Argonaut Octopus Mystery Solved | Wired Science. After centuries of speculation, biologists have documented one way a strange group of octopus-like creatures use their seashell-shaped cases. Female argonauts, a group of four species that are close cousins of octopuses, grow delicate white shell-like cases. Biologists have found argonauts with air bubbles in their cases, and now it turns out the animals use the trapped air to float at a comfortable depth, says Julian Finn of Museum Victoria in Melbourne, Australia.
In the first reports from scuba observations of wild argonauts, Finn maneuvered Argonauta argo females so air escaped from their cases. The animals flailed as if struggling to maintain their orientation and quickly jetted to the water surface. Once at the surface, argonauts rocked their cases and took on air, he says. Then they positioned body parts to seal in some of the air and jetted downward, leaving behind a trail of bubbles. Bubble trapping, however, may not be the only function of the shell-like case, he says. African Footprint Fossils Are Oldest Evidence of Upright Walk |
Despite a penchant for hanging out in trees, human ancestors living 3.6 million years ago in what’s now Tanzania extended their legs to stride much like people today do, a new study finds. If so, walking may have evolved in leaps and bounds, rather than gradually, among ancient hominids. The discovery comes from the famed trackway site in Laetoli, Tanzania, where more than 30 years ago researchers discovered footprint trails from two, and possibly three, human ancestors who had walked across a wet field of volcanic ash.
The new analysis shows that the Laetoli hominids made equally deep heel and toe impressions while walking across a soft surface, say anthropologist David Raichlen of the University of Arizona in Tucson and his colleagues. That pattern is a cardinal sign of a humanlike gait, and suggests that an energetically efficient, extended-leg stride appeared surprisingly early in hominid evolution, Raichlen’s team proposes in a paper published online March 22 in PLoS ONE. Dinosaurs Rode Volcanic Armageddon to Victory | Wired Science | Geologists have turned a series of 200 million-year-old lake-bed sediments into an epic narrative of the dinosaurs’ journey from ecological obscurity to Earthly supremacy, a mystery that has lingered even as their disappearance is explained.
The dino path to dominance appears to have been cleared when the supercontinent Pangea cracked, setting off 600,000 years of volcanic activity that wiped out the dinosaurs’ crocodilian competitors. “This is the strongest case for a volcanic cause of a mass extinction event to date,” wrote geoscientists in a paper published March 22 in the Proceedings of the National Academy of Sciences. From 250 million to 200 million years ago, dinosaurs were just upstart lizards. The planet was dominated by a family of vaguely crocodile-like animals called crurotarsans that filled every major ecological niche, from slow-munching herbivores to fleet predators.
About halfway through that period, known as the Triassic, an asteroid struck Earth. A clear picture emerged. ‘Lucy’s Grandfather’ Fossil Makes Humanity’s Ancestor Seem More. A 3.6 million-year-old fossil from one of humanity’s earliest ancestors is more human-like than expected — and much taller. The discovery makes Lucy, the best-known fossil of all, appear to be exceptionally short by comparison.
Lucy and the new skeleton are both Australopithecus afarensis, the first fully bipedal primate and a direct ancestor of humanity. Unlike Lucy and every other A. afarensis fossil, the new skeleton has complete forelimb and hindlimb bones, allowing researchers to estimate its size more accurately. The new A. afarensis specimen stood between 5 and 5 1/2 feet tall, towering over Lucy’s 3-foot height.
Other fossil fragments suggested that Lucy was an unreliable measuring stick for A. afarensis, but the new fossil is the most conclusive evidence yet. Big Man’s limbs also appear well-suited for running, in contrast to the shortened gait implied by Lucy’s skeleton. “The difference between Australopithecus and humans is much less than everyone expected,” said Lovejoy. EPA Reverses Controversial ‘Human Guinea Pig’ Rule | Wired Scien. Under proposed changes to federal research ethics standards, the Environmental Protection Agency will no longer accept studies that use people as guinea pigs in chemical tests.
In 2006, under chemical-industry pressure, and over arguments that the studies were scientifically and ethically bankrupt, the EPA declared such data acceptable. On June 16, the EPA reversed its decision. “What we were really concerned about is toxicity studies, where they’re trying to do a study on humans to determine the dose response of a chemical,” said Jennifer Sass, a senior scientist at the Natural Resources Defense Council, a liberal nonprofit. “If the EPA stops accepting them, there’s no motivation for companies to conduct them.” Almost every standard code of medical ethics — including the Nuremberg Code, written in response to Nazi doctors’ nightmare studies — forbid human tests of drugs or chemicals that may cause harm, but can provide no direct benefit.
