tools played a huge role in making sure that the humans “went home for dinner and weren’t the meal.”

Per NOVA, “most predators rely on strength or speed to kill their prey, and our ancestors had neither.” Instead, according to Harvard’s Dan Lieberman, Homo erectus relied on the combination of “endurance running and high activity in the middle of the day.” Unlike animal predators, early humans were mostly hairless, giving them the ability to sweat and keep cool while running and tracking their prey over long distances.

The evidence for Turkana Boy’s hairlessness comes in part from the study of louse DNA. Hair is “rarely present in the fossil record” so researchers have turned to the study of parasites associated with hair, i.e. head and pubic lice. It turns out that the human head louse is very different from the human pubic louse. On top of that the pubic louse is closely related to lice found on gorillas. Viewers are left to draw their own opinions about how humans contracted pubic lice from gorillas. When humans lost their hair, the lice were forced to navigate “the hairless geographic barrier” between the head and pubic regions.

By studying the genetic code of the two louse species, geneticists like Mark Stoneking of the Max Planck Institute can tell when the two species diverged from their common ancestor. Their research suggests that humans lost their thick coat of body hair almost three million years ago, paving the way for Turkana Boy to outrun and kill the meat he needed to feed his growing brain.

A Literally Crappy House Protects Beetle Larva From Predators | Discoblog

Mon, 09 Nov 2009 09:59:03 -0800

Leaf beetle mothers give their children an inheritance that many people wouldn’t quite appreciate—a mobile home made of poop. Gee thanks, mom. As Not Exactly Rocket Science describes:

After [a female] lays her eggs, she seals each one in a bell-shaped case. When the larva hatches, it performs some renovations, cutting a hole in the roof and enlarge the structure with their own poo. By sticking its head and legs out, it converts its excremental maisonette into a mobile home, one that it carries around with them until adulthood.

This beetle behavior has been well established by scientists. However, the leaf beetle Neochlamisus platanithey has been singled out by researchers for its “elaborate example of faecal architecture.” The larvae add a little insulation in the form of plant hairs, called trichomes, which help ward off predators, according to new research.

Staged attacks on larvae with and without fecal shelters demonstrated that poop-protected larva were less likely to be attacked by crickets, spined soldier bugs, and green lynx spiders than unprotected larva. NERS explains why:

Even if a predator investigates the case, they must first breach the unappetising shield, and the larva doesn’t make it easy for them. [The researchers] saw that, in some cases, the larvae pulled their cases down flush with the floor, making them even harder to penetrate. That defence was particularly effective against the bugs, whose stabbing mouthparts couldn’t break through the wall of the case. Some of the larvae also wiggled their cases back and forth, which could serve to shake off or startle a predator.

Even if a predator breaks through the case (as frequent holes in the structures suggest), they’d meet a large concentration of trichomes in the attic before they reached the larva underneath.

For beetles at least, putting up with their mothers’ crap can save their lives.

Image: Wikimedia Commons / Neochlamisus

Mother Tongue, Indeed: Newborn’s Cries Mimic Mama’s Accent | 80beats

Fri, 06 Nov 2009 11:43:46 -0800

Babies pick up their parents’ accents while still in the womb, according to a new study. After studying the crying patterns of 30 French and 30 German newborns, researchers concluded that the French newborns cried with a rising “accent” while the German babies’ cries had a falling inflection [BBC News]. The researchers believe that by mimicking their mothers’ inflections, the babies are attempting to form an early bond with their mothers.

Scientists already knew that a baby in the womb can memorize sounds from the outside world, and is particularly sensitive to the melodies of her mother’s language. But the new research showed an “extremely early” impact of native language and confirmed that babies’ cries are their first proper attempts to communicate specifically with their mothers [Reuters]. The data support the idea that crying seeds language development for infants, according to the scientists, who published their research in the journal Current Biology.

To hear the different between German and French crying babies for yourself, click here to listen.

