A two-faced star just helped weigh an extra-massive pulsar.
The star takes about four hours to orbit its companion, a fast-spinning stellar corpse called a pulsar that’s about 10,000 light-years from Earth. That means the pair’s orbital dance is tight enough that the star always shows the same face to the pulsar, similar to how the moon is oriented to Earth.
Radiation from the pulsar has fried the near side of the companion star to a scorching 7800° Celsius, Manuel Linares of the Polytechnic University of Catalonia in Barcelona and colleagues report May 23 in the Astrophysical Journal. That’s as hot as an A-type star, which are typically around twice the mass of the sun and burn at higher temperatures. But the side facing away from the pulsar is just roughly 5400° Celsius, similar to stars like the sun. Linares and colleagues also measured the Doppler shift — the change in the wavelength of the star’s light as it moves toward and away from the Earth — of the star’s two sides as it moved around the pulsar to calculate its orbit precisely. The team used that precision to estimate the mass of the pulsar, and found it was surprisingly heavy: around 2.3 times the mass of the sun.
A type of neutron star, pulsars are extremely dense, cramming the mass of a star into an orb the size of a planet. Previous studies of packing neutrons together at high pressures had suggested that a pulsar can’t be more massive than 2.2 solar masses without collapsing into a black hole (SN: 12/23/17, p. 7). The new finding may force a rethink of how these particles interact at high densities, Linares says.
The duo, named PSR J2215+5135, is called a “redback” binary, after the cannibalistic spider of the same name, because the pulsar is gradually stealing material from its neighbor. Eventually, the pulsar may gobble enough of the regular star to become a black hole. But at the rate the pulsar is eating, this pair seems to be stable. “They will keep dancing for a while,” Linares says.
Police are using a new type of DNA sleuthing, called genetic genealogy. Already the technique has caught murder and rape suspects in California and Washington. While solving the cases has given cause for celebration, the tactics used in catching the alleged culprits have many privacy and civil rights experts worried.
Closing the Golden State Killer case (SN Online: 4/29/18) and the previously unsolved double murder of a young Canadian couple (SN Online: 5/23/18) involved probing a public online database of people’s DNA and family-tree information called GEDmatch. In a May 29 opinion piece published in the Annals of Internal Medicine, bioethicist Christine Grady and colleagues argue that police should be more transparent about how they use forensic DNA searches. Meanwhile, law professor Natalie Ram and colleagues go even further in an essay in the June 8 Science, writing that eroding limits on the use of crime-solving technology “threatens our collective civil liberties and opens the door to socially and politically unacceptable genetic surveillance.”
Here are a few key points in the debate:
Why are police using GEDmatch instead of DNA testing companies? If police wanted to use 23andMe or AncestryDNA to help solve crimes, they would need a clean saliva sample from a potential suspect to send to the company for testing and analysis. But crime scene DNA doesn’t come in that form, so police can’t send DNA to the companies for testing. That’s not the case with the DNA analysis service GEDmatch, to which customers can upload raw DNA data received from testing companies.
“That means the police or law enforcement investigators are equally able, if they have enough DNA to create a sufficiently complete genetic sequence, to upload that to GEDmatch” to find potential suspects, says Ram, of the University of Baltimore School of Law.
Companies like 23andMe and Ancestry also require consent from the person the DNA belongs to before the companies will do testing. That’s, obviously, not possible with crime scene DNA. However, GEDmatch in May changed its terms of service “to explicitly embrace the use of their service by law enforcement,” Ram says.
Could these searches lead to people being investigated needlessly? Before police tracked the Golden State Killer suspect through GEDmatch, investigators subpoenaed Family Tree DNA for information about a customer whose Y chromosome partially matched DNA from one of the crime scenes. Police then used that information to order a man in an Oregon nursing home to give a DNA sample. He was not a match.
