Recognizing the urgent need for comprehensive approaches to opioid use disorder that address the needs of the entire family, the Foundation for Opioid Response Efforts (FORE) is today issuing a new Request for Proposals for projects that will engage and empower vulnerable families and communities to prevent opioid use disorder and overdose.
Even in the harshest environments, microbes always seem to get by. They thrive everywhere from boiling-hot seafloor hydrothermal vents to high on Mt. Everest. Clumps of microbial cells have even been found clinging to the hull of the International Space Station (SN: 08/26/20).
There was no reason for microbial ecologist Noah Fierer to expect that the 204 soil samples he and colleagues had collected near Antarctica’s Shackleton Glacier would be any different. A spoonful of typical soil could easily contain billions of microbes, and Antarctic soils from other regions host at least a few thousand per gram. So he assumed that all of his samples would host at least some life, even though the air around Shackleton Glacier is so cold and so arid that Fierer often left his damp laundry outside to freeze-dry.
Surprisingly, some of the coldest, driest soils didn’t seem to be inhabited by microbes at all, he and colleagues report in the June Journal of Geophysical Research: Biogeosciences. To Fierer’s knowledge, this is the first time that scientists have found soils that don’t seem to support any kind of microbial life.
The findings suggest that exceedingly cold and arid conditions might place a hard limit on microbial habitability. The results also raise questions about how negative scientific results should be interpreted, especially in the search for life on other planets. “The challenge comes back to this sort of philosophical [question], how do you prove a negative?” Fierer says.
Noah Fierer and colleagues found soil samples from the Shackleton Glacier region of Antarctica that did not have traces of life, an unexpected observation since samples from the continent typically contain thousands of microbes.Courtesy of N. Fierer
Proving a negative result is notoriously difficult. No measurement is perfectly sensitive, which means there’s always a possibility that a well-executed experiment will fail to detect something that is actually there. It took years of experiments based on multiple, independent methods before Fierer of the University of Colorado Boulder and his collaborator Nick Dragone, finally felt confident enough to announce that they’d found seemingly microbe-free soils. And the scientists intentionally stated only that they were unable to detect life in their samples, not that the soils were naturally sterile. “We can’t say the soils are sterile. Nobody can say that,” Fierer says. “That’s a never-ending quest. There’s always another method or a variant of a method that you could try.”
Polar microbiologist Jeff Bowman interprets the team’s findings as a false-negative. “Certainly, there were things there,” says Bowman of the Scripps Institution of Oceanography in La Jolla, Calif. “This is Earth. This is an environment that is massively contaminated with life.”
Even if there were a few undetected microbes in the soil, said Dragone, that wouldn’t undermine his team’s evidence that cold and aridity pose a serious challenge to life. “It’s the combination of multiple very challenging environmental conditions that restricts life more than just one acting by itself,” says Dragone. “It’s a very different sort of restriction than, say, just high temperature.”
As scientists search for evidence of life beyond Earth (SN: 7/28/20), they will inevitably be forced to walk the line between evidence of absence and absence of evidence. “What we’re trying to do on Mars is kind of the reverse of what we’ve tried to do on Earth,” says polar microbiologist Lyle Whyte of McGill University in Montreal. On Earth, claiming that an environment is lifeless is a tough scientific sell. On Mars, it will be the other way around.
Winter on the Qinghai-Tibetan Plateau is unfriendly to pikas. Temperatures across the barren, windy highlands routinely dip below –30° Celsius, and the grass that typically sustains the rabbitlike mammals becomes dry and brittle. It would seem the perfect time for these critters to hibernate, or subsist on stores of grass in burrows to stay warm, like the North American pika.
Instead, plateau pika (Ochotona curzoniae) continue foraging in winter, but reduce their metabolism by about 30 percent to conserve energy, researchers report July 19 in the Proceedings of the National Academy of Sciences. Some pikas also resort to unusual rations: yak poop.
Camera data from four sites confirmed that pikas regularly brave the cold to forage. “Clearly they’re doing something fancy with their metabolism that’s not hibernation,” says John Speakman, an ecophysiologist at the University of Aberdeen in Scotland.