Image: flickr / chalky lives

Brain-Like Chip May Solve Computers' Big Problem: Energy

Fri, 06 Nov 2009 09:10:00 -0800

Kwabena Boahen is working to create a computer that will fulfill his boyhood vision—a new kind of computer, based not on the regimented order of traditional silicon chips but on the organized chaos of the human brain. Designing this machine will mean rejecting everything that we have learned over the past 50 years about building computers. But it might be exactly what we need to keep the information revolution going for another 50. The human brain runs on only about 20 watts of power, equal to the dim light behind the pickle jar in your refrigerator. By contrast, the computer on your desk consumes a million times as much energy per calculation. If you wanted to build a robot with a processor as smart as the human brain, it would require 10 to 20 megawatts of electricity. “Ten megawatts is a small hydroelectric plant,” Boahen says dismissively. “We should work on miniaturizing hydroelectric plants so we can put them on the backs of robots.” You would encounter similar problems if you tried to build a medical implant to replace just 1 percent of the neurons in the brain, for use in stroke patients. That implant would consume as much electricity as 200 households and dissipate as much heat as the engine in a Porsche Boxster. “Energy efficiency isn’t just a matter of elegance. It fundamentally limits what we can do with computers,” Boahen says. Despite the amazing progress in electronics technology—today’s transistors are 1/100,000 the size that they were a half century ago, and computer chips are 10 million times faster—we still have not made meaningful progress on the energy front. And if we do not, we can forget about truly intelligent humanlike machines and all the other dreams of radically more powerful computers.

Can Your Pet Catch & Spread Swine Flu? Yes, If Your Pet’s a Ferret | 80beats

Fri, 06 Nov 2009 07:32:26 -0800

News that an Iowa cat has been diagnosed with swine flu has sparked a new round of concerns, as pet-owners worry both that their furry companions could get sick, and that their pets could pass the virus on to other humans. The 13-year-old, mixed-breed cat showed the symptoms of lethargy, sneezing and coughing typical to sick cats [ABC News]. The veterinarians who treated him say that several people in the cat’s home had been experiencing flu-like symptoms, and lab work confirmed that the feline had the H1N1 virus.

Happily, the cat is expected to make a full recovery. But both vets and public health officials are rushing to reassure the public that one sick cat probably does not indicate a coming crisis. While it’s possible that more cats will be diagnosed with the swine flu, vets point out that the virus was circulating for more than six months before the first cat case was discovered, indicating that the virus probably doesn’t jump from species to species very easily. Doctors also note that there’s very little chance that a cat will spread the virus to humans: Even when inter-species transmissions do occur, the H1N1 virus seems more likely to move from humans to animals, rather than the other way around [HealthDay News].

There have been no reported cases of dogs catching the virus, but there is one type of pet that is known to be vulnerable. Ferrets are generally susceptible to the seasonal flu, and the AP reported Wednesday that H1N1 infection has been confirmed in two ferrets, one in Nebraska and the other in Oregon. “Not only can they be infected with the flu but they are clearly able to transmit the flu back to people,” Treanor said [HealthDay News]. But the bottom line appears to be: Unless you’re a ferret-owner, you probably have nothing to worry about.

Image: flickr / theogeo

The Secret Lives and Loves of Great White Sharks | 80beats

Wed, 04 Nov 2009 13:15:05 -0800

Great white sharks, much like humans, tend to stick to familiar turf, according to new research. Also like a lot of people, they like to hang out along the coastal waters of California. Sharks tagged with acoustic devices often spent up to 107 days at four key sites along the central and northern California coast where seals and sea lions are abundant: Southeast Farallon Island, Tomales Point, Año Nuevo Island and Point Reyes [LiveScience]. A few of the fearsome predators were tracked as far inland as the Golden Gate Bridge, apparently in search of snacks, say the researchers. The study, the largest and most detailed study of North American great white sharks, provides evidence contrary to the popular notion of great white sharks swimming aimlessly in the ocean.

