Murder was a calculated family affair among Iceland’s early Viking settlers. And the bigger the family, the more bloodthirsty.

Data from three family histories spanning six generations support the idea that disparities in family size have long influenced who killed whom in small-scale societies. These epic written stories, or sagas, record everything from births and marriages to deals and feuds.

Iceland’s Viking killers had on average nearly three times as many biological relatives and in-laws as their victims did, says a team led by evolutionary psychologist Robin Dunbar of the University of Oxford. Prolific killers responsible for five or more murders had the greatest advantage in kin numbers, the scientists report online September 20 in Evolution and Human Behavior.
Particularly successful killers chose their victims carefully, knowing that their large families would deter revenge attacks by smaller families of the slain, the researchers contend. Those killings were motivated by land grabs, they suspect. One-time killers tended to have only slightly bigger families than those of their victims; insults or goading possibly prompted those murders.
Strikingly, around 18 percent of all men mentioned in the sagas were murdered. Similarly high homicide rates, mainly due to cycles of revenge killing between feuding families, have been reported for some modern hunter-gatherer and village-based societies ( SN Online: 9/27/12 ). Lethal raids by competing groups may go back 10,000 years or more ( SN: 2/20/16, p. 9
Murder rates rise in the absence of central authorities that enforce social order, Dunbar proposes. “The real issue is not that there were so many murders among Icelandic Vikings, but that murders were carefully calculated based on knowing whether one had a sufficient family advantage to take the risk.”

That idea relates to mathematical formulas of fighting strength developed during World War I by British engineer Frederick Lanchester. One of Lanchester’s laws calculates that the fighting advantage of a larger group over a smaller group grows disproportionately as the disparity in the size of war parties increases. That rule also holds for family-size differences in small-scale societies, such as Icelandic Vikings, Dunbar’s group concludes.

Tests of the possibility that greater kin numbers encourage lethal attacks in preindustrial groups, such as the Vikings, are rare, says Oxford evolutionary biologist and political scientist Dominic Johnson, who did not participate in the new study. Johnson has reviewed evidence suggesting that humans, chimps and social hunters such as wolves have evolved ways to monitor group sizes and launch attacks when they can gang up on a few opponents.

Dunbar and his colleagues studied three Icelandic family sagas covering events from around 900 to 1100. Iceland’s first settlers arrived from Scandinavia and northern Europe in the late 800s (SN: 5/14/16, p. 13).

The sagas contained information about events, including feuds and murders, involving 1,020 individuals. For everyone mentioned, the researchers identified a network of biological and in-law relationships.

Under Norse law, a murder entitled a victim’s relatives to compensation, either via a revenge murder or blood money. Icelandic sagas describe the importance of avenging murdered relatives to save face and prevent further attacks, regardless of family size.

In the three sagas, a total of 66 individuals caused 153 deaths; two or more attackers sometimes participated in the same killing. No killers were biologically related to their victims (such as cousins or closer), but one victim was a sister-in-law of her killer.

About two-thirds or more of killers had more biological kin on both sides of their families, and more in-laws, than their victims did.

Six men accounted for about 45 percent of all murders, each killing between five and 19 people. Another 23 individuals killed two to four people. The rest killed once. Frequent killers had many more social relationships, through biological descent and marriage, than their victims did, suggesting that they targeted members of families in vulnerable situations, the researchers say.

Apes understand what others believe to be true. What’s more, they realize that those beliefs can be wrong, researchers say. To make this discovery, researchers devised experiments involving a concealed, gorilla-suited person or a squirreled-away rock that had been moved from their original hiding places — something the apes knew, but a person looking for King Kong or the stone didn’t.

“Apes anticipated that an individual would search for an object where he last saw it, even though the apes knew that the object was no longer there,” says evolutionary anthropologist Christopher Krupenye.
If this first-of-its-kind finding holds up, it means that chimpanzees, bonobos and orangutans can understand that others’ actions sometimes reflect mistaken assumptions about reality. Apes’ grasp of others’ false beliefs roughly equals that of human 2-year-olds tested in much the same way, say Krupenye of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues.

Considering their targeted gazes during brief experiments, apes must rapidly assess others’ beliefs about the world in wild and captive communities, the researchers propose in the October 7 Science. Understanding the concept of false beliefs helps wild and captive chimps deceive their comrades, such as hiding food from those who don’t share, Krupenye suggests.