Speakman and colleagues measured daily energy expenditure of 156 plateau pikas in summer and winter, and implanted 27 animals with temperature sensors. While many nonhibernating animals keep warm in winter by using more energy, these pikas did the opposite (SN: 1/22/14). On average, pikas reduced their metabolism by 29.7 percent, in part by cooling their bodies a couple degrees overnight. The animals were also less active, relative to summertime levels.
But at sites with yaks, pikas were more abundant but even less active. That puzzled the researchers “until we found a sort of half-eaten yak turd in one of the burrows,” Speakman says. Eating excrement can cause sickness. But with few options, yak poop could be an abundant, easily digestible meal that “massively reduces the amount of time [pikas] need to spend on the surface,” he says.
The researchers caught pikas scarfing scat on video, and DNA evidence from stomach contents solidified that this behavior is common. Whether dining on dung has downsides remains to be seen, but clearly, not being too picky pays off for pika.
Where pika and yak overlap, the rabbitlike mammals (shown) find an abundant and easily digestible source of food in yak feces. Eating the excrement helps pikas, which don’t hibernate, survive during hard winter months on the Qinghai-Tibetan Plateau.
The Event Horizon Telescope is expanding its portfolio of black hole images.
In 2019, the telescope unveiled the first image of a black hole, revealing the supermassive beast 55 light-years from Earth at the center of galaxy M87 (SN: 4/10/19). That lopsided orange ring showed the shadow of the black hole on its glowing accretion disk of infalling material. Since then, observations from the Event Horizon Telescope, or EHT, have yielded more detailed views of M87’s black hole (SN: 9/23/20). Now, EHT data have revealed new details of the supermassive black hole at the heart of a galaxy near our own, called Centaurus A.
Rather than zooming in close enough to see the black hole’s shadow, the new picture offers the clearest view yet of the powerful plasma jets erupting from the black hole. This perspective gives insight into how supermassive black holes blast such plasma jets into space, researchers report online July 19 in Nature Astronomy.
“It’s a fairly impressive feat,” says radio astronomer Craig Walker of capturing the new high-resolution image. “These [jets] are some of the most powerful things in the universe,” says Walker, of the National Radio Astronomy Observatory in Socorro, N.M., who was not involved in the work. Because such superfast plasma streams are thought to influence how galaxies grow and evolve, astronomers are keen to understand how the jets form (SN: 3/29/19).
Researchers pointed the global network of radio dishes that make up the EHT at Centaurus A for six hours in April 2017, during the same observing run that delivered the first picture of a black hole (SN: 4/10/19). About 12 million light-years from Earth, Centaurus A is one of the brightest galaxies in the sky and is known for the huge jets expelled by its central black hole.
“They extend to pretty much the entire scale of the galaxy,” says Michael Janssen, a radio astronomer at the Max Planck Institute for Radio Astronomy in Bonn, Germany. “If we were to see radio light [with our eyes], and we were to look at the night sky, then we would see these jets of Centaurus A as a structure that is 16 times bigger than the full moon.”
Using the EHT, Janssen and colleagues homed in on the base of those jets, which gush out from either side of the black hole’s accretion disk. The new image is 16 times as sharp as previous observations of the jets, probing details less than one light-day across — about four times the distance from the sun to Pluto. One of the most striking features that the image reveals is that only the outer edges of the jets seem to glow.
The supermassive black hole in the galaxy Centaurus A launches two jets of plasma in opposite directions (zoomed-out view of the jets at left). In a new close-up view taken by the Event Horizon Telescope (at right; estimated location of the black hole indicated with an arrow), the jet moving toward Earth points toward the image’s top left, with two bright edges and a dark center. The jet moving away from Earth, also bright only at the edges, points toward the bottom right.M. Janssen et al/Nature Astronomy 2021
“That’s still a puzzle,” Janssen says. One possibility is that the jets are rotating, which might cause material in some regions of the jets to emit light toward Earth, while others don’t. Or the jets could be hollow, Janssen says.
Recent observations of a few other galaxies have hinted that the jets of supermassive black holes are brighter around the edges, says Denise Gabuzda, an astrophysicist at University College Cork in Ireland, who wasn’t involved in the work. “But it’s been hard to know whether it was a common feature, or whether it was something quirky about the few that had been observed.”
