Arabian camels (Camelus dromedarius) have trekked across ancient caravan routes in Asia and Africa for 3,000 years. But it’s unclear how camels’ domestication has affected their genetic blueprints.

To find out, Faisal Almathen of King Faisal University in Saudi Arabia and his colleagues combed through the DNA of 1,083 modern camels and ancient remains of wild and domesticated camels found at archaeological sites going back to 5000 B.C.

Camels run high on genetic diversity thanks to periodic restocking from now-extinct wild populations in the centuries after their domestication, the team reports May 9 in the Proceedings of the National Academy of Sciences. Travel on human caravan routes also created a steady flow of genes between different domesticated populations, except in a geographically isolated group in East Africa. That diversity may give some camel populations a leg up in adapting to future changes in climate, the authors suggest.

Zapping Zika
As Zika virus spreads, researchers are racing to find Zika-carrying mosquitoes’ Achilles’ heel, Susan Milius reported in “Science versus mosquito” (SN: 4/2/16, p. 30). Some approaches include genetic sterilization so mosquitoes can’t reproduce and infecting them with bacteria to decrease their disease-spreading power.

One reader had another suggestion. “Maybe we could just secure some wilderness areas for birds and bats,” Kurt Feierabend wrote on Facebook. “Let the feasting begin.”

“Some bats and birds do eat mosquitoes, but Aedes aegypti mosquitoes, which are Zika carriers, typically dwell in or around people’s houses — not an easy hunting ground for predators,” says Meghan Rosen, who also reported on the virus for this special report (SN: 4/2/16, p. 26). The mosquitoes lay eggs in water though, so predatory fish and crustaceans could serve as a type of biological control. But, according to the U.S. Centers for Disease Control and Prevention, that option may not be practical. Ae. aegypti larvae can also develop in dog bowls, plant saucers and rain splash left in crumpled plastic bags, Milius notes.
Wandering baby Jupiter
As proto-Jupiter moved through the solar system, it may have absorbed so much planet-building material that it reduced the number of planets that could form near the sun, Christopher Crockett reported in “Jupiter could have formed near sun,” (SN: 4/2/16, p. 7).

“Over what time span would this have occurred, and are any of our planets currently moving in or out?” asked online reader Mark S.

If Jupiter formed close to the sun, it spent only about 100,000 years in the inner solar system, well before the rocky planets started to form, Crockett says. “Researchers suspect that the outer planets danced around quite a bit during their formative years. All the sun’s worlds are now, fortunately, staying put for the foreseeable future,” he says.

Addicted to microbes
In “Microbes and the mind” (SN: 4/2/16, p. 22), Laura Sanders reported on the surprising ways in which gut microbes influence depression, anxiety and other mental disorders. But it’s not a one-way street. “Our behavior can influence the microbiome right back,” she wrote.

Reader George Szynal wondered how addiction to drugs, alcohol and other substances may influence microbes and vice versa. “Can treatments of microbiome enhance and aid the recovery of addicted persons?” he asked.

“That’s a fascinating idea, but so far, little research has been done on this question,” Sanders says. “Alcohol disorders have been linked to changes in the gut microbiome, and smoking has been linked to differences in mouth bacteria. But until scientists figure out whether those microbe changes are consequences or causes of the addictions, we won’t know whether changing the microbes could help people kick the habits,” she says.

Water rising
Without a sharp decrease in carbon dioxide emissions, rapid melting of the Antarctic ice sheet could raise sea levels by 60 meters by the end of the century, Thomas Sumner reported in “Tipping point for ice sheet looms” (SN: 4/2/16, p. 10).

In addition to melting ice sheets, reader Carolyn Lawson asked if human depletion of groundwater also contributes to sea level rise.

About 80 percent of groundwater losses end up in the oceans, according to a recent study in Nature Climate Change. Simulations showed that groundwater contributed about 0.02 millimeters of sea level rise annually in 1900 and increased to around 0.27 millimeters annually by 2000. “Current sea level rise is about 3 millimeters per year, so that’s a pretty large chunk,” Sumner says. “Unfortunately, Earth’s groundwater reserves are disappearing. It’s unclear whether the groundwater contribution to sea level rise will continue to increase indefinitely.”

Bad weather may have driven the mighty Mongols from Hungary. The Mongols’ retreat shows that small climate changes can influence historical events, researchers argue May 26 in Scientific Reports.

In the early 1200s, the Mongol empire had expanded across Eurasia into Russia and Eastern Europe. But when the Mongols got to Hungary in 1241, they invaded and then suddenly retreated back to Russia in 1242. Though theories abound, historians have never found a clear reason for the abrupt exit.

