A Social Parasite’s Sophisticated Mimicry
New York Times,
July 16, 2015Link
An ant colony is an insect fortress: When enemies invade, soldier ants quickly detect the incursion and rip their foes apart with their oversize mandibles.
But some invaders manage to slip in with ease, none more mystifyingly than the ant nest beetle.
Adult beetles stride into an ant colony in search of a mate, without being harassed. They lay eggs, from which larva hatch. As far as scientists can tell, workers feed the young beetles as if they were ants.
When the beetles grow into adults, the ants swarm around them, grooming their bodies. In exchange for this hospitality, the beetles sink their jaws into ant larvae and freshly moulted adults in order to drink their body fluids.
“They’re like vampire beetles wandering in the ant nests,” said Andrea Di Giulio, an entomologist at Roma Tre University in Rome.
Scientists Demonstrate Animal Mind-Melds
New York Times,
July 9, 2015Link
A single neuron can’t do much on its own, but link billions of them together into a network and you’ve got a brain.
But why stop there?
In recent years, scientists have wondered what brains could do if they were linked together into even bigger networks. Miguel A. Nicolelis, director of the Center for Neuroengineering at Duke University, and his colleagues have now made the idea a bit more tangible by linking together animal brains with electrodes.
In a pair of studies published on Thursday in the journal Scientific Reports, the researchers report that rats and monkeys can coordinate their brains to carry out such tasks as moving a simulated arm or recognizing simple patterns. In many of the trials, the networked animals performed better than individuals.
“At least some times, more brains are better than one,” said Karen S. Rommelfanger, director of the Neuroethics Program at the Center for Ethics at Emory University, who was not involved in the study.
The Cambrian Explosion’s Strange-Looking Poster Child
New York Times,
July 2, 2015Link
The animal kingdom got off to a slow start. Studies on DNA indicate that the first animals evolved more than 750 million years ago, but for well over 200 million years, they left a meager mark on the fossil record. As best as paleontologists can tell, the animal kingdom during that time consisted of little more than sponges and other creatures rooted to the ocean floor.
But then, about 520 million years ago during the Cambrian Period, animal evolution shifted into high gear. Fast-moving predators, scavengers and burrowers evolved. Many of the major living groups of animals left their first fossils during this so-called Cambrian explosion, including our own ancestors. But the Cambrian explosion also brought many bizarre species that have long puzzled paleontologists.
For almost 40 years, the poster child for the Cambrian explosion’s strangeness has been a hand-size armored worm with a name to suit its bizarre appearance: Hallucigenia.
But recently, Hallucigenia has lost much of its mystery. Scientists have worked out the creature’s anatomy, and they have figured out a lot about how Hallucigenia and its relatives thrived in the Cambrian oceans. And despite its odd appearance, Hallucigenia isn’t an incomprehensible zoological experiment. Paleontologists have been able to place it comfortably on the evolutionary branch that led to a group of invertebrates alive today called velvet worms.
Picture This? Some Just Can’t
New York Times,
June 22, 2015Link
Certain people, researchers have discovered, can’t summon up mental images — it’s as if their mind’s eye is blind. This month in the journal Cortex, the condition received a name: aphantasia, based on the Greek word phantasia, which Aristotle used to describe the power that presents visual imagery to our minds.
I find research like this irresistible. It coaxes me to think about ways to experience life that are radically different from my own, and it offer clues to how the mind works.
And in this instance, I played a small part in the discovery.
In 2005, a 65-year-old retired building inspector paid a visit to the neurologist Adam Zeman at the University of Exeter Medical School. After a minor surgical procedure, the man — whom Dr. Zeman and his colleagues refer to as MX — suddenly realized he could no longer conjure images in his mind.
Dr. Zeman couldn’t find any description of such a condition in medical literature. But he found MX’s case intriguing. For decades, scientists had debated how the mind’s eye works, and how much we rely on it to store memories and to make plans for the future.
New DNA Results Show Kennewick Man Was Native American
New York Times,
June 18, 2015Link
In July 1996, two college students were wading in the shallows of the Columbia River near the town of Kennewick, Wash., when they stumbled across a human skull.
At first the police treated the case as a possible murder. But once a nearly complete skeleton emerged from the riverbed and was examined, it became clear that the bones were extremely old — 8,500 years old, it would later turn out.
The skeleton, which came to be known as Kennewick Man or the Ancient One, is one of the oldest and perhaps the most important — and controversial — ever found in North America. Native American tribes said that the bones were the remains of an ancestor and moved to reclaim them in order to provide a ritual burial.
But a group of scientists filed a lawsuit to stop them, arguing that Kennewick Man could not be linked to living Native Americans. Adding to the controversy was the claim from some scientists that Kennewick Man’s skull had unusual “Caucasoid” features. Speculation flew that Kennewick Man was European.