The new view of Centaurus A’s black hole provides evidence that this edge-brightening is common, Gabuzda says. “It’s fairly rare to be able to detect the jets coming out in both directions, but in the images of Centaurus A … you can clearly see that both of them are brighter at the edges.”
The next step will be to compare the EHT image of Centaurus A with computer simulations based on Einstein’s general theory of relativity, to test how well relativity holds up in this extreme environment, Janssen says. Examining the polarization, or orientation, of the light waves emanating from Centaurus A’s jets could also reveal the structure of their magnetic fields — just as polarization revealed the magnetism around M87’s black hole (SN: 3/24/21).
Climate change is interfering with how researchers count bonobos, possibly leading to gross overestimates of the endangered apes, a new study suggests.
Like other great apes, bonobos build elevated nests out of tree branches and foliage to sleep in. Counts of these nests can be used to estimate numbers of bonobos — as long as researchers have a good idea of how long a nest sticks around before it’s broken down by the environment, what’s known as the nest decay time.
New data on rainfall and bonobo nests show that the nests are persisting longer in the forests in Congo, from roughly 87 days, on average, in 2003–2007 to about 107 days in 2016–2018, largely as a result of declining precipitation. This increase in nests’ decay time could be dramatically skewing population counts of the endangered apes and imperiling conservation efforts, researchers report June 30 in PLOS ONE.
“Imagine going in that forest … you count nests, but each single nest is around longer than it used to be 15 years ago, which means that you think that there are more bonobos than there really are,” says Barbara Fruth, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Konstanz, Germany.
Lowland tropical forests, south of the Congo River in Africa, are the only place in the world where bonobos (Pan paniscus) still live in the wild (SN: 3/18/21). Estimates suggest that there are at least 15,000 to 20,000 bonobos there. But there could be as many as 50,000 individuals. “The area of potential distribution is rather big, but there have been very few surveys,” Fruth says.
From 2003 to 2007, and then again from 2016 to 2018, Fruth and colleagues followed wild bonobos in Congo’s LuiKotale rain forest, monitoring 1,511 nests. “The idea is that you follow [the bonobos] always,” says Mattia Bessone, a wildlife researcher at the Liverpool John Moores University in England. “You need to be up early in the morning so that you can be at the spot where the bonobos have nested, in time for them to wake up, and then you follow them till they nest again.”
In doing so, day after day, Fruth, Bessone and colleagues were first able to understand how many nests a bonobo builds in a day, what’s known as the nest construction rate. “It’s not necessarily one because sometimes bonobos build day nests,” Bessone says. On average, each bonobo builds 1.3 nests per day, the team found.
Tracking how long these nests stuck around revealed that the structures were lasting an average of 19 days longer in 2016–2018 than in 2003–2007. The researchers also compiled fifteen years of climate data for LuiKotale, which showed a decrease in average rainfall from 2003 to 2018. That change in rain is linked to climate change, the researchers say, and helps explain why nests have become more resilient.
By counting the numbers of nests and then dividing that number by the product of the average nest decay time and nest construction rate, scientists can get an estimate of the number of bonobos in a region. But if researchers are using outdated, shorter nest decay times, those estimates could be severely off, overestimating bonobo counts by up to 50 percent, Bessone says.
“The results are not surprising but also highlight how indirect (and therefore prone to errors) our methods of density estimates of many species are,” Martin Surbeck, a behavioral ecologist at Harvard University, wrote in an e-mail.
Technologies such as camera traps can be used to directly count animals instead of using proxies like nests and are the way forward for animal population studies, researchers say. But until those methods become more common, nest counts remain vital for scientists’ understanding of bonobo numbers.
This phenomenon is probably not limited to bonobos. All great apes build nests, and nest counts are used to estimate those animals’ numbers too. So, the researchers say, the new results could have implications for the conservation of primates far beyond bonobos.
The genetic tweaks that make humans uniquely human may come in small parcels interspersed with DNA inherited from extinct ancestors and cousins.
Only 1.5 percent to 7 percent of the collective human genetic instruction book, or genome, contains uniquely human DNA, researchers report July 16 in Science Advances.
That humans-only DNA, scattered throughout the genome, tends to contain genes involved in brain development and function, hinting that brain evolution was important in making humans human. But the researchers don’t yet know exactly what the genes do and how the exclusively human tweaks to DNA near those genes may have affected brain evolution.
