Dec 18, 2014
The 248-million-year-old fossil, which has been named Eohupehsuchus brevicollis, belongs to a group of mysterious early Triassic marine reptiles called hupehsuchians, which have so far only been unearthed in two counties in Hubei Province.
The 40-centimetre-long creature lived in a shallow inland sea, and was a distant cousin of the ichthyosaur.
"Probably the best living analogue for this marine reptile is the duck-billed platypus from Australia," says one of the paper's authors Professor Ryosuke Motani of the University of California Davis.
"Although it's a very different animal, it had a skull and beak like a duck without teeth, a very heavily built body with thick bones, and paddles to swim through the water. The details are different, but the general body design looks similar to a platypus."
Motani thinks the new species, described today in the journal PLOS ONE, probably lived on a diet of worms and shrimp, hence the unusual duck bill for sifting through sediments on the sea floor.
Unlike other hupehsuchians which have distinctive moderately long necks containing nine or ten cervical vertebrae, Eohupehsuchus brevicollis is the first member of the group to have a very short neck with only six cervical vertebrae.
The animal's skull is also different with a narrow forehead and parietal bones on the top of the head shifted back.
Ossification on the bones indicated this was a fully-grown adult member of its species rather than a juvenile.
The fossil was discovered in 2011 during a systematic excavation undertaken by the Geological Survey of China in the Yuan'an County in Hubei Province.
The nearly complete fossil is only missing the tip of the left forelimb which ended in a series of broken digits.
"The tip of the paddle is broken in a strange way, that could only have happened prior to burial," says Motani.
"It looks like the tip was bitten off by a predator, but the creature escaped and the wound healed.
"This small animal was living with much bigger predators reaching three metres or more, with big teeth, and they probably saw it as prey."
Hupehsuchians have been known about for half a century, however this new discovery shows they were far more diverse than previously thought with at least four species now known.
"We're finding many new specimens and surprisingly these bizarre-looking animals have a lot of diversity about them," says Motani.
Hupehsuchians lived just after the end Permian mass extinction event which peaked about 252 million years ago, killing off some 96 per cent of all marine life, and 70 per cent of terrestrial life on Earth.
"This was the planet's worst mass extinction event and it took a long time for the ecosystem to recover, so we were surprised to see so much diversity so soon after the mass extinction," says Motani.
Read more at Discovery News
The remains of a child, laid to rest more than 1,500 years ago when the Roman Empire controlled Egypt, was found in an ancient cemetery that contains more than 1 million mummies, according to a team of archaeologists from Brigham Young University in Provo, Utah.
The cemetery is now called Fag el-Gamous, which means "Way of the Water Buffalo," a title that comes from the name of a nearby road. Archaeologists from Brigham Young University have been excavating Fag el-Gamous, along with a nearby pyramid, for about 30 years. Many of the mummies date to the time when the Roman or Byzantine Empire ruled Egypt, from the 1st century to the 7th century A.D.
"We are fairly certain we have over a million burials within this cemetery. It's large, and it's dense," Project Director Kerry Muhlestein, an associate professor in the Department of Ancient Scripture at Brigham Young University, said in a paper he presented at the Society for the Study of Egyptian Antiquities Scholars Colloquium, which was held last month in Toronto.
This cemetery was not a burial ground for kings or royalty. The people buried here were often laid to rest without grave goods, and without coffins for that matter, the researchers said. The deceased's internal organs were rarely removed; instead, it was the arid natural environment that mummified them. "I don't think you would term what happens to these burials as true mummification," Muhlestein said. "If we want to use the term loosely, then they were mummified."
Despite the low status of the dead, the researchers found some remarkably beautiful items, including linen, glass and even colorful booties designed for a child.
"A lot of their wealth, as little as they had, was poured into these burials," Muhlestein said.
The mummified child was buried with several other mummies. It was wrapped in a tunic and wore a necklace with two bracelets on each arm.
"There was some evidence that they tried much of the full mummification process. The toes and toenails and brain and tongue were amazingly preserved," the researchers wrote on the project's Facebook page. "The jewelry makes us think it was a girl, but we cannot tell."
