Advances in studying genes mean that scientists in evolutionary developmental biology or "evo-devo" can now explain more clearly than ever before how bats got wings, the turtle got its shell and blind cave fish lost their eyes, says University of Massachusetts Amherst evolutionary biologist Craig Albertson.
He recently won a five-year, $625,000 Faculty Early Career Development grant from the National Science Foundation (NSF) to study the evo-devo of jaws in cichlid fish, tropical freshwater relatives of the tilapia. These highly adaptable cousins of sunfish, usually medium-sized and looking a bit like perch, have a phenomenal ability to undergo evolutionary change. They've developed 1,000 new species in Lake Malawi, Africa, over the past million years, a far faster pace than usual for other vertebrates in a similar period.
The NSF grant is the foundation's most prestigious award in support of junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of both.
Through evo-devo studies, scientists now know that much biodiversity is due not only to differences in genes, but to changes in how and when genes are expressed, says Albertson. They also now recognize that genes interact with each other and the environment in development to determine phenotype, or an animal's observable traits.
"This carries Charles Darwin's ideas forward to a new level, to previously unconsidered sources of variation that can affect the evolution of traits. One in particular is phenotypic plasticity, the idea that different patterns of variation will be produced in different environments," Albertson says.
He chose to study evo-devo in cichlid fish because "they're obviously doing something right, from an evolutionary perspective, in a very dynamic environment, Africa's Rift Valley." Lake Malawi water levels have fluctuated up to 300 meters in the past 2 million years, providing everything from clear fresh water to an oxygen-poor soup high in salt, alkali or sediment, for example, but cichlids continue to adapt and survive.
Jaws are a good marker of adaptation because they are linked to survival, and the jaws of Lake Malawi cichlids can change rapidly to take advantage of new food resources. For example, open-water feeders have long jaws to snatch free-swimming, mobile prey, while bottom-feeders tend to have short, stout jaws for scraping algae from rocks. It is clear that these differences in jaw type are genetically determined, but Albertson wants to find out how much is also determined by the environment.
In studies he started at Syracuse University before coming to UMass Amherst in 2011, Albertson and colleagues are working to identify the set of genes responsible for determining jaw shape in both "normal" and "extreme" environments. They are taking a genetic mapping approach, using hybrids from a cross between two species differing subtly in jaw length. To begin, they raised an initial group of hybrids on an algae-based flake food, which is very easy for the fish to eat, Albertson explains. This population will be used to map genetic determinants of jaw shape under "normal" conditions.
Next, the biologists split the resulting hybrid families and reared them on two different diets, an algae-based diet spread on lava rocks, requiring fish to scrape to feed. These fish developed shorter jaws to accomplish this. The other treatment involved the same food, this time ground and sprinkled on the water surface. These fish had to suck food out of the water column; they developed longer jaws as they became more efficient at this task.
As Albertson explains, "The idea is that these two conditions should be similar to those in early Lake Malawi, when fish first arrived from surrounding rivers. Presumably the ancestors of Lake Malawi cichlids all looked the same, but some went up to suction feed while others went down to scrape, and plasticity produced fish with different jaw lengths. By re-creating this scenario and mapping the genes that underlie these environmentally induced shape differences, we hope to learn about the genetic interactions that were the first step in producing the 1,000-plus species in the lake today."
One key question he and his colleagues want to answer is whether the same set of genes are involved in developing crushing jaws and sucking jaws under normal and extreme environments. "We don't know if patterns of plasticity will affect patterns of evolution. We may see a different genetic response to distinct mechanical stimuli. But if we do recover a common set of genes under both normal and extreme conditions, it would substantiate key theories with respect to plasticity's role in evolutionary change."
Read more at Science Daily
Feb 11, 2012
Estrogen Turns Male Snakes into Same-Sex Charmers
The finding, published in the Journal of Experimental Biology, has implications for understanding the environmental impact of compounds that mimic the effect of estrogen, found in some chemicals and pesticides.
Estrogen, the researchers found, is key to a female's release of pheromones and thus, reproduction.
