Ways to beat heat have hidden costs for birds

WASHINGTON — In the short-term, ways to beat the heat are cool. But for desert birds, even simple panting or flying into the shade have some sneaky long-term costs.

When male southern yellow-billed hornbills pant, they’re less able to snap up food, Susan Cunningham reported August 18 at the North American Ornithological Conference. The hornbills are the third bird species that Cunningham, of the University of Cape Town in South Africa, and various colleagues have shown face hidden costs of trying not to overheat.
Birds certainly have ways to ease the immediate dangers of heat. But determining the full consequences of all those small accommodations becomes more urgent as the climate changes.

Yellow-billed hornbills (Tockus leucomelas) could be especially vulnerable to hidden costs of heat because males become the sole provisioners of their families during breeding season. A female walls herself and her eggs into a cavity (or a research nest box), leaving open a hole big enough only for her mate to poke food through. In southern Africa’s Kalahari region, a female may stay walled in the cavity for a month or more, leaving the male to scour hot, dry land for her food, his own and eventually, the chicks’.

During bouts of panting, males caught less food than they did in minutes before or after while not panting, Cunningham’s student Tanja van de Ven has found. A specially rigged perch on nest boxes registered a male’s weight every time he landed on it. When the temperature rose above 36.5° Celsius, males typically failed to maintain weight, raising concerns about their ability to care not only for themselves, but for dependents, too.

Cunningham had already seen costs of chronic panting in another Kalahari species, the southern pied babbler (Turdoides bicolor). A population of these social birds had become blasé about nearby scientists taking notes thanks to patient effort by Amanda Ridley of the University of Western Australia in Crawley. The birds even hopped onto a portable scale, allowing weight monitoring in the field. Ridley, Cunningham and other babbler chroniclers found that on hot days, the birds persevered in foraging but caught less for their effort. As temperatures rose above 35.5° C, the scales showed that birds were struggling to maintain body weight. Typically they lost more weight overnight than they could make up during a day, the team reported in 2012

Even a cooling strategy as simple as taking shelter in the shade can cut into a bird’s ability to collect resources in arid lands. Southern fiscals (Lanius collaris), chunky predators with fierce bills, prefer high, sunny perches from which to scan for the rodents and insects they attack in lightning-bolt dives. As the Kalahari’s temperatures rose, these birds spent more and more time on shady perches, usually lower to the ground. The birds didn’t catch as much from such spots, the researchers found, and growth slowed among younger chicks when parents had to hunt from substandard posts. Each day with a temperature above 35° C kept chicks in the nests a half day longer. That’s perilous, Cunningham and colleagues argued in a 2013 report on fiscals. The risk that predators will scavenge a nest, or it will fail in some other way, increases 4 percent for every day the chicks remain in it.
Uncovering the downsides of such simple behaviors “is pretty cool,” said Blair Wolf of the University of New Mexico in Albuquerque. Birds can’t sweat, he pointed out, and the many species that pant as a cooldown technique have to compensate for the water lost in the process. Birds let their body temperatures rise to heights that would cook a human, and Wolf’s work has shown that this tolerance lessens water loss. Whether there are some hidden costs to this heat-fighting measure, as there are to panting and shade-seeking, remains to be seen.

Fossils hint at India’s crucial role in primate evolution

Remarkably preserved bones of rat-sized creatures excavated in an Indian coal mine may come from close relatives of the first primatelike animals, researchers say.