Researchers estimate the infant was 18 months old when she died. "She was buried with great care, as someone who obviously loved her very much did all they could to take care of this little girl in burial," the researchers wrote. It's "very sad, but they succeeded. It was a beautiful burial."
Where exactly these million mummies came from is an ongoing mystery, and one that the team has yet to solve. A nearby village seems too small to warrant such a large cemetery, the researchers said. There is an ancient town named Philadelphia (so named after King Ptolemy II Philadelphus) not far away, but that town has burial sites of its own.
While there is a small pyramid nearby, it was built more than 4,500 years ago, which is more than two millennia before the cemetery was first used.
"It's hard to know where all these people were coming from," Muhlestein told Live Science.
The stories that these million mummies tell appear endless. The Brigham Young team has excavated more than 1,000 of the mummies over the past 30 years, and Muhlestein admits the team has a publishing backlog.
One discovery that hasn't been published is of a mummy who is more than 7 feet (2 meters) tall. "We once found a male who was over 7 feet tall who was far too tall to fit into the shaft, so they bent him in half and tossed him in," Muhlestein told the audience in Toronto.
That's an extraordinary height given the generally poor nutrition these people had, Muhlestein told Live Science in an interview, adding that "even with great nutrition, it's really unusual" for an individual to reach that height. The great height could be because of a medical condition that caused an excess of growth hormone, but more research needs to be done to determine this.
This surprisingly tall mummy was discovered before Muhlestein became director, and the findings have yet to be published, he said. "We have a large publishing backlog, we're trying to catch up on making our colleagues and the public aware [of the finds]."
Read more at Discovery News
Researchers have long known that algae and other small organisms thrive on the undersurface of Arctic sea ice — particularly in regions thin enough for sunlight to shine through and support photosynthesis. But, scientists have not been able to closely examine this environment in its pristine state, because the icebreakers they typically use to reach field sites tend to disturb the sea ice.
Researchers based at the Woods Hole Oceanographic Institution in Massachusetts have now built a new remotely operated vehicle (ROV), called the Nereid Under Ice (NUI) vehicle, that solves this problem by diving beneath ice and delicately transmitting oceanographic data and real-time video footage to researchers on a ship through a thin fiber-optic cable.
Sixteen hours of video footage from the NUI vehicle's first four trial runs this past summer revealed a surprising abundance of life under the ice, including algae, jellyfish, and gelatinous animals called larvaceans, the team reported here Tuesday (Dec. 16) at the 47th annual meeting of the American Geophysical Union.
"What might look on the surface like a barren wasteland may actually be a thriving ecosystem," study co-author Christopher German, a researcher at the Woods Hole Oceanographic Institution, told reporters in a news briefing.
The underwater robot's thin fiber-optic cable is only about as thick as a human hair, and gives it more flexibility and finesse than typical ROVs with thicker tethers that usually only travel directly below a ship. During its trial runs, the NUI vehicle was able to travel as far as 2,600 feet (800 meters) laterally from the ship, and was able to complete 2.3 miles (3.7 kilometers) of track-line surveys, the team reported. If the cable breaks, the robot is programmed to find its way back to the ship autonomously.
The robot documented organisms that form not only the base of the Arctic food web that supports larger animals like seals and polar bears, but smaller organisms that also play an important role in the global carbon cycle, by pulling carbon dioxide out of the atmosphere and eventually dragging it to the seafloor when they die. This so-called biological pump helps mitigate the warming effects of fossil fuel emissions by drawing greenhouse gases out of the atmosphere, the researchers said.
The scientists are using the NUI's data to gather baseline information about this important sub-ice environment now, so they can better understand how its role in the global carbon cycle may change in the future, with thinning ice due to climate change.
"It's one of these habitats that we have never seen before and we are understanding them as we are changing them," study researcher Antje Boetius, a marine biologist at the Alfred Wegener Institute in Germany, said during the news briefing.
The team is now working to analyze the data collected from the robot, and eventually hopes to equip the ROV to explore more extreme environments. The team's ultimate goal is to send it beneath the underbelly of a floating glacial tongue to study the region where a glacier meets the seabed, called its grounding line. A glacier's grounding line plays an important role in the speed at which it melts and slips into a body of water, which has key implications for rising sea levels.