Here's how it works: For the red-sided garter snake, picking up a mate takes but a second and a flick of the tongue. When a male detects a possible mate nearby, he licks the female with a quick flick of his tongue. The chemical cues, called pheromones, exuded by the females are so strong it takes but an instant, the researchers say, for the male to determine the other snake's species, sex, population, reproduction condition, size and age. In fact, the males are totally dependent on these pheromones for snake reproduction.
Every spring, tens of thousands of these garter snakes emerge from their limestone caves north of Manitoba, Canada, for mating. Intense competition ensues, as males swarm (and tongue) female snakes in an effort to be the first to mate with her. The frenzy appears as twisting balls of snakes called mating balls.
The males tend to choose the larger, more mature gals, because these females can produce more babies; they also have a slightly different chemical signature in their pheromones. While young, small females do get action, they aren't the preferred mates.
Once they mate, the females emit a different pheromone, confirming "no more sex," causing other males to lose interest and leave the area.
In the new study, the researchers implanted male garter snakes in their natural environment, each with a capsule that raised their estrogen levels to approximately match those of female snakes. After one year of these estrogen supplements, the male snakes started secreting a pheromone that seemed to cause other males to swarm to them, forming clumps of writhing snakes tangled together. Apparently, the estrogen caused the males to secrete "female" pheromones.
"We thought this might work, but we were surprised the results were so compelling," study researcher Robert Mason, a professor of zoology at Oregon State University, said in a statement. "The amount of estrogen the male snakes received was nothing unusual, just about what a normal female would produce."
Read more at Discovery News
Feb 10, 2012
Ocean Warming Causes Elephant Seals to Dive Deeper
The southern elephant seals from Marion Island, located in the south western part of the Indian Ocean, are extreme divers in the truest sense of the word. The animals spend more than 65 per cent of their lives in depths of over 100 metres, diving far deeper than their fellow species in southern areas. The maximum dive depth of these seals is over 2000 metres. However, the water masses through which the elephant seals from Marion Island swim in search of food are becoming increasingly warmer due to climate change and are forcing the animals to dive deeper. The Southern Ocean is warmed primarily in the water levels up to a depth of 1000 metres and therefore in those areas in which squid and fish ought to be found. "This prey is moving down to greater depths presumably due to the increasing water temperatures and this is forcing the seals to follow them," explains Dr. Horst Bornemann from the Alfred Wegener Institute.
Over the course of several years he and his colleague Dr. Joachim Plötz together with Dr. Trevor McIntyre and other seal researchers from the Mammal Research Institute (MRI) in South Africa have fitted over 30 elephant seals with satellite transmitters. These transmitters, the size of a fist, are attached to the head of the seals using artificial resin immediately after moulting and measure the dive depth, water temperature and salinity every time the animals dive. When the animal resurfaces to breathe the transmitters send their data to the respective research institutes via satellite. The results show that the elephant seals need to dive deeper in warmer water so that they ultimately have less time to actually search for food. "We therefore assume that the animals will find less prey in warmer water masses," explains Joachim Plötz.
The scientists from Bremerhaven will be going back to Marion Island in April of this year to collect evidence for their theory. This time they wish to equip the animals with a "jaw movement" sensor which has been developed by Japanese biologists at the National Institute of Polar Research in Tokyo. It is not much larger than a small finger and notices when the seal opens its mouth. "So far we can only derive from the dive profile whether an elephant seal was probably following a fish swarm. With this new measuring device we learn whether he has actually eaten," says Joachim Plötz.
Using this forage data the AWI biologists wish to draw conclusions as to the spatial and temporal distribution of particularly productive zones in the South Polar Sea. "The food in the sea is unevenly distributed. It is not worth the seals fishing anywhere and at any time. With the new data we hope to see the routes taken by the elephant seals of Marion Island and the water levels in which they find food," says Horst Bornemann.