Experiments included 41 apes — 19 chimps, 15 bonobos and seven orangutans. These animals had been born in captivity and lived in open enclosures at research centers in Germany and Japan. Apes watched two short videos designed to grab their attention. In one, a person in a King Kong gorilla suit hides in one of two haystacks while a man watches. After the man leaves through a door, King Kong runs away. Then the man returns and looks for King Kong. In a second video, a man returns for a stone that King Kong stole from him and hid in one of two boxes while the man watched. During the man’s absence, however, King Kong runs off with the stone or, in another version, moves the stone from one box to the other.

A camera equipped with an eye-tracking sensor revealed that, when the man in these videos returned, apes usually looked first at where King Kong or the stone had initially been hidden. They also spent more time looking at those initial locations than at any other spots in the videos. Those behaviors indicate that the apes assumed the man would return to those same spots based on where he had last seen what he was looking for. Of 29 animals that viewed both videos, gazes of 23 indicated that they expected the man in one or both scenarios to hold a false belief, the researchers say.
Krupenye’s team shows for the first time that a nonhuman animal can track others’ false beliefs, agrees psychologist Amanda Seed of the University of St. Andrews in Fife, Scotland. But it has yet to be demonstrated that apes, like humans, can act on such knowledge, say by hiding food from others, she adds. It’s also unclear whether, aside from knowing where an observer will look for an item, apes truly know that the object is no longer there, Seed says. Further experiments could see if apes express surprise upon seeing an observer find an item hidden in its original location after it had been moved, she suggests.

An ability to infer what others are thinking, dubbed “theory of mind” by psychologists (SN Online: 3/27/13), likely evolved in ancient ancestors of humans and apes, writes primatologist Frans de Waal of Emory University in Atlanta in the same issue of Science. Those ancestors lived in increasingly complex communities where it paid to predict accurately how others would behave, he proposes.

Yale University psychologist Laurie Santos isn’t so sure apes track false beliefs. Previous research has consistently indicated that no nonhuman animals monitor others’ beliefs, even on tasks similar to those used by Krupenye’s team, Santos says. In the new study, she adds, apes may have realized that an observer was ignorant about an object’s new location but not that he had false expectations about where to find it.

Krupenye disagrees. “The apes specifically anticipated that the actor in the video would search for an object where we humans know the actor falsely believed the object to be,” he says.

A GPS app can plan the best route between two subway stops if it has been specifically programmed for the task. But a new artificial intelligence system can figure out how to do so on the fly by learning general rules from specific examples, researchers report October 12 in Nature.

Artificial neural networks, computer programs that mimic the human brain, are great at learning patterns and sequences, but so far they’ve been limited in their ability to solve complex reasoning problems that require storing and manipulating lots of data. The new hybrid computer links a neural network to an external memory source that works somewhat like RAM in a regular computer.

Scientists trained the computer by giving it solved examples of reasoning problems, like finding the shortest distance between two points on a randomly generated map. Then, the computer could generalize that knowledge to solve new problems, like planning the shortest route between stops on the London Underground. Rather than being programmed, the neural network, like the human brain, responds to training: It can continually integrate new information and change its response accordingly.

The development comes from Google DeepMind, the same team behind the Alpha Go computer program that beat a world champion at the logic-based board game.

The Schiaparelli Mars lander remains silent since its attempted landing October 19 on the Red Planet. All data transmitted by the lander during its descent have been relayed to Earth, and mission scientists are now in the thick of trying to figure out what went wrong.

“I am extremely confident that we’ll be able to fully understand what happened,” ESA spacecraft operations manager Andrea Accomazzo said at an October 20 news briefing. Schiaparelli is most likely on the surface, but its condition remains unknown.

Early data indicate that Schiaparelli survived most of its parachute entry, but in the last few seconds before jettisoning the chute, something unexpected happened. Mission scientists cannot say yet what that “something” was. The retrorocket designed to slow it down further did appear to fire, but for a shorter time than expected. Mission scientists also don’t yet know if all the rockets fired as planned. Further details will come with the analysis of data received from the lander.

Other spacecraft orbiting Mars will continue to listen for a signal from Schiaparelli, which has enough battery power to last a few Martian days, maybe more. The lander was designed as an experiment to test technologies and protocols for safely dropping a payload on the surface of the Red Planet, such as a rover planned to arrive in 2021.

The Trace Gas Orbiter, which also arrived as part of the ExoMars mission, appears healthy and in orbit around the Red Planet, ready to undertake an investigation of trace gases in the Martian atmosphere.

Clever chemistry could take the salt out of water softening.