Read more at Discovery News
DNA tells no lies, so the findings, published in the American Journal of Human Genetics, reveal just what a melting pot of different racial and ethnic groups exists in the United States.
“Our study not only reveals the historical underpinnings of regional differences in genetic ancestry, but also sheds light on the complex relationships between genetic ancestry and self-identified race and ethnicity,” study author Katarzyna Bryc of 23andMe and Harvard Medical School said in a press release.
Bryc and her team studied DNA sequence variations called “single-nucleotide polymorphisms” in the genomes of more than 160,000 African Americans, Latinos and European Americans. Study participants provided saliva samples, where the DNA sequence variations were found.
The researchers found that more than 6 million Americans who self-identify as European likely carry African ancestry. As many as 5 million self-described European Americans might have at least 1 percent Native American ancestry, according to the study.
The researchers also determined that regional ancestry differences reflect historical events in the United States, such as waves of immigration. For example, Scandinavian ancestry is found in trace proportions in most states, but it makes up about 10 percent of ancestry in European Americans living in Minnesota and the Dakotas.
The scientists also discovered that people identify roughly with the majority of their genetic ancestry.
Read more at Discovery News
One of those experiments, as discussed by a collaboration of particle physicists in a new paper published in the journal Physical Review D, could focus on why the universe is dominated by matter and not antimatter, one of the most enduring mysteries in modern physics.
And the focus of the study? Yes, the infamous Higgs boson may be at least partially to blame for our universe’s matter-antimatter asymmetry.
When the universe began, right at the ignition of the Big Bang some 13.75 billion years ago, particles of matter and antimatter should have been generated in equal numbers. As all Star Trek fans know, should matter and antimatter meet, total annihilation occurs. Therefore, if equal quantities of matter and antimatter were generated, there should be no matter or antimatter left in the universe — instead, the universe would have remained as a soup of energy where matter (or antimatter) could not form.
But as we look around us, although tiny quantities of antimatter can be found, the universe is obviously filled with matter. So the question is: Why did matter win out?
Since the discovery of the Higgs boson, physicists have been studying its characteristics in the LHC data. As the particle accelerator collides protons inside its building-sized detectors, a few isolated Higgs bosons are generated. But they don’t last long in isolation; they quickly break down — or “decay” — into other subatomic particles and energy.
The Higgs boson itself is not directly observed by the LHC, instead it is the Higgs’ decay particles that are detected. After billions and billions of collisions, eventually a strong enough signal was generated that, in 2012, LHC scientists were able to triumphantly announce the Higgs boson’s historic discovery. This was significant, not only because it was observational evidence of a boson that was theorized back in the 1960s, but because it appeared to be a Standard Model Higgs at a theorized energy of 125 GeV/c2 — basically the final and elusive piece of the Standard Model that describes all particles and forces (except gravity) in nature.
Now there could be a twist to the Higgs story.
As the Higgs field is intimately tied to matter, physicists are understandably asking whether the Higgs could be the driving force of the matter-antimatter unbalance, which specifically focuses on a phenomenon known as charge-parity (CP) violation.
“Searching for CP violation at the LHC is tricky,” said Matt Dolan, a research associate at the Department of Energy’s SLAC National Accelerator Laboratory at Stanford University, Calif. “We’ve just started to look into the properties of the Higgs, and the experiments must be very carefully designed if we are to improve our understanding of how the Higgs behaves under different conditions.”
In its most basic sense, CP violation means that nature treats a particle (matter) and its antiparticle (antimatter) differently, a phenomenon that SLAC’s BaBar experiment studies. When the universe was born, there must have been a CP violation as nature somehow treats matter differently from antimatter, so there is some physical subtlety that we haven’t yet understood.
As detailed in a SLAC news release, physicists first need to confirm the Higgs fits into the Standard Model, then they need to take extremely detailed measurements of the decay products and the jets of energy the Higgs decay generates. One particular type of Higgs decay centers on the production of two tau particles — leptons that are basically massive electrons — where the remaining energy of the proton-proton collisions sprays into two defined jets.