“Just having DNA match something at the crime scene doesn’t mean the person committed the crime,” says Grady, who heads the National Institutes of Health Clinical Center’s Department of Bioethics in Bethesda, Md. “It just means that they were there, or something that they used was there.” Police still have to prove the suspect committed the crime.
If DNA tests are helping to catch criminals, shouldn’t we be all for it? “Catching criminals is great,” Ram says. “But privacy is also important. Police could solve more crime if they, for instance, could go rifle through anybody’s home at any time for no reason.” But such searches are illegal, because they violate people’s rights to privacy and security against unreasonable search and seizure.
Some people have suggested this type of search could be limited to solving very serious crimes and cold cases. But such limits have been tried before, Ram notes. Over the past decade, some U.S. states have begun allowing the use of police DNA databases for “familial searches.” Such searches may implicate close relatives of people in the police database as suspects in a crime. “States that embraced that technology initially said, ‘we’re only going to use this for really, really serious crimes.’ ” But then Colorado in 2009 convicted its first suspect with this technique — for “a burglary where someone broke into a car and stole about a dollar and a half in change,” Ram says.
Many people say DNA data should be treated differently than other personal information. “There are things that are unique about genetic data. Most importantly, that it has implications for others,” Grady says. People strive to protect medical information, but medical records reveal things about only an individual. DNA reveals things about relatives, too.
“If I give up my genetic data, you can learn things about people who are related to me that you can’t learn from my cholesterol or my blood pressure, or even my psych history,” Grady says. There should be some safeguards, she adds. “No law enforcement agencies have rules or standards about how they use this kind of information.”
Do any laws protect against this type of search? Because GEDmatch is a public database, privacy protections that govern private companies probably don’t apply. “If people voluntarily put their data on GEDmatch, they’ve given it away,” Grady says. It’s like they’ve cut their hair and left the hair on the floor. There’s no protection for that.” Other laws governing the privacy of genetic and medical information don’t apply genealogical DNA data deposited in public databases.
But Grady believes that could soon change. “I suspect there will be people entertaining new laws in light of the recent uses.”
A little brain can be surprisingly good at nothing. Honeybees are the first invertebrates to pass a test of recognizing where zero goes in numerical order, a new study finds.
Even small children struggle with recognizing “nothing” as being less than one, says cognitive behavioral scientist Scarlett Howard of the Royal Melbourne Institute of Technology in Australia. But honeybees trained to fly to images of greater or fewer dots or whazzits tended to rank a blank image as less than one, Howard and colleagues report in the June 8 Science. Despite decades of discoveries, nonhuman animals still don’t get due credit outside specialist circles for intelligence, laments Lars Chittka of Queen Mary University of London, who has explored various mental capacities of bees. For the world at large, he emphasizes that the abilities described in the new paper are “remarkable.”
Researchers recognize several levels of complexity in grasping zero. Most animals, or maybe all, can understand the simplest level — just recognizing that the absence of something differs from its presence, Howard says. Grasping the notion that absence could fit into a sequence of quantities, though, seems harder. Previously, only some primates such as chimps and vervet monkeys, plus an African gray parrot named Alex, have demonstrated this level of understanding of the concept of zero (SN: 12/10/16, p. 22).
The researchers first trained bees to visit a spot with either a Y-shaped maze or an upright display, both offering images with different numbers of elements, such as dark circles of different sizes. Some bees were trained to fly to the image with the lower numbers of objects, while other bees were taught to go to the higher-number image. The researchers offered the bees a sweet treat for the correct image, and a bitter quinine solution for a wrong answer.
“I was fairly afraid of bees when I began working with them,” Howard says. But learning their ways convinced her that a lot of what humans mistake for aggression from a foraging bee buzzing around is usually “just curiosity.” The trained bees then performed a series of tests with no rewards. In one test that offered the bees a choice between a single shape image versus a blank image, bees trained to pick the lower number of objects flew to the blank image — the zero — 63 percent of time. Overall, the test results showed the bees treating zero as being less than one, Howard says.