The sharks under study divided most of their time between three locations: Northern California, Hawaii, and an area that the researchers called the white shark café, a spot in the open ocean about halfway between the Baja Peninsula and the Hawaiian Islands. Exactly what goes on at the café is still unknown–although researchers suspect it may be a hot spot for mating. Lead researcher Salvador Jorgensen explains that male white sharks “converge in a very specific area of the cafe,” Jorgensen said, while female sharks move in and out of the area. “It adds a little more evidence to the argument that this could be an important reproductive area” [Washington Post].

The scientists tracked the snaggly toothed predators between 2000 and 2008 from the Bay Area to San Diego, Hawaii and back as the sharks followed a route that was carried out with surprising precision and under a strict time frame [San Francisco Chronicle]. These great whites have been isolated from other great white sharks near Australia and South Africa for so long that they are now genetically distinct. The study was published in the journal Proceedings of the Royal Society B.

Image: flickr / hermanusbackpackers

In Controversial Scent Lineups, a Dog’s Nose Picks Out the Perp | 80beats

Wed, 04 Nov 2009 11:10:04 -0800

Curvis Bickham spent eight months in prison for a triple-homicide because a police dog confused his scent with that of the killer. Now Bickham and others who spent months in jail after dogs linked their scents to evidence from crimes they did not commit are filing a lawsuit claiming Texas authorities falsely arrested and imprisoned them, their attorney said Tuesday [AP]. In a scent lineup, dogs sniff items found at a crime scene, and then sniff jars swabbed with the suspects’ scents and the scents of others not involved in the crime. When the dogs link crime scene and suspect, that evidence is often relied on heavily in court by the prosecution. Alaska, Florida, New York and Texas all use scent lineups to link suspects to crimes.

Dogs are used all the time to fight crime—from sniffing out bombs and drugs to locating dead bodies. However, scent lineups have critics barking. They say the lineups are poorly controlled, and argue that avoiding cross-contamination is basically impossible. The main target of the current lawsuit is Fort Bend County Deputy Keith Pikett—whose home-trained bloodhounds identified the suspects. A 2004 F.B.I. report warned that dog scent work “should not be used as primary evidence,” but only to corroborate other evidence. In several of the cases that were based on Deputy Pikett’s dogs, however, the scent lineups appear to have provided the primary evidence, even when contradictory evidence was readily available [The New York Times]. Deputy Pikett, by his own estimation, has conducted thousands of scent lineups.

The three men who filed the lawsuit against Deputy Pickett were all eventually set free after contradictory evidence proved their innocence. The Innocence Project of Texas, a legal defense organization … released a report last month that excoriated dog scent lineups as a “junk science injustice” [The New York Times]. Dog scent lineups bring to mind another high profile forensic science debate in Texas that many believe led to the execution of an innocent man. Now that the science behind dog scent lineups is coming under the same scrutiny, one can’t help but wonder if scent lineups might have led to a similar outcome.

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Image: flickr / contadini

Finally! An iPhone App That Lets You Track Your Bathroom Habits | Discoblog

Wed, 04 Nov 2009 09:23:17 -0800

The folks behind the best-selling book, “What’s Your Poo Telling You?” aren’t satisfied with being mere bathroom reading material. So they’ve dropped a new iPhone app, the Poo Log, which allows you to time, log, and graph your BMs—and learn about your gastrointestinal health while doing so.

Via The Presurfer:

The ‘Poo Log’ is a digital timer and journal for recording and studying the wondrous uniqueness of each bowel movement. With a clever mix of bathroom humor and legitimate medical information, the ‘Poo Log’ allows the user to track his/her digestive workings and graph their ‘poo’ – all with one hand.

According to the app’s developers, AvatarLabs Inc, the tracker features medically accurate info that is suitable for all ages, and of course helpful tips such as, “Light a match. Now.”