Read more at Discovery News
Dec 17, 2014
But her signals are deceptive. While they promise sex, the female's real quest is to eat the male so she has the energy to reproduce, says evolutionary biologist Dr Kate Barry of Macquarie University.
"The male is quite a large meal compared to any other prey type that the female would consume, and they can therefore use those resources to produce more eggs and have more babies," says Barry.
For a couple of decades now, some scientists have believed that malnourished female mantises can use sex pheromones to deceptively attract males so they can cannibalise them for food.
But studies to date, including two by Barry herself, have not supported this Femme Fatale hypothesis.
Instead, research has found that the more nourished a female mantis is, the more pheromones she produces. And poorly-nourished females have not been found to attract more males than those that are well-nourished.
This has led many scientists to conclude that a female needs to be well-nourished to produce pheromones, and that these chemicals are a reliable signal to males that a female is in good condition, with lots of eggs, and is likely to be a good mate.
However, Barry was still convinced hungry females were practising chemical deception but the design of experiments was just failing to pick this up, so she set up a new experiment designed to make up for what she saw as defects in earlier studies.
She put three groups of eight female false garden mantids (Pseudomantis albofimbriata) in cages made of mesh, which obscured the females from sight.
Each group of eight included females whose nourishment status was either 'very poor', 'poor', 'medium' or 'good'.
Barry then watched what happened as she released males around the caged females.
She found that for the 'poor', 'medium' and 'good' groups, the higher the nourishment status the more males the females attracted (5, 10 and 15, respectively).
"There was a nice positive correlation between female body condition and the number of males attracted," says Barry. "That's what you would expect in a normal non-deceptive system."
But Barry found the females in the 'very poor' group attracted the most males of all (25).
She says this was presumably due to the production of better quality or greater amounts of pheromones for deceptive purposes.
The findings support the Femme Fatale hypothesis, and the idea that a hungry female will spend resources on producing pheromone because it's worth the benefits she gets from deceiving the male.
The results are published today in the Royal Society journal Proceedings B.
A key difference between Barry's most recent study and earlier research was that it took into consideration research showing that a female mantis needs to have at least one egg to produce sex pheromones.
While previous studies had not considered this, Barry confirmed the presence of eggs in all the females by dissecting them at the end of the experiment.
Cannibalism in Pseudomantis albofimbriata begins before copulation, says Barry.
The first thing the female does is bite off the male's head and forelegs to disable him as quickly as possible.
But, says Barry, the male can still get his end in before he is completely eaten.
Because he has two brains — one in his head, and one in his abdomen — a headless male is able to bend the rest of his long body around to copulate.
Read more at Discovery News
The sparkly chunk was pulled from Russia's huge Udachnaya diamond mine and donated to science (the diamonds' tiny size means they're worthless as gems). It was a lucky break for researchers, because the diamond-rich rock is a rare find in many ways, scientists reported Monday (Dec. 15) at the American Geophysical Union's annual meeting.
"The exciting thing for me is there are 30,000 itty-bitty, perfect octahedrons, and not one big diamond," said Larry Taylor, a geologist at the University of Tennessee, Knoxville, who presented the findings. "It's like they formed instantaneously."
The concentration of diamonds in the rock is millions of times greater than that in typical diamond ore, which averages 1 to 6 carats per ton, Taylor said. A carat is a unit of weight (not size), and is roughly equal to one-fifth of a gram, or 0.007 ounces.
The astonishing amount of diamonds, and the rock's unusual Christmas coloring, will provide important clues to Earth's geologic history as well as the origin of these prized gemstones, Taylor said. "The associations of minerals will tell us something about the genesis of this rock, which is a strange one indeed," he said.
Although diamonds have been desired for centuries, and are now understood well enough to be recreated in a lab, their natural origins are still a mystery.
"The reactions in which diamonds occur still remain an enigma," Taylor told Live Science.
Scientists think diamonds are born deep below Earth's surface, in the layer between the crust and core called the mantle. Explosive volcanic eruptions then carry hunks of diamond-rich mantle to the surface. However, most mantle rocks disintegrate during the trip, leaving only loose crystals at the surface. The Udachnaya rock is one of the rare nuggets that survived the rocketing ride.