The results convince evolutionary behavioral biologist Rafael Rodríguez of the University of Wisconsin–Milwaukee that honeybees are indeed getting the basics of zero. Now he’s wondering about earlier studies that might hint that certain spiders would be worth testing, too.
Still, the most sophisticated sense of zero, using a symbol for it in mathematical calculation, is a feat only humans have demonstrated. So far. Howard muses about the possibility of someday testing bees’ prowess on that harder feat.
I’m making my way through my third round of breastfeeding a newborn and taking stock of how things are going. Some aspects are definitely easier: My milk came in really quickly (a perk of being a repeat lactator), the fancy breastfeeding baby holds are no longer mysterious to me and I already own all of the weird pillows I need to prop up my tiny baby.
But one thing isn’t easier this time around: the bone-crushing, mind-numbing exhaustion. Just like my other two, this sweet baby seems to eat all the time. All day. All night. Sometimes multiple times an hour, especially in the witching hours of the evening. This frequency got me curious about the biology of newborns’ stomachs. Just how small are they? Are they so microscopic that one can hold only enough sustenance to keep my newborn satisfied for a thousandth of a second? Birth educators and medical professionals often use a marble to illustrate the size of a newborn’s stomach, a tiny orb that holds about 5 to 7 milliliters of liquid. But that small estimate has come into question. A 2008 review published in the Journal of Human Lactation points out that there aren’t many solid studies on the size of the infant stomach, and some of the ones that do exist come to different conclusions. Another review of existing studies concluded that the average newborn stomach is slightly smaller than a Ping-Pong ball and can hold about 20 milliliters, or about two-thirds of an ounce.
The question of stomach size at birth isn’t settled, and that may be in part because there is no one answer. Just as babies come in a variety of sizes, their stomachs may too. What’s more, size isn’t everything. Drinking ability, the stretchiness of the stomach and the speed at which food gets digested are all part of the equation, and those physiological skills may take a few days, or longer, to get sorted out. There’s evidence that brand new stomachs get better at relaxing after a few days, which lets them expand and hold more liquid, for instance.
Because we don’t really know how big any particular newborn’s stomach is, the best approach to feeding frequency comes from watching the baby’s behavior. Babies should be fed on demand, the American Academy of Pediatrics recommends. And babies “demand” a meal — either breastmilk or formula — by rooting around with their heads or starting to suck on something (their hands, their parents’ arms, whatever’s within reach). Crying is often one of the last signals they send. Breastfeeding sessions should be attempted eight to 12 times in a 24-hour period.
We’re definitely in round-the-clock territory in my house. During a recent back-to-back nursing session, I had a vague memory of a study on the !Kung hunter-gatherers of Namibia and Botswana. Reading the study again gave me a whole new appreciation for these women. During the daytime (when researchers were observing), the women’s babies, who ranged in age from 12 weeks to more than 2 1/2 years, nursed an average of four times an hour, with about 13 minutes between nursing bouts. Those astonishing numbers put my own nursing marathons into perspective, and reminded me that the struggle to keep up with growing babies’ appetites is universal.
As the Hawaiian volcano’s latest outburst enters its third month, scientists are still watching Kilauea 24/7. Such constant monitoring not only provides danger warnings aimed at keeping those nearby safe, but it also offers remote viewers the rare opportunity to observe the evolution of an eruption in real time.
As magma within Kilauea’s summit crater, called Halemaumau, continues to drain and move toward the lower east rift zone, the crater floor is becoming increasingly unstable. The U.S. Geological Survey has observed frequent rockfalls into the crater since mid-May; each collapse triggers a small explosion. One of the largest explosions happened June 30, when a collapse-explosion cycle released energy equivalent to a magnitude 5.3 earthquake. While a “Whomp!” and a slow-rising cloud of volcanic gas and ash marked that collapse, the real pyrotechnics are happening along nearly two dozen fissures, vents through which lava erupts, in that lower east rift zone. Lava fountains spurting from two fissures, Nos. 8 and 22, are feeding most of the lava flows now pouring into the ocean.