“I don’t know if we’ll ever be able to say what makes us uniquely human,” says Emilia Huerta-Sanchez, a population geneticist at Brown University in Providence, R.I., who was not involved in the study. “We don’t know whether that makes us think in a specific way or have specific behaviors.” And Neandertals and Denisovans, both extinct human cousins, may have thought much like humans do (SN: 2/22/18).
The results don’t mean that individual people are mostly Neandertal or Denisovan, or some other mix of ancient hominid. On average, people in sub-Saharan Africa inherited 0.096 percent to 0.46 percent of their DNA from ancient interbreeding between their human ancestors and Neandertals, the researchers found (SN: 4/7/21). Non-Africans inherited more DNA from Neandertals: about 0.73 percent to 1.3 percent. And some people inherited a fraction of their DNA from Denisovans as well.
Using a new computational method, researchers at the University of California, Santa Cruz examined every spot of DNA in the genomes of 279 people. The team compiled results from those individual genomes into a collective picture of the human genome. For each spot, the team determined whether the DNA came from Denisovans, Neandertals or was inherited from a common ancestor of humans and those long-lost relatives.
Although each person may carry about 1 percent Neandertal DNA, “if you look at a couple hundred people, they mostly won’t have their bit of Neandertal DNA in the same place,” says Kelley Harris, a population geneticist at the University of Washington in Seattle who wasn’t involved in the work. “So if you add up all the regions where someone has a bit of Neandertal DNA, that pretty soon covers most of the genome.”
In this case, about 50 percent of the collective genome contains regions where one or more people inherited DNA from Neandertals or Denisovans, the researchers discovered. Most of the rest of the genome has been passed down from the most recent common ancestor of humans and their extinct cousins. After whittling away the ancient heirloom DNA, the team looked for regions where all people have human-specific tweaks to DNA that no other species have. That got the estimate of uniquely human DNA down to anywhere between 1.5 percent and 7 percent of the genome.
The finding underscores just how much interbreeding with other hominid species affected the human genome, says coauthor Nathan Schaefer, a computational biologist now at the University of California, San Francisco. The researchers confirmed previous findings from other groups that humans bred with Neandertals and Denisovans, but also with other extinct, unknown hominids (SN: 2/12/20). It’s not known whether those mysterious ancestors are the groups that included “Dragon Man” or Nesher Ramla Homo, which may be closer relatives to humans than Neandertals (SN: 6/25/21; SN: 6/24/21). And the mixing and mingling probably happened multiple times between different groups of humans and hominids, Schaefer and colleagues found.
The tweaks that make the uniquely human DNA distinctive arose in a couple of evolutionary bursts, probably around 600,000 years ago and again about 200,000 years ago, the team found. Around 600,000 years ago is about the time that humans and Neandertals were forming their own branches of the hominid family tree.
The estimate of the amount of uniquely human DNA doesn’t take into account places where humans have gained DNA through duplication or other means, or lost it, says James Sikela, a genome scientist at the University of Colorado Anschutz Medical Campus in Aurora who wasn’t involved in the study (SN: 8/6/15). Such extra or missing DNA may have allowed humans to evolve new traits, including some involved in brain evolution (SN: 3/9/11; SN: 2/26/15).
Ancient DNA usually has been degraded into tiny fragments and researchers have pieced together only portions the genomes from extinct hominids. The fragmented genomes make it difficult to tell where big chunks of DNA may have been lost or gained. For that reason, the researchers studied only small tweaks to DNA involving one or more DNA bases — the information-carrying parts of the molecule. Given that humans and Neandertals went their separate evolutionary ways relatively recently, it’s not surprising that only 7 percent or less of the genome has evolved the uniquely human tweaks, Sikela says. “I’m not shocked by that number.” Considering DNA that humans alone have added to their genomes might produce a higher estimate of exclusively human DNA, he says.
Or it could go the other way. As more genomes are deciphered from Neandertals, Denisovans and other extinct hominids, researchers may discover that some of what now seems like uniquely human DNA was also carried by those extinct relatives, Harris says. “This estimate of the amount of uniquely human regions is only going to go down.”