Taylor works with researchers at the Russian Academy of Sciences to study Udachnaya diamonds. The scientists first probed the entire rock with an industrial X-ray tomography scanner, which is similar to a medical CT scanner but capable of higher X-ray intensities. Different minerals glow in different colors in the X-ray images, with diamonds appearing black.
The thousands upon thousands of diamonds in the rock cluster together in a tight band. The clear crystals are just 0.04 inches (1 millimeter) tall and are octahedral, meaning they are shaped like two pyramids that are glued together at the base. The rest of the rock is speckled with larger crystals of red garnet, and green olivine and pyroxene. Minerals called sulfides round out the mix. A 3D model built from the X-rays revealed the diamonds formed after the garnet, olivine and pyroxene minerals.
Exotic materials captured inside diamonds, in tiny capsules called inclusions, can also provide hints as to how they were made. The researchers beamed electrons into the inclusions to identify the chemicals trapped inside. The chemicals included carbonate, a common mineral in limestone and seashells, as well as garnet.
Read more at Discovery News
The coroner determined that the parents, who are Seventh Day Adventists, hadn’t taken their 14-month-old boy, John Clark, to a doctor since birth and are strict vegans. According to an article on CTV News:
“An autopsy and additional tests confirmed the child’s death was the result of a Staph infection complicated by malnutrition. According to police, the parents, Jeromie and Jennifer, attempted to conceal the infant’s failing health. ‘We believe that the family followed a strict dietary regiment based on their beliefs,’ said CPS S/Sgt. Doug Andrus.”
Calgary police determined that John Clark was not born at a hospital but instead at home—a lawful practice, but one that led to the child not receiving any neonatal care or indeed any medical attention at all during his life. The infection the boy died from would have been easily treatable with antibiotics had his parents brought him to medical attention during its early stages. The child, weakened by the extreme vegan diet enforced by his parents, was not healthy enough to allow him to recover on his own.
The Seventh Day Adventist Church is known for promoting a healthy lifestyle among its members, including not smoking, avoiding “unclean” food products mentioned in Leviticus (such as pork) and vegetarianism. The church does not officially endorse veganism, though according to an article in the Calgary Sun, “more than 60 percent of Adventists are vegetarian.”
The rise over the past decade of health eating, driven by a renewed health consciousness, has also given rise to an increase in the number of babies and children dying of starvation induced by their vegetarian and vegan parents. As an article in “The New York Times” notes:
“A vegan diet is dangerous for weaned babies and toddlers, who need plenty of protein and calcium. Too often, vegans turn to soy, which actually inhibits growth and reduces absorption of protein and minerals. That’s why health officials in Britain, Canada and other countries express caution about soy for babies.”
Read more at Discovery News
|Oh cheer up, old pal. You had one of the greatest ideas ever. So what if you got a bit of it wrong? Plus, you’ve got that sweet beard. Not all of us can have such sweet beards.|
But contrary to popular belief today, scientists were kicking around the idea of evolution before Darwin—even Charles’ grandpa, Erasmus, alluded to it in verse, like a true OG. Charles’ contribution was specifically the natural selection bit, that organisms vary, and these variations can better suit individuals to their environment, thus boosting their chances of passing down these traits to future generations. (Weirdly, Darwin’s friend, the brilliant naturalist Alfred Russel Wallace, had arrived at the same idea independently at around the same time. The two presented their preliminary findings to the Linnean Society of London, before Darwin blew the lid off the whole thing with On the Origin of Species.)
There was a bit of a problem with all of this natural selection stuff, though: Darwin didn’t know how it, uh, worked. Offspring had a mix of their parents’ features, sure. But how? What was going on at the moment of conception? It was a huge hole in Darwin’s theory of evolution. So in 1868, almost a decade after he published On the Origin of Species, Darwin tried to plug that hole with the theory of “pangenesis,” a wildly wrong idea that goes a little something like this:
|Charles’ grandaddy, Erasmus, a real gangsta.|
Because both parents contribute these cell seeds, offspring end up blending the features of mom and dad. But what about a child exhibiting more features of one parent than the other? This comes about when “the gemmules in the fertilized germ are superabundant in number,” where the gemmules “derived from one parent may have some advantage in number, affinity, or vigor over those derived from the other parent.” In other words, they kinda just put more effort into it.