It’s hard not to stare slack-jawed at images of molten rock spurting into the air, of glowing, fast-moving rivers of lava rushing into the ocean, or of the tangles of wispy-sharp shards of glass known as Pele’s hair. Check out these highlights of Kilauea’s show and the science (and volcanic vocabulary) we’re learning from them. Of nearly two dozen fissures, No. 8 at the eastern edge of the now devastated Leilani Estates neighborhood is producing some of the most spectacular pyrotechnics, including this lava whirlwind, or lavanado. Lavanadoes form much like “firenadoes” do from the wrath of wildfires: Intense heat (in this case, from the volcano itself) causes air to swiftly rise and form a tall column, and strong winds can then cause the column to rotate. Here, the lavanado dances with the molten rock before flinging the lava several meters away. In the vog A thick fog curls out of fissures and seeps along the ground. Dubbed vog, this volcanic smog forms as sulfur dioxide and other gases and particles seeping out from the fissures react with oxygen, water vapor and sunlight. Since Kilauea began erupting along its lower east rift zone, within Leilani Estates, scientists warned anyone in the vicinity to wear protective masks due to emissions of this toxic air pollution. Ropy rock The kind of lava erupting from Hawaiian volcanoes, a molten basalt rock, cools into two main types of formation. When the lava flows slowly, air cools its “skin”— but beneath that skin, the lava continues to ooze ahead, advancing toe by toe. The smooth, ropy skin and toe-shaped lobes are characteristic of pahoehoe lava. By contrast, more swiftly flowing lava, known as Aa, appears chunky and angular. That’s because faster-moving lava loses heat more quickly and becomes more resistant to flow. Instead of a slow, sinuous advance, the lava tears ahead, forming large, hardened chunks.
Fast flow Glowing torrents of lava fed by fissure 8 on Kilauea’s lower east rift zone jet through a channel at speeds of about 7.7 meters per second. USGS scientists shot this video June 19, but the rivers continue to flow. Much like a river of water, flow is fastest at the center of the river and slowest along the edges of the lava channel due to friction. Lava waves form as the molten rock sloshes through lava rapids, along its 13-kilometer journey before it spills into the ocean.
On a boat Also like many water rivers, the lava rivers have occasional passengers. Lava boats are rafts made of pieces of hardened lava that clump together and get carried downstream, like boats on a waterway. A huge chunk of lava, dubbed a lava boat, sails away on this river of lava as Kilauea erupts.
As the lava boats travel, more pieces of lava may cool and glom onto their surface, forming accretions called lava balls.
Toxic steam As Kilauea’s rivers of fire pour into the ocean, they boil the water, sending great clouds of corrosive steam billowing into the air. The steam is a concoction that volcanologists call laze, or lava haze, and it’s the product of a chemical reaction between the hot lava and seawater. The lava, at a temperature of about 1150° Celsius, basically boils away the seawater, leaving behind very reactive sea salts, such as magnesium chloride. These salts react with the steam to form hydrochloric acid. Similar in strength to weak battery acid, laze can irritate eyes and skin, and cause breathing difficulties.
Glass hair When tiny droplets of lava spray into the air and rapidly cool, they can form fine threads of volcanic glass. Dubbed Pele’s hair, they are named for the Hawaiian goddess of fire and volcanoes. The fibers are so fine that they can be carried along by the wind before raining out. But it’s not a gentle rain: The sharp threads are abrasive enough to scratch car windshields and can irritate skin and eyes, or contaminate open water reservoirs.
The new lava delta filling in what was once Kapoho Bay now spans more than 162 hectares, USGS scientists say, the equivalent of more than 300 U.S. football fields. And with the eruption – and Kilauea’s pyrotechnics – showing no signs of slowing (SN Online: 5/8/18), the Big Island will probably continue to grow.