The scientists also take days of walking over the "island of horizontal rain" into the bargain to achieve their research goal. "The elephant seals of Marion Island are very loyal to their location. They return to this island time and again to moult and mate. This behaviour gives us the opportunity to consistently fit measuring devices to the same animals thereby gaining an insight into the movement patterns of individual animals. Their movement and dive routes help us to find out where the oceanic food grounds of the Marion Island elephant seals are located," explains Joachim Plötz.
Read more at Science Daily
Kids Show Cultural Gender Bias
Talk about gender confusion! A recent study by University of Alberta researchers Elena Nicoladis and Cassandra Foursha-Stevenson in the Journal of Cross-Cultural Psychology into whether speaking French influenced how children assigned gender to objects yielded some interesting observations. Nicoladis and Foursha-Stevenson found some differences between the unilingual English children and the bilingual French-English children they surveyed.
Some of the more startling results from the Anglo crowd? Cows are boys. Cats and stars are girls.
Le culture or la culture: our bias
The researchers showed objects or images to the children participating in the study and asked them whether the objects seemed to be masculine or feminine in nature. While the unilingual children seemed to identify most objects as masculine, many younger bilingual children were willing to consider that, globally speaking, some objects could be feminine in nature even though, Nicoladis says, "their categorizations didn't correspond very well to whether the objects were masculine or feminine in French."
As to how Bessie may have inadvertently became Bernie, Nicoladis says that there is an explanation as to why the children may have chosen masculine more often than feminine, even for cows: it reveals a bias embedded in the language.
"Traditionally, in most languages -- and English is no exception -- the kind of default pronoun is a masculine pronoun," Nicoladis says. "If you read prescriptive grammar books, they might say 'everyone put on his coat' not 'everyone put on his or her coat.' The default, even when the gender isn't specified, is masculine."
No need to check under the hood
These gender-bending statements are no cause for panic. The researchers note that the identity issues were actually relatively common among the unilingual and bilingual kids, with French seeming to have only a small influence with pre-school children.
"What we found is that the monolingual children had a huge boy bias for all of the objects we asked them about," says Nicoladis. "Cats are girls, stars are girls." But to the participants, pretty much everything else was masculine, including cows. To the researchers, it said more about culture and language rather than factual knowledge.
Don't know much about biology…
Nicoladis says that the gender identification is not based on biological knowledge in the younger years. She notes that the older children she surveyed seemed able to reason that cows were the female members of the cattle clan, indicating their understanding of the biology of the animals. And, while some may be tempted to chalk it up to "kids saying the darndest things," some adults seemed to get a little mixed up, too.
"We found the same trends with adults who clearly should be able to reason about the biology," says Nicoladis. "But I think when you're just answering the question really fast, it's picking up some other aspect of their understanding of the world." The embedded bias towards the masculine pronoun was, in effect, trumping the obvious fact that cows are female.
Read more at Science Daily
Some of the more startling results from the Anglo crowd? Cows are boys. Cats and stars are girls.
Le culture or la culture: our bias
The researchers showed objects or images to the children participating in the study and asked them whether the objects seemed to be masculine or feminine in nature. While the unilingual children seemed to identify most objects as masculine, many younger bilingual children were willing to consider that, globally speaking, some objects could be feminine in nature even though, Nicoladis says, "their categorizations didn't correspond very well to whether the objects were masculine or feminine in French."
As to how Bessie may have inadvertently became Bernie, Nicoladis says that there is an explanation as to why the children may have chosen masculine more often than feminine, even for cows: it reveals a bias embedded in the language.
"Traditionally, in most languages -- and English is no exception -- the kind of default pronoun is a masculine pronoun," Nicoladis says. "If you read prescriptive grammar books, they might say 'everyone put on his coat' not 'everyone put on his or her coat.' The default, even when the gender isn't specified, is masculine."
No need to check under the hood
These gender-bending statements are no cause for panic. The researchers note that the identity issues were actually relatively common among the unilingual and bilingual kids, with French seeming to have only a small influence with pre-school children.
"What we found is that the monolingual children had a huge boy bias for all of the objects we asked them about," says Nicoladis. "Cats are girls, stars are girls." But to the participants, pretty much everything else was masculine, including cows. To the researchers, it said more about culture and language rather than factual knowledge.