Gemmules must develop in the proper order to build a healthy organism. When something glitches along the way, though, you get birth defects. “According to the doctrine of pangenesis,” Darwin wrote, “the gemmules of the transposed organs become developed in the wrong place, from uniting with wrong cells or aggregates of cells during their nascent state.”
But most important of all, Darwin’s theory of pangenesis could finally explain variations among organisms—the raw fuel of evolution. This has two causes. First, “fluctuating variability” comes from “the deficiency, superabundance, and transposition of gemmules, and the redevelopment of those which have long been dormant.” In other words, they’re expressed in a grandchild after skipping a generation, though the gemmules themselves haven’t “undergone any modification.”
Darwin’s theory of pangenesis could finally explain variations among organisms—the raw fuel of evolution.
The second touches on a now discredited theory of Lamarckism, which argued that traits an organism acquires during its lifetime, perhaps because of environmental factors, can then be inherited by its young. Darwin believed gemmules could be altered during an organism’s lifetime, and these newly altered gemmules could multiply and supplant the old ones. (Lamarckism is dead, but some modern scientists argue that because behaviors like your language are acquired, this represents nongenetic inheritance that can change the course of an organism’s evolution. But it’s still quite a controversial subject that we needn’t get into here. Those interested should read this good primer on the topic.)
So to sum up: Gemmules are seeds of cells that you get when your parents conceive you. They must form in the proper order to build a healthy organism, and the way they mix results in variations. Some gemmules can lie dormant, resulting in traits that skip generations, or change over an organism’s lifetime, resulting in offspring inheriting traits that their parents had developed due to environmental factors.
Any theory needs a solid experiment, and that fell to Darwin’s cousin, Francis Galton. To prove gemmules induce variation, he took the blood of one rabbit and injected it into another, with the idea that the offspring of the latter would show traits of the former. In his essay “Darwin and Heredity: The Evolution of His Hypothesis of Pangenesis,” Gerald Geison writes: “These experiments, like all that followed, failed utterly to confirm Darwin’s view; and when, in addition, the idea of the inheritance of acquired characters became discredited, Pangenesis was rapidly swept out of court by more satisfying explanations.”
|Francis Galton, tester of theories on bunnies, and person of general sadness.|
I’ve said it before in this column and I’ll say it again: Being wildly wrong is perfectly healthy in science, because when someone comes along to prove that you’re wrong, that’s progress. Somewhat embarrassing progress for the person being corrected, sure, but progress nonetheless.
The real logic behind genetics was first discovered, oddly enough, by a monk and his pea plants in the 1850s, just as Darwin was preparing On the Origin of Species. By breeding these plants and recording how traits get passed down from generation to generation, Gregor Mendel noticed that offspring weren’t simply a blend of their two parents, as biologists had reckoned at that time. The offspring of a plant with smooth peas and another with wrinkled peas, for instance, wouldn’t itself have kinda-wrinkled peas, but either full-blown smooth or wrinkled peas. This is what we now refer to as dominant and recessive alleles, or versions of a particular gene: If you have blue eyes, for instance, you’re expressing a recessive allele, and if you have brown eyes, it’s the dominant trait. This happens because you get two copies of each gene, one from your mother and another from your father.
|DNA isn’t actually this colorful in your body, unless you’re like a Muppet or clown or something.|
We now know that inheriting traits has nothing to do with gemmules mixing together. We of course get our DNA, which contains genes, from both our mother and father. But these are combined in unique ways at each conception, leading to variations even among siblings. Variation can also come from mutations: When our cells divide they frequently make copies of their DNA that don’t always come out perfect (you probably have a whole lot of mutations that you don’t even notice). So these mutations, combined with genetic shuffling at birth, drive variations and therefore evolution: Some individuals are born with traits that may suit them better to their environment, which boosts their chances of surviving and breeding and passing those genes to future generations.
Read more at Wired Science
Dec 16, 2014
The surface of Mars is currently inhospitable to life as we know it, but there is evidence that the Red Planet once had a climate that could have supported life billions of years ago. For example, features resembling dry riverbeds and minerals that only form in the presence of liquid water have been discovered on the Martian surface. The Curiosity rover with its suite of instruments including SAM was sent to Mars in 2011 to discover more about the ancient habitable Martian environment by examining clues in the chemistry of rocks and the atmosphere.