When President Donald Trump took a mental test as part of his physical in January, the results called attention to far more than his fitness for office. (He passed with a perfect score, according to his physician.) It put a test commonly used to catch early signs of dementia in the spotlight. That publicity could lead to missed diagnoses, researchers warn July 16 in JAMA Neurology.
Google searches of the Montreal Cognitive Assessment, a 10-minute screening test consisting of 30 questions, spiked in the week after news coverage of Trump’s physical. Of 190 news articles about his performance identified by the researchers, 53.7 percent included some or all of the test’s questions and answers. And 17 percent encouraged readers to see how their mental abilities stacked up against the president’s.
That might make it more difficult for clinicians to screen patients for early signs of dementia. Taking the test once increases your score the next time you take it, a phenomenon called a learning effect. The study didn’t track how many readers took the memory test. But for those who did, researchers say, the learning effect could artificially inflate some patients’ scores and make it harder for doctors to pick up on the memory symptoms linked to Alzheimer’s and other neurodegenerative diseases.
Most of the news articles quoted questions from one specific version of the test, so the researchers suggest that doctors should administer alternate versions to prevent skewed results.
The northwestern United States has become an air pollution hot spot — literally.
Air quality in states from Nevada to Montana is worse than it was 30 years ago on the days with the most extreme air pollution. Bigger and more frequent wildfires that spew plumes of fine particulate matter into the sky are largely to blame, researchers report July 16 in Proceedings of the National Academy of Sciences.
By contrast, the rest of the country has seen decreasing trends in similar smog and haze over the last three decades. Legislation such as the Clean Air Act, which mandates air quality standards and the regulation of vehicle and factory emissions of particulate matter, is making a difference, says study coauthor Daniel Jaffe, an atmospheric scientist at the University of Washington in Bothell. But the increase in lung-clogging particulate matter from wildfires shows how the effects of climate change — which is, in part, driving the worsening fires — can counteract those gains, Jaffe says.
Wildfire smoke is filled with fine particulates, minuscule solids or droplets that can be inhaled into the lungs, exacerbating breathing problems. Children, the elderly and people with asthma are most at risk, but communities near wildfires can temporarily experience levels of pollutants so high that it’s unsafe for anyone to be outside for very long. “When we start to think about people’s health, episodic events matter a lot,” says Gannet Hallar, an atmospheric scientist at the University of Utah in Salt Lake City, who wasn’t part of the study.
Regular exposure to elevated levels of these fine airborne pollutants (less than 2.5 micrometers wide, or about 3 percent of the width of a human hair) has also been linked to an increased risk of chronic health conditions such as heart disease and diabetes (SN: 9/30/17, p. 18). Tracking the broader influence of wildfires on air pollution can be tricky because the fires are intermittent and patchy, says Jaffe, who carried out the study with Crystal McClure, also an atmospheric scientist at the University of Washington in Bothell. “Most of the year, wildfires aren’t impacting air quality, but on some of the worst days they are.” And the blazes can hit one community hard, but leave neighboring towns relatively unaffected.
Jaffe and McClure looked at daily measurements of fine particulate matter at more than 100 rural monitoring sites around the country, from 1988 to 2016. In most parts of the country, the data showed a success story of cleaner air over time — but not in the northwest, an area that gets hit hard by wildfires every summer. The team made similar calculations for levels of a few specific pollutants — particulate carbon, a hallmark of fire emissions, and sulfate, a by-product of burning fossil fuels. Particulate carbon levels had increased over time in the northwest, but sulfate levels didn’t, supporting the conclusion that wildfires are mainly driving the air pollution trend in the western United States, rather than industrial activity.
Wildfires weren’t making air pollution on an average day worse in the northwest, the team found. Most of the time, air quality is fine — wildfires might only affect a given community for a few days or weeks out of a year. But the air quality on the bad days, when air pollutants are especially high, is getting worse over time, the analysis shows. Those particularly bad days tended to be in the summer, when wildfires are at their peak. In the northwest, levels of fine particulates on the handful of days with the worst air quality each year have increased at an average rate of 0.21 micrograms per cubic meter per year, though there’s substantial local variability in that number.
