An international team of researchers, co-led by scientists at the University of York and Yunnan Normal University, has produced the first multi-disciplinary evidence for management of cattle populations in northern China, around the same time cattle domestication took place in the Near East, over 10,000 years ago.
The domestication of cattle is a key achievement in human history. Until now, researchers believed that humans started domesticating cattle around 10,000 years ago in the Near East, which gave rise to humpless (taurine) cattle, while two thousand years later humans began managing humped cattle (zebu) in Southern Asia.
However, the new research, which is published in Nature Communications, reveals morphological and genetic evidence for management of cattle in north-eastern China around 10,000 years ago, around the same time the first domestication of taurine cattle took place in the Near East. This indicates that humans may have started domesticating cows in more regions around the world than was previously believed.
A lower jaw of an ancient cattle specimen was discovered during an excavation in north-east China, and was carbon dated to be 10,660 years old. The jaw displayed a unique pattern of wear on the molars, which, the researchers say, is best explained to be the results of long-term human management of the animal. Ancient DNA from the jaw revealed that the animal did not belong to the same cattle lineages that were domesticated in the Near East and South Asia.
The combination of the age of the jaw, the unique wear and genetic signature suggests that this find represents the earliest evidence for cattle management in north-east China; a time and place not previously considered as potential domestication centre for cattle.
The research was co-led in the Department of Biology at the University of York by Professor Michi Hofreiter and Professor Hucai Zhang of Yunnan Normal University.
Professor Hofreiter said: "The specimen is unique and suggests that, similar to other species such as pigs and dogs, cattle domestication was probably also a complex process rather than a sudden event."
Johanna Paijmans, the PhD student at York who performed the DNA analysis, said: "This is a really exciting example of the power of multi-disciplinary research; the wear pattern on the lower jaw itself is already really interesting, and together with the carbon dating and ancient DNA we have been able to place it in an even bigger picture of early cattle management."
Read more at Science Daily
Nov 9, 2013
'Tiger Stripes' Underneath Antarctic Glaciers Slow the Flow
Just as no-slip strips on flooring prevent people from slipping on a wet floor, these ribs or "tiger stripes" -- named in reference to Princeton's tiger mascot -- provide friction that hinders the glaciers from slipping along the underlying bed of rock and sediment, the researchers report online in the journal Science.
The researchers discovered these tiger stripes, which occur in large, slippery regions under the glaciers, using mathematical modeling based on data from the National Snow and Ice Data Center and the British Antarctic Survey. The work was conducted by Olga Sergienko, an associate research scientist in Princeton's Program in Atmospheric and Oceanic Sciences, and Richard Hindmarsh, a scientist at the British Antarctic Survey.
Researchers would like to understand what factors determine the flow of glaciers, which are massive, moving ice sheets that, when they flow into the ocean, can contribute substantially to sea-level rise. The researchers studied two glaciers, the Pine Island Glacier and the Thwaites Glacier in West Antarctica, which together contribute about 10 percent of the observed sea-level rise over the past 20 years, despite their small areas. The Pine Island Glacier moves at a velocity of about 1.5 miles per year, according to the researchers.
Studying the bottom of these glaciers is next to impossible due to the inability to see through the ice, which is over a mile-and-a-half thick. Instead, the researchers used satellite measurements of the ice velocity and ground-penetrating radar collected from airplane flyovers to detect bedrock and surface topography, as well as field observations. Using the data, Sergienko created a mathematical model that calculated what happens inside the glacier as it flows along the bedrock. The model predicted the formation of the tiger stripes or ribs, which Hindmarsh had theorized some years earlier.
The friction at the interface of the bedrock and glacier ice is a major factor in the speed of a glacier, Sergienko said. When friction is high, the glacier moves slowly. When friction is low, as when melting ice provides a liquid layer that allows the ice to slide over the bedrock, the glacier moves more quickly.
The tiger stripes, which the researchers also call ribs due to their slightly curved structure, lie at roughly 30-degree angles to the direction of the glacier's movement. These ribs arise and decay in response to natural processes over roughly 50 to 100 years, according to the researchers' calculations. The process is strongly affected by how water, which comes from ice melting due to the inherent heat trapped in Earth, infiltrates the space between the ice sheet and the bedrock, the researchers found.
"The ribs may play an important role in buffering the effects of a warming climate, since they slow the movement of ice that reaches the ocean and contributes to sea-level rise," said Sergienko. "These changes can happen independently of climate change, too," she added.