Maybe hold off on that Martian ice fishing trip. Two new studies splash cold water on the idea that potentially habitable lakes of liquid water exist deep under the Red Planet’s southern polar ice cap.
The possibility of a lake roughly 20 kilometers across was first raised in 2018, when the European Space Agency’s Mars Express spacecraft probed the planet’s southern polar cap with its Mars Advanced Radar for Subsurface and Ionosphere Sounding, or MARSIS, instrument. The orbiter detected bright spots on radar measurements, hinting at a large body of liquid water beneath 1.5 kilometers of solid ice that could be an abode to living organisms (SN: 7/25/18). Subsequent work found hints of additional pools surrounding the main lake basin (SN: 9/28/20).
But the planetary science community has always held some skepticism over the lakes’ existence, which would require some kind of continuous geothermal heating to maintain subglacial conditions (SN: 2/19/19). Below the ice, temperatures average –68° Celsius, far past the freezing point of water, even if the lakes are a brine containing a healthy amount of salt, which lowers water’s freezing point. An underground magma pool would be needed to keep the area liquid — an unlikely scenario given Mars’ lack of present-day volcanism.
“If it’s not liquid water, is there something else that could explain the bright radar reflections we’re seeing?” asks planetary scientist Carver Bierson of Arizona State University in Tempe.
In a study published in the July 16 Geophysical Research Letters, Bierson and colleagues describe a couple other substances that could explain the reflections. Radar’s reflectivity depends on the electrical conductivity of the material the radar signal moves through. Liquid water has a fairly distinctive radar signature, but examining the electrical properties of both clay minerals and frozen brine revealed those materials could mimic this signal.
Adding weight to the non-lake explanation is a study from an independent team, published in the same issue of Geophysical Research Letters. The initial 2018 watery findings were based on MARSIS data focused on a small section of the southern ice cap, but the instrument has now built up three-dimensional maps of the entire south pole, where hundreds to thousands of additional bright spots appear.
“We find them literally all over the region,” says planetary scientist Aditya Khuller, also of Arizona State University. “These signatures aren’t unique. We see them in places where we expect it to be really cold.”
Creating plausible scenarios to maintain liquid water in all of these locations would be a tough exercise. Both Khuller and Bierson think it is far more likely that MARSIS is pointing to some kind of widespread geophysical process that created minerals or frozen brines.
While previous work had already raised doubts about the lake interpretation, these additional data points might represent the pools’ death knell. “Putting these two papers together with the other existing literature, I would say this puts us at 85 percent confidence that this is not a lake,” says Edgard Rivera-Valentín, a planetary scientist at the Lunar and Planetary Institute in Houston who was not involved in either study.
The lakes, if they do exist, would likely be extremely cold and contain as much as 50 percent salt — conditions in which no known organisms on Earth can survive. Given that, the pools wouldn’t make particularly strong astrobiological targets anyway, Rivera-Valentín says. (SN: 5/11/20).
Lab work exploring how substances react to conditions at Mars’ southern polar ice cap could help further constrain what generates the bright radar spots, Bierson says.
In the meantime, Khuller already has his eye on other areas of potential habitability on the Red Planet, such as warmer midlatitude regions where satellites have seen evidence of ice melting in the sun. “I think there are places where liquid water could be on Mars today,” he says. “But I don’t think it’s at the south pole.”
Combined perceptions of the risk and availability of cannabis influence the risk of cannabis use more than perceived risk and perceived availability alone, according to a new study at Columbia University Mailman School of Public Health.
Science fiction writers have imagined just about every aspect of life in some far-off future — including how humans will reproduce. And usually, their visions have included a backlash against those who tamper with Mother Nature.
In his 1923 stab at speculative fiction, for instance, British biologist JBS Haldane said that while those who push the envelope in the physical sciences are generally likened to Prometheus, who incurred the wrath of the gods, those who mess around with biology risk stirring something far more pointed: the wrath of their fellow man. “If every physical or chemical invention is a blasphemy,” he wrote in Daedalus, or Science and the Future, “every biological invention is a perversion.”
This article is part of a series highlighting some of the biggest advances in science over the last century. For more on the history of our understanding of reproduction, visit Century of Science: The mystery of reproduction.
