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Deep-sea bacteria redefine life in the slow lane | Not Exactly Rocket Science
Your laziest days are positively frenetic compared to the lifestyle of some deep-sea bacteria, buried in the sediments of the Pacific Ocean. These microbes are pushing a slow-going lifestyle to an extreme. They subsist on vanishingly low levels of oxygen, in sediments that have not received any new food sources since the time of the dinosaurs. And yes, they survive.
Not only that, but these microbes could make up 90 per cent of those on the planet. “We’re looking at the most common forms of life on this planet, and we know almost nothing about them,” said Hans Røy, who has been studying them for many years. Now, Røy has finally measured just how slow their metabolism really is.
I’ve written about this discovery for The Scientist, so head over there for the full story.
Image by Shelly Carpenter, NOAA Ocean Explorer
discovermagazine.com | 17-May-2012 20:05
Arrested Development Pays Off for Male Orangutans: Meek Ones Often Get the Girls | 80beats
A sexually mature male with cheek flanges, throat pouch, and very long fur.
Why would a sexually mature male orangutan want to look too young to father children? Just ask male dung beetles or goby fish. All these species have two types of males: big, aggressive ones that elaborately woo females and smaller sneaker males who, well, sneak behind the backs of the bigger ones. Both can end up successful fathers.
Male orangutans become sexually mature around age 10, but some will stay in arrested development for up to 20 years, even after fathering children of their own. These immature-looking males don’t have the broad cheek flanges, throat pouches, and long orange hair we normally associate with male orangutans. They also don’t produce the long calls that mature-looking males use to attract mates. Even with none of these secondary sex characteristics, male orangutans can get mates and have children. A previous study that tracked an orangutan population in Sumatra for 27 years found that 6 of 11 new babies were fathered by the immature-looking males.
A new paper in the American Journal of Physical Anthropology models how arrested development works in a population. The ...
discovermagazine.com | 17-May-2012 18:00
As oxygen filled the world, life’s universal clock began to tick | Not Exactly Rocket Science
The Earth’s earliest days were largely free of oxygen. Then, around 2.5 billion years ago, primitive bacteria started to flood the atmosphere with this vital gas. They produced it in the process of harnessing the sun’s energy to make their own nutrients, just as plants do today. The building oxygen levels reddened the planet, as black iron minerals oxidised into rusty hues. They also killed off most of the world’s microbes, which were unable to cope with this new destructive gas. And in the survivors of this planetary upheaval, life’s first clock began to tick and tock.
Today, all life on Earth runs on internal clocks. These ‘circadian rhythms’ are the reason we feel sleepy at night, and why our hormones, temperature and hunger levels rise and fall with a 24-hour cycle. They’re molecular metronomes that keep the events inside our bodies ticking in time with the world around us.
Until now, it seemed that the major branches of the tree of life each had their own timekeeping systems, evolved independently of the others. But Akhilesh Reddy and John O’Neill from the University of Cambridge have disproved that ...
discovermagazine.com | 16-May-2012 19:00
Trapped in Amber, the Oldest Evidence of Pollination | 80beats
Peering inside an ancient piece of amber, scientists have uncovered the oldest direct evidence of pollination: insects covered in pollen grains, likely from a gingko tree, from between 105 and 110 million years ago. These insects—a new genus of thrips, insects that still scuttle around today—had likely gathered pollen for food, trailing it from plant to plant along the way. To get an even closer look at the specimens (without cracking open the amber), the researchers took the lump to the European Synchrotron Radiation Facility. There, they used synchrotron X-ray tomography to generate a detailed 3-D image of the bugs, revealing tiny, specialized hairs they used to collect pollen grains (which are shown here in yellow).
Flowering plants first evolved about 130 million years ago, making them relative evolutionary newcomers; dinosaurs had already been around for 100 million years by then. Since early on, these plants have been aided in reproduction by insects that spread their pollen from one flower to the next, and in turn helped the insects by providing sustenance. “The co-evolution of flowering plants and insects, thanks to pollination, is a great evolutionary success story,” ...
discovermagazine.com | 16-May-2012 16:54
Sleeper viruses explain why HIV evolves more slowly between people than within them | Not Exactly Rocket Science
HIV – the virus behind AIDS – is the most diverse of all viruses. Once it infects someone new, it mutates so rapidly that it can spawn a million genetically different strains in just a few months. This evolutionary onslaught overwhelms the host’s immune system, and creates big problems for any scientist trying to create a cure or a vaccine. By evolving so quickly, HIV turns itself into a million moving targets.
But when HIV jumps from one individual to another, something odd happens. The virus still mutates at a breakneck speed, but it does so 2 to 6 times more slowly than within any single person. Unexpectedly, the virus seems to evolve faster in a single host, than in a population.
There are three possible explanations for this puzzling trend, but Katrina Lythgoe and Christophe Fraser from Imperial College London think that only one is correct. They think that the ancestral strain – the one that kicked off someone’s infection – is more likely to spread to other people than its millions of descendants.
The progeny of the ancestral virus quickly evolve to avoid their host’s immune system and ...
discovermagazine.com | 16-May-2012 01:00
Come For the Beautiful “Glass Gem” Corn; Stay for a Dose of Genetics | 80beats
No, this isn’t Photoshop or a gemstone-studded trinket—just an ear of corn. Seedsman Greg Schoen of the Seeds Trust got this “Glass Gems” corn from his “corn-teacher,” a part-Cherokee man in his 80s. He planted the seeds, had a gorgeous harvest last fall, and posted the posts on Seeds Trust’s Facebook page in October. Then last week, the photos of the gem-like corn got picked up on the internet and went viral. Good luck trying to get your hands on any seeds now…
But kernel color is a fascinating—dare we say, colorful—topic in the annals of genetics research. For one, why are there so many vibrant colors in a single ear of corn? You don’t usually see flowers of different colors on a single tree. Each kernel is actually a different corn plant (or the seed of one) with a unique mix of genes inherited from its parents. That’s why counting up kernels of different colors in the more familiar purple and yellow corn cobs is a common way of teaching how pigment genes are inherited in Mendelian genetics.