Don't know much about biology…
Nicoladis says that the gender identification is not based on biological knowledge in the younger years. She notes that the older children she surveyed seemed able to reason that cows were the female members of the cattle clan, indicating their understanding of the biology of the animals. And, while some may be tempted to chalk it up to "kids saying the darndest things," some adults seemed to get a little mixed up, too.
"We found the same trends with adults who clearly should be able to reason about the biology," says Nicoladis. "But I think when you're just answering the question really fast, it's picking up some other aspect of their understanding of the world." The embedded bias towards the masculine pronoun was, in effect, trumping the obvious fact that cows are female.
Read more at Science Daily
Breaking the Code: Why Yuor Barin Can Raed Tihs
For emaxlpe, it deson't mttaer in waht oredr the ltteers in a wrod aepapr, the olny iprmoatnt tihng is taht the frist and lsat ltteer are in the rghit pcale. The rset can be a toatl mses and you can sitll raed it wouthit pobelrm.
S1M1L4RLY, Y0UR M1ND 15 R34D1NG 7H15 4U70M471C4LLY W17H0U7 3V3N 7H1NK1NG 4B0U7 17.
Passages like these have been bouncing around the Internet for years. But how do we read them? And what do our incredibly low standards for what's legible say about the way our brains work?
According to Marta Kutas, a cognitive neuroscientist and the director of the Center for Research in Language at the University of California, San Diego, the short answer is that no one knows why we're so good at reading garbled nonsense. But they've got strong suspicions.
"My guess is that context is very, very, very important," Kutas told Life's Little Mysteries.
We use context to pre-activate the areas of our brains that correspond to what we expect next, she explained. For example, brain scans reveal that if we hear a sound that leads us to strongly suspect another sound is on the way, the brain acts as if we're already hearing the second sound. Similarly, if we see a certain collection of letters or words, our brains jump to conclusions about what comes next. "We use context to help us perceive," Kutas said. [6 Fun Ways to Exercise Your Brain]
It's not a perfect system, however. In the above passages, Kutas suspects that you probably didn't get every single word right just from knowing what came before it. You onlythought you were reading the passage perfectly, because you automatically (and subconsciously) went back and filled in any gaps in your knowledge based on subsequent context — the words that came later.
Additionally, in the case of the first example (the words with jumbled middle letters), it helps that your brain processes all the letters of a word at once, rather than one at a time. Thus, the letters "serve as contexts for each other," Kutas said.
Read more at Discovery News
Wild Lions Live in Constant Fear
Lions have drastically changed the way they behave and perceive their environment because of new, numerous and deadly clashes with humans, according to a new study, published in the Journal of Applied Ecology,
“The ‘landscape of fear’ represents relative levels of predation risk as peaks and valleys that reflect the level of fear of predation an animal experiences in different parts of its territory,” lead author Marion Valeix of the University of Oxford’s Wildlife Conservation Research Unit, told Discovery News.
She and colleagues Graham Hemson, Andrew Loveridge, Gus Mills and David Macdonald explained that most prey animals live within a fearful mindset which keeps them on a constant, stressed out watch. Now even high-level predators may live this way too when they exist in or around human-dominated landscapes.
The researchers studied the behavior, foraging and territory of lions living in one of the last natural migratory systems, the Makgadikgadi Pans National Park in Botswana, where abundant packs of Burchell’s zebra and blue wildebeest live in different parts of the park on a seasonal basis.
Lands used by people for grazing their livestock surround the protected wilderness area. This creates a human-lion conflict, since when the zebra and wildebeest move en masse out of lion areas, many lions will resort to hunting livestock, such as cattle, to avoid losing established territories and reproductive loss, among other reasons.
GPS tracking of the lions determined that the major driver of lion behavior was the risk of conflict with humans. While the herders in Botswana do not always have easy access to firearms, some do.