Kenya’s Man-Eating Lions Not as Man-Hungry as Previously Thought | 80beats

Tue, 03 Nov 2009 05:57:49 -0800

According to legend, the infamous Tsavo man-eating lions dined on 135 people near a Kenyan labor camp prior to their capture in 1898. The two maneless lions have been a crowd favorite at Chicago’s Field Museum, where the stuffed beasts have been on display for over 80 years. But after analyzing fragments of the lions’ bones and fur, scientists at the University of California in Santa Cruz have determined that the true number of humans eaten by the lions was likely closer to 35. By comparing isotopes in the lions’ samples with their normal prey of zebra, wildebeest and buffalo, with other lions, and with the remains of 19th century Kenyans, the scientists estimated that one of the lions ate 24 humans, while the other ate 11 [Chicago Tribune]. The results suggest that the lions hunted together but didn’t always share food, which makes the pair the first example of a cooperative hunting group that ate different prey.

The two lions developed a taste for man after drought, pestilence, and hunting killed of most of their usual prey, according to previous research. Also, the Tsavo lions lived near a slave trading route, which offered easy access to sick, injured, or dead slaves. The lions dragged people from tents at night…. After nine months of this, the beasts were finally killed in December [Nature News]. The recent analysis suggests one of the lions had developed a toothache, which made eating humans easier than devouring its normal prey. The study attributes 24 deaths to one cat, or 30 per cent of its diet, and 11 deaths to the other, just 13 per cent of its food [New Scientist].

Colonel John H. Patterson, a British engineer, shot the lions and then wrote a book about their killing spree, claiming that “28 railroad workers and scores of unfortunate Africans” had been killed [Chicago Tribune]. Some believe that in order to boost the selling price of the lions, he exaggerated the lions’ man-killing ways and inflated the death count to 135. Patterson sold the lion skins for $5,000 to the Field Museum in 1924.

The current study appears in the journal Proceedings of the National Academy of Sciences.

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Image: flickr / lisa andres

So You Think You Can Dance: Spider Edition | Discoblog

Mon, 02 Nov 2009 09:06:19 -0800

If you thought going to the club was bad, imagine having to dance in front of potential mates for over an hour and a half, lest they will eat you. Male Australian redback spiders, members of the black widow family, pay the ultimate price if their mating dance doesn’t impress.

Here’s how it works, via Livescience.com:

Males, which are just 1 percent to 2 percent of a female’s body weight, dance about the web of a potential mate, plucking at the threads and sending out vibrations. Once the male redback has performed an adequate dance, the female will allow him to mount her and insert one of his two palps, or copulatory organs, into one of a pair of sperm storage organs. The male then somersaults to place its abdomen directly above his mate’s fangs. That’s perfect positioning for the female to begin devouring the male’s body.

To avoid being gobbled up by the female halfway through mating, males need to dance for 100 minutes, according to new research. But the dancing males better have a good internal clock. Females can’t determine the source of courtship, so if the dancer exceeds the optimal time, a slick male could sneak in a mate with the female while the dancer ends up alone on the web.

For a video of the life-or-death dance, click on over to the Discovery News.

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Image: Ken Jones

“Bug smut peddler Carl Zimmer” | The Loom

Fri, 30 Oct 2009 07:57:49 -0700

Time to print up some new business cards.

Women’s Stockings Used to Measure Whales’ Sex Drive | Discoblog

Wed, 28 Oct 2009 09:49:35 -0700

To see if a whale’s libido is going full-throttle, grab a pair of nylons and head to the ocean, reports the New Scientist:

For the first time, testosterone and progesterone—two key hormones that signal whether whales are pregnant, lactating or in the mood to mate—have been extracted from whales’ lung mucus, captured in nylon stockings dangled from a pole over their blowholes as they surface to breathe.

This method could allow scientists to study whales without having to slaughter them, and could be used to simply give them a pregnancy test to try to learn why some species aren’t breeding, say the authors of the study.

Image: flickr / percita

Butterfly Discovered With Ears on Its Wings | Discoblog

Mon, 26 Oct 2009 14:58:14 -0700

It’s a question you wouldn’t be surprised to hear a toddler ask: Do butterflies have ears? Well yes, yes they do. And one species was recently discovered to have ears on their wings. The blue morpho butterfly from Central and South America has beautiful bright blue wings complete with a simple ear structure that picks up noise and relays it to the brain.