More investigations are needed to verify models of rib formation, according to the researchers. "Our guess is that these ribs are related to typical landforms that exist in the formerly glaciated areas of North America and Europe," said Hindmarsh. "A great example are the drumlins -- raised areas of soil and rock -- that make the hills in Seattle or Glasgow," he said.
The study reveals new patterns of friction that help control the speed of ice flow and determine the effect of Antarctic ice on sea level, according to Douglas MacAyeal, a professor of glaciology at the University of Chicago who was not involved in the work. "This is strongly suggestive of a new style of physical controls over friction, like water flow in the thin zone between the rock of the bed and the ice," he said. "The results of this study will drive new theoretical and observational efforts to understand what causes this pattern."
Read more at Science Daily
Nov 8, 2013
The Anglerfish and the Absolute Worst Sex on Earth
Teen movies are, at their core, veiled studies in evolutionary biology, with young men and women coming to sexual maturity and either giving into or resisting what is arguably an animal’s sole purpose on this planet — to find a mate. Some decide to wait until they’re married, others lack the desirable traits to even get that far, and still others succeed and consequently have to put off college for a while.
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| A female Linophryne polypogon. |
The over 300 extremely varied species of anglerfishes inhabit everything from shallow to super-deep waters, and are so named because they are fish that fish for fish using lures, which are actually highly modified spines of dorsal fins that have migrated to their snouts. But among the 160 deep-sea species, only some 25 engage in the aforementioned biting-fusing-mating, what is known as sexual parasitism. In this group, the diminutive male looks like an entirely different species, lacking the female’s enormous jaws and characteristic lure.
This is because he doesn’t need to hunt. He only exists to attach to a female, and according to evolutionary biologist Theodore W. Pietsch of the University of Washington, mates are so scarce down here that it might be that only 1 percent of males ever find a female. The rest starve to death as virgins — unfortunate guys in a sea that doesn’t have plenty of other fish.
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| Close-up of the head of a male Linophryne sp. showing its greatly enlarged nostril. |
And with two dozen other species of anglerfishes that engage in this manner of reproduction, the male had better be damn sure he chooses the right one. Luckily, the female puts on the red blue light — in the form of glowing bacteria living in her lure. Incredibly, some 90 percent of species in the deep utilize such bioluminescence.
“The bait out there is not only an organ of luminescence, but structurally it’s species-specific,” said Pietsch. “Every species of these 160 forms within this group, they have a pattern of filaments, and pigment patterns, and probably also light flash patterns, like fireflies. And they separate themselves out that way so that males can find females,” distinguishing “the tiny little differences between the structure of the bait.”
Once the male closes in, he bites onto the female, usually her belly, and their tissues fuse together to permanently join the pair in incredibly unholy matrimony. The male’s eyes and fins atrophy away, and here he will live out the rest of his life nourished by her blood, still breathing with his own gills and, importantly, still producing sperm.
“This establishes a hormonal connection,” said Pietsch, “so that probably the maturation of eggs and sperm is synchronized by the sharing of hormones. And once the eggs are mature and the male is ready, she extrudes the eggs” in a kind of gelatinous sheath that can be 30 feet long. This acts like a sponge, readily absorbing the water that the male has released his sperm into.
Keep in mind that this is happening several miles down, where there is little plankton for juvenile fish to eat. So the whole gelatinous mess is buoyant, slowly making its way to the surface, where the larvae hatch and feed, ideally growing big and then migrating down to the depths.
The females of these species can live 30 years, according to Pietsch, and over that time might collect several males, who provide sperm season after season after season (there is no “not now, honey, I have a headache” with anglerfishes). But other than the security of maintaining a constant source of sperm, why evolve such a complex ritual of reproduction in the first place?
“The idea is basically that it’s a deep-sea economy measure,” ichthyologist James Maclaine of London’s Natural History Museum wrote in an email to WIRED. “An anglerfish couple requires about half of the amount of food they would if the male was the same size as the female (and presumably living an unattached life). He is stripped down to the absolute bare essentials, she has to remain big due to the relative cost of making large eggs as opposed to tiny sperm.”
Where such a size difference between sexes, known as sexual dimorphism, gets really interesting is its manifestation in the world at large. The famed evolutionary biologist Stephen Jay Gould wrote about this in his essay “Big Fish, Little Fish” — which stars the anglerfishes, of course — arguing that in the majority of animal species, females are larger than males, because the latter often never need to fight for the former.
Read more at Wired Science
Pig-Like Beast Leads Way to Ancient Cave Drawings
On the trail of the pig-like creatures in Brazil, researchers made an unexpected and rare discovery: cave drawings showing armadillos, birds and reptiles, etched into stone thousands of years ago.