A California pagan group went so far as to file a lawsuit seeking to bury the skeleton in a pre-Christian Norse ceremony.
On Thursday, Danish scientists published an analysis of DNA obtained from the skeleton. Kennewick Man’s genome clearly does not belong to a European, the scientists said.
DNA Deciphers Roots of Modern Europeans
New York Times,
June 10, 2015Link
For centuries, archaeologists have reconstructed the early history of Europe by digging up ancient settlements and examining the items that their inhabitants left behind. More recently, researchers have been scrutinizing something even more revealing than pots, chariots and swords: DNA.
On Wednesday in the journal Nature, two teams of scientists — one based at the University of Copenhagen and one based at Harvard University — presented the largest studies to date of ancient European DNA, extracted from 170 skeletons found in countries from Spain to Russia. Both studies indicate that today’s Europeans descend from three groups who moved into Europe at different stages of history.
The first were hunter-gatherers who arrived some 45,000 years ago in Europe. Then came farmers who arrived from the Near East about 8,000 years ago.
Finally, a group of nomadic sheepherders from western Russia called the Yamnaya arrived about 4,500 years ago. The authors of the new studies also suggest that the Yamnaya language may have given rise to many of the languages spoken in Europe today.
Ron Pinhasi, an archaeologist at University College Dublin who was not involved in either study, said that the new studies were “a major game-changer. To me, it marks a new phase in ancient DNA research.”
Death on the Steppes: Mystery Disease Kills Saigas
New York Times,
May 29, 2015Link
Before the end of the last Ice Age, saigas roamed by the millions in a range stretching from England to Siberia, even into Alaska. Eventually they moved to the steppes of Central Asia, where they continued to thrive — until the 20th century, when these strange-looking antelopes began flirting with extinction.
Hunted for its horns, 95 percent of the population disappeared, and the saiga was declared critically endangered.
After the implementation of strict antipoaching measures, the population recovered, from a low of 50,000 to about 250,000 last year. “It was a big success story,” said Eleanor J. Milner-Gulland, the chairwoman of the Saiga Conservation Alliance.
Now that success is in jeopardy. Last month, a mysterious disease swept through the remaining saiga herds, littering the steppes with carcasses. The so-called die-off claimed more than a third of the world’s population in just weeks.
“I’m flustered looking for words here,” said Joel Berger, a senior scientist at the Wildlife Conservation Society. “To lose 120,000 animals in two or three weeks is a phenomenal thing.”
The Human Family Tree Bristles With New Branches
New York Times,
May 27, 2015Link
For scientists who study human evolution, the last few months have been a whirlwind. Every couple of weeks, it seems, another team pulls back the curtain on newly discovered bones or stone tools, prompting researchers to rethink what we know about early human history.
On Wednesday, it happened again. Yohannes Haile-Selassie of the Cleveland Museum of Natural History and his colleagues reported finding a jaw in Ethiopia that belonged to an ancient human relative that lived sometime between 3.3 and 3.5 million years ago. They argue that the jaw belongs to an entirely new species, which they named Australopithecus deyiremeda.
While some experts agree, skeptics argue that the jaw belongs to a familiar hominid species, known as Australopithecus afarensis, that existed about 3.9 to 3 million years ago.
Studies like this one are adding fresh fuel to the debate over the pace of human evolution. Some researchers now believe the human family tree bore exuberant branches early on.
“I’m so excited about these discoveries I’m driving my friends crazy,” said Carol V. Ward, a paleoanthropologist at the University of Missouri. “It makes us stop and rethink everything.”
Scientists Map 5,000 New Ocean Viruses
May 21, 2015Link
In March 2011, the Tara, a 36-meter schooner, sailed from Chile to Easter Island — a three-week leg of a five-year global scientific expedition. All but one of the seven scientists aboard the ship spent much of their time on the sun-drenched deck hauling up wondrous creatures such as luminous blue jellyfish and insects known as sea-skaters, which spend their entire lives skimming the surface of the ocean far from land.
At the stern of the Tara, a shipping container was bolted to the deck, with a door and a tiny window cut through the metal walls. One of the scientists, Melissa Duhaime, spent most of the voyage inside the dark, tiny cell, where she fought off an endless bout of seasickness.
“People would come in to see what I was doing and leave pretty quickly,” Duhaime said.
Inside her cell, Duhaime sat next to a hose as wide as an outstretched hand. A pump drew water through the hose from several meters below the boat and then pushed it through a series of filters. Each filter was finer than the last, blocking smaller and smaller life forms. The setup stopped animals first, then zooplankton and algae. The last filter in the hose, with pores just 220 nanometers wide, was fine enough to block bacteria. Scrubbed of all these living things, the water finally flowed into three 30-liter vats.
To the untrained eye, these vats might seem to be full of sterile water. But they were seething with ocean life — or life-like things, at the very least. The three vats held up to 1 trillion viruses.