Now, Ulf Büntgen of the Swiss Federal Research Institute in Birmensdorf and Nicola Di Cosmo of the Institute for Advanced Study in Princeton, N.J., think they may have an explanation. Weather data preserved in tree rings points to a series of warm, dry summers in the region until 1242, when temperatures dropped and rainfall increased. The shift to a wet, cold climate caused flooding and created marshy terrain. That would have been less than ideal for the nomadic Mongol cavalry, reducing their mobility and pastureland.

Say hello to hobbits’ possible ancestors. Excavations of fossils from roughly 700,000-year-old hominids on the Indonesian island of Flores have reinvigorated scientific debate over the evolutionary origins and identity of Homo floresiensis, a half-sized member of the human genus — dubbed hobbits — that lived much later on Flores.

Remains of at least three individuals found at a central Flores site, called Mata Menge, probably represent early versions of H. floresiensis, says a team led by paleontologist Gerrit van den Bergh of the University of Wollongong in Australia and Japanese biological anthropologist Yousuke Kaifu. A lower-jaw fragment and six teeth excavated in 2014 come from hominids that were about as small as hobbits. These fossils look enough like hobbit jaws and teeth to be assigned provisionally to H. floresiensis, the researchers conclude in the June 9 Nature.
Researchers are divided over what the new finds imply about hobbit evolution. “Nothing related to humans on Flores has a simple explanation,” says paleoanthropologist María Martinόn-Torres of University College London. She calls the new discoveries “puzzling and exciting.”

In a second paper in Nature, archaeologist Adam Brumm of Griffith University in Nathan, Australia, and colleagues describe chemical analyses of one hominid tooth and two animal teeth, as well as of volcanic ash and sediment layers at Mata Menge, that yielded the age estimate for the finds. Excavations also uncovered 149 stone artifacts, including 47 that lay among hominid fossils, Brumm says. Nonhuman animal bones unearthed in the new dig indicate that Mata Menge hominids lived in a river valley dominated by grasslands.

Mata Menge hominids were “a dwarfed descendant of early Homo erectus that somehow got marooned on Flores,” suggests Kaifu, of the National Museum of Nature and Science in Tokyo. The Mata Menge fossils look more like H. erectus than other ancient hominids, his team reports.

H. erectus reached the Flores vicinity deep in the Stone Age, arriving on the nearby island of Java at least 1 million years ago. An unknown hominid species inhabited the Indonesian island of Sulawesi by 194,000 years ago (SN: 2/6/16, p. 7).

Hobbit fossils, previously unearthed 74 kilometers west of Mata Menge in Flores’ Liang Bua Cave, range in age from 100,000 to 60,000 years ago (SN: 4/30/16, p. 7). Stone tools probably made by hobbits date to as early as 190,000 years ago.
Stone implements previously found at Mata Menge and another Flores site date to between around 1 million and roughly 800,000 years ago (SN: 6/3/06, p. 341). The new hominid fossil finds provide the first peek at the likely makers of the Mata Menge tools, Brumm says.

Too few fossils have been found to exclude the possibility that, even if Mata Menge and Liang Bua hominids were related, they belonged to different populations that arrived on Flores at different times, Martinόn-Torres says.

Even so, the new discoveries fit a scenario in which presumably large-bodied H. erectus settled on Flores around 1 million years ago and shrank in size over the next 300,000 years, a surprisingly short time for such dramatic brain and body changes to evolve, Kaifu says. These hominids may have evolved smaller bodies over a relatively short period in response to limited island resources, proposes archaeologist Robin Dennell of the University of Sheffield in England.

But biological anthropologist William Jungers of Stony Brook University School of Medicine in New York says it’s unlikely that H. erectus shrunk to two-thirds of its initial body size and half its original brain size over only several hundred thousand years on Flores. He predicts that ongoing excavations at Mata Menge and nearby sites will uncover 1-million-year-old fossils of small-bodied hobbit ancestors that differed in many respects from H. erectus.

Like the Mata Menge team, though, Jungers says the new discoveries challenge an argument that a partial hobbit skeleton represents a Homo sapiens with Down syndrome (SN Online: 8/5/14).

Proponents of that idea disagree. Different hominids could have reached Flores at different times, as suggested by Martinόn-Torres, says Penn State developmental geneticist Robert Eckhardt. Not enough fossil evidence exists to show an evolutionary link between Mata Menge and Liang Bua individuals, Eckhardt and biological anthropologist Maciej Henneberg of the University of Adelaide in Australia argue.

The Olympic and Paralympic Games probably won’t further the international spread of Zika virus, the World Health Organization concluded in a news conference June 14.

Data from past events, including previous Olympics and World Cup tournaments, suggest that mass gatherings don’t greatly increase the spread of diseases. In addition, the 2016 Olympics will take place in August during Brazil’s winter months, when mosquito-borne diseases aren’t so rampant. Brazil also is stepping up efforts to curb mosquito populations. According to WHO, both factors are likely to reduce Zika transmission during the games.

“Everything is being done to minimize what is already a low risk,” said Bruce Aylward, who heads WHO’s division on outbreaks and health emergencies.