Archaeologists who examined the rock art say hunter-gatherers likely created the drawings between 4,000 and 10,000 years ago.
Researchers with the Wildlife Conservation Society (WCS) made the find while surveying white-lipped peccaries in Brazil's Cerrado plateau, a vast savanna region, in 2009. The animals, which travel long distances, are considered environmental indicators of healthy forests.
"Since we often work in remote locations, we sometimes make surprising discoveries, in this case, one that appears to be important for our understanding of human cultural history in the region," Alexine Keuroghlian, a researcher with WCS's Brazil program, said in a statement.
The researchers encountered a series of sandstone formations with caves containing the artwork while tracking the peccaries near the remote city of Corguinho, in the Brazilian state of Mato Grosso do Sul.
Archaeologists say the style of the drawings is more diverse than expected. While some resemble ancient art from the central Brazilian plateau, others, surprisingly, seem etched in the artistic tradition of northeastern Brazil, the researchers said. In addition to human figures and geometric shapes, many different kinds of animals were represented, from big cats and armadillos to birds and reptiles, but alas, no peccaries.
The cave art is described (in Portuguese) in the journal Revista Clio Arqueológica.
"These discoveries of cave drawings emphasize the importance of protecting the Cerrado and Pantanal ecosystems, both for their cultural and natural heritage," Julie Kunen, director of WCS's Latin America and the Caribbean program, said in a statement. "We hope to partner with local landowners to protect these cave sites, as well as the forests that surround them, so that the cultural heritage and wildlife depicted in the drawings are preserved for future generations."
Read more at Discovery News
Indians and Europeans Share 'Light-Skin' Mutation
The study, published today (Nov. 7) in the journal PLOS Genetics, also revealed that the gene, which is responsible for 27 percent of skin color variation in Indians, was positively selected for in North, but not South Indian populations. When something is "selected for," that means it provides some advantage and so gets passed down to offspring, becoming more prevalent in a population over time.
Many shades
The Indian subcontinent has an enormous variation in skin color.
"We have dark brown (tones), yellow tones and whitish-pinkish tones," said study lead author Chandana Basu Mallick, a biologist at the University of Tartu in Estonia. "We have quite a range and diversity in the biological spectrum of skin color."
But because South Asian gene studies are relatively rare, it wasn't clear which genes contributed to this variation. Past research has found at least 126 genes that code for pigmentation in general, Basu Mallick said.
Genetic mosaic
To find out, Basu Mallick and her colleagues took skin color measurements for about 1,228 individuals in Southern India. The researchers then conducted a genetic analysis and found that about 27 percent of the skin color variation was due to a variation in a skin pigmentation gene. Called SLC24A5, this gene code for lighter skin is present in almost 100 percent of Europeans.
The team also examined the gene in 95 people around the subcontinent and found that both South Asian and European populations inherited this particular variant from a common ancestor who lived sometime between 22,000 and 28,000 years ago.
"We don't know the origin of this mutation. We just know that they have a common ancestor," Basu Mallick told LiveScience, referring to both South Asians and Europeans.
The team then looked for the gene in more than 2,000 people from 54 ethnic groups around the subcontinent. Some groups, such as populations in Tibet and Burma, didn't have the gene variant at all, whereas the Northwestern tip of the subcontinent had a nearly 90 percent prevalence of the gene.
Lighter skin has less melanin, a pigment that blocks the sun's UV rays; the body uses these rays to make vitamin D. The SLC24A5 gene is linked to less melanin production, so the gene may have become more common in Europe because it allowed people's skin to make more vitamin D in the continent's low-light conditions.
Read more at Disocvery News
Weird Ancient Black Hole Has Extra Suck
Quasars dominated the early Cosmos, generating vast quantities of radiation that can be observed today right at the edge of our observable Universe. Consisting of an active supermassive black hole and a searing disk of plasma in the cores of young galaxies, the vast majority of quasars eject material from their energetic environments at high speed.
This may sound counter-intuitive; black holes consume matter after all, they don’t eject it. But in a quasar’s hot accretion disk — composed of a superheated soup of blended stars, gas and dust that strayed too close to the supermassive black hole’s gravitational wrath — the intense radiation blasts the surrounding material away from the black hole. Although some material inevitably gets fed from the accretion disk into the black hole, vast quantities are ejected at up to a significant fraction of the speed of light.
However, by taking a Doppler speed check of the motion of gas around known quasars, a team of researchers analyzing data from the Sloan Digital Sky Survey (SDSS-III) have discovered a very rare subset of quasars that don’t fit the norm.