Kernel color has also been used to unravel an ...
discovermagazine.com | 15-May-2012 19:57
Dogs Catch Yawns From Their Owners. Does That Mean They Empathize with Us? | 80beats
One sleepy person can start a bout of contagious yawning that quickly spreads through a room. But a new study suggests the effect may not be limited to the room’s human inhabitants: Dogs can “catch” yawns from people, the study found—especially their owners, hinting that pooches may empathize with familiar people.
When listening to recordings of people yawning, 12 of the 29 dogs in the study yawned themselves. It made a big difference, however, whom they heard: The dogs yawned more than four times as much when they heard their owner yawn as when they heard as a stranger.
Earlier work has suggested a link between contagious yawning and empathy. Humans and chimps both yawn more when friends and acquaintances yawn than when strangers yawn, and people who don’t have much insight into what others are feeling—such as very young children and people with autism—don’t seem to catch contagious yawns. This is some of the strongest evident yet that dogs—humans’ constant companions for 15,000 years—may be able to empathize with us. But a yawn alone can’t tell us what’s going on in a dog’s brain, or its heart of hearts. A similar ...
discovermagazine.com | 15-May-2012 19:45
The Brain: Hidden Epidemic: Tapeworms Living Inside People's Brains | DISCOVER
Theodore Nash sees only a few dozen patients a year in his clinic at the National Institutes of Health in Bethesda, Maryland. That’s pretty small as medical practices go, but what his patients lack in number they make up for in the intensity of their symptoms. Some fall into comas. Some are paralyzed down one side of their body. Others can’t walk a straight line. Still others come to Nash partially blind, or with so much fluid in their brain that they need shunts implanted to relieve the pressure. Some lose the ability to speak; many fall into violent seizures.
Underneath this panoply of symptoms is the same cause, captured in the MRI scans that Nash takes of his patients’ brains. Each brain contains one or more whitish blobs. You might guess that these are tumors. But Nash knows the blobs are not made of the patient’s own cells. They are tapeworms. Aliens.
A blob in the brain is not the image most people have when someone mentions tapeworms. These parasitic worms are best known in their adult stage, when they live in people’s intestines and their ribbon-shaped bodies can grow as long as 21 feet. But that’s just one stage in the animal’s life cycle. Before they become adults, tapeworms spend time as larvae in large cysts. And those cysts can end up in people’s brains, causing a disease known as neurocysticercosis.
“Nobody knows exactly how many people there are with it in the United States,” says Nash, who is the chief of the Gastrointestinal Parasites Section at NIH...
Image: A human brain overrun with cysts from Taenia solium, a tapeworm that normally inhabits the muscles of pigs. Courtesy of Theodore E. Nash , M.D.
discovermagazine.com | 15-May-2012 17:00
Jurassic bends – the rise of fast predators bubbled the blood of prehistoric reptiles | Not Exactly Rocket Science
Experienced divers know that rising too quickly can be a fatal mistake. The changing pressure yanks previously dissolved gases out of one’s blood and forms tiny bubbles, like the fizz in a newly opened can of soda. Depending on where they emerge, the bubbles can cause everything from a rash (the skin) to seizures (the brain). To avoid this condition, known as decompression sickness or “the bends”, divers rise slowly.
Then again, if you’re being chased by a gigantic prehistoric shark, you may have no choice.
The bends were first described as a human ailment in 1841, but it has been afflicting diving animals for far longer. For decades, Bruce Rothschild has been studying bone diseases in prehistoric animals. He has found traces of the bends in the fossils of many ancient reptiles, which ruled the oceans while the dinosaurs walked the land. When the bubbles formed in bones, they blocked the local blood vessels, killed the surrounding tissue, and eventually caused the bone to collapse. The humerus – the bone of the upper arm – was particularly vulnerable.
Rothschild has found such signs among prehistoric turtles, dolphin-like ichthyosaurs, crocodile-like ...
discovermagazine.com | 15-May-2012 15:00
Why Preserved Food is So Bad: “Retort Flavor” | 80beats
Autoclaves—would you cook a turkey in this?
At Popular Science is a profile of food scientists given an impossible task: make year-old mashed potatoes taste good. Food that lasts a year on the shelf needs to be sterilized, and that is a battle against extremophiles. Our most effective weapon is a very blunt one—heat. 252 degrees Fahrenheit to be exact.
Writer Paul Adams tours a food science lab and gets a taste of “retort flavor” in his sterilized mashed potatoes. The unappetizing term refers to the retort, a machine that obliterates microbes and flavor in one fell (and very hot) swoop:
The potatoes look right, once we’ve fluffed them up a bit, but the wholesome earthy taste and smell of fresh potatoes is almost gone from the dish. In its place there’s a tired, wet-paper flavor with notes of old steam pipe. This side effect of confined high-heat cooking is known in the trade as “retort flavor.” Stuckey’s theory is that it’s just underlying parts of the flavor coming through. Before food is retorted, she says, the dank base notes present in it are masked in part “by the beautiful aromatic volatile notes that we ...
discovermagazine.com | 14-May-2012 14:29
Cancer evolution at TEDMED | The Loom
Earlier this year, TEDMED took place in Washington DC, showcasing people doing innovative research in medicine. This year’s talks are now being loaded online, and today I was happy to see that cancer and evolution got their due. Franziska Michor of Harvard explained how the threat of cancer is a legacy of our evolution into multicellular animals, and how every case of cancer is a miniature unfolding of evolution within our own bodies. What makes Michor’s work particular exciting is that she is bringing the mathematical precision of population genetics and other aspects of evolution to the treatment of cancer.
I wrote about some of Michor’s work in my 2007 Scientific American article, “Evolved for Cancer?” (carlzimmer.com, sciam.com) I’ve also explored cancer evolution here on the Loom: “Inside Darwin’s Tumor” and “The Mere Existence of Whales.” And you can find lots of Michor’s papers as free pdf’s on her publication page.
discovermagazine.com | 11-May-2012 15:00
You ask for signed bookplates, you get signed bookplates | The Loom
At some of my recent talks, I’ve been running into people who’ve been annoyed that they forgot to bring a book of mine to get signed. You really couldn’t think of a better way to cheer up a writer, and so I feel the need to reciprocate.