Hemson said “we extracted lead shot from one lion in the study and another lion was shot in the spine and paralyzed. As such, we have evidence that lions may survive encounters with better armed people, and these surely make a lasting impression” on the other lions.
He does not think lions are born with this fear, since cubs are very inquisitive and would regularly follow his “vehicle and circle it and even test the bumper with their teeth and paws.” But through their mother and other pride members, they learn to fear humans as they grow up.
While a handful of very large protected areas, such as in Kalahari national parks, may permit lions to live without encroaching on human, “these areas are getting fewer and fewer,” Hemson said.
In Botswana, the researchers hope herders will reduce the abundance of livestock left unattended at night, since these attract lions that are looking for a meal but are also trying to avoid humans. They also call for overall improved livestock husbandry, which might include more consistent use of protective enclosures.
The scientists, however, lament that during this present difficult socio-economic time, such measures are not likely to be implemented anytime soon. They hope an incentive structure might be put into place for herders, providing them with financial and other rewards to make the improvements and to promote tolerance of lions and other wildlife.
Read more at Discovery News
Feb 9, 2012
Most Lethal Known Species of Prion Protein Identified
Scientists from the Florida campus of The Scripps Research Institute have identified a single prion protein that causes neuronal death similar to that seen in “mad cow” disease, but is at least 10 times more lethal than larger prion species.
This toxic single molecule or “monomer” challenges the prevailing concept that neuronal damage is linked to the toxicity of prion protein aggregates called “oligomers.”
The study was published this week in an advance, online edition of the journal Proceedings of the National Academy of Sciences.
“By identifying a single molecule as the most toxic species of prion proteins, we’ve opened a new chapter in understanding how prion-induced neurodegeneration occurs,” said Scripps Florida Professor Corinne Lasmézas, who led the new study. “We didn’t think we would find neuronal death from this toxic monomer so close to what normally happens in the disease state. Now we have a powerful tool to explore the mechanisms of neurodegeneration.”
In the study, the newly identified toxic form of abnormal prion protein, known as TPrP, caused several forms of neuronal damage ranging from apoptosis (programmed cell death) to autophagy, the self-eating of cellular components, as well as molecular signatures remarkably similar to that observed in the brains of prion-infected animals. The study found the most toxic form of prion protein was a specific structure known as alpha-helical.
New Paths to Explore
In addition to the insights it offers into prion diseases such as “mad cow” and a rare human form Creutzfeldt-Jakob disease, the study opens the possibility that similar neurotoxic proteins might be involved in neurodegenerative disorders such as Alzheimer’s and Parkinson diseases.
In prion disease, infectious prions (short for proteinaceous infectious particles), thought to be composed solely of protein, have the ability to reproduce, despite the fact that they lack DNA and RNA. Mammalian cells normally produce what is known as cellular prion protein or PrP; during infection with a prion disease, the abnormal or misfolded protein converts the normal host prion protein into its disease form.
Lasmézas explains that prion diseases are similar to Alzheimer's and other protein misfolding diseases in that they are caused by the toxicity of a misfolded host protein. Recent work, as reported in The New York Times, also found that diseases such as Alzheimer's resemble prion diseases by spreading from cell to cell.
Read more at Science Daily
This toxic single molecule or “monomer” challenges the prevailing concept that neuronal damage is linked to the toxicity of prion protein aggregates called “oligomers.”
The study was published this week in an advance, online edition of the journal Proceedings of the National Academy of Sciences.
“By identifying a single molecule as the most toxic species of prion proteins, we’ve opened a new chapter in understanding how prion-induced neurodegeneration occurs,” said Scripps Florida Professor Corinne Lasmézas, who led the new study. “We didn’t think we would find neuronal death from this toxic monomer so close to what normally happens in the disease state. Now we have a powerful tool to explore the mechanisms of neurodegeneration.”
In the study, the newly identified toxic form of abnormal prion protein, known as TPrP, caused several forms of neuronal damage ranging from apoptosis (programmed cell death) to autophagy, the self-eating of cellular components, as well as molecular signatures remarkably similar to that observed in the brains of prion-infected animals. The study found the most toxic form of prion protein was a specific structure known as alpha-helical.