For an Octopus, Seeing the Light Doesn’t Require Eyes
New York Times,
May 20, 2015Link
Octopuses, squid and cuttlefish — a group of mollusks known as cephalopods — are the ocean’s champions of camouflage.
Octopuses can mimic the color and texture of a rock or a piece of coral. Squid can give their skin a glittering sheen to match the water they are swimming in. Cuttlefish will even cloak themselves in black and white squares should a devious scientist put a checkerboard in their aquarium.
Cephalopods can perform these spectacles thanks to a dense fabric of specialized cells in their skin. But before a cephalopod can take on a new disguise, it needs to perceive the background that it is going to blend into.
Cephalopods have large, powerful eyes to take in their surroundings. But two new studies in The Journal Experimental Biology suggest that they have another way to perceive light: their skin.
Reverse Engineering Birds’ Beaks Into Dinosaur Bones
New York Times,
May 12, 2015 Link
Birds evolved from dinosaurs 150 million years ago, a slow but thorough transformation. Their bodies gained aerodynamic feathers, their digits fused into wings, and they acquired a beak used to gather food.
We can see some details of this evolutionary marvel in the fossil record. Yet even the most exquisitely preserved fossil can’t tell us which pieces of DNA had to change in order to turn ground-running dinosaurs into modern birds.
Some researchers are now trying to pinpoint those genetic changes with experiments on chicken embryos. If the scientists succeed, they should eventually be able to reverse the evolution of birds — and then they may be able to engineer animals more at home in “Jurassic Park” than in a henhouse.
One group of these scientists, led by Bhart-Anjan Bhullar of Yale University and Arhat Abzhanov of Harvard University, has spent the past eight years investigating one piece of bird anatomy in particular: the beak. Now, in a study published in the journal Evolution, they report that they have found a way to turn the beaks of chicken embryos back into dinosaur-like snouts.
Under the Sea, a Missing Link in the Evolution of Complex Cells
New York Times,
May 6, 2015Link
Unlike bacteria, humans have big, complex cells, packed with nuclei containing DNA and mitochondria that produce energy. All so-called eukaryotes share our cellular complexity: animals, plants, fungi, even single-celled protozoans like amoebae.
Scientists estimate that the first eukaryotes evolved about 2 billion years ago, in one of the greatest transitions in the history of life. But there is little evidence of this momentous event, no missing link that helps researchers trace the evolution of life from simple microbes to eukaryotes..
On Wednesday, a team of scientists announced the discovery of just such a transitional form. At the bottom of the Arctic Ocean, they found microbes that have many — but not all — of the features previously only found in eukaryotes. These microbes may show us what the progenitors of complex cellular organisms looked like.
“This is a genuine breakthrough,” said Eugene Koonin, an evolutionary biologist at the National Center for Biotechnology Information who was not involved in the research. “It’s almost too good to be true.”
Study Finds Climate Change as Threat to 1 in 6 Species
New York Times,
April 30, 2015Link
Climate change could drive to extinction as many as one in six animal and plant species, according to a new analysis.
In a study published Thursday in the journal Science, Mark Urban, an ecologist at the University of Connecticut, also found that as the planet warms in the future, species will disappear at an accelerating rate.
“We have the choice,” he said in an interview. “The world can decide where on that curve they want the future Earth to be.”
As dire as Dr. Urban’s conclusions are, other experts said the real toll may turn out to be even worse. The number of extinctions “may well be two to three times higher,” said John J. Wiens, an evolutionary biologist at the University of Arizona.
Global warming has raised the planet’s average surface temperature about 1.5 degrees Fahrenheit since the Industrial Revolution. Species are responding by shifting their ranges.
In 2003, Camille Parmesan of the University of Texas and Gary Yohe of Wesleyan University analyzed studies of more than 1,700 plant and animal species. They found that, on average, their ranges shifted 3.8 miles per decade toward the planet’s poles.
If emissions of carbon dioxide and other greenhouse gases continue to grow, climate researchers project the world could warm by as much as 8 degrees Fahrenheit. As the climate continues to change, scientists fear, some species won’t be able to find suitable habitats.
Ancient Viruses, Once Foes, May Now Serve as Friends
New York Times,
April 23, 2015Link
Our genomes are riddled with the detritus of ancient viruses. They infected our hominid ancestors tens of millions of years ago, inserting their genes into the DNA of their hosts.
Today, we carry about 100,000 genetic remnants of this invasion. So-called endogenous retroviruses make up 8 percent of the human genome.
Mostly, these genetic fragments are generally nothing more than molecular fossils. Over thousands of generations, they have mutated so much that they cannot replicate in our cells. And our cells keep the viral DNA muzzled to minimize the harm it might cause.
But scientists are finding that some endogenous retroviruses do wake up, and at the strangest time.