Via MSNBC.com

In the new study, Kathleen Lucas of the University of Bristol in England and her colleagues were interested in the odd-looking hearing membrane that sits at the base of the blue morpho’s wing. The tympanal membrane, as it is called, is oval-shaped with a dome at its center that kind of resembles the yolk at the center of a fried egg, Lucas said.

Researchers determined that the butterflies can distinguish high and low frequencies, uncommon in simple ears, and they speculate this could help them determine if a hungry bird is about to swoop down and attack.

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Image: flickr / DavidDennisPhotos.com

Ten Evolution Picks For Nova | The Loom

Mon, 26 Oct 2009 13:24:07 -0700

NOVA isn’t just a great television series; it’s also a formidable web site. (And, as with so many things media these days, it’s hard to draw the line between the two.)

They’ve just launched an evolution-rich site, with information on their evolution-related shows and lots of other goodies. (As you can see, it’s still beta.)

As part of the unveiling, NOVA asked me if I’d pick ten of the most important developments in evolutionary biology over the past decade. I came up with a far-from-exhaustive list. Check it out.

The Man Who Discovered What Killed the Dinosaurs

Mon, 26 Oct 2009 10:55:00 -0700

Walter Alvarez has been credited with many geologic findings—including the precise time and cause of the death of dinosaurs. Here, he offers tales from his career as a truth-teller with rocks.

Will the Super Rich Evolve Into a Separate Species? | Discoblog

Mon, 26 Oct 2009 09:25:52 -0700

As medicine becomes super advanced, and super expensive, the super rich may evolve into a completely different species from everyone else, according to American futurologist Paul Saffo. He thinks medical technology such as replacement organs, specially tailored drugs, and genetic research tools to alert the moneybags of any possible hereditary health dangers, could all lead to a new class of rich, elite, and longer-living humans.

Here are Saffo’s thoughts on the advantages this would give the rich, as reported in the Guardian:

“I sometimes wonder if the very rich can live, on average, 20 years longer than the poor. That’s 20 more years of earning and saving. Think about wealth and power and the advantages that you pass on to your children.”

At the very least, they’ll be able to afford health care—and keep opposing it for the rest of is.

Image: iStockphoto

Sneak Preview of Darwin: The Musical | Discoblog

Wed, 21 Oct 2009 15:23:19 -0700

It seems people can’t get enough of songs about science. Scientists can’t stop making them, and we can’t stop watching them. David Haines loves science and he loves songs, so he’s putting on a concert called Tremendous Journey to celebrate his love.

Haines gives the deets to New Scientist:

The concert will feature 15 songs about the science of life and evolution. It’s a shorter version of my “science oratorio”, Lifetime. We open with a song called Mr Darwin, which tells the story of his historic voyage aboard the Beagle. Then there is Selfish Gene, a song referring to Richard Dawkins’s work, and Living Light, Queen Bee, Bacteria and Taxonomy.

Check out his song, Mister Darwin, below:

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Video: YouTube / greatplanthunt

Who Killed All Those Honeybees? We Did

Mon, 19 Oct 2009 08:35:00 -0700

The great bee die-off is not such a mystery after all: Industrial agriculture has stressed our pollinators to the breaking point.

Field Notes: Stalking Fish in the Name of Science

Sat, 17 Oct 2009 14:00:00 -0700

An exhaustive new marine census is tracking everything that swims in the sea, one fish at a time.

Weekly News Roundup: Burning Bunnies and Stolen Hands | Discoblog

Fri, 16 Oct 2009 10:26:22 -0700

• Waste not, want not: Stockholm burns culled bunnies for heating fuel.

• Helicopters search for radioactive rabbit poop near the Hanford nuclear reservation. Workers to begin removing the poop soon, which might be the worst job ever.

• Mathematician predicts an ESPN fantasy—a Dodgers-Yanks World Series. FOX Sports also has its fingers crossed.

• Doctors enjoy the five-fingered discount by pocking watches, severed hands from hospitals.