Aluminum ions can strip minerals from water without the need for sodium, researchers report online October 4 in Environmental Science & Technology. The new technique could sidestep health and environmental concerns raised about the salt released by existing sodium-based water softening systems, says study coauthor Arup SenGupta.

“This is a global need that hasn’t been met,” says SenGupta, an environmental engineer at Lehigh University in Bethlehem, Pa. “We’re just changing the chemistry by adding aluminum ions, which is not something outlandish, but with that we can reduce the environmental impact.”
Hard water contains dissolved minerals such as calcium and magnesium that make it harder for soap to lather and that can leave scaly deposits inside faucets and showerheads. Many water softening systems combat these problems by passing water through a special tank containing beads covered in sodium ions, charged particles that can swap places with the calcium and magnesium, resulting in softer water.

This technique adds extra sodium to the outgoing water, though, which can raise blood pressure when used as drinking water (SN Online: 3/12/14). The system also has to be recharged periodically using a sodium-rich brine. That extra salt can end up in local groundwater and streams, prompting bans on salt-based water softeners in many areas, including many counties in California.
While some sodium-free substitutes exist, many are expensive while others are “snake oil” and don’t actually work, SenGupta says. He and colleagues decided to try aluminum, a counterintuitive choice based on its chemistry. An aluminum ion has a net positive charge of three, meaning that it has three fewer negatively charged electrons than a neutral aluminum atom. That charge difference makes it less likely for aluminum to swap places with a calcium or magnesium ion, which each have a positive charge of two.
But when an ion exchange does happen, the aluminum often quickly precipitates back onto the water softener’s beads rather than dissolving into the water and being swept away. The process allows the same aluminum ion to swap in for multiple calcium and magnesium ions.
Setting up a prototype water softening system in the laboratory, the researchers successfully reduced the amount of calcium and magnesium in a groundwater-like mixture using aluminum ions. Recharging the system also resulted in fewer wasted ions than sodium-based systems, the researchers found, lowering the potential environmental impact. The process uses a similar setup to sodium-based systems, SenGupta says, meaning existing systems could be easily retrofitted to use aluminum ions.

While an exciting idea, the new design might not work as well in real life as it does in the lab, says Steven Duranceau, an environmental engineer at the University of Central Florida in Orlando. Bacteria and other substances in groundwater can reduce effectiveness, and strict guidelines surrounding drinking water could prove an unsurmountable hurdle, he says. “I see these great things all the time, but a lot of them just don’t make it financially.”

SenGupta remains optimistic, though. “This is not a magic bullet; there are shortcomings, but none of these problems are impossible to overcome.”

This forlorn-looking face of a 4-day-old zebrafish embryo represents “a whole new avenue of research” for geneticist Oscar Ruiz, who studies how faces and facial abnormalities develop at the cellular level.

The research is possible thanks to a new method, developed by Ruiz and colleagues at the University of Texas MD Anderson Cancer Center in Houston, for mounting embryos in a gel that allows for clear, head-on pictures. A technique called confocal microscopy captures images like the one above, the first-place winner of this year’s Nikon Small World photography contest.
The embryo was euthanized before having its picture taken. But Ruiz is experimenting with taking time-lapse images of live, anesthetized zebrafish embryos. The camera snaps an image every five minutes for up to 48 hours, meaning that “we’re able to watch the development happening,” Ruiz says.

So far, the team has looked at embryos ranging from 1 to 6 days old. The researchers are compiling the images into an atlas documenting the developmental stages of the zebrafish face. They plan to use CRISPR/Cas9, a powerful gene-editing tool, to alter genes involved in facial abnormalities in the fish and then watch what changes, if any, occur. The research could one day be used to help scientists understand how a cleft lip or cleft palate develops in humans and possibly help treat it, Ruiz says.

In the image above, shown at 10x magnification, basal cells (green) in the bottom layer of skin give rise to more developed surface skin cells (red). Cell nuclei appear in blue.

“Everyone’s first impression is that those two holes in the center are its developing eyes,” Ruiz says. But they’re not. Those deceptive hollows are nascent olfactory tissue, used to smell. The eyes are actually the big bulges on either side of the face.
Although this was the first time Ruiz entered the microscopy photography contest, he is an amateur photographer. Landscape or travel photos — not fish photos — are his subject matter of choice.