So if you’ve gotten a book of mine and want to get it signed, I’ve printed up some bookplates that I can autograph and send to you.
Just to ensure I’m not signing bookplates for alien robots who will take these bookplates to their home planet to…do whatever evil thing alien robots do with bookplates from science writers…please follow these steps:
1. Take your picture with the book.
2. Email it to me, with your mailing address and any special signing request. As in, “To Ken Ham, so that someday he may appreciate transitional fossils….”
Optional step 3. For those on Twitter: instead of emailing me your photo, you can upload it to Twitter (mentioning my Twitter name @carlzimmer). Be sure to email me your address, too, so that I know where to send the bookplate.
So far, I’ve got three bookplates–one for Parasite Rex, one for Science Ink (in matching Goth type), and one for ...
discovermagazine.com | 11-May-2012 01:27
The Hagfish's Special Trick for Warding Off Predators: Thick, Sticky Mucus
Sharks are superb predators, but even they are no match for the animal kingdom’s most disgusting yet effective defense: the gag-inducing slime of the hagfish.
Hagfish are elusive deep-sea creatures that have mucus-secreting glands positioned all over their long, writhing bodies. Last fall marine ecologist Vincent Zintzen of the Museum of New Zealand Te Papa Tongarewa published a study describing the first-ever observations of hagfish exploiting those glands to ward off predators. He analyzed 500 hours of video from cameras placed in deep waters off the New Zealand coast and found 14 encounters between hagfish and fierce hunters like the seal shark and the conger eel. In every case the hagfish emerged unharmed while the predators fled the scene, gagging on the irritating slime that rapidly expands in seawater and clogs the gills. “It was striking how effective this defense mechanism was,” Zintzen says.
The videos also reveal that at least one species of hagfish can go on the attack...
discovermagazine.com | 10-May-2012 23:30
Millions of Taxpayer Dollars are Used to Secretly Massacre Wildlife, Family Pets, Threatened Species | 80beats
Nearly a million coyotes have been killed by Wildlife Services since 2000.
In the western US, conflict between ranchers and wild animals who might harm their stock is an old, old story. But in 1915, the federal government started helping ranchers and farmers out by killing animals suspected of attacking livestock, eventually forming an agency known as Animal Damage Control. Today, though, the agency has morphed into something that appalled many of the readers who learned of its activities last week in the Sacramento Bee.
When Wildlife Services, as the group is now called, finds a bald eagle, a family’s beloved husky, or a young badger in a trap laid for coyotes or prairie dogs, its back broken or leg snapped, it is shot and its body buried. Its death at the hands of federal employees is rarely, if ever, reported as required. This happens thousands of times a year, on top of all the killings of wildlife that are the agency’s intended targets.
The Bee’s evidence against Wildlife Services’s claims of killing only when necessary, assembled in three investigative articles, is damning. The series is worth reading for yourself, along with the follow-up articles ...
discovermagazine.com | 10-May-2012 19:10
Meat-eating plant digests insects using ants | Not Exactly Rocket Science
Many insects eat plants, but some plants can turn the tables on their would-be diners. The pitcher plants are among several groups that can capture insects and digest their flesh. And one species – the fanged pitcher plant – goes even further. It digests insects with insects.
There are around 120 species of pitcher plants and all of them have large leaves that fold to produce fluid-filled traps. The rims of the pitchers are usually extremely slippery, and insects that wander by lose their foothold and fall into the pool of fluid within. There, they drown and are digested by the plant.
The fanged pitcher is unusual. Its rim lacks the usual waxy layer and is less slippery than those of its cousins. And it’s the only species that recruits ants. The base of each pitcher contains a swollen tendril that houses ants of the species Camponotus shcmitzi. These insects are permanent residents; they’ve never been seen in any other plant.
People have assumed that this is yet another case of a plant-ant alliance. Aside from accommodation, the ants also get food from the nectar that exudes ...
discovermagazine.com | 09-May-2012 23:00
Three nations divided by common gut bacteria | Not Exactly Rocket Science
A child from the village of Chamba in rural Malawi has very little in common with one living in the city of Philadelphia in the USA. They eat different food, speak different languages, and enjoy different lifestyles. But they are both united by the fact that they are vessels for teeming hordes of bacteria.
These children, like all of us, are home to trillions of bacteria and other microbes. These passengers outnumber our own cells by ten to one, and their genes outnumber ours by a hundred to one. Collectively, they’re known as the microbiome, and they are as much a part of us as any one of our own organs. They break down our food, safeguard our health, and affect our minds. And they have become intensely fashionable.
Microbiome research is booming, fuelled by the realisation that these microbes might provide a deeper understanding of our bodies, and new ways of diagnosing or treating diseases. But, with some exceptions, most microbiome studies have focused on wealthy populations from Europe, North America and Japan. There’s a risk that the bacteria of people from the developing ...
discovermagazine.com | 09-May-2012 19:00
Insects that skate on the ocean benefit from plastic junk | Not Exactly Rocket Science
Imagine a world of two dimensions, a world with no up or down… just across. No climbing, falling, jumping, or ducking… just shimmying and sidling. Welcome to the world of the sea skater.
Sea skaters, or ocean striders, are small bugs. They’re relatives of the pond skaters or water striders that zip spread-eagled across the surface of ponds and lakes. Except they skate over the open ocean, eating plankton at the surface. “They skate through storms and wind and waves,” says Miriam Goldstein from the University of California San Diego and the Deep Sea News blog. “They even have a little ‘life jacket’ – the hairs on their body trap air so if they get sunk by a wave, they pop back up. They’re amazing!”
There are only five species of sea skaters, all belonging to the Halobates group. Of all the millions of insect species, these five are the only ones to live out at sea. Now, Goldstein has discovered that one sea skater Halobates sericeus actually benefits from what most people would regard as an ecological disaster – the circling mass of plastic and debris known as the ...
discovermagazine.com | 09-May-2012 01:00
Rare Footage of Endangered Gorillas Includes Chest-Pounding Silverback | 80beats
The Cross River gorillas are an elusive bunch: there are fewer 250 individuals left of this western gorilla subspecies, and, understandably, they are afraid of humans. A few hours ago, though, the Wildlife Conservation Society announced that they’d managed to capture a tape of 8 gorillas—about 3% of the remaining population—in their native Cameroonian habitat, by using a motion-activated camera.