“The gas in this new type of quasar is moving in two directions: some is moving toward Earth but most of it is moving at high velocities away from us, possibly toward the quasar’s black hole,” said Niel Brandt, study co-author and Distinguished Professor of Astronomy and Astrophysics at Penn State University. “Just as you can use the Doppler shift for sound to tell if an airplane is moving away from you or toward you, we used the Doppler shift for light to tell whether the gas in these quasars is moving away from Earth or toward these distant black holes, which have a mass from millions to billions of times that of the sun.”
“Matter falling into black holes may not sound surprising,” added team leader Patrick Hall of York University in Toronto, “but what we found is, in fact, quite mysterious and was not predicted by current theories.
“The gas in the disc must eventually fall into the black hole to power the quasar, but what is often seen instead is gas blown away from the black hole by the heat and light of the quasar, heading toward us at velocities up to 20 percent of the speed of light,” he said. “If the gas is falling into the black hole, then we don’t understand why it’s so rare to see infalling gas. There’s nothing else unusual about these quasars. If gas can be seen falling into them, why not in other quasars?”
So how rare are these objects? 1-in-10,000 rare. Of the tens of thousands of quasars known, only 17 such objects have been discovered so far.
For now, the researchers are baffled as to why these few distant supermassive black holes, which have masses millions to billions of times of the mass of our sun, appear to have more suck than the rest of their quasar cousins. Their work has been published in the journal Monthly Notices of the Royal Astronomical Society (doi: 10.1093/mnras/stt1012).
Read more at Discovery News
Nov 7, 2013
Big Bang Afterglow Shows Earth Has No Special Place in Expanding Universe
While the findings don't explain the cosmic speed-up, they eliminate one provocative possibility that our planet, solar system and galaxy are at the center of the universe and that there is no dark energy. The findings appear in the journal Physical Review D.
The 2011 Nobel Prize was awarded for the discovery that the expansion of the universe is accelerating. One leading idea to explain the acceleration is a new, mysterious substance called dark energy, which is thought to make up nearly three-fourths of the energy of the universe. But another alternative is that Earth, our solar system and Milky Way galaxy are at the center of the universe. That theory violates the standard assumption that the universe has no center, but if true, then cosmic acceleration could be explained without dark energy or any new laws of physics.
But Dartmouth researchers found that this model can't hold up to other observational tests. The sky glows with light left over from the Big Bang, also known as the Cosmic Microwave Background, so they calculated how that glow would be affected. Their findings show that the model's prediction is completely contrary to the glow that has been measured.
"Essentially, we held a mirror up to the universe and asked if the reflection was special," says Robert Caldwell, a professor of physics and astronomy who co-wrote the article with undergraduate physics major Nina Maksimova. "The reflection shows that we do not appear to live in a special location, and decisively excludes this explanation for the universe's accelerating expansion. It would be a great relief to be able to understand a basic problem of cosmology within the known laws of physics, but our research is an important step in explaining the physics responsible for the cosmic acceleration."
From Science Daily
'Freakish' Asteroid Discovered, Resembles Rotating Lawn Sprinkler
Normal asteroids appear simply as tiny points of light. This bizarre asteroid has six comet-like tails of dust radiating from it like spokes on a wheel.
"It's hard to believe we're looking at an asteroid," said lead investigator David Jewitt, a professor in the UCLA Department of Earth and Space Sciences and the UCLA Department of Physics and Astronomy. "We were dumbfounded when we saw it. Amazingly, its tail structures change dramatically in just 13 days as it belches out dust."
One interpretation is that the asteroid's rotation rate increased to the point where its surface started flying apart, ejecting dust in episodic eruptions, starting last spring. The team has ruled out a recent asteroid impact scenario because a large quantity of dust would have been blasted into space all at once. This object, designated P/2013 P5, has ejected dust for at least five months, Jewitt said.
The asteroid was first seen as an unusually fuzzy-looking object with the Pan-STARRS survey telescope in Hawaii. Its multiple tails were discovered in images taken by NASA's Hubble Space Telescope on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, its appearance had totally changed; it looked as if the entire structure had swung around.
"We were completely knocked out," said Jewitt.
The tails could have been formed by a series of "impulsive dust-ejection events," modeling by team member Jessica Agarwal revealed. Agarwal, of the Max Planck Institute for Solar System Research in Lindau, Germany, calculated that the first ejection event occurred on April 15 and the last one on Sept. 4. The intervening eruptions occurred on July 18, July 24, Aug. 8 and Aug. 26.