New Paths to Explore
In addition to the insights it offers into prion diseases such as “mad cow” and a rare human form Creutzfeldt-Jakob disease, the study opens the possibility that similar neurotoxic proteins might be involved in neurodegenerative disorders such as Alzheimer’s and Parkinson diseases.
In prion disease, infectious prions (short for proteinaceous infectious particles), thought to be composed solely of protein, have the ability to reproduce, despite the fact that they lack DNA and RNA. Mammalian cells normally produce what is known as cellular prion protein or PrP; during infection with a prion disease, the abnormal or misfolded protein converts the normal host prion protein into its disease form.
Lasmézas explains that prion diseases are similar to Alzheimer's and other protein misfolding diseases in that they are caused by the toxicity of a misfolded host protein. Recent work, as reported in The New York Times, also found that diseases such as Alzheimer's resemble prion diseases by spreading from cell to cell.
Read more at Science Daily
Black Hole Eats Asteroids, Burps Out X-Rays
Though nothing, including light, can escape a black hole, most are ringed by a disk of gas and dust. As it falls in, this material heats up to incredible temperatures, generating energy.
For several years, NASA’s Chandra X-ray Observatory has spotted daily fluctuations in the emissions coming from the Milky Way’s central black hole. Known as Sagittarius A*, this 2-million- to 4-million-solar-mass black hole is approximately 26,000 light-years from Earth near the border of the constellations Sagittarius and Scorpius.
Sagittarius A*’s daily flares generally last a few hours and increase the black hole’s brightness by a hundred times. Scientists have been at a loss to explain why the black hole would have such regular eruptions.
Researchers now suggest that tens of trillions of asteroids and comets, stolen from their parent stars, might float around the black hole. If a 12-mile-wide (or larger) asteroid should get within 100 million miles of the black hole, tidal forces would rip it to shreds. These fragments would then fall in and be vaporized by friction as they encounter the gas and dust churning around the black hole.
The central supermassive black hole could sustain these regular flares for billions of years. Even at a rate of one asteroid per day, it would have only consumed a few trillion asteroids over the lifetime of the galaxy, leaving plenty of fodder.
An unfortunate planet coming loose from its parent star could also get ripped apart in this manner. Because planets are far less numerous than asteroids, this process would be much rarer. Were a planet to be eaten, it would produce a dramatic flare, brightening the black hole by a million times its normal output.
Read more at Wired Science
How The Zebra Got Its Stripes
But while Kipling addressed the leopard's spots and the camel's hump, he never explained the zebra's stripes. A new study helps fill in the void, this time with actual data.
Casting aside a long list of possible explanations, the new research proposes that a zebra's bold pattern of black and white stripes reflects light in a way that helps the animals evade disease-infested flies.
Hungry flies might not be the only force that pushed zebras to develop stripes. But the findings might offer new strategies for defending animals, and even people, against some insects.
"We have been breeding animals based on meat or milk production, and we haven’t paid much attention to their coat colorations or patterns," said Susanne Åkesson, an evolutionary ecologist at Lund University in Sweden. "Maybe it's something we need to consider. Maybe there's some trick we can learn form the zebra that could help."
Scientists have been speculating about the purpose of the zebra's stripes since the 1870s, when Charles Darwin criticized Alfred Russel Wallace's theory that the stripes provided camouflage in tall grass. Zebras prefer open savannahs, Darwin argued, where the grass is too short to make stripes useful hiding tools.
Since then, theories have invoked zebra-to-zebra recognition, defense against lions who can't pick out an individual zebra from amongst a mass of stripes, and thermoregulation -- as the patterns of dark and light fur might cause air turbulence, helping cool the animals off.
Åkesson and colleagues wondered if horseflies, which belong to a group called tabanids, might have something to do with the story. These flies are major pests for zebras, cows, horses and related animals. Their bites can be irritating enough to reduce grazing. And they can carry deadly diseases.