Image: Flickr/Michelle Tribe See Also: Tricky Sea Ice Predictions Call for Scientists to Open Their Dat. With sea ice levels in the Arctic at record lows this month, a new report comparing scientists’ predictions calls for caution in over-interpreting a few weeks worth of data from the North Pole. The Sea Ice Outlook, which will be released this week, brings together more than a dozen teams’ best guesses at how much sea ice will disappear by the end of the warm season in September. This year began with a surprise.
More sea ice appeared than anticipated, nearing its mean level from 1979-2007. But then ice levels plummeted through May and into June. Scientists have never seen the Arctic with less ice at this time of year in the three decades they’ve been able to measure it, and they expect below average ice for the rest of the year. But looking ahead, the ultimate amount of sea ice melt is hard to determine. Some trends, like the long-term warming of the Arctic and overall decreases in the thickness of sea ice, argue for very low levels of sea ice. Images: 1) Two icebreakers side-by-side. Before the Mississippi: Ancient Rivers Flowed West | Wired Scien. Like vacationers taking a pit stop on a long road trip, zircon mineral grains from the northern Appalachians may have stopped off in Michigan before ending up on the Colorado Plateau, a new study suggests.
The finding, reported in the June Geology, is a major boost to the notion that a continent-spanning, Amazon-like river system once carried sediments west across North America. A large proportion of the zircons found in Jurassic-era sandstones throughout a Texas-sized portion of the Colorado Plateau originated in the Appalachians (SN: 8/30/03, p. 131), previous analyses have shown. Those erosion-resistant mineral grains were carried westward by an immense river, deposited on floodplains and then stirred back up innumerable times before ending up in massive dune fields that later solidified into western sandstones, says William R.
Dickinson, a geologist at the University of Arizona in Tucson. “It’s not as good as a barcode, but the match is really quite good,” says Scott D. See Also: Feathered Dinosaurs Molted Like Birds | Wired Science | Wired.co. Like kids today who don’t want to dress like Mom and Dad, some young feathered dinosaurs sported a look totally unlike their elders, a new study shows. The finding hints that feathered dinosaurs, like modern birds, molted as they grew, says study coauthor Xing Xu, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. The dramatic age-related shift in plumage was noted in newly described fossils of Similicaudipteryx, a feathered creature that lived in what is now China about 125 million years ago. Xu and his colleagues analyzed two well preserved specimens of Similicaudipteyrx and report their findings in the April 29 Nature.
Both fossils are thought to come from juveniles, because the vertebrae aren’t completely fused, which happens as animals reach adulthood, Xu says. But in the pigeon-sized smaller creature, feathers on the forelimb and tail look modern only near their tips, Xu says. See Also: Unearthed Trash at Jamestown Reveals Tough Times for Settlers | Oyster shells excavated from a well in Jamestown, Virginia, the first permanent British settlement in North America, bolster the notion that the first colonists suffered an unusually deep and long-lasting drought. The shells reveal that water in the James River near the colony, where many of those oysters were harvested, was much saltier then than along that stretch of the estuary today, says Howard Spero, a geochemist at the University of California, Davis.
For the water to have been so brackish, river flow must have been slacker compared to today, a sign that precipitation was dramatically lower when those oysters were growing. Spero and his colleagues report their findings online May 31 in the Proceedings of the National Academy of Sciences. Jamestown was established in 1607. The early years weren’t easy: Many accounts of Jamestown’s early settlers, including journal entries and letters home, chronicled the drought. So did the region’s trees, Spero says. See Also: Brain Scan Lie-Detection Deemed Far From Ready for Courtroom | W. A landmark decision has excluded fMRI lie-detection evidence from a federal court case in Tennessee. The defense tried to use brain scans of the defendant to prove its client had not intentionally defrauded the government. In a 39-page opinion, Judge Tu Pham provided both a rebuke of this kind of fMRI evidence now, and a roadmap for how future defendants may be able to satisfy the Daubert standard, which governs the admissibility of scientific evidence.
“It has no automatic binding force on any other court, but because it’s been so carefully done, it will very likely carry a lot of persuasive value,” said Owen Jones, a professor of law and biological sciences at Vanderbilt University, who observed the entire hearing. The specific facts of the Tennessee case revolve around whether defendant Lorne Semrau, CEO of two nursing home facilities, intentionally had his employees fraudulently fill out Medicare and Medicaid forms. But Pham did not take his criticism too far. “Dr. See Also: Neanderthal Genome Shows Most Humans Are Cavemen | Wired Science.