As the overall air quality picture in the country has improved, we now have harder work to do, says Jenny Hand, an atmospheric scientist at Colorado State University in Fort Collins who wasn’t part of the study. Those challenges include figuring out how to prevent and mitigate these more uncontrollable sources of air pollution that can’t be regulated like emissions from human sources can, she says.
Mouth wounds heal faster than injuries to other parts of the skin, and now scientists are learning how the mouth performs its speedy repairs.
Some master regulators of gene activity work overtime in the mouth to heal wounds without scarring, researchers report July 25 in Science Translational Medicine. Those regulators — proteins known as SOX2, PITX1, PITX2 and PAX9 — are active in skin cells called keratinocytes in the mouth, but not in skin cells from the arm. The regulators hold down inflammation that can lead to scarring and turn on molecular programs involved in cell movement and wound closure, say the researchers, from the University of California, San Diego and the National Institutes of Health in Bethesda, Md. Knowing how the mouth performs its speed healing may eventually lead to therapies that fix skin sores without forming scars. Because the regulators are involved in many biological processes, including guiding an organism’s development, scientists need to discover which of these processes is important for wound healing, says Luis Garza, a skin researcher and dermatologist at Johns Hopkins School of Medicine. The study may provide some clues.
Researchers made small wounds in both the mouths and the inner upper arms of 30 volunteers. The mouth wounds healed about three times as fast as the wounds made in the arm skin — on average at a rate of about 0.3 millimeters a day in the mouth compared with less than 0.1 millimeter a day on the arm. Reducing amounts of PITX1 and SOX2 in mouth keratinocytes grown in lab dishes altered the activity of genes involved cell movement. Boosting SOX2 levels in the skin of mice shortened healing time — from about nine days to about three.Knowing how the mouth performs its speed healing may eventually lead to therapies that fix skin sores without forming scars. Because the regulators are involved in many biological processes, including guiding an organism’s development, scientists need to discover which of these processes is important for wound healing, says Luis Garza, a skin researcher and dermatologist at Johns Hopkins School of Medicine. The study may provide some clues.
Researchers made small wounds in both the mouths and the inner upper arms of 30 volunteers. The mouth wounds healed about three times as fast as the wounds made in the arm skin — on average at a rate of about 0.3 millimeters a day in the mouth compared with less than 0.1 millimeter a day on the arm. Reducing amounts of PITX1 and SOX2 in mouth keratinocytes grown in lab dishes altered the activity of genes involved cell movement. Boosting SOX2 levels in the skin of mice shortened healing time — from about nine days to about three. Perhaps it shouldn’t be a surprise that the lining of the mouth and other mucus membranes heal quickly. It may be a product of vertebrates evolving in the ocean, Garza says. “We spent most of our time learning how to repair wounds underwater. So it makes sense that we repair wounds really well on our moist mucosa.”
A single star, careening around the monster black hole in the center of the Milky Way, has provided astronomers with new proof that Albert Einstein was right about gravity.
More than 100 years ago, Einstein’s general theory of relativity revealed that gravity is the result of matter curving the fabric of spacetime (SN: 10/17/15, p. 16). Now, in a paper published July 26 in Astronomy & Astrophysics, a team of researchers reports the observation of a hallmark of general relativity known as gravitational redshift. The measurement is the first time general relativity has been confirmed in the region near a supermassive black hole. As light escapes a region with a strong gravitational field, its waves get stretched out, making the light redder, in a process known as gravitational redshift. The scientists, a team known as the GRAVITY collaboration, used the Very Large Telescope array, located in the Atacama Desert of Chile, to demonstrate that light from the star was redshifted by just the amount predicted by general relativity.