• Think technology is invasive now? A new camera is under development that could capture your entire life.

Play Doh And Multicellular Life Together, At Last | The Loom

Thu, 15 Oct 2009 19:39:30 -0700

Check out this movie that uses Play Doh to explain the evolution of single-celled microbes to multicellular animals. It’s from Creature Cast, a very promising blog on biology from Casey Dunn of Brown University and his compadres.

CreatureCast Episode 2 from Casey Dunn on Vimeo.

The Blind Locksmith Continued: An Update from Joe Thornton | The Loom

Thu, 15 Oct 2009 15:56:28 -0700

I’ve written a few times here about the ongoing work of Joe Thornton, a biologist at the University of Oregon and the Howard Hughes Medical Institute. Thornton studies how molecules evolve over hundreds of millions of years. He does so by figuring out what the molecules were like in the distant past and recreating those ancestral forms in his lab to see how they worked. I first wrote about his work looking at how one molecule in our cells evolved from one function to another (here, here, and here). [Update: These links are now fixed.]

Most recently, I wrote in the New York Times about his latest experiment, in which he and his colleagues found that the evolution from the old function to the new one has now made it very difficult for natural selection to drive the molecule back to its old form. Its evolution has moved forward like a ratchet.

Thornton’s new work turned up last week on a web site run by the Discovery Institute, a clearinghouse for all things intelligent design (a k a the progeny of creationism). Michael Behe, a fellow at the Institute, wrote three posts (here, here, and here) about the new research, which he pronounced “great.”

This is the same Michael Behe who, when Thornton published the first half of this research, declared it “piddling.”

Why the change of heart? Because Behe thinks that the new research shows that evolution cannot produce anything more than tiny changes. And if evolution can’t do it, intelligent design can. (Don’t ask how.)

I pointed out Behe’s posts to Thornton and asked him what he thought of them. Thornton sent me back a lengthy, enlightening reply. Since the Discovery Institute doesn’t allow people to comment on their site, I asked Thornton if I could reprint his message here.

You may want to revisit my posts I linked to above to get a more detailed description of Thornton’s work before delving into Thornton’s reply. And while his reply is quite clear, there are a few terms that may be confusing, so let me preface it with a quick and dirty glossary of terms:

Cortisol: A hormone

Genetic drift: the change in the frequency of an allele (a version of a gene) in a population thanks to chance, not natural selection. Genetic drift can spread an allele through an entire population even if it provides no boost to reproductive success. It can even spread some mildly harmful ones under the right conditions

Glucocorticoid receptor: A receptor that binds cortisol. This is the molecule Thornton has studied, documenting the series of mutations that transformed it from an ancestral receptor sensitive to another hormone.

GR: Glucocorticoid receptor

Steroid receptors: A class of receptors that can bind steroids (a group of molecules that includes hormones such as cortisol).

And without further ado, here’s Thornton’s message–

**************

Dear Carl,

Thanks for asking for my reaction to Behe’s post on our recent paper in Nature. His interpretation of our work is incorrect. He confuses “contingent” or “unlikely” with “impossible.” He ignores the key role of genetic drift in evolution. And he erroneously concludes that because the probability is low that some specific biological form will evolve, it must be impossible for ANY form to evolve.

Behe contends that our findings support his argument that adaptations requiring more than one mutation cannot evolve by Darwinian processes. The many errors in Behe’s Edge of Evolution — the book in which he makes this argument — have been discussed in numerous publications.

In his posts about our paper, Behe’s first error is to ignore the fact that adaptive combinations of mutations can and do evolve by pathways involving neutral intermediates. Behe says that if it takes more than one mutation to produce even a crude version of the new protein function, then selection cannot drive acquisition of the adaptive combination.

This does not mean, however, that the evolutionary path to the new function is blocked or that evolution runs into a “brick wall,” as Behe alleges. If the initial mutations have no negative effect on the ancestral function, they can arise and hang around in populations for substantial periods of time due to genetic drift, creating the background in which an additional mutation can then yield the new function and be subject to selection. This is precisely what we observed in our studies of the evolution of the glucocorticoid receptor (GR).

