Over the last several years, spacecraft have beamed back images from all across the solar system, revealing a complex tapestry of landscapes. Dust shapes the scenery on comet 67P, whereas ice rules on Pluto and the moons of Saturn.
At first glance, many of these terrains seem the same — mountains, craters and canyons show up everywhere. But each world adds its own geologic signature that marks the land as utterly alien.
While several of the spacecraft’s missions will end in the coming year, a fleet of new explorers ensures that our interplanetary adventures are far from over.
Inside a large cave in northwestern Australia’s remote Kimberley region, someone painted an elongated, yamlike shape on a ceiling at least 16,000 years ago, new research suggests. That long-ago creation in the unnamed cavern adds fuel to the argument that rock art in Australia goes back even earlier to the continent’s first inhabitants, researchers contend.
This discovery joins a small number of drawings and paintings from Down Under that have been dated to around the same time or earlier, say archaeologist June Ross of the University of New England in Armidale, Australia, and colleagues. Some scientists have questioned the accuracy of these dates. But the new work, Ross’ team asserts, gives a critical boost to a previous, contested report that a piece of Kimberley rock art depicting a humanlike figure painted over a hand stencil dates to a minimum of about 16,400 years ago. Ross’ group also obtained minimum age estimates, ranging from around 5,100 to 530 years, for nine other pieces of Kimberley rock art, the researchers report August 31 in PLOS ONE. People first reached Australia around 50,000 years ago ( SN: 3/15/03, p. 173 ). Researchers generally assume the continent’s colonizers brought rock art traditions with them from Asia. In southeastern Australia’s Yaranda Cave, for instance, claw marks of a type of marsupial that died out around 50,000 years ago appear on top of pigmented human finger marks, says Robert Bednarik, an independent scholar and self-taught rock art authority based in Caulfield South, Australia. But it is difficult to accurately date such art. Ross’ team — like the researchers who dated the humanlike figure — focused on dating sand grains found inside mud wasps’ nests that the insects built on cave walls and ceilings, covering parts of artistic depictions. Eventually, surviving nests fossilized. Light-induced release of radiation from sand grains in the lab enabled calculations of the time since each grain was last exposed to sunlight, providing a minimum age for the painting beneath the nest. Four pieces of Kimberley rock art — but not the proposed 16,000-year-old painting — also yielded radiocarbon dates from bits of surviving nests and beeswax stuck to drawings.
Without a confirming radiocarbon date, the new minimum age estimate of 16,000 years for the yamlike Kimberley painting is provisional, Bednarik says. But the timeframe isn’t out-of-bounds. Mineral deposits partly covering hand stencils in an Indonesian cave date to nearly 40,000 years old (SN: 11/15/14, p. 6), although, similarly, no radiocarbon dates exist to confirm that. And researchers have known for decades that meandering impressions on the walls of Koonalda Cave in southern Australian, made by pigment-coated human fingers, must be older than 15,000 years, Bednarik says. The marked walls in Koonalda Cave became inaccessible after that time.
PASADENA, Calif. — The forecast on Pluto is clear with less than a 1 percent chance of clouds. Images from the New Horizons spacecraft show hints of what could be a few isolated clouds scattered around the dwarf planet, the first seen in otherwise clear skies.
Seven cloud candidates appear to hug the ground in images taken shortly after the probe buzzed by the planet in July 2015. Along the line where day turns to night, several isolated bright patches appear. These are consistent with clouds forming at sunset and sunrise, said mission head Alan Stern during an October 18 news conference at a meeting of the American Astronomical Society’s Division for Planetary Sciences.
If they are clouds, they’re probably made of ethane, acetylene or hydrogen cyanide, based on what researchers have learned about Pluto’s atmosphere — though they might not be clouds, just reflective splotches on the surface, Stern said. Without stereo imaging, it’s impossible to tell how high off the ground the patches are, or whether they’re in the sky at all. Since New Horizons isn’t returning to Pluto — it’s hurtling deep into the Kuiper belt — the spacecraft won’t be able to take another look at the cloud candidates and answer these questions. That will have to wait until another spacecraft goes back to orbit Pluto, Stern said.
It’s a familiar sight: Your mom or grandmother picks up a document and immediately holds it out at arm’s length to make out the small letters on the page, while simultaneously reaching for her reading glasses. As people age, their ability to see things close up often fades, a condition known as presbyopia. The eye can no longer focus light on the retina, focusing it instead just behind and causing poor close-up vision.
Many have thought that presbyopia was a consequence of living in an era in which people are overburdened by tasks that require frequently focusing in the near-field of vision. But perhaps not: A new study finds that if bonobos could read, they too would need glasses as they age.