Here are more finalists and honorable mentions from the competition:

More vaccines promised — “The decline of poliomyelitis among more than 350 million people of the world … (offers) a promise of vaccines that will soon be used against other diseases considered hopeless or untreatable until recently. Vaccines against some of the many viruses causing the common cold, as well as those causing rubella, mumps and other diseases are on the way.” — Science News, November 19, 1966

UPDATE
In 1971, vaccines against mumps and rubella were combined with the measles vaccine into one MMR shot. All three diseases are now very rare in the United States. But persistent pockets of lower vaccination rates (spurred in part by the repeatedly debunked belief that vaccines cause autism) have allowed sporadic outbreaks of all three illnesses. A vaccine against the common cold has not yet materialized. Creating one vaccine that protects against the hundred or so strains of rhinoviruses that can cause colds is not easy. But some scientists are giving it a shot, along with vaccines against HIV, Ebola and Zika.

El Niño’s meteorological sister, La Niña, has officially taken over.

This year’s relatively weak La Niña is marked by unusually cool sea surface temperatures in the central and eastern equatorial Pacific Ocean. That cold water causes shifts in weather patterns that can cause torrential downpours in western Pacific countries, droughts in parts of the Americas and more intense Atlantic hurricane seasons.

The event has about a 55 percent chance of sticking around through the upcoming Northern Hemisphere winter and is expected to be short-lived, the National Oceanic and Atmospheric Administration’s Climate Prediction Center reported November 10.

Picture a learning curve. Most of us imagine a smooth upward slope that rises with steady mastery. It is the ultimate image of progress.
But that image, as behavioral sciences writer Bruce Bower reports in “Kids learning curve not so smooth” (SN: 11/26/16, p. 6), may well be an illusion of statistics, created when people look at averages of a group instead of how individuals actually learn. That’s what scientists at the University of Cambridge found when quizzing preschoolers’ developing ability to understand that other people can have false beliefs, an important milestone in the development of a theory of mind.
For many learners, the study suggests, mastery comes in fits and starts, a graphical zigzagging that denotes steps forward and back. Insight into a problem can be quick for some, but many people follow a more meandering path to knowledge and understanding.

I recognize the truth of this in my own life, be it learning about a new subject or (especially) a new skill. I see it in my 5-year-old daughter as she learns to read. If you are not struck by a single dramatic aha! you can still make it work by moving forward, then back, aiming for progress and mastery.

Scientific advances also do not always follow a smooth upward curve. As staff writer Meghan Rosen writes in “Dinosaurs may have used color as camouflage” (SN: 11/26/16, p. 24), paleontologists did have a fairly sudden insight into how to get clues about the colors that decorated dinosaur skin: Look for pigment-containing structures called melanosomes. But identifying these microscopic structures in well-preserved fossils of soft tissue, while distinguishing them from bacteria that might have feasted on the fresh dead dino skin, has been a bit of a zigzag. There’s an ongoing back-and-forth critique between those scientists who claim they’ve discovered melanosomes and those who question such claims. It may be a long time before we know whether we will be able to truly repaint dinosaurs’ colors accurately, or use that information to better understand their lifestyles or habitats (as many scientists working in the field hope). But current investigations are already taking us closer to that goal, even if via a meandering path.

The danger of looking at the average, as evidenced in Bower’s news story, is also at play in Amy McDermott’s story “Lichens are an early warning system for forest health” (SN: 11/26/16, p. 20). Lichens are very sensitive to air pollution, a quality exploited for decades to monitor the air quality of forests and alert forest managers to looming issues. But if you were to look at overall lichen abundance you might not see any problem. Air pollution tends to encourage some species while discouraging others — a subtlety that a lichen average growth rate might miss. With on-the-scene reporting in the Pacific Northwest, McDermott details the history of lichen use in environmental quality studies and the new effort to use lichens as an indicator of climate change in forests.

Looking at averages can tell you part of a story, but it rarely tells you the whole story. What you may miss is the rich variety found in the real world — be it in students or lichens or even scientific perspectives.

That past-its-prime bag of spinach buried in the back of your fridge should probably hit the compost heap instead of your dinner plate. The watery gunk that accumulates at the bottom of bagged salad mix is the perfect breeding ground for Salmonella bacteria that could make people sick, researchers report November 18 in Applied and Environmental Microbiology.

The culprit? The juice that oozes out of cut or damaged leaves. After five days in the fridge, small amounts of plant juice sped up Salmonella growth. The bacteria grew avidly on the bag and stuck persistently to the salad leaves, so much so that washing didn’t remove the microbes.

Salmonella’s success inside bagged salads means it’s important for producers to avoid bacterial contamination from the get-go — and for consumers to eat those greens before they get soggy. Popeye would approve.