The organic molecules found by the team were in a drilled sample of the Sheepbed mudstone in Gale crater, the landing site for the Curiosity rover. Scientists think the crater was once the site of a lake billions of years ago, and rocks like mudstone formed from sediment in the lake. Moreover, this mudstone was found to contain 20 percent smectite clays. On Earth, such clays are known to provide high surface area and optimal interlayer sites for the concentration and preservation of organic compounds when rapidly deposited under reducing chemical conditions.
While the team can't conclude that there was life at Gale crater, the discovery shows that the ancient environment offered a supply of reduced organic molecules for use as building blocks for life and an energy source for life. Curiosity's earlier analysis of this same mudstone revealed that the environment offered water and chemical elements essential for life and a different chemical energy source.
"We think life began on Earth around 3.8 billion years ago, and our result shows that places on Mars had the same conditions at that time -- liquid water, a warm environment, and organic matter," said Caroline Freissinet of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "So if life emerged on Earth in these conditions, why not on Mars as well?" Freissinet is lead author of a paper on this research submitted to the Journal of Geophysical Research-Planets.
The organic molecules found by the team also have chlorine atoms, and include chlorobenzene and several dichloroalkanes, such as dichloroethane, dichloropropane and dichlorobutane. Chlorobenzene is the most abundant with concentrations between 150 and 300 parts-per-billion. Chlorobenzene is not a naturally occurring compound on Earth. It is used in the manufacturing process for pesticides (insecticide DDT), herbicides, adhesives, paints and rubber. Dichloropropane is used as an industrial solvent to make paint strippers, varnishes and furniture finish removers, and is classified as a carcinogen.
It's possible that these chlorine-containing organic molecules were present as such in the mudstone. However, according to the team, it's more likely that a different suite of precursor organic molecules was in the mudstone, and that the chlorinated organics formed from reactions inside the SAM instrument as the sample was heated for analysis. Perchlorates (a chlorine atom bound to four oxygen atoms) are abundant on the surface of Mars. It's possible that as the sample was heated, chlorine from perchlorate combined with fragments from precursor organic molecules in the mudstone to produce the chlorinated organic molecules detected by SAM.
In 1976, the Gas Chromatograph Mass Spectrometer instrument on NASA's Viking landers detected two simple chlorinated hydrocarbons after heating Martian soils for analysis (chloromethane and dichloromethane). However they were not able to rule out that the compounds were derived from the instrument itself, according to the team. While sources within the SAM instrument also produce chlorinated hydrocarbons, they don't make more than 22 parts-per-billion of chlorobenzene, far below the amounts detected in the mudstone sample, giving the team confidence that organic molecules really are present on Mars.
The SAM instrument suite was built at NASA Goddard with significant elements provided by industry, university, and national and international NASA partners.
For this analysis, the Curiosity rover sample acquisition system drilled into a mudstone and filtered fine particles of it through a sieve, then delivered a portion of the sample to the SAM laboratory. SAM detected the compounds using its Evolved Gas Analysis (EGA) mode by heating the sample up to about 875 degrees Celsius (around 1,600 degrees Fahrenheit) and then monitoring the volatiles released from the sample using a quadrupole mass spectrometer, which identifies molecules by their mass using electric fields. SAM also detected and identified the compounds using its Gas Chromatograph Mass Spectrometer (GCMS) mode. In this mode, volatiles are separated by the amount of time they take to travel through a narrow tube (gas chromatography -- certain molecules interact with the sides of the tube more readily and thus travel more slowly) and then identified by their signature mass fragments in the mass spectrometer.
The first evidence for elevated levels of chlorobenzene and dichloroalkanes released from the mudstone was obtained on Curiosity Sol 290 (May 30, 2013) with the third analysis of the Cumberland sample at Sheepbed. The team spent over a year carefully analyzing the result, including conducting laboratory experiments with instruments and methods similar to SAM, to be sure that SAM could not be producing the amount of organic material detected.
Read more at Science Daily