Not all scientists are convinced. More than 200 scientists and doctors have now signed an open letter to WHO’s director calling for postponing the Olympics and Paralympics or moving them from Rio de Janeiro.

BOSTON — Moms get blamed for a lot — including their kids’ cavities. But new data show that the most common cause of tooth decay, the bacterium Streptococcus mutans, doesn’t always come from mother-to-child transmission.

Researchers from the University of Alabama at Birmingham studied 119 children in rural Alabama and 414 of their household contacts, tracking the path of S. mutans. Contrary to expectation, 40 percent of the children did not share any strains with their mothers. Instead, those strains usually overlapped with those of siblings and cousins. And 72 percent of children carried a strain of S. mutans that no one else in the family had, probably picked up from other children at school, day care or other locations. The research was presented June 17 at ASM Microbe 2016, a meeting of the American Society for Microbiology and the Interscience Conference on Antimicrobial Agents and Chemotherapy.

While maternal transmission was still the most common route, “we’re not trying to say ‘Don’t kiss your babies,’” said Stephanie Momeni, a doctoral candidate at UAB. Rather, the ultimate goal of the research is to learn whether particular strains of S. mutans pose a greater hazard for dental health. Knowing that would help identify children who might be in need of more aggressive dental hygiene.

Driverless cars are revved up to make getting from one place to another safer and less stressful. But clashing views over how such vehicles should be programmed to deal with emergencies may stall the transportation transformation, a new study finds.

People generally approve of the idea of automated vehicles designed to swerve into walls or otherwise sacrifice their passengers to save a greater number pedestrians, say psychologist Jean-François Bonnefon of the Toulouse School of Economics in France and his colleagues. But here’s the hitch: Those same people want to ride in cars that protect passengers at all costs, even if pedestrians end up dying, the researchers report in the June 24 Science.
“Autonomous cars can revolutionize transportation,” says cognitive scientist and study coauthor Iyad Rahwan of the University of California, Irvine and MIT. “But they pose a social and moral dilemma that may delay adoption of this technology.”

Such conflict puts makers of computerized cars in a tough spot, Bonnefon’s group warns. Given a choice between driverless cars programmed for the greater good or for self-protection, consumers will overwhelmingly choose the latter. Regulations to enforce the design of passenger-sacrificing cars would backfire, the scientists suspect, driving away potential buyers. If so, plans for easing traffic congestion, reducing pollution and eliminating many traffic accidents with driverless cars would be dashed.
Further complicating matters, the investigators say, automated vehicles will need to respond to emergency situations in which an action’s consequences can’t be known for sure. Is it acceptable, for instance, to program a car to avoid a motorcycle by swerving into a wall, since the car’s passenger is more likely to survive a crash than the motorcyclist?

“Before we can put our values into machines, we have to figure out how to make our values clear and consistent,” writes Harvard University philosopher and cognitive scientist Joshua Greene in the same issue of Science.
But moral dilemmas have long dogged human civilizations and are sometimes unavoidable, says psychologist Kurt Gray of the University of North Carolina in Chapel Hill. People may endorse conflicting values depending on the situation — say, saving others when taking an impersonal perspective and saving oneself when one’s life is on the line.

Workable compromises can be reached, Gray says. If all driverless cars are programmed to protect passengers in emergencies, automobile accidents will still decline, he predicts. Despite being a danger to pedestrians on rare occasions, those vehicles “won’t speed, won’t drive drunk and won’t text while driving, which would be a win for society.”

Bonnefon’s team examined attitudes toward driverless vehicles in six online surveys conducted between June and November 2015. A total of 1,928 U.S. participants completed surveys.

Participants generally disapproved of automated vehicles sacrificing a passenger to save one pedestrian, but approval rose sharply with the number of pedestrians’ lives that could be saved. For instance, about three-quarters of volunteers in one survey said it was more moral for an automated car to sacrifice one passenger rather than kill 10 pedestrians. That trend held even when volunteers imagined they were in a driverless car with family members.

Bonnefon doubts those participants were simply trying to impress researchers with “noble” answers. But opinions changed when participants were asked about their views of driverless cars in actual practice. Responders to another survey similarly rated pedestrian-protecting automated cars as more moral, but most of those same people readily admitted that they wanted passenger-protecting cars for themselves. Other participants considered driverless cars that swerved to avoid pedestrians as good for others to drive but had little intention to buy one.

Volunteers expressed weak support for a law forcing either human drivers or automated cars to swerve to avoid pedestrians. Even in a hypothetical case where a passenger-sacrificing automated car saved the lives of 10 pedestrians, participants rated their willingness to have such sacrifices legally enforced at only 40 on a scale of 0 to 100. A final survey found that participants were much less likely to consider buying driverless cars subject to pedestrian-protecting regulations after being presented with situations in which they were riding alone, with an unspecified family member or with their child.