Bonobos aren’t burdened with having to read tiny newsprint or letters on a mobile phone screen, but they do perform one task that regularly requires close focus: grooming. This behavior not only removes tiny bits of dirt and ectoparasites from the animals but also promotes social relationships. Most of the time, a bonobo grooms by putting its face within 20 centimeters of its partner and picking off the offending debris with its fingers. But older bonobos place their partner at arm’s length, probably because they can no longer see close up, researchers report November 7 in Current Biology.
For more than 40 years, researchers from Japan’s Kyoto University have studied wild bonobos in the Luo Scientific Reserve near a village called Wamba. Some researchers had noticed that older bonobos groomed differently than young ones, keeping their companions at arm’s length. Then in 2015, Heunglin Ryu of Kyoto University and colleagues decided to try to quantify this. Was it all older bonobos, or just some? They photographed 14 bonobos as they groomed, using the bonobos’ ear length and a ruler to determine grooming distance. Then they plotted out their data.
Grooming distance increased exponentially after a bonobo hit age 35, with the oldest bonobos, at age 45, keeping their partners around five times as far away as did young bonobos. A video of one bonobo taken in 2009 showed how her vision changed. When Ki was 29 years old, she placed his face 11.9 centimeters from her fingers as she plucked away at her partner. But at age 35, that had increased to 16.9 centimeters.
Scientists had reported anecdotes of older female chimpanzees (male chimps generally do not reach old age) that developed presbyopia. The bonobo finding combined with our own bad eyesight may indicate that presbyopia is a condition that dates to at least our most recent common ancestor.
As in humans, bad eyesight may come with a price for older bonobos. People who are farsighted often have trouble seeing in the dark. If that is also true for bonobos, they may have difficulty seeing in the low light of the rainforest canopy. Plus, if they are not able to groom others well, that may affect their social lives. Maybe they would benefit from reading glasses.
A robot caterpillar can use squishy legs to sense the world.
Roboticist Takuya Umedachi and colleagues designed the robot after studying real-life caterpillars. These insects can “bend, wrinkle, buckle, twist, droop, and creep” their way through the environment, and they do it “without massively complex brains,” the researchers write December 7 in Royal Society Open Science.
To mimic a caterpillar, Umedachi’s team built a version that included motors, pulleys and wire. It’s 23 centimeters long — about the length of a tissue box — with four contracting segments, and those squishy legs. Sensors detect when the legs bend. That’s a cue for the robot to crawl, one segment contracting after another in a wave.
But when Umedachi covered the middle two legs with tape, they no longer had enough purchase to push off the ground — they didn’t bend. “It’s slippery, like walking on ice,” says Umedachi, of the University of Tokyo. That’s enough info for the robot to change its gait — without using a lot of “brain” power. When those middle legs stay straight, the robot switches to a new caterpillar-like movement: like an inchworm, back leg scooching to front, and then front leg stretching forward.
A pliable body lets robots sense and interact with the environment, Umedachi says. And it could give machines yet another way to become more aware of themselves — and their surroundings.
This stone engraving of an aurochs, or wild cow, found in a French rock-shelter in 2012, provides glimpses of an ancient human culture’s spread across Central and Western Europe, researchers say.
Rows of dots partly cover the aurochs. A circular depression cut into the center of the animal’s body may have caused the limestone to split in two, says Stone Age art specialist Raphaëlle Bourrillon of the University of Toulouse-Jean Jaurès in France. Radiocarbon dating of animal bones unearthed near the discovery at Abri Blanchard rock-shelter put the engraving’s age at roughly 38,000 years, Bourrillon and colleagues report online January 24 in Quaternary International.
The rock art is similar to some engravings and drawings found at other French and German sites, including the famous Chauvet Cave (SN: 6/30/12, p. 12), and attributed to the Aurignacian culture, which dates to between 43,000 and 33,000 years ago. Like the new find, that art includes rows of dots, depictions of aurochs and various animals shown in profile with a single horn and a long, thin muzzle.
Within a few thousand years of arriving in Europe from Africa, Aurignacian groups developed regional styles of artwork based on images that had deep meaning for all of them, proposes anthropologist and study coauthor Randall White of New York University, who directed the excavation.
In recent years, rates of colorectal cancer cases and deaths in the United States rose among young and middle-aged adults, an American Cancer Society study of colorectal cancer trends between 2000 and 2014 finds. That increase came even as rates of colon and rectal tumors and deaths dropped in people 50 and older, researchers report online March 1 in CA: A Cancer Journal for Clinicians.