In our 2007 paper in Science, we showed that multiple mutations were indeed required for the GR to evolve its specificity for the hormone cortisol; some of the mutations that trigger the change in function are deleterious if introduced in isolation, but others are “permissive”: they have no apparent effect on the function of the protein, but once they are in place the protein can tolerate the other mutations that shift and then optimize the new function.

By experimentally characterizing the functional effect of the key historical mutations in various combinations, we showed that there were indeed pathways from the ancestral protein to the new function that passed only through permissive and beneficial intermediate states.

A path to a new function that involves neutral intermediates is entirely accessible to the evolutionary processes of mutation, drift, and selection. Our work showed that these classic neodarwinian processes are entirely adequate to explain the evolution of GR’s new function. (I should mention that pathways involving mildly deleterious intermediates are also accessible in reasonable time under some population genetic conditions; it’s just that their relative probability is lower than those involving neutral or beneficial intermediates.)

Behe’s discussion of our 2009 paper in Nature is a gross misreading because it ignores the importance of neutral pathways in protein evolution. We studied whether the key mutations that drove the “forward” evolution of GR’s new function could be reversed in a later version of the GR, restoring the ancestral conformation and function. We found that the later version of the protein could no longer tolerate the ancestral amino acids at these key sites, despite the fact that they had been present in the protein at an earlier stage of evolution.

We identified the specific “restrictive” historical mutations, which occurred after the shift in function, that either clashed with or failed to support the ancestral conformation. If these mutations are reversed first before the key function-switching mutations, the ancestral structure and function can be restored.

Reversing the restrictive mutations alone does not enhance the ancestral function, but in some orders they have no effect on the GR’s function. These restrictive mutations are simply the flip-side of permissive mutations: reversal of a restrictive mutation is a permissive mutation for reverse evolution. As Fig. 4 in our paper shows, there are several pathways back to the ancestral sequence that pass only through steps that are neutral or beneficial with respect to the protein’s functions.

Thus, all pathways to the ancestral sequence and structure are not blocked, as Behe says they are. The chance effects of genetic drift could allow the protein to “float” along such paths, producing the appropriate background in which the function-shifting mutations could be reversed. However, selection alone would not be sufficient to drive the protein deterministically through the neutral steps. If selection for the ancestral function were imposed, reversal to the same sequence and conformation as the ancestor would be unlikely, though not impossible.

Taken together, the existence of permissive and restrictive mutations indicates that neutral paths to specific adaptive combinations of mutations are opening and closing during evolution. If the clock could be turned back and history allowed to run again, it’s likely that some different path would be followed, and different protein forms would evolve by the natural processes of evolution.

This brings us to Behe’s second error, which is to confuse reversal to the ancestral sequence and structure with re-acquisition of a similar function. We showed that restrictive mutations make selection alone insufficient to drive the protein back to the same form as that found in the ancestor. But nothing in our results implies that, if selection were to favor the ancestral function again, the protein could not adapt by evolving a different, convergent, underlying basis for the function.

Indeed, directed evolution experiments in the laboratory have shown that mutation and selection alone can cause steroid receptor proteins to rapidly evolve sensitivity to new hormones; some of the mutations involved are different from those that occurred during the historical evolution of ancient proteins.

Our paper shows that re-evolution of the underlying ancestral form is unlikely, but it says nothing about the re-evolution of the ancestral function. We found that chance processes play a key role in determining which adaptive forms actually evolve under selection, but this does not mean, as Behe alleges, that no adaptive form can evolve.

Finally, Behe erroneously equates “evolving non-deterministically” with “impossible to evolve.” He supposes that if each of a set of specific evolutionary outcomes has a low probability, then none will evolve. This is like saying that, because the probability was vanishingly small that the 1996 Yankees would finish 92-70 with 871 runs scored and 787 allowed and then win the World Series in six games over Atlanta, the fact that all this occurred means it must have been willed by God.