A new study published in the journal Nature on Monday suggests that endogenous retroviruses spring to life in the earliest stages of the development of human embryos. The viruses may even assist in human development by helping guide embryonic development and by defending young cells from infections by other viruses.
“The fact that viruses may be playing a vaccine role inside the cell is pretty amazing,” said Guillaume Bourque, a genomicist at McGill University who was not involved in the study.
Clues to How an Electric Treatment for Parkinson’s Works
New York Times,
April 16, 2015Link
In 1998, Dr. Philip A. Starr started putting electrodes in people’s brains.
A neurosurgeon at the University of California, San Francisco, Dr. Starr was treating people with Parkinson’s disease, which slowly destroys essential bits of brain tissue, robbing people of control of their bodies. At first, drugs had given his patients some relief, but now they needed more help.
After the surgery, Dr. Starr closed up his patients’ skulls and switched on the electrodes, releasing a steady buzz of electric pulses in their brains. For many patients, the effect was immediate.
“We have people who, when they’re not taking their meds, can be frozen,” said Dr. Starr. “When we turn on the stimulator, they start walking.”
First developed in the early 1990s, deep brain stimulation, or D.B.S., was approved by the Food and Drug Administration for treating Parkinson’s disease in 2002. Since its invention, about 100,000 people have received implants. While D.B.S. doesn’t halt Parkinson’s, it can turn back the clock a few years for many patients.
Yet despite its clear effectiveness, scientists like Dr. Starr have struggled to understand what D.B.S. actually does to the brain.
“We do D.B.S. because it works,” said Dr. Starr, “but we don’t really know how.”
Natural Selection May Help Account for Dutch Height Advantage
New York Times,
April 9, 2015Link
Gert Stulp stands 6 feet, 7 inches tall. His height makes him especially self-conscious at scientific conferences when he rises to describe his research as a demographer at the London School of Tropical Medicine. “It’s always quite embarrassing,” he said.
Dr. Stulp, who is Dutch, studies why his fellow citizens are so tall.
Today, the Dutch are on average the tallest people on the planet. Just 150 years ago, they were relatively short. In 1860, the average Dutch soldier in the Netherlands was just 5 feet 5 inches. American men were 2.7 inches taller.
Since 1860, average heights have increased in many parts of the world, but no people have shot up like the Dutch. The average Dutchman now stands over six feet tall. And while the growth spurt in the United States has stopped in recent years, the Dutch continue to get taller.
Why do we have allergies?
April 7, 2015Link
For me, it was hornets.
One summer afternoon when I was 12, I ran into an overgrown field near a friend’s house and kicked a hornet nest the size of a football. An angry squadron of insects clamped onto my leg; their stings felt like scorching needles. I swatted the hornets away and ran for help, but within minutes I realised something else was happening. A constellation of pink stars had appeared around the stings. The hives swelled, and new ones began appearing farther up my legs. I was having an allergic reaction.
My friend’s mother gave me antihistamines and loaded me into her van. We set out for the county hospital, my dread growing as we drove. I was vaguely aware of the horrible things that can happen when allergies run amok. I imagined the hives reaching my throat and sealing it shut.
I lived to tell the tale: my hives subsided at the hospital, leaving behind a lingering fear of hornets. But an allergy test confirmed that I was sensitive to the insects. Not to honey bees or wasps or yellow jackets. Just the particular type of hornet that had stung me. The emergency room doctor said I might not be so fortunate the next time I encountered a nest of them. She handed me an EpiPen and told me to ram the syringe into my thigh if I was stung again. The epinephrine would raise my blood pressure, open my airway – and perhaps save my life. I’ve been lucky: that afternoon was 35 years ago, and I haven’t encountered a hornet’s nest since. I lost track of that EpiPen years ago.
Behind Each Breath, an Underappreciated Muscle
New York Times,
April 2, 2015Link
Some muscles get all the glory. Bodybuilders show off their swollen triceps; sprinters flash their sharp-edged calves. But deep inside all of us, a sheet of muscle does heroic work in obscurity.
In order to breathe in, we must flatten the dome-shaped diaphragm; to breath out, we let it relax again. The diaphragm delivers oxygen to us a dozen times or more each minute, a half-billion times during an 80-year life.
“We are completely dependent on the diaphragm,” said Gabrielle Kardon, a biologist at the University of Utah. “But we take it for granted every moment we’re breathing.”
To Dr. Kardon, the diaphragm is not just underappreciated but puzzling. All mammals, from platypuses to elephants, have a diaphragm. But no other animal has one. “We have a very different solution for breathing than reptiles and birds,” said Dr. Kardon.
Before the evolution of a diaphragm, our reptilelike ancestors probably breathed the way many reptiles do today. They used a jacket of muscles to squeeze the rib cage.
In Iceland’s DNA, New Clues to Disease-Causing Genes
New York Times,
March 25, 2015Link
Scientists in Iceland have produced an unprecedented snapshot of a nation’s genetic makeup, discovering a host of previously unknown gene mutations that may play roles in ailments as diverse as Alzheimer’s disease, heart disease and gallstones.