Some of Haldane’s projections were remarkably specific. He wrote, for instance, that the world’s first “ectogenic babies” would be born in 1951. These lab-grown babies would come about when two fictitious scientists, “Dupont and Schwarz,” acquire a fresh ovary from a woman who dies in a plane crash. Over the next five years, the ovary produces viable eggs, which the team extracts and fertilizes on a regular basis.
Eventually, Haldane writes, Dupont and Schwarz solve the problem of “the nutrition and support of the embryo.” Soon lab-grown babies become routine, as scientists learn to remove an ovary from any living woman, maintain it in the lab for up to 20 years, extract a new egg every month, grab some sperm (from where, he never says), and successfully fertilize 90 percent of the eggs. Then — and here the details get murky — the embryos are “grown successfully for nine months, and then brought out into the air.”
JBS Haldane, a British biologist, wrote in the 1920s about the possibility of babies being conceived and gestated in laboratories outside the womb.Mirrorpix/Getty Images
In Haldane’s imaginary future, 60,000 babies a year are “brought out into the air” in France, the first country to adopt the new technology, by the year 1968. At some later date, he wrote, ectogenic babies go international, and become more common than natural births, with only 30 percent of children “born of woman.”
Haldane was wrong to leave out the human uterus entirely from these reproductive machinations. But he wasn’t wrong about the eventual ability of scientists to remove a living woman’s ovary and keep it in the lab as a source of eggs for a very long time. This was first reported was in 2001, when fertility doctor Kutluk Oktay, then at Weill Medical College of Cornell University, reported freezing strips of ovarian tissue taken from women who needed or wanted to delay childbearing. When the woman is ready for pregnancy, she returns to the lab to have her ovarian tissue thawed and returned to the ovary. If all goes well, the implant will, within a few months, resume secreting hormones normally again, leading the revived ovary to go back to maturing and releasing eggs on a regular cycle. Today, babies born after ovarian tissue cryopreservation number in the hundreds. (And babies born through all forms of assisted reproductive technology number in the millions.)
British writer Aldous Huxley, too, was preoccupied with laboratory-made babies as the gateway to the future — in his case, to a totalitarian dystopia. (Haldane devoted relatively little time to the social implications of ectogenesis.) Artificial reproduction was at the heart of his 1932 novel Brave New World. Carefully selected eggs and sperm were mixed in glass dishes and grown in an artificial uterus, where they could either be cultured with nutrients to breed an intelligent and healthy upper crust, or spiked with poisons to create an underclass of not-quite-human servants.
Huxley himself was curious about how accurate his prophesies were. So, in 1958, he took another look in Brave New World Revisited. It was still two decades before the birth of the world’s first “test tube baby” in his native England, which might explain why Huxley, by that time living in California, seemed to think he had missed the mark in his original projection of endless rows of fake wombs in the baby-making lab. “Babies in bottles and the centralized control of reproduction are perhaps not impossible,” he conceded, but they certainly were not around the corner. He added that “it is quite clear that for a long time to come we shall remain a viviparous species breeding at random.”
British writer Aldous Huxley, author of Brave New World, imagined a dystopian future in which people’s traits and social status are determined before they’re born.Edward Gooch Collection/Getty Images
Yes, even 60-plus years after Huxley wrote those words, humans do indeed still breed mostly viviparously — meaning in live birth from a mother’s body — and mostly “at random.” Yet assisted reproductive technology has become almost mainstream, in a way that neither Huxley nor Haldane quite could have predicted. Nor did they really signal the emergence, within this same startling century, of a technique like CRISPR, with the potential to change an embryo’s genetic code as easily as making changes in a Word document.
In this regard, writers from a much more recent era, such as those who wrote the screenplay for the 1997 movie Gattaca, were in a better position to get the science basically right, envisioning a grim future in which, as film critic Roger Ebert wrote in his review, genetic engineering of embryos becomes as humdrum as a kind of “preemptive plastic surgery.”
Even as long ago as 1923, though, Haldane was able to offer one unusually provocative prediction: “We can already alter animal species to an enormous extent, and it seems only a question of time before we shall be able to apply the same principles to our own.”
The July 30 virtual conference is part of a three-year grant to train clinicians to prescribe medications to treat addiction.