Scientists have observed gravitational redshift before. In fact, GPS satellites would fail to function properly if gravitational redshift weren’t taken into account. But such effects have never been seen in the vicinity of a black hole. “That’s completely new, and I think that’s what makes it exciting — doing these same experiments not on Earth or in the solar system, but near a black hole,” says physicist Clifford Will of the University of Florida in Gainesville, who was not involved with the new study.
At the Milky Way’s heart there lurks a hulking supermassive black hole, with a mass about 4 million times that of the sun. Many stars swirl around this black hole (SN Online: 1/12/18). The researchers zeroed in on one star, known as S2, which completes an elliptical orbit around the black hole every 16 years. In May 2018, the star made its closest approach to the black hole, zipping by at 3 percent of the speed of light — extremely fast for a star. At that point, the star was just 20 billion kilometers from the black hole. That may sound far away, but it’s only about four times the distance between the sun and Neptune. Measuring the effects of general relativity in the black hole’s neighborhood is challenging because the region is jam-packed with stars, says astrophysicist Tuan Do of UCLA, who studies S2, but was not involved with this work. If attempting to observe this region with a run-of-the-mill telescope, “you’ll just see this big blur.”
To obtain precise measurements and pinpoint individual stars in the crowd, the scientists used a technique called adaptive optics (SN Online: 7/18/18), which can counteract the distortions caused by the Earth’s atmosphere, and combined information from four telescopes in the Very Large Telescope’s array. “You can bring the light together from these four telescopes and thereby generate a super telescope … and that does the trick,” says study coauthor Reinhard Genzel, an astrophysicist at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. Genzel and colleagues have been observing this star for decades, since before its previous swing by the black hole 16 years ago.
In future work, the scientists hope to test other aspects of general relativity, including the theory’s prediction that S2’s orbit should rotate over time. A similar rotation was previously seen in Mercury’s orbit around the sun, which puzzled astronomers until Einstein’s theory explained the effect (SN Online: 4/11/18).
The GRAVITY researchers might find other stars that orbit even closer to the black hole, allowing them to better understand the black hole and further scrutinize general relativity. If that happens, Will says, “they’ll really start to explore this black hole up close and personal, and it’ll be a very cool new set of tests of Einstein’s theory.”
Hobbits took a separate evolutionary path to becoming small than did short, modern-day humans living on the same Indonesian island, a new DNA analysis suggests.
Rampasasa pygmies residing near a cave on Flores that previously yielded small-bodied hobbit fossils inherited DNA from Neandertals and Denisovans but not from any other now-extinct hominid, an international team of researchers reports in the Aug. 3 Science. The finding provides genetic backup for a fossil-based argument portraying these controversial Stone Age hominids as a separate species, Homo floresiensis, not small-bodied Homo sapiens that could have represented ancestors of Rampasasa people. Diminutive hobbits, standing roughly a meter tall, lived on Flores from at least 100,000 to 60,000 years ago, with possible ancestors on the island dating to about 700,000 years ago (SN: 7/9/16, p. 6). Some scientists contend that hobbits were actually short humans, not an ancient hominid species (SN: 11/18/06, p. 330). So far, researchers have been unable to extract DNA from hobbit fossils. Comparing hobbit and present-day human DNA would go a long way toward clarifying the evolutionary ID of the half-size Flores hominids. In the new study, evolutionary geneticist Serena Tucci of Princeton University and colleagues compared DNA from 32 Rampasasa individuals with that of Neandertals, Denisovans and present-day humans around the world. The Flores pygmies got smaller due in part to alterations to genes linked to height and the breakdown of fatty acids in foods, the researchers found.
Still, without hobbit DNA, it’s impossible to say with certainty that Rampasasa pygmies — on average more than 30 centimeters taller than hobbits — inherited no genes from H. floresiensis, says evolutionary geneticist and coauthor Richard Green of the University of California, Santa Cruz. “But we looked hard for [H.] floresiensis ancestry in Rampasasa people and could not find it.”