Radiation pressure from the sun smears out the dust into streamers. The asteroid could possibly have been spun up if the pressure of sunlight exerted a torque on the body, Jewitt said.
If its spin rate became fast enough, he said, the asteroid's weak gravity would no longer be able to hold it together. Dust might avalanche downslope toward the asteroid's equator and eventually drift into space to make a tail. So far, only a small fraction of the asteroid's main mass -- perhaps 100 to 1,000 tons of dust -- has been lost, Jewitt said. The 700-foot-radius nucleus is thousands of times more massive.
Follow-up observations may reveal whether the dust leaves the asteroid in the equatorial plane; if so, that would indicate a "rotational breakup," Jewitt said.
This must be a common phenomenon in the asteroid belt, Jewitt said, and may even be the main way in which small asteroids die.
"In astronomy, where you find one, you eventually find a whole bunch more," he said. "This is an amazing object and almost certainly the first of many more to come."
Read more at Science Daily
Ants, Like Humans, Can Change Their Priorities
For the first time, Arizona State University researchers have discovered that at least in ants, animals can change their decision-making strategies based on experience. They can also use that experience to weigh different options.
The findings are featured today in the early online edition of the scientific journal Biology Letters, as well as in its Dec. 23 edition.
Co-authors Taka Sasaki and Stephen Pratt, both with ASU's School of Life Sciences, have studied insect collectives, such as ants, for years. Sasaki, a postdoctoral research associate, specializes in adapting psychological theories and experiments that are designed for humans to ants, hoping to understand how the collective decision-making process arises out of individually ignorant ants.
"The interesting thing is we can make decisions and ants can make decisions -- but ants do it collectively," said Sasaki. "So how different are we from ant colonies?"
To answer this question, Sasaki and Pratt gave a number of Temnothorax rugatulus ant colonies a series of choices between two nests with differing qualities. In one treatment, the entrances of the nests had varied sizes, and in the other, the exposure to light was manipulated. Since these ants prefer both a smaller entrance size and a lower level of light exposure, they had to prioritize.
"It's kind of like a humans and buying a house," said Pratt, an associate professor with the school. "There's so many options to consider -- the size, the number of rooms, the neighborhood, the price, if there's a pool. The list goes on and on. And for the ants it's similar, since they live in cavities that can be dark or light, big or small. With all of these things, just like with a human house, it's very unlikely to find a home that has everything you want."
Pratt continued to explain that because it is impossible to find the perfect habitat, ants make various tradeoffs for certain qualities, ordering them in a queue of most important aspects. But, when faced with a decision between two different homes, the ants displayed a previously unseen level of intelligence.
According to their data, the series of choices the ants faced caused them to re-prioritize their preferences based on the type of decision they faced. Ants that had to choose a nest based on light level prioritized light level over entrance size in the final choice. On the other hand, ants that had to choose a nest based on entrance size ranked light level lower in the later experiment.
This means that, like people, ants take the past into account when weighing options while making a choice. The difference is that ants somehow manage to do this as a colony without any dissent. While this research builds on groundwork previously laid down by Sasaki and Pratt, the newest experiments have already raised more questions.
"You have hundreds of these ants, and somehow they have to reach a consensus," Pratt said. "How do they do it without anyone in charge to tell them what to do?"
Pratt likened individual ants to individual neurons in the human brain. Both play a key role in the decision-making process, but no one understands how every neuron influences a decision.
Read more at Science Daily
Mating Bugs Etched in Stone for 165 Million Years
The fossil, described in the latest PLoS ONE, presents a pair of copulating froghoppers that lived 165 million years ago in what is now northeastern China. The fossil is the earliest record of copulating insects to date.
“We found these two very rare copulating froghoppers, which provide a glimpse of interesting insect behavior and important data to understand their mating position and genitalia orientation during the Middle Jurassic,” co-author Dong Ren of Capital Normal University in China, said in a press release.
Ren and his colleagues point out that our current knowledge of mating positions and genitalia orientation of prehistoric insects and animals is limited, to say the least.
In this fossil, no one doubts what was going on.
Froghoppers are tiny insects that hop from plant to plant in the way that small frogs hop around.
The insects also apparently slept around. The now-fossilized male (in the photo above, at left) inserted his reproductive organ into the female’s copulatory structure.
It’s unclear what happened after that, though. Somehow the two were entombed in this position.
What’s remarkable is that their belly-to-belly mating position, and their genital symmetry, have remained static in froghoppers over the millions of years. We humans are forever “upgrading” this and that gadget but, in nature, if it isn’t broken and the circumstances remain similar, it stays the same.
Read more at Discovery News
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