After years of anticipation, the Neanderthal genome has been sequenced. It’s not quite complete, but there’s enough for scientists to start comparing it with our own. According to these first comparisons, humans and Neanderthals are practically identical at the protein level. Whatever our differences, they’re not in the composition of our building blocks. However, even if the Neanderthal genome won’t show scientists what makes humans so special, there’s a consolation prize for the rest of us. Most people can likely trace some of their DNA to Neanderthals. “The Neanderthals are not totally extinct. In some of us they live on a little bit,” said Max Planck Institute evolutionary geneticist Svante Pääbo.
It took four years for Pääbo’s team to assemble a working sequence from DNA in the bones of three 38,000-year-old Neanderthal women, found in Croatia’s Vindija Cave. At all but 88 of those hot spots, Neanderthals were no different than us. Images: 1. See Also: Lightning May Cause Hallucinations | Wired Science. Talk about a flash of insight. Lightning strokes could stimulate people’s brains and cause them to hallucinate bright blobs of light the same way a medical procedure that applies magnetic fields to the brain does, two physicists propose. The findings could help explain some reports of “ball lightning,” mysterious floating orbs that have been reported for centuries but are poorly understood. A paper describing the idea will appear in Physics Letters A. [partner id="sciencenews" align="right"] “We don’t claim to have a solution for the mystery of ball lightning,” says study co-author Alexander Kendl, a plasma physicist at the University of Innsbruck in Austria.
Lightning forms when electrical charges become physically separated in a storm cloud and build up electrical potential between them, which is then discharged in the sudden bolt. TMS applies magnetic fields to the brain to treat neurological and psychiatric conditions like stroke and depression. Image: Ball Lightning, 1886. See Also: Elusive Neutrino Change-Up Finally Detected | Wired Science | Wi. In a truly transformative event, physicists have for the first time found direct evidence that a neutrino, a ghostly elementary particle that barely interacts with matter, morphs from one type into another. The finding, announced May 31 in a news release, provides additional support for the notion that neutrinos have mass, a property that requires an explanation beyond the realm of the standard model of particle physics. Since the late 1990s, experiments such as Super-Kamiokande in Japan have indicated that neutrinos spontaneously transform themselves, or oscillate, among three varieties or “flavors”: the electron neutrino, the muon neutrino and the tau neutrino.
Such oscillations indicate that neutrinos, long thought to be weightless, must have some small amount of mass. Those experiments revealed a lower-than-predicted abundance of a certain type of neutrino compared with the number produced at the neutrinos’ source. See Also: Testosterone Makes People Suspicious of One Another | Wired Scie. A dose of testosterone might be enough to save gullible types from being ripped off, a new study reveals. Testosterone is linked to aggression, competition and social status. Now scientists have found that the hormone also reduces naive individuals’ confidence in others. “Testosterone reduces trust just enough to make people vigilant and careful,” said psychologist Jack van Honk of Utrecht University in the Netherlands, who led the study published May 24 in Proceedings of the National Academy of Sciences.
In the study, a few dozen females received half a milligram of testosterone under the tongue — enough to increase hormone levels tenfold. Van Honk speculates that the effect does not occur in cautious individuals, because the hormone would make them so paranoid that they would become socially disabled. Previous studies have found that oxytocin, a hormone involved in bonding, increases faith in others. Image: flickr/an untrained eye See Also: Fossils Suggest Menu That Made Humans Possible | Wired Science |
New fossils have provided a snapshot of proto-human diets during a critical evolutionary moment, when better fare helped our small-brained ancestors boost their cognitive capacity. Two-million-year-old bones that belonged to fish, crocodiles and turtles — aquatic animals rich in brain-fueling fatty acids — were found together with stone tool fragments near Kenya’s Lake Turkana. “We know that the hominin brain was growing at this time, but we’ve had little evidence that people were able to increase the quality of their diets,” said University of Cape Town archaeologist David Braun. “It may be that this was part of a broader hominin pattern.”
Preserved in sediments left by sudden flooding and described June 1 in Proceedings of the National Academy of Sciences, the fossil trove could have been left by any of several hominid species – Homo habilis, Homo rudolfiensis, Paranthropus boisei — who once lived around Lake Turkana. The brain is an extremely energy-intensive organ. See Also: The Science of Horror-Movie Screams | Wired Science. Ancient Beehives Yield 3,000-Year-Old Bees | Wired Science | Wir. Reverse-Engineering a Quantum Compass | Wired Science | Wired.co.