In previous work, Åkesson and her team had found that horseflies are more attracted to dark animals than to white ones, likely because of the way that light reflects off of different surfaces. Direct sunlight is full of rays that shine in all directions. But when sunlight bounces off of water -- or off of a dark brown horse or cow -- its reflections align horizontally.
Tabanid flies are attracted to this kind of linearly polarized light: It often leads them to water, where they can lay their eggs and mate. Just as often, though, their polarized light sense leads them to large animals, which they bite and annoy to no end.
Since zebras are both dark and light, the researchers wondered if these striking animals might have an intermediate-level of attractiveness to flies. To find out, they conducted a series of experiments with oil-filled trays, odorless insect tape-covered panels and zebra-like plastic models that where black or brown, white or striped.
Every day for a few weeks during the summer on a Hungarian horse farm, flies flew to their preferred color patterns and got trapped, allowing the researchers to collect the insects, count them and gauge their preferences.
As expected, very few flies landed on the white surfaces, the researchers report today in the Journal of Experimental Biology, while hundreds went for the black objects in some cases. Surprisingly, the striped objects attracted just as few -- and sometimes fewer -- flies than the white surfaces did. More flies landed on black stripes than on white stripes.
When the researchers made the black stripes wider than a typical zebra's pattern, objects attracted more flies. Measurements confirmed that the most polarized surfaces attracted the most insects.
Given the major advantage that zebras would get by avoiding fly bites that could kill them before they reproduced, Åkesson said, the paper offers a strong argument that stripes developed to protect the animals against insects and their diseases.
As solid as the new data is, though, the story is far from over, said Tim Caro, a behavioral ecologist at the University of California, Davis, who is writing a book about the evolution of the zebra's looks.
If stripes are so helpful, for example, why aren't all Eurasian horses striped? Meanwhile, studies have yet to carefully examine most of the other theories about zebra evolution. There might be many reasons why they are black and white.
Animal coloration has a long history of inspiring applications in military and other situations, Caro said, pointing to the black-and-white geometric patterns that decorated navy ships with "dazzle camouflage" during World War I. Still, studies like the new one may have their biggest impact on young minds, sparking excitement about science and the natural world.
Read more at Discovery News
Large Meteorite Likely Found in Druid Burial Site
The giant rock, spanning about 1.6 feet (0.5 meters) across and weighing 205 pounds (93 kilograms), was likely discovered by an archaeologist about 200 years ago at a burial site created by the Druids (an ancient Celtic priesthood) near Stonehenge, according to said Colin Pillinger, a professor of planetary sciences at the Open University.
Pillinger curated the exhibition "Objects in Space," which opened Feb. 9 and is the first time the public will get a chance to see the meteorite. The exhibition will explore not only the mystery that surrounds the origins of the giant meteorite, but also the history and our fascination with space rocks.
As for how the meteorite survived its long stint on Earth, researchers point to the ice age.
"The only meteorites that we know about that have survived these long ages are the ones that were collected in Antarctica," said Pillinger, adding that more recently, some ancient meteorites have been collected in the Sahara Desert. This rock came from neither the Sahara Desert nor Antarctica, but rather the Lake House in Wiltshire.
"Britain was under an ice age for 20,000 years," Pillinger told LiveScience, explaining the climate would have protected the rock from weathering.
At some point, the Druids likely picked up the meteorite when scouting for rocks to build burial chambers. "They were keen on building burial sites for [the dead] in much the same way the Egyptians built the pyramids," Pillinger said.
Then, years later, an archaeologist with ties to other, famous archaeologists, likely found the rock while excavating the Druids' burial sites, he said. The archaeologist then brought the rock back to his house in Wiltshire, where its more recent residents took notice and alerted researchers.
"The men whose house this was found at spent a lot of time opening these burial sites 200 years ago for purposes of excavating them," Pillinger said. "Our hypothesis is that the stone probably came out of one of those burial chambers."
The meteorite is called a chondrite, a group that includes primitive meteorites that scientists think were remnants shed from the original building blocks of planets. Most meteorites found on Earth fit into this group.
Read more at Discovery News
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