“This is amazing work, there’s no question about it,” said Daniel G. MacArthur, a geneticist at Massachusetts General Hospital who was not involved in the research. “They’ve now managed to get more genetic data on a much larger chunk of the population than in any other country in the world.”
In a series of papers published on Wednesday in the journal Nature Genetics, researchers at Decode, an Icelandic genetics firm owned by Amgen, described sequencing the genomes — the complete DNA — of 2,636 Icelanders, the largest collection ever analyzed in a single human population.
With this trove of genetic information, the scientists were able to accurately infer the genomes of more than 100,000 other Icelanders, or almost a third of the entire country.
“From the technical point of view, these papers are a tour-de-force,” said David Reich, a geneticist at Harvard Medical School who was not involved in the research.
The Next Frontier: The Great Indoors
New York Times,
March 19, 2015Link
In 1962, the ecologist Robert Whitaker set out to categorize the different realms of life on Earth. Some were deserts, others tundra, still others tropical forests. He coined a word for these inhabited environments, one that scientists have used ever since: biomes.
The planet’s biomes emerged over hundreds of millions of years. Coastal wetlands sprang up along the edges of continents about 400 million years ago. About 20 million years ago, grasslands became widespread. But the biome that we’re most familiar with — one that has a huge impact on our everyday life — is the youngest of all: the indoor biome.
When humans began building shelters about 20,000 years ago, we unrolled a welcome mat for other species. Over the past few thousand years, the indoor biome has grown to colossal proportions as cities and suburbs spread across the continents. More recently elevators and other technology have lifted the indoor biome into the sky.
If you add up the area of the indoor biome in Manhattan — including its walk-ups and high-rise apartments — it’s three times bigger than the area of the island of Manhattan itself.
An Unlikely Driver of Evolution: Arsenic
New York Times,
March 12, 2015Link
Around 11,000 years ago, humans first set foot in the driest place on Earth.
The Atacama Desert straddles the Andes Mountains, reaching into parts of Chile, Peru, Bolivia and Argentina. Little rain falls on the desert — some spots haven’t received a single drop in recorded history.
But the people who arrived at the Atacama managed to turn it into a home. Some Atacameños, as they are known today, fished the Pacific. Others hunted game and herded livestock in the highlands. They mummified their dead, decorating them with ceremonial wigs before leaving them in the mountains.
Those mummies reveal a hidden threat in the Atacama. When scientists analyzed the hair in 7,000-year-old mummy wigs, they discovered high levels of arsenic. Through their lives, the Atacameños were gradually poisoned.
Arsenic can poison people today through exposure to pesticides and pollution. But arsenic is also naturally present in the water and soil in some parts of the world. The Atacama Desert, sitting on top of arsenic-rich volcanic rock, is one of them. The concentration of arsenic in Atacama drinking water can be 20 times higher than the level considered safe for human consumption.
Protection without a Vaccine
New York Times,
March 9, 2015Link
Last month, a team of scientists announced what could prove to be an enormous step forward in the fight against H.I.V.
Scientists at Scripps Research Institute said they had developed an artificial antibody that, once in the blood, grabbed hold of the virus and inactivated it. The molecule can eliminate H.I.V. from infected monkeys and protect them from future infections.
But this treatment is not a vaccine, not in any ordinary sense. By delivering synthetic genes into the muscles of the monkeys, the scientists are essentially re-engineering the animals to resist disease. Researchers are testing this novel approach not just against H.I.V., but also Ebola, malaria, influenza and hepatitis.
“The sky’s the limit,” said Michael Farzan, an immunologist at Scripps and lead author of the new study.
Is Most of Our DNA Garbage?
New York Times,
March 8, 2015Link
T. Ryan Gregory’s lab at the University of Guelph in Ontario is a sort of genomic menagerie, stocked with creatures, living and dead, waiting to have their DNA laid bare. Scorpions lurk in their terrariums. Tarantulas doze under bowls. Flash-frozen spiders and crustaceans — collected by Gregory, an evolutionary biologist, and his students on expeditions to the Arctic — lie piled in beige metal tanks of liquid nitrogen. A bank of standing freezers holds samples of mollusks, moths and beetles. The cabinets are crammed with slides splashed with the fuchsia-stained genomes of fruit bats, Siamese fighting fish and ostriches.
Gregory’s investigations into all these genomes has taught him a big lesson about life: At its most fundamental level, it’s a mess. His favorite way to demonstrate this is through what he calls the “onion test,” which involves comparing the size of an onion’s genome to that of a human. To run the test, Gregory’s graduate student Nick Jeffery brought a young onion plant to the lab from the university greenhouse. He handed me a single-edged safety razor, and then the two of us chopped up onion stems in petri dishes. An emerald ooze, weirdly luminous, filled my dish. I was so distracted by the color that I slashed my ring finger with the razor blade, but that saved me the trouble of poking myself with a syringe — I was to supply the human genome. Jeffery raised a vial, and I wiped my bleeding finger across its rim. We poured the onion juice into the vial as well and watched as the green and red combined to produce a fluid with both the tint and viscosity of maple syrup.