A set of 25 arm, leg, ankle and foot fossils, dating to roughly 54.5 million years ago, raises India’s profile as a possible hotbed of early primate evolution, say evolutionary biologist Rachel Dunn of Des Moines University in Iowa and her colleagues. Bones from Vastan coal mine in Gujarat, India’s westernmost state, indicate that these tiny tree-dwellers resembled the first primates from as early as 65 million years ago, the scientists report in the October Journal of Human Evolution.
These discoveries add to previously reported jaws, teeth and limb bones of four ancient primate species found in the same mine. “The Vastan primates probably approximate a common primate ancestor better than any fossils found previously,” says paleontologist and study coauthor Kenneth Rose of Johns Hopkins University School of Medicine.
The Vastan animals were about the size of living gray mouse lemurs and dwarf lemurs, weighing roughly 150 to 300 grams (roughly half a pound), the investigators estimate. Dunn’s group has posted 3-D scans of the fossils to Morphosource.org ( SN: 3/19/16, p. 28 ) so other researchers can download and study the material.
Most Vastan individuals possessed a basic climbing ability unlike the more specialized builds of members of the two ancient primate groups that gave rise to present-day primates, the researchers say. One of those groups, omomyids, consisted of relatives of tarsiers, monkeys and apes. The other group, adapoids, included relatives of lemurs, lorises and bushbabies. The Indian primates were tree-dwellers but could not leap from branch to branch like lemurs or ascend trees with the slow-but-sure grips of lorises, the new report concludes.

Vastan primates probably descended from a common ancestor of omomyids and adapoids, the researchers propose. India was a drifting landmass headed north toward a collision with mainland Asia when the Vastan primates were alive. Isolated on a huge chunk of land, the Indian primates evolved relatively slowly, retaining a great number of ancestral skeletal traits, Rose suspects.

“It’s possible that India played an important role in primate evolution,” says evolutionary anthropologist Doug Boyer of Duke University. A team led by Boyer reported in 2010 that a roughly 65-million-year-old fossil found in southern India might be a close relative of the common ancestor of primates, tree shrews and flying lemurs (which glide rather than fly and are not true lemurs).

One possibility is that primates and their close relatives evolved in isolation on the island continent of India between around 65 million and 55 million years ago, Boyer suggests. Primates then spread around the world once India joined Asia by about 50 million years ago.

That’s a controversial idea. An increasing number of scientists suspect primates originated in Asia. Chinese primate fossils dating to 56 million to 55 million years ago are slightly older than the Vastan primates (SN: 6/29/13, p. 14; SN: 1/3/04, p. 4). The Chinese finds show signs of having been omomyids.

And in at least one respect, Boyer says, some of the new Vastan fossils may be more specialized than their discoverers claim. Vastan ankle bones, for instance, look enough like those of modern lemurs to raise doubts that the Indian primates were direct descendants of primate precursors, he holds.

Dunn, however, regards the overall anatomy of the Vastan fossils as “the most direct evidence we have” that ancestors of early primates lacked lemurs’ leaping abilities, contrary to what some researchers have argued.

Reef rehab could help threatened corals make a comeback

Coral reefs are bustling cities beneath tropical, sunlit waves. Thousands of colorful creatures click, dash and dart, as loud and fast-paced as citizens of any metropolis.

Built up in tissue-thin layers over millennia, corals are the high-rise apartments of underwater Gotham. Calcium carbonate skeletons represent generations of tiny invertebrate animals, covered in a living layer of colorful coral polyps. Their structures offer shelter, and for about 114 species of fish and 51 species of invertebrates, those coral skyscrapers are lunch.

Important as they are, corals are in jeopardy. Warming oceans are causing more and more corals to bleach white and become vulnerable to destruction. A prolonged spike in temperatures, just 1 to 2 degrees Celsius, is enough to kill the marine animals. Greenhouse gas emissions also acidify the water, dissolving the calcium skeletons. In some countries, fishermen use dynamite to catch fish, leaving behind coral rubble. Today, more than 60 percent of the world’s reefs are at risk of disappearing.
Threats to reefs have “dramatically escalated in the last few decades,” says marine scientist Peter Harrison of Southern Cross University in Lismore, Australia. He has studied corals for three decades. “In my time as a reef researcher,” Harrison says, “I’ve seen it get worse, firsthand.”

Thirty years ago, massive coral bleachings were unheard of. Today, reefs are suffering through a third global bleaching event since 1998. With high ocean temperatures dragging on since 2014, this summer marked the longest and most widespread episode of worldwide coral bleaching on record (SN: 7/23/16, p. 5). Australia has been hit especially hard. More than 80 percent of the northern part of the Great Barrier Reef is bleached and close to half of those corals have died, according to a report in April from Australia’s National Coral Bleaching Taskforce.