Few people who are under 50 get colorectal cancer, but the incidence in this group has risen since 2000, from 5.9 new cases diagnosed in every 100,000 people to 7.2 per 100,000 in 2013. In contrast, the incidence rate for people age 50 and older was 119.3 per 100,000 in 2013. New cases are still most prevalent in people 65 and older: 58 percent of the estimated 135,430 new diagnoses projected for 2017 will occur in that age group. Overall, colorectal cancer incidence and death rates are declining. This drop is attributed to decreases in smoking and red meat consumption, an increase in aspirin usage — which can calm inflammation that spurs tumor growth — and improvements in screening and treatment. Increased prevalence of obesity, unhealthy diets and sedentary lifestyles contributed to the rise in colorectal cancer cases and deaths among adults younger than 50, the researchers suspect.
Simulating the assembly of the solar system around 4.56 billion years ago, researchers propose that the Red Planet didn’t form in the inner solar system alongside the other terrestrial planets as previously thought. Mars instead may have formed around where the asteroid belt is now and migrated inward to its present-day orbit, the scientists report in the June 15 Earth and Planetary Science Letters. The proposal better explains why Mars has such a different chemical composition than Earth, says Stephen Mojzsis, a study coauthor and geologist at the University of Colorado Boulder. The new work is an intuitive next step in a years-long rethink of the early solar system, says Kevin Walsh, a planetary scientist at the Southwest Research Institute in Boulder, Colo., who was not involved with the new simulation. “We only became comfortable within the last 10 years with the idea that planets move around, possibly a lot,” he says. “Planets may not have formed where we see them today.”
Mars, like Mercury, is a runt of the inner solar system, weighing in at only about a ninth of Earth’s mass. One of the reigning theories of planetary formation, the Grand Tack model, blames Jupiter for the Red Planet’s paltry size. In that scenario, the newly formed Jupiter migrated toward the sun until it reached Mars’ present-day orbit. A gravitational tug from Saturn then reversed Jupiter’s course, sending the gas giant back to the outer solar system (SN: 4/2/16, p. 7).
Gravitational effects of Jupiter’s sunward jaunt acted like a snowplow, scientists believe, causing a pileup of material near where Earth’s orbit is today. The bulk of that material formed Venus and Earth, and the scraps created Mercury and Mars. This explanation predicts that all the terrestrial planets formed largely from the same batch of ingredients (SN: 4/15/17, p. 18). But studies of Martian meteorites suggest that the Red Planet contains a different mix of various elements and isotopes, such as oxygen-17 and oxygen-18, compared with Earth.
Planetary scientist Ramon Brasser of the Tokyo Institute of Technology, Mojzsis and colleagues reran the Grand Tack simulations, keeping an eye on the materials that went into Mars’ creation to see if they could explain the different mix.
As with previous studies, the researchers found that the most probable way of creating a solar system with the same planet sizes and positions as seen today is to have Mars form within Earth’s orbit and migrate outward. How Another possible scenario, though seen in only about 2 percent of the team’s new simulations, is that Mars formed more than twice as far from the sun as its present-day orbit in the region currently inhabited by the asteroid belt. Then as Jupiter moved sunward, its gravitational pull yanked Mars into the inner solar system. Jupiter’s gravity also diverted planet-making material away from Mars, resulting in the planet’s relatively small mass. With Mars forming so far from the planetary feeding frenzy responsible for the other rocky planets, its composition would be distinct. While this scenario isn’t as likely as Mars forming in the inner solar system, it at least matches the reality of Mars’ makeup, Mojzsis says.
Such a distant origin means that the fledgling Mars would have received far less sunlight than originally thought, a challenge to early Mars’ possible habitability. Without a sustained thick atmosphere of heat-trapping greenhouse gases, the planet would have been too cold to sustain liquid water on its surface for long periods of time, Mojzsis argues. Though large meteorite impacts could have temporarily warmed Mars above freezing, the planet wouldn’t have had a consistently warm and wet youth similar to that of the early Earth, he says.
Confirming whether Mars really was born that far out in space will require taking a closer look at Venus’ mix of elements and isotopes, which the researchers predict would be similar to Earth’s. Venus’ composition is largely unknown because of a lack of Venusian meteorites found on Earth, and that mystery won’t be unlocked anytime soon: No missions to Venus are planned.
Even though a sprained ankle rarely needs an opioid, a new study of emergency room patients found that about 7 percent of patients got sent home with a prescription for the potentially addictive painkiller anyway. And the more pills prescribed, the greater the chance the prescription would be refilled, raising concerns about continued use.
The research adds to evidence that it’s hard for some people to stop taking the pills even after a brief use. State officials in New Jersey recently enacted a law limiting first-time prescriptions to a five-day supply, and other states should consider similar restrictions, says Kit Delgado, an assistant professor of Emergency Medicine and Epidemiology at the University of Pennsylvania. “The bottom line is that we need to do our best not to expose people to opioids,” Delgado says. “And if we do, start with the smallest quantity possible.” The research was presented May 17 at the Society for Academic Emergency Medicine’s annual meeting in Orlando.