Two Strains of H.I.V. Cut Vastly Different Paths
New York Times,
March 2, 2015Link
Thirty-four years ago, doctors in Los Angeles discovered that some of their patients were succumbing to a normally harmless fungus. It soon became clear that they belonged to a growing number of people whose immune systems were hobbled by a virus, eventually known as human immunodeficiency virus, or H.I.V.
To date, an estimated 78 million people have become infected, 39 million of whom have died.
As the true scale of the virus’s devastation began to emerge, a number of scientists set out to investigate its origins. Piece by piece, year after year, the scientists reconstructed its history. Their research slowly revealed that the virus did not make a single leap from animals, but several.
On Monday, a team of researchers filled in the final gaps in the history. It’s now clear, they say, that the virus originated in humans on 13 separate occasions, evolving in humans from ancestral viruses that infected monkeys, chimpanzees and gorillas.
“We’ve got an amazing amount of the story nailed down, more than any reasonable person could have expected in the 1980s,” said Michael Worobey, a professor of ecology and evolutionary biology at the University of Arizona, who was not involved in the new study.
The first clue to the evolution of H.I.V. emerged in 1985, when scientists discovered a virus in macaque monkeys that was closely related to H.I.V. As it turned out, forty African primate species harbored H.I.V.-like viruses, called simian immunodeficiency viruses, or S.I.V. It became clear that H.I.V. had evolved from an S.I.V. ancestor.
But looking for H.I.V.’s precise origins proved a difficult task.
In Short-Lived Fish, Secrets to Aging
New York Times,
February 27, 2015Link
The turquoise killifish lives in a fleeting world: the ponds that appear only during the rainy season in East Africa.
As a new pond forms, turquoise killifish eggs buried in the mud spring from suspended animation. The eggs hatch, and in just 40 days the fish grow to full size, about 2.5 inches. They feed, mate and lay eggs. By the time the ponds dry up, the fish are all dead.
Even when hobbyists pamper them in aquariums, turquoise killifish survive only a few months, making them among the shortest-lived vertebrates on Earth. So the turquoise killifish may not seem the best animal to study to discover the secrets of a long life.
But researchers are finding that this tiny fish ages much as we do, only at a much faster pace. “It’s a compressed life span,” said Itamar Harel, a postdoctoral researcher at Stanford University. Dr. Harel and his colleagues recently developed a set of tools to probe the biology of the turquoise killifish.
Old people may seem a more logical focus for scientists looking to discover the mechanics of aging, but progress would be glacial.
“Who has 70 years to study somebody else’s aging process?” asked Sarah J. Mitchell, a postdoctoral researcher at the National Institute on Aging.
A New Theory on How Neanderthal DNA Spread in Asia
New York Times,
February 19, 2015Link
In 2010, scientists made a startling discovery about our past: About 50,000 years ago, Neanderthals interbred with the ancestors of living Europeans and Asians.
Now two teams of researchers have come to another intriguing conclusion: Neanderthals interbred with the ancestors of Asians at a second point in history, giving them an extra infusion of Neanderthal DNA.
The findings are further evidence that our genomes contain secrets about our evolution that we might have missed by looking at fossils alone. “We’re learning new, big-picture things from the genetic data, rather than just filling in details,” said Kirk E. Lohmueller, a geneticist at the University of California, Los Angeles, and co-author of one of the new studies.
The oldest fossils of Neanderthals date back about 200,000 years, while the most recent are an estimated 40,000 years old. Researchers have found Neanderthal bones at sites across Europe and western Asia, from Spain to Siberia.
Some of those bones still retain fragments of Neanderthal DNA. Scientists have pieced those DNA fragments together, reconstructing the entire Neanderthal genome. It turns out that Neanderthals had a number of distinct genetic mutations that living humans lack. Based on these differences, scientists estimate that the Neanderthals’ ancestors diverged from ours 600,000 years ago.
Studying Oversize Brain Cells for Links to Exceptional Memory
New York Times,
February 12, 2015Link
In 2010, a graduate student named Tamar Gefen got to know a remarkable group of older people.
They had volunteered for a study of memory at the Feinberg School of Medicine at Northwestern University. Although they were all over age 80, Ms. Gefen and her colleagues found that they scored as well on memory tests as people in their 50s. Some complained that they remembered too much.
She and her colleagues referred to them as SuperAgers. Many were also friends. “A couple tried to set me up with their grandsons,” Ms. Gefen said.
She was impressed by their resilience and humor: “It takes wisdom to a whole new level.”