As reefs take a nose dive, scientists from Hawaii to the Philippines and the Caribbean are scrambling to save corals. Approaches that were once considered radical are “now seen as necessary in some places,” says coral biologist Ruth Gates of the Hawaii Institute of Marine Biology on Oahu.

In Florida, researchers are restoring reefs with tiny coral fragments. In Hawaii, Gates is scouring the water for stress-tolerant corals and experimenting in the lab to breed the hardiest individuals. At the 13th International Coral Reef Symposium in Honolulu in June, Harrison’s team reported early promising results of its effort to flood damaged reefs in the Philippines with tiny coral larvae.

What works on one reef won’t necessarily save another. So researchers are testing an arsenal of options to rescue a diversity of underwater communities.

A different story
In the early 1980s, Harrison was a graduate student at James Cook University in Townsville, Australia, working on the Great Barrier Reef. At the time, textbooks taught that most corals reproduce by brooding: Fertilization occurred inside the body and larvae were released into the water to replenish reefs year-round. But Harrison witnessed something very different. For a few nights around a full moon in springtime, corals spawned, spewing eggs and sperm into the water to be externally fertilized. The sea was covered in a pink, oily slick.

“We found the corals hadn’t read the textbooks,” Harrison says. Eggs and sperm were meeting outside of the coral bodies, and larvae were developing while drifting in the currents.

That discovery spurred a cascade of studies on coral reproduction that led to the modern understanding that many corals reproduce only once or twice a year, in coordinated mass releases of eggs and sperm. Most of the resulting larvae die or drift out to sea, Harrison says. Only a small fraction survive to adulthood. Even so, mass spawns are “how reefs replenish themselves over time,” he says.

Just after Harrison’s discovery, the Great Barrier Reef, and then reefs around the globe, experienced bleaching on a massive scale. Normally, tiny algae live inside coral polyps. The algae make sugar and other nutrients for the coral, and can give polyps their characteristic bright colors. But when temperatures spike, algae become toxic. Corals spit out their partners, bleach white and can die if temperatures don’t cool enough for the algae to return (SN Online: 10/8/15).

Corals worldwide were bleaching more often and more severely than had been recorded in the past. Scientists began to worry that reefs were in trouble. Some researchers, like Dave Vaughan, who manages the Coral Reef Restoration program at the Mote Tropical Research Laboratory in Summerland Key, Fla., took action.

In those days, Vaughan was a fish farmer, raising saltwater fish species in captivity. He began growing corals for tropical aquarium tanks. At the time, all the corals in the aquarium trade were taken from the wild, Vaughan says. He started growing coral species in captivity as an environmentally friendly alternative.

One day, Philippe Cousteau, grandson of legendary aquanaut Jacques, toured the operation. When the young Cousteau saw that Vaughan was raising corals for aquariums, “he shook his head,” Vaughan remembers, “and said ‘Dave, if you could do this for the aquarium trade, you can do this for the reef.’”

In those earliest days, most scientists were tackling small-scale reef damage caused by dropped anchors or boat groundings, Vaughan says. To repair that kind of minor damage, scientists began breaking 3- to 5-centimeter fragments from healthy corals on a neighboring reef and transplanting the chunks in damaged spots.

Cousteau’s visit convinced Vaughan that he should try restoring reefs. While doing so, 11 years ago, Vaughan made a game-changing discovery: Tinier fragments of coral, only 1 centimeter long, repair themselves 25 to 40 times as fast as scientists had ever recorded corals growing.

Today Vaughan’s team is spreading many of these microfragments over the surface of dead coral skeletons in the Florida Keys. As those bits fuse back together, they create a fast-growing “skin” over an otherwise dead reef. Condemned buildings are refurbished rather than razed.

The hope is that thousands of microfragments will carpet a small reef in two to three years, says Chris Page, a biologist at Mote Marine Laboratory working with Vaughan. That’s super fast. “There’s no way that’s happening in nature,” Page says.

Vaughan