Consider the future: there are countless possible that could emerge from our present state, making the probability of the one that actually does evolve extraordinarily low. Does this mean that the future state that will ultimately emerge is impossible? Obviously not. To say that our present biology did not evolve deterministically means simply that other states could have evolved instead; it does not imply that it did not evolve.

Consider your own life history as an analogy. We can all look back at the road we have traveled and identify chance events that had profound effects on how our lives turned out. “If the movie I wanted to see that night when I was 25 hadn’t been sold out, I never would have gone to that party at my friend’s house, where I met my future spouse….” Everyone can tell a story like this. The probability of the life we actually lead is extraordinarily small. That obviously doesn’t mean that its historical unfolding was impossible.

That we inhabit an improbably reality requires a divine explanation only if we, like Behe, take the teleological view that this is the only reality that could exist. But if we recognize that the present is one of many possibilities, then there is no difficulty reconciling the nature of evolutionary processes with the complexity of biological forms. As history unfolds, potential pathways to different futures are constantly opening and closing. Darwinian processes are entirely adequate to move living forms along these pathways to a remarkable realization – but just one realization out of many others that could have, but didn’t, take place.

I considered hard whether I should address Behe’s argument or ignore it. I am well aware that Behe and his supporters might portray my response as an indication that there is scientific debate over the possibility of adaptive protein evolution: “Look, an evolutionary biologist who actually does scientific research is arguing with me; let’s teach this controversy in public schools!” Because Behe has grossly misinterpreted the results of my research to support his position, however, I feel some responsibility to set the record straight.

Behe’s argument has no scientific merit. It is based on a misunderstanding of the fundamental processes of molecular evolution and a failure to appreciate the nature of probability itself. There is no scientific controversy about whether natural processes can drive the evolution of complex proteins. The work of my research group should not be misintepreted by those who would like to pretend that there is.

Best regards,
Joe

Like Humans, Plants Fare Better When They’re Among “Family” | Discoblog

Thu, 15 Oct 2009 12:27:34 -0700

In 2007, Canadian researchers amazed us with the discovery that plants can distinguish whether nearby plants are their siblings —in other words, if they’ve grown from seeds from the same source.

Now, University of Delaware professor Harsh Bais has identified just how plants do this: by secreting chemical signals to other plants.

Plants grow more horizontal roots when they’re in the presence of “strangers,” better enabling them to compete for necessary nutrients. However, when plants are near their “siblings,” they grew fewer roots—leaving researchers to think that plants don’t need to grow as many roots to survive when they know they’re among “kin.”

In a series of experiments, the researchers exposed young seedlings of Arabidopsis thaliana to the root secretions from their “siblings” as well as to those of “strangers.” When exposed to unfamiliar root secretions, the test plants grew more roots. However, when the plants were around kin, they “knew” that they would be competing for nutrients, so their roots didn’t grow as much. Additionally, when the researchers treated the first group of plants (the ones next to strangers) with sodium orthovanadate—a chemical that stops secretion but doesn’t stop roots from growing—the plants seemed to loose their sense of “strangers.”

Physorg reports:

“Plants have no visible sensory markers, and they can’t run away from where they are planted,” Bais says. “It then becomes a search for more complex patterns of recognition…”

Bais says he and his colleagues also have noticed that as sibling plants grow next to each other, their leaves often will touch and intertwine compared to strangers that grow rigidly upright and avoid touching.

The study leaves a lot of unanswered questions that Bais hopes to explore further. How might sibling plants grown in large “monocultures,” such as corn or other major crop plants, be affected?

In a related study, when plants were planted next to “strangers,” their growth was stunted—because all their energy was spent growing more roots, the rest of the plant suffered. Siblings, on the other hand, fared better overall. So like humans, plants often do best when they’re among family.

Images: flickr/ BlueRidgeKitties

How Invaders Break Through the Brain's Great Wall

Thu, 15 Oct 2009 10:00:00 -0700

Some bacteria pierce the imposing blood-brain barrier by breaking links in the chain; sneakier ones do it by fooling the guard cells.