Recently, Ms. Gefen’s research has taken a sharp turn. At the outset of the study, the volunteers agreed to donate their brains for medical research. Some of them have died, and it has been Ms. Gefen’s job to look for anatomical clues to their extraordinary minds.
“I had this enormous privilege I can’t even begin to describe,” she said. “I knew them and tested them in life and in death. At the end, I was the one looking at them through a microscope.”
Breakthrough DNA Editor Borne of Bacteria
February 6, 2015Link
On a November evening last year, Jennifer Doudna put on a stylish black evening gown and headed to Hangar One, a building at NASA’s Ames Research Center that was constructed in 1932 to house dirigibles. Under the looming arches of the hangar, Doudna mingled with celebrities like Benedict Cumberbatch, Cameron Diaz and Jon Hamm before receiving the 2015 Breakthrough Prize in life sciences, an award sponsored by Mark Zuckerberg and other tech billionaires. Doudna, a biochemist at the University of California, Berkeley, and her collaborator, Emmanuelle Charpentier of the Helmholtz Centre for Infection Research in Germany, each received $3 million for their invention of a potentially revolutionary tool for editing DNA known as CRISPR.
Doudna was not a gray-haired emerita being celebrated for work she did back when dirigibles ruled the sky. It was only in 2012 that Doudna, Charpentier and their colleagues offered the first demonstration of CRISPR’s potential. They crafted molecules that could enter a microbe and precisely snip its DNA at a location of the researchers’ choosing. In January 2013, the scientists went one step further: They cut out a particular piece of DNA in human cells and replaced it with another one.
In the same month, separate teams of scientists at Harvard University and the Broad Institute reported similar success with the gene-editing tool. A scientific stampede commenced, and in just the past two years, researchers have performed hundreds of experiments on CRISPR. Their results hint that the technique may fundamentally change both medicine and agriculture.
In Bedbugs, Scientists See a Model of Evolution
New York Times,
February 5, 2015Link
In the closing sentence of “The Origin of Species,” Charles Darwin marvels at the process of evolution, observing how “from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”
Few people would describe bedbugs as most beautiful or most wonderful. Yet this blood-feeding pest may represent an exceptional chance to observe the emergence of Darwin’s “endless forms”: New research indicates that some bedbugs are well on their way to becoming a new species.
“For something that is so hated by so many people, it might just be a perfect model organism for evolutionary questions,” said Warren Booth, a biologist at the University of Tulsa and a co-author of the new study, published in Molecular Ecology.
Scientists have been very slow to appreciate the biology of bedbugs despite the fact that the insects have infiltrated human shelters for thousands of years. That’s because the insects practically vanished at the dawn of modern biology in the 1940s, thanks to the widespread use of DDT.
Bedbugs have returned with a vengeance in recent years, partly because they have evolved resistance to pesticides, and scientists are struggling to learn more about these pests. It’s a much bigger challenge than examining, say, monarch butterflies.
In the Way Cancer Cells Work Together, a Possible Tool for Their Demise
New York Times,
January 29, 2015Link
A tumor, as strange as it may sound, is a little society. The cancer cells that make it up cooperate with one another, and together they thrive.
Scientists are only starting to decipher the rules of these communities. But if they can understand how these cells work together, then they may be able to stop the tumor. “You can drive it to collapse,” said Marco Archetti, a biologist at the University of East Anglia and at the Icahn School of Medicine at Mount Sinai.
Cancer starts when healthy cells mutate and lose the safeguards that normally keep their growth in check. The cells start to multiply quickly, and their descendants gain new mutations, some of which make the cells even better at multiplying.
As tumors rapidly develop, they outgrow their blood supply, and stores of nutrients and growth-stimulating chemicals, known as growth factors, run low. As it turns out, cancer cells survive this harsh new environment by helping one another.
New mutations can cause cancer cells to start making their own growth factors, and they don’t keep these essential chemicals to themselves. Growth factors seep throughout the tumor, affecting all the cells. “It’s one of the hallmarks of cancer,” Dr. Archetti said.
Even Elusive Animals Leave DNA, and Clues, Behind
New York Times,
January 22, 2015Link
You wouldn’t think hellbenders would be hard to find: The huge salamanders, the biggest amphibians in North America, can grow up to 30 inches long. Yet hellbenders make themselves scarce, living on the bottoms of mountain streams, lurking under massive rocks.
As a result, locating hellbenders takes a crew of scientists. First, some of them must wedge a long pole under a rock to hoist it up, and then their colleagues must plunge into the chilly water to catch their quarry.
A couple of years ago, Stephen Spear, a conservation scientist at the Orianne Society in Athens, Ga., heard about a possible alternative. Instead of finding rare animals, some experts were gathering animal DNA from their habitats. That way, they didn’t have to track down a species to be sure it was there.