Previous research has found that the more opioids such as hydrocodone and oxycodone are prescribed, the more likely patients are to keep taking them. But previous studies have been too broad to account for differences in diagnoses — for instance, whether people who received refills kept taking the drug simply because they still were in pain, Delgado says. He and colleagues limited their study to prescriptions written after ankle sprains to people who had not used an opioid in the previous six months. Usually, those injuries aren’t serious and don’t require opioids.
About 7 percent of 53,222 people who visited ERs with ankle sprains in 2011 and 2012 were sent home with an opioid prescription, the researchers found. Patients’ experiences varied by state: Less than 2 percent treated in Delaware were prescribed an opioid compared with 16 percent in Mississippi.
The number of pills obtained within a week of those visits also varied greatly, from as few as five to more than 60. Typical prescriptions were for 15 to 40 pills. Those who received prescriptions for 30 pills or more were twice as likely to get refills as those with prescriptions for 15 or fewer, Delgado and colleagues found.
“Because these are patients who have a uniformly minor injury, it emphasizes how much arbitrariness there is in how physicians prescribe opioids,” says Michael Barnett, an assistant professor at the Harvard T.H. Chan School of Public Health, who was not involved in the study. In February, Barnett and colleagues published a study of ER opioid prescribing in the New England Journal of Medicine, which found that higher exposures carry greater odds of long-term use. The strength of the new study, he said, is that “an ankle sprain is an ankle sprain. It’s a minor injury that requires very little treatment beyond rest, ice and elevation.”
The company mice keep can change their behavior. In some ways, genetically normal littermates behave like mice that carry an autism-related mutation, despite not having the mutation themselves, scientists report.
The results, published July 31 in eNeuro, suggest that the social environment influences behavior in complex and important ways, says neuroscientist Alice Luo Clayton of the Simons Foundation Autism Research Initiative in New York City. The finding comes from looking past the mutated mice to their nonmutated littermates, which are usually not a subject of scrutiny. “People almost never look at it from that direction,” says Clayton, who wasn’t involved in the study. Researchers initially planned to investigate the social behavior of mice that carried a mutation found in some people with autism. Studying nonmutated mice wasn’t part of the plan. “We stumbled into this,” says study coauthor Stéphane Baudouin, a neurobiologist at Cardiff University in Wales.
Baudouin and colleagues studied groups of mice that had been genetically modified to lack neuroligin-3, a gene that is mutated in some people with autism. Without the gene, the mice didn’t have Neuroligin-3 in their brains, a protein that helps nerve cells communicate. Along with other behavioral quirks, these mice didn’t show interest in sniffing other mice, as expected. But Baudouin noticed that the behavior of the nonmutated control mice who lived with the neuroligin-3 mutants also seemed off. He suspected that the behavior of the mutated mice might be to blame.
Experiments confirmed this hunch. Usually, mice form strong social hierarchies, with the most aggressive and vocal males at the top. But in mixed groups of mutated and genetically normal male mice, there was no social hierarchy. “It’s flat,” Baudouin says.
Raised and housed together, the mutated and nonmutated mice all had less testosterone than nonmutated mice raised in genetically similar groups. The testosterone levels in both types of mice were comparable to those found in females — “one of the strongest and most surprising results,” Baudouin says.
The mice’s social curiosity was lacking, too. Usually, mice are interested in the smells of others, and will spend lots of time sniffing a cotton swab that had been swiped across the bedding of unfamiliar mice. But when given a choice of strange mouse scent or banana scent, the nonmutated littermates spent just as much time sniffing banana as did the mutant mice. When Baudouin and colleagues added back the missing Neuroligin-3 protein to parts of the mutant mice’s brains, aspects of their behavior normalized. The mice became interested in the odor from another mouse’s bedding, for instance. These behaviors also shifted in the mice’s nonmutated littermates. That experiment suggests that the missing protein — and the resulting abnormal behavior of the mutants — was to blame for their littermates’ abnormal actions.
Still, it’s hard to tease apart the mice’s roles, says behavioral neuroscientist Mu Yang of Columbia University. “It is a shared environment, and there is no sure way to tell who is influencing whom, or whether both parties are being impacted.”
Female mice that completely lacked the neuroligin-3 gene also influenced the behaviors of littermates that carried one mutated version of the gene, other behavior tests revealed. More experiments are needed to determine whether the social environment affects male and female mice differently, and if so, whether those differences relate to autism, says Luo Clayton.