It’s a fascinating glimpse into the behavior of an animal that, given current trends, more than likely won’t exist in the near future. Lumbering on their knuckles through the crackling leaves, the gorillas occasionally plunk themselves down under a tree before continuing on their journey. About half-way through the edited clip, a large male gorilla charges past the camera, striking his chest with cupped hands, a motion that produces a high, distinctive, almost yodeling sound, and as he falls back on all fours, you can see the silver hair on his back. Shortly afterward, a gorilla missing its left hand moves across the scene; WCS thinks the hand could have been lost to a poacher’s snare.
It seems, though, that the ululating sound threw a few people off. CBS News’ coverage is studded with some choice work-arounds demonstrating that they’re not really sure ...
discovermagazine.com | 08-May-2012 23:53
Do Unhatched Chicks Sleep and Wake In Their Eggs? | 80beats
You go to sleep at night, you wake up in the morning—the definition of sleep doesn’t seem so complicated. But start asking questions and things start getting thorny: Are dolphins that never stop swimming sleeping? Are migrating birds that “shut down” half their brains sleeping? Is someone under general anesthesia sleeping? And what about babies in the womb?
Unborn human babies in the womb are pretty difficult to monitor 24/7, so the researchers interested in that last question got ahold of unhatched chicken eggs. In a new Current Biology paper, they report that chicks show higher-brain activity patterns similar to sleep, and the cries of a hen could “wake up” the chick even when other loud but not chicken-salient sounds could not. These higher-brain activity patterns only appear in the last stage of incubation, presumably after their brains become well developed.
To monitor brain activity in the chicks, the scientists carefully made a small hole in the top of the egg and injected radioactive sugars onto the egg’s inner membrane. The developing embryo absorbed these sugars, which the team could then track with a PET scan. Active neurons need energy, which they get from sugar, so ...
discovermagazine.com | 08-May-2012 16:07
How frogs climbed up into the Lost World: My story in tomorrow’s New York Times | The Loom
The tepuis of northern South America–tabletop mountains ringed by sheer cliffs rising up thousands of feet–inspired Sir Arthur Conan Doyle’s novel The Lost World. Doyle envisioned dinosaurs and other primordial creatures surviving on these remote islands in the sky.
It turns out that the tepuis are indeed ancient vestiges. The surrounding land eroded away 70 million years ago. Biologists have long been fascinated by the plants and animals that live on top of them today. In many cases, the species on a tepui are found nowhere else on Earth. Many have argued for the wonderfully-named “Lost World Hypothesis”–the unique species of the tepuis been stranded up there for 70 million years.
In tomorrow’s New York Times, I report on a team of scientists who tested that hypothesis by looking at the DNA of frogs that live on tepuis. And for them, at least, the hypothesis fails. Somehow, those tiny frogs managed to scale walls that strike fear in even the toughest rock climbers. For the full details, check out the story.
Image by Xyrenita on Flickr/via Creative Commons
discovermagazine.com | 08-May-2012 02:36
Zombie Ant Parasite Has Its Own Parasite—a Fungus That Attacks Fungi | 80beats
Fruit body of a parasitic fungus, growing out of a dead ant.
The tale of the ant and the mind-controlling fungus Ophiocordyceps is straight out of a horror story.
An unlucky ant inhales a spore, the fungus begins to eat the ant from inside, and, in a particularly sinister twist, Ophiocordyceps hijacks the ant’s brain. The “zombie” ant is forced to leave its nest to climb up onto a tree, clamping its jaws into a leaf vein with abnormal force. A stalk sprouts from the now dead ant’s head. This stalk is fruiting body of the fungus, which will produce new spores that rain down onto the unlucky ants below.
Ophiocordyceps seems like a lean mean killing machine in that scenario, but the fungus itself is vulnerable—to another fungus it turns out. A new paper published in PloS ONE models the disease dynamics of Ophiocordyceps with respect to ants and a hyperparasitic fungi, which is the name for parasite whose host is also a parasite. Unfortunately, this hyperparasite is not of much help for the ant, as it only infects the Ophiocordyceps after the ant has died.
The researchers collected 432 fungus-infected ants from “graveyards” ...
discovermagazine.com | 07-May-2012 21:19
In Memory of Lucy #scienceink | The Loom
Victoria McGowan writes,
Please find attached a photo of my Australopithecus tattoo. I’m a medical anthropologist researching the historical relationship between school meals and obesity in children as part of my PhD at Durham University. Obviously this has very little to do with Australopithecus but my interest in “Lucy” began when I started my UG degree in Anthropology here at Durham. One of my first lectures was on our Biological and Social Origins and we learnt about our evolutionary heritage. Lucy caught my eye because she was one of the most complete finds of this species at that time. Also as it was thought that she was more closely related to Homo genus than any other Australopithecus at that time.
I found it fascinating that from her remains we could postulate that she was bipedal and from her pelvis we could deduce that she would have gave birth to a larger brained infant than previous species. We can further postulate that her infant care practices would be more similar to our own, larger brained infant would have to complete their growth outside the womb and would require ...
discovermagazine.com | 06-May-2012 17:13
The Mystery of the Melanesian Blondes | 80beats
A blond boy from the island of Vanatu
In many places, blond hair usually goes with white skin and European ancestry. But in the islands of Melanesia and among the Aborigines of Australia, blond hair crops up on dark-skinned people with no known European heritage. Scientists have long wondered, is it because they have some (very, very) long-lost European ancestors? Or did blond hair arise from a genetic mutation in the population there?
A paper published in Science this week lays that question to rest. The researchers found that blond Solomon Islanders in Melanesia have a single amino acid difference in the tyrosinase-related protein 1 (TYRP1) gene, which codes for an enzyme involved in the production of the pigment melanin. Other mutations in TYRP1 can give people albinism; this one gives them light-colored hair. The mutation is recessive, so only people who have two mutant copies of the TYRP1 gene are blond.
This mutation is not responsible for European blondness, which hammers home the fact that pale hair didn’t arrive on a boat with early European explorers—it’s definitely native to the islands.
For the full story and lots of tasty genetics, head over to Discover’s Gene ...
discovermagazine.com | 04-May-2012 22:28
A duplicated gene shaped human brain evolution… and why the genome project missed it | Not Exactly Rocket Science
The Human Genome Project was officially completed in 2003, but our version of the genome is far from truly complete. Scientists are still finishing the last parts, correcting errors in the official sequence, and discovering new genes. These new genes did not go unnoticed because they are useless or insignificant. Some of them may be key players in our evolutionary story.
Two groups led by Evan Eichler and Franck Polleux have found that humans, alone among all animals, have three extra copies of a gene called SRGAP2, which is involved in brain development. The second of these copies, SRGAP2C, is particularly interesting because it affects the development of neurons, and produces features that are distinctively human. It also emerged between 2 and 3 million years ago, during the time when our brains became much bigger.
Genes are often duplicated by mistake when DNA is copied or shuffled around. These duplications provide raw fuel for fast evolution. Suddenly, genes get back-up copies. Either the original or the duplicate can mutate with impunity and take on new roles. But duplications ...
discovermagazine.com | 04-May-2012 15:00
Case closed: blonde Melanesians understood | Gene Expression
As a small child perusing old physical anthropology books I would occasionally stumble upon images of people of Oceanian stock with light hair color. I would wonder: is this a biological or cultural feature? In other words, were people bleaching their hair? If it was biological, was it heritable, or was it simply malnutrition? Another aspect of the phenotype was also straightforward: it did not seem that light hair color resulted in any concomitant lightening of the skin. Granting that this was a heritable biological trait, the questions then were simple: was this trait an independent occurrence of de-pigmentation in Oceania, or was it due to introgression of European alleles?
First, one must note that this is not an isolated feature in Oceania. Rather, blondism crops up in the Solomon Islands, in New Guinea, as well as among some Australian desert groups. This in itself should make us skeptical of the model of European admixture. Additionally, blue eyes, which exhibits a higher frequency in Europeans than blonde hair, is not similarly common in these populations. But all this speculation is now a historical curiosity. The results are widely known from conference ...
discovermagazine.com | 04-May-2012 08:21
Cockroaches Get Lonely, Kind of (But a Little Feather-Poking Can Help) | 80beats
When people think of cockroaches, some may think of the much-smarter-than-a-bug Gregor Samsa, but it takes a special kind of person—a social biologist, really—to think of them as “gregarious.” Yes, these unloved (by humans), trash-eating creatures have social lives too. A recent review in the journal Insectes Sociaux highlights the social behavior of two so-called gregarious cockroach species: Blattella germanica and Periplaneta americana. Although not as sophisticated as eusocial insects like ants or bees, these cockroaches can communicate, recognize kin, and even get “lonely” in isolation. Now we’re getting Kafka-esque.
To talk to and recognize one another, cockroaches use hydrocarbons, molecules that are made of only hydrogen and carbon atoms. These chemical markings help them identify group shelter spots, where they hang out together during the day between nightly foraging runs. (When they are out looking for new shelter or food, they tend to follow the crowd too.) The hydrocarbon signature is unique to each cockroach. Siblings can recognize each other and avoid incest, which is not so great for genetic diversity.
When forced into isolation by lab researchers, these gregarious cockroaches get “isolation syndrome,” taking longer to molt and reach sexual maturity. Isolated cockroaches also have problems ...
discovermagazine.com | 03-May-2012 22:07
Male water striders evolved antennae to grab females by the eyes | Not Exactly Rocket Science
The worst sex you have ever had pales in comparison to what female water striders have to put up with. Put it this way: you have never been held down by your eyes.
As the female skates over the surface of ponds and lakes, males will try to force themselves upon her. She resists by struggling vigorously. But in some species, males can avoid being thrown off with antennae that have evolved into antler-shaped restraints. They bend in on themselves and are loaded with an array of prongs and spikes that perfectly fit to the shape of a female’s head.
Locke Rowe from the University of Toronto has been studying water striders for almost 20 years. In many species, males have evolved structures that give them an edge in their indelicate liaisons with females. “But the traits I studied before were rather simple – a spine here or there,” says Rowe. The subject of his latest study, a species called Rheumatobates rileyi – is… well, the opposite of simple.
The females have normal antennae. The males however, have “spectacularly modified grasping devices”, says Rowe. “They’re large, muscular, and fitted with spines and ...
discovermagazine.com | 03-May-2012 20:00
Mutant flu paper is finally published, reveals pandemic potential of wild viruses | Not Exactly Rocket Science
It’s finally out. After months of will-they-won’t they and should-they-shouldn’t-they deliberations, Nature has finally published a paper about a mutant strain of bird flu that can spread between mammals.
The strain was produced by Yoshihiro Kawaoka from the University of Wisconsin-Madison, who was trying to understand whether wild bird flu viruses have the potential to start a pandemic. These viruses can occasionally infect humans, but so far, they’ve been contained by their inability to efficiently jump from human to human. Kawaoka’s work makes it clear that they can evolve that ability.
Kawaoka’s study, along with a similar one from Ron Fouchier, has been the subject of intense debate for the last several months (catch up on the backstory here). What are the benefits of the research, and do they outweigh the risks? Now that the paper is finally out, we can start to answer those questions.
I’ve written about the paper for Nature News, focusing very heavily on the science rather than the politics. Head over there for a tighter version of this story. In this post, I’m going to highlight four important themes from the paper.
One: H5N1 can evolve to spread ...
discovermagazine.com | 02-May-2012 19:00
How Our Circadian Cycle Helps Us Not Need to Pee Overnight | Discoblog
How to keep track of mouse urine
Eight hours is a long time without a trip to the bathroom when awake, yet most of us can sleep through the night without peeing. And no, it’s not just because you (presumably) stop drinking coffee in your sleep: even when food and drink are factored out, you both make less urine and have better bladder capacity during the night. As with most behaviors that change from day to night, it does indeed have everything to do with the circadian rhythm.
In a new study published in Nature Communications, researchers compared normal mice with mice whose circadian rhythms were disrupted by genetic mutations. To keep track of mice urination over time, they used a rather charming contraption that slowly unspooled urine paper under the cages (see image). Urine spots on the paper were counted up and, sure enough, urination in the normal mice showed 24-hour patterns while the mutant mice did not.
The study also identified a molecular mechanism that lets bladders hold more urine during sleep. Concentrations of the bladder protein Cx43 goes up and down over the course of 24 hours. It makes bladder muscles more sensitize to ...
discovermagazine.com | 02-May-2012 18:48
Dolphins that help humans to catch fish form tighter social networks | Not Exactly Rocket Science
In the coastal waters of Laguna, Brazil, a shoal of mullet is in serious trouble. Two of the most intelligent species on the planet – humans and bottlenose dolphins – are conspiring to kill them. The dolphins drive the mullet towards the fishermen, who stand waist-deep in water holding nets. The humans cannot see the fish through the turbid water. They must wait for their accomplices.
As the fish approach, the dolphins signal to the humans by rolling at the surface, or slapping the water with their heads or tails. The nets are cast, and the mullet are snared. Some manage to escape, but in breaking formation, they are easy prey for the dolphins.
According to town records, this alliance began in 1847, and involves at least three generations of both humans and dolphins. Today, there are around 55 dolphins in the neighbourhood, and around 45 per cent of them interact with the fishermen.
Now, Fabio Daura-Jorge from the Federal University of Santa Catarina, Brazil studied Laguna’s dolphins to learn how their unusual collaboration has shaped their social networks. He spent two years taking photographs of the local dolphins, and ...
discovermagazine.com | 02-May-2012 01:00
Bees That Drink Sweat From People’s Skin and Tears From People’s Eyes | 80beats
Drink up!
Have you ever thought about how nutritious your bodily fluids are? Full of goodies like salts and proteins…Wild bees know all about it, feeding human sweat and tears as a source of nutrition.
Urban sweat bees, for example, use humans like a salt lick. “These bees prefer sweaty people—over most animals—because the human diet usually is so salty that their perspiration is saturated with the essential nutrient,” according to a recent feature in the Wall Street Journal on sweat bees. A new species (Lasioglossum gotham) of these bees was recently identified from a specimen netted in the heart of Brooklyn. Although they are as a group fairly common, they’re tiny and they don’t sting, which is why you probably haven’t heard New Yorkers complaining about them. “[M]ost people never notice when the tiny bees alight on a bare arm or leg,” says the WSJ.
But what about a bee in your eye, you’d probably notice that right? Scientists have investigated different families of bees in Thailand that drink tears, both human and animal. Eyes wide open, the researchers used themselves as bee bait. (They also used meat, Ovaltine, cheese, and ...
discovermagazine.com | 01-May-2012 18:12
Top tip: do not steal food from ant traps | Not Exactly Rocket Science
The Amazonian tree known Hirtella physophora looks rather unassuming, but it is the site of several grisly spectacles. Amid its leaves and branches, an animal, a plant and a fungus conspire to create a nightmarish trap where trespassers become meals, robbers get the death penalty, and assassins are assassinated.
The tree is home to ants called Allomerus decemarticulatus, which defend it from hungry insects. In return, the tree provides the ants with leaf pouches and swollen thorns as shelter, and feeds them with nectar and sugary nodules. These food sources are rich in carbohydrates but low in proteins. To supplement their diets, the ants need flesh, and they get it by shaping the tree into traps.
The ants cut hairs from the plant and weave them together into a hollow gallery, which extends down the side of the tree’s branches. Within the gallery, the ants hide inside small holes, jaws agape. From the outside, nothing can see them. If an insect lands on the trap, hundreds of lurking jaws seize its legs and pull it spread-eagled, as if on a medieval ‘torture rack’. The victim is overpowered and dismembered.
http://www.youtube.com/watch?v=zrL5BYRqrTI
This ...
discovermagazine.com | 01-May-2012 15:00
Her identity by descent made flesh | Gene Expression
As I have indicated before, my daughter has a family tree where everyone out to 0.25 coefficient of relatedness has been genotyped by 23andMe. This is convenient in many ways. Before, relatedness was a theory. Now relatedness can be ascertained on the genomic level. Sometimes this can lead to peculiar consequences. “On paper” my daughter is 1/8 Scandinavian. Or 12.5%. But truly the expected value is 13.5%! (weighting by contributions from each maternal grandparent). Still, this remains an expected value. I would need a large sample of Scandinavians from that locale to make a truly precise guess as to the genetic contribution. Similarly, though I come in at about ~15 percent East Asian, my daughter looks to be a bit more East Asian than you’d expect based on that value (i.e., closer to 8-8.5 percent; I run her genotype more than a dozen times now). This may be a bias in the methodology, or, more likely it is simply the sampling error from my genome (I contributed more East Asian segments in the chromosomes passed down).
In any case, 23andMe has a “family inheritance” feature which is very convenient. ...
discovermagazine.com | 29-Apr-2012 23:49
Dogs Are Manipulable, Cats Are Manipulative, and Both Act Like Babies | Discoblog
How you doin’?
After thousands of years living in our homes, cats and dogs have gotten pretty good at tuning into human social cues—as good as as human babies anyways.
Dogs, with their adorable puppy faces, are easily swayed by the actions of humans. A new study in PLoS ONE shows that dogs will prefer a plate of food preferred by a person, even if that plate has less food on it. Cats, on the other hand, have an especially annoying “solicitation” purr that they deploy when they want something from their owners, much like (though quieter than) a hungry baby that will not stop screaming. Pet owners who fancy themselves parents may actually be onto something.
Although babies can’t understand words, they are good at following body language and the gazes of their parents—what are called “ostensive cues.” Dogs do the same thing; when they see you looking in a particular direction, for example, they look there too. Researchers in this new study show that dogs made their decisions based on these ostensive cues as well. They began by presenting the dogs with two plates with unequal amounts of food. Then an experimenter would look at ...
discovermagazine.com | 28-Apr-2012 16:54
This Scientist Endures 15,000 Mosquito Bites a Year | Discoblog
The things we do for science.
Researchers who study mosquitoes and other blood-sucking insects sometimes use themselves as skeeter chow. In some cases, it’s because certain species of mosquitoes seem to prefer human blood to animal blood. In others, though, it’s a cheap, convenient alternative to keeping animals around for the insects to feed on or buying blood. And as it turns out, once you’ve been bitten a certain number of times you develop a tolerance to mosquito saliva.
Entomologist Steve Schutz, seen above paging through a magazine while the bloodsuckers go to work on his arm, feeds his mosquito colony once a week. He has welts for about an hour, but after that the bites fade, occasionally leaving a few red spots. That’s good, because at 300 bites a week, he averages about 15,000 a year. That’s dedication.
discovermagazine.com | 27-Apr-2012 19:35
A Multitude of Hands: My new essay for National Geographic | The Loom
In the May issue of National Geographic, I contemplate the hand. Human hands are unique and versatile–and yet we are far from the only animals with them. By looking at the variety of hands in nature, we can see some of the most striking evidence of how evolution tinkers in all sorts of unexpected way. Check it out.
The print version is accompanied by lovely sketches of a wide range of hands. If you read the story online, you can see an animation of the human hand. And if you have the National Geographic iPad app, you can see videos of other hands, from frogs to aye-ayes.
[Image: White -handed gibbon by Ingo Arndt, on Arkive.]
discovermagazine.com | 27-Apr-2012 17:26
Scientists brave ‘world’s worst water’ to watch wild bacteria evolving | Not Exactly Rocket Science
For almost a decade, Jillian Banfield has been travelling to a place that “pushes the limits of human endurance” – Richmond Mine in Northern California. Its abandoned caverns can reach 48 degrees Celsius and 100 per cent humidity. They are low in oxygen. They contain possibly the most acidic naturally occurring water on Earth, with a pH value of minus 3.6.
But even in these conditions, there is life. Bacteria grow within the cave, floating in thin films on top of its hot, acidic water. They are the lords of their extreme world, and they provide an unrivalled opportunity to study how wild microbes evolve.
The mine ecosystem is extremely simple. The dominant species is a bacterium called Leptospirillum that lives in sulphuric acid and eats iron. Only a handful of other microbes share the mine, and most migrants would simply die. This is an ideal community for keen scientists – it’s small, well-defined, not very diverse, and self-contained. “The fact that it’s a simple, closed community makes it feasible to observe the evolution of the main players, without worrying about genotypes coming in from outside,” says Richard ...
discovermagazine.com | 26-Apr-2012 22:00
Neurons in a pigeon’s brain respond to magnetic fields | Not Exactly Rocket Science
In retrospect, the helmet should have been a clue…
Of all the super-senses that animals possess, the ability to sense the Earth’s magnetic field must be the most puzzling. We’ve known that birds can do it since the 1960s, but every new attempt to understand this ability – known as magnetoreception – just seems to complicate matters even further.
Take the latest discovery. Le-Qing Wu and David Dickman from the Baylor College of Medicine have found neurons in a pigeon’s brain that encode the properties of a magnetic field. They buzz in different ways depending on how strong the field is, and which direction it’s pointing in.
This is a big step. Scientists have identified parts of the brain that are important for magnetoreception, but no one has managed to nail down the actual neurons responsible for the sense. Miriam Liedvogel, who studies magnetic senses, calls it “a milestone in the field”. It’s a key puzzle piece that has been unavailable for a very long time.
But Wu and Dickman’s discovery doesn’t solve the magnetoreception puzzle. If anything, it makes it more complex. Until recently, scientists thought that ...
discovermagazine.com | 26-Apr-2012 20:00
DC and Philly: A Bundle of Talks | The Loom
I’m heading south to give a series of talks about everything from evolution to science tattoos, the future of journalism, and the mutant bird flu saga. Most of these talks are open to the public. Here’s the rundown, with the public talks noted:
Thursday 11 am: Bethesda, MD: “Telling the Stories of Science in Words and Images.”
National Institute of Diabetes and Digestive and Kidney Diseases Fellows Scientific Retreat.
Thursday 3 pm: Arlington VA: “The Darwin Beat.”
National Science Foundation
Friday 9:30 am: US Science Engineering Festival, Washington DC Convention Center:
I’m part of the festival’s “Nifty Fifty”–speakers who talk to high school students about science. In room 146A, I’ll be giving a sneak peek of my Science Ink talk to a group of students, in advance of the festival, which officially starts on Saturday.
Saturday: US Science and Engineering Festival, Washington DC Convention Center: open to the public
I’ll be speaking twice about Science Ink –both talks are open to the public
10:55 AM-11:40 AM Stage Meeting Room Number: 147AB
Noon to 1: Book signing Expo Hall B
2-2:30 PM National Academy of Sciences Booth 603
Sunday 2pm: Philadelphia : open to the public
Philadelphia Science Festival. I’ll be talking about Science ...
discovermagazine.com | 25-Apr-2012 16:14
Will we ever correct diseases before birth? | Not Exactly Rocket Science
Here’s the sixth piece from my new BBC column
Every year, millions of people are born with debilitating genetic disorders, a result of inheriting just one faulty gene from their parents. They may have been dealt a dud genetic hand, but they do not have to stick with it. With the power of modern genetics, scientists are developing ways of editing these genetic errors and reversing the course of many hard-to-treat diseases.
These gene therapies exploit the abilities of viruses – biological machines that are already superb at penetrating cells and importing genes. By removing their ability to reproduce, and loading them with the genes of our choice, we can transform viruses from causes of disease into vectors for cures.
After a few shaky starts, some of these approaches are beginning to hit their stride. Thirteen children with SCID, an immune disorder that leaves people fatally vulnerable to infections, now have working immune systems. Several British patients with haemophilia, which prevents their blood from clotting properly, can now produce a clotting protein called factor IX, which they once had to inject. A British man and ...
discovermagazine.com | 25-Apr-2012 15:00
Blood in Leeches Alerts Scientists to the Presence of Hard-to-Spot Endangered Animals | 80beats
The scientists’ blood-sucking accomplices
What’s the News: Scientists searching for new and endangered species in tropical highlands face a Catch 22. Spotting shy creatures is the order of the day, but bushwhacking through forests is anything but subtle. How can you get a sense of what’s there when you can’t get close enough to see it?
Environmental DNA analysis is one of the answers—checking out the DNA in soil, for instance, can reveal what pooped there recently in amazing detail. But for a technique that can reach beyond a given patch of ground, scientists have been investigating using leeches from streamwater as their source of DNA. It turns out that blood from their last meal sticks around in their gut for a good long time, and they happen to be partial to human blood too—which makes them, in the scientists’ words, “easy to collect.” A new paper gives proof that the technique is valuable: blood in leeches collected from a Vietnamese rainforest reveals the presence of six mammalian species, some of them rare.
How the Heck:
The team had checked previously how long leeches would hang onto host DNA. It turns out leeches are picky little ...
discovermagazine.com | 24-Apr-2012 18:21
In the Philippines, A Bright Purple New Crab Species | 80beats
In the 1980s, scientists identified a crab species in the Philippines and gave it the delightful of name of Insulamon unicorn. Twenty years later, scientists have found some of its cousins (pdf): four new freshwater crab species in the same genus. This purple one with red-tipped claws is I. palawanese.
Isolated on the island, the Insulamon have evolved to live in freshwater rather than seawater, hiding out under roots and rocks near stream beds. This little guy is remarkably colorful and easy to spot, despite being less than two inches across.
[via Discovery News]
Image via Hendrik Freitag / Senckenberg Museum of Comparative Zoology
discovermagazine.com | 24-Apr-2012 18:07
How ‘superspreader’ viruses invaded our genes by hanging up their coats | Not Exactly Rocket Science
Around 8 to 10 per cent of your DNA comes from viral ancestors. These sequences are the remains of prehistoric viruses that inserted their DNA into the genes of our ancestors, hundreds of millions of years ago. Some of them became permanent residents, and were passed down from parent to child. These endogenous retroviruses, or ERVs, are a legacy of epidemics past.
We understand how ERVs got into our DNA in the first place. But why have they been such successful invaders, to the point where they fill around a tenth of our genome? Gkikas Magiorkinis from the University of Oxford has an answer. By comparing the ERVs of 38 mammals, from humans to dolphins, he has found that the critical step in these invasions was the moment when the viruses hung up their coats.
Retroviruses, such as HIV, can copy their genetic material by inserting it into the DNA of their host. That way, whenever the host copies its own genes, it also makes more viruses. But to infect a new cell, the viruses need to package their duplicated DNA in a protein coat. This process depends on ...
discovermagazine.com | 24-Apr-2012 16:18
Bug becomes instantly resistant to insecticide by swallowing the right bacteria | Not Exactly Rocket Science
Many insects eventually evolve to resist insecticides. This process typically takes many generations and involves tweaks to the insect’s genes. But there is a quicker route. Japanese scientists have found that a bean bug can become instantly resistant to a common insecticide by swallowing the right bacteria.
The bug forms an alliance with Burkholderia bacteria, and can harbour up to 100 million of these microbes in a special organ in its gut (see arrow above). Some strains of Burkholderia can break down the insecticide fenitrothion, detoxifying it into forms that are harmless to insects. In fields where the chemical is sprayed, these pesticide-breaking bacteria rise in number. And if bugs swallow them, they become immune to the otherwise deadly chemical.
I’ve written about this story for The Scientist, so head over there to read the details of the study.
To me, the alliance is fascinating because the bug is coping with a new environmental challenge by bolstering its own genome with that of a microbe.
Many creatures rely on microscopic partners to safeguard their health. Insects inherit beneficial bacteria from their mothers, which help them to resist other bacteria that would cause disease, ...
discovermagazine.com | 24-Apr-2012 15:00
Whales May Use Globs of “Ear Fats” to Hear Underwater | Discoblog
CT scan of whale head; fat in yellow, ear bones in magenta.
For us landlubbers, jiggling fat may just be an unsightly presence. For whales, jiggling clumps of fat in their jaws may pick up sound waves underwater, helping them communicate over long distances in the sea. We knew that dolphins and porpoises have “ear fats,” but baleen whales have not been as well-studied for one simple reason: their heads are just too big to fit into a scanner.
A new study looks at minke whales, a genus of balleen whales that top out at only seven meters long. (Tiny compared to 30-meter blue whales.) Scientists put six frozen whale heads, salvaged from beached animals, in CT and MRI scanners to analyze the soft tissues. Some of the heads were still too big, so the lower jaw had to be removed or excess flesh trimmed away. The scans and subsequent dissections showed a glob of fat sitting right next to the ear bones. While the anatomical evidence is compelling, the researchers admit they still have to show how exactly the fat works to help in hearing.
[via ScienceNow]
discovermagazine.com | 23-Apr-2012 21:35
What are you looking at? People follow each other’s gazes, but without a tipping point | Not Exactly Rocket Science
On an uneventful day, five passers-by in busy Oxford shopping street suddenly stop and look upwards. They have spotted a camera mounted on a nearby roof, pointed straight at them. But these aren’t strangers who have suddenly realised that Big Brother is watching them. They are actors, who are taking part in a natural experiment that looks at how information spreads through crowds of people.
Andrew Gallup from Princeton University is behind the camera. Using its lens, and technology based on the video-gaming graphics cards, he can track the movement of each pedestrian, and calculate where they’re looking. With this set-up confirmed that people have a natural tendency to look where others are looking. But this contagion of glancing is much weaker than popular psychology books would have us believe.
Many psychologists have studied how humans and other animals follow each others’ gazes. But the vast majority of these studies have been done in laboratory settings, in which volunteers sit face-to-face. Very few scientists have studied natural crowds of people.
Stanley Milgram (he of the famous obedience experiment) was one of the first. In 1969, he asked groups of actors ...
discovermagazine.com | 23-Apr-2012 21:00