Dr. Spear decided to try. He traveled to rivers in the Southeast where he and his colleagues had found hellbenders, and scooped water into jugs.
Raising Alarm, Study Finds Oceans on Brink of Wave of Extinctions
New York Times,
January 15, 2015Link
A team of scientists, in a groundbreaking analysis of data from hundreds of sources, has concluded that humans are on the verge of committing unprecedented damage to the oceans and the animals living in them.
“We may be sitting on a precipice of a major extinction event,” said Douglas J. McCauley, an ecologist at the University of California, Santa Barbara, and a co-author of the new research, which was published on Thursday in the journal Science.
But there is still time to avert catastrophe, Dr. McCauley and his colleagues also found. Compared with the continents, the oceans are mostly intact, still wild enough to bounce back to ecological health.
“We’re lucky in many ways,” said Malin L. Pinsky, a marine biologist at Rutgers University and a co-author of the new report. “The impacts are accelerating, but they’re not so bad we can’t reverse them.”
Unraveling the Key to a Cold Virus’s Effectiveness
New York Times,
January 8, 2015Link
If there is a champion among contagions, it may well be the lowly rhinovirus, responsible for many of the coughs and sniffles that trouble us this time of year. Rhinoviruses are spectacularly effective at infecting humans. Americans suffer one billion colds a year, and rhinoviruses are the leading cause of these infections.
Scientists have never been sure why they are so effective, but now a team at Yale University may have found a clue. The scientists argue that rhinoviruses have found a blind spot in the human immune system: They take advantage of the cold air in our noses.
In the 1960s, researchers first noticed that if they incubated rhinoviruses a few degrees below body temperature, the viruses multiplied much faster. It was an intriguing finding, since rhinoviruses often infect the lining of the nostrils, which are cooled by incoming air.
In subsequent years, scientists searched for an explanation. “People have taken the virus apart and studied its parts,” said Akiko Iwasaki, an immunobiologist at Yale. “But none of this really added up to explain why the virus replicated faster at a lower temperature.”
Can Hermaphrodites Teach Us What It Means To Be Male?
This View of Life,
January 4, 2015Link
The vinegar worm (officially known as Caenorhabditis elegans) is about as simple as an animal can be. When this soil-dwelling nematode reaches its adult size, it measures a millimeter from its blind head to its tapered tail. It contains only a thousand cells in its entire body. Your body, by contrast, is made of 36 trillion cells. Yet the vinegar worm divides up its few cells into the various parts you can find in other animals like us, from muscles to a nervous system to a gut to sex organs.
In the early 1960s, a scientist named Sydney Brenner fell in love with the vinegar worm’s simplicity. He had decided to embark on a major study of humans and other animals. He wanted to know how our complex bodies develop from a single cell. He was also curious as to how neurons wired into nervous systems that could perceive the outside world and produce quick responses to keep animals alive. Scientists had studied these two questions for decades, but they still knew next to nothing about the molecules involved. When Brenner became acquainted with the vinegar worm in the scientific literature, he realized it could help scientists find some answers.
Its simplicity was what made it so enticing. Under a microscope, scientists could make out every single cell in the worm’s transparent body. It would breed contentedly in a lab, requiring nothing but bacteria to feed on. Scientists could search for mutant worms that behaved in strange ways, and study them to gain clues to how their mutations to certain genes steered them awry.
A Weakness in Bacteria’s Fortress
At the University of Zurich, Rolf Kümmerli investigates new drugs to stop deadly infections. He spends his days in a laboratory stocked with petri dishes and flasks of bacteria—exactly the place where you would expect him to do that sort of work. But Kümmerli took an odd path to get to that lab. As a graduate student, he spent years hiking through the Swiss Alps to study the social life of ants. Only after he earned a Ph.D. in evolutionary biology did he turn his attention to microbes.
The path from ants to antibiotics is not as roundabout as it may seem. For decades scientists have studied how cooperative behavior evolves in animal societies such as ant colonies, in which sterile female workers raise the eggs of their queen. A new branch of science—sometimes called “sociomicrobiology”—is revealing that some of the same principles that govern ants can explain the emergence of bacterial societies. Like ants, microbes live in complex communities, where they communicate with one another to cooperate for the greater good. This insight of social evolution suggests a new strategy for stopping infections: instead of attacking individual bacteria, as traditional antibiotics do, scientists are exploring the notion of attacking entire bacterial societies.
New strategies are exactly what is needed now. Bacteria have evolved widespread resistance to antibiotics, leaving doctors in a crisis. For example, the Centers for Disease Control and Prevention estimates that 23,000 people die in the U.S. every year of antibiotic-resistant infections. Strains of tuberculosis and other pathogens are emerging that are resistant to nearly every drug. “It already is a substantial problem,” says Anthony S. Fauci, director of the National Institute of Allergy and Infectious Disease. “And there's every reason to believe it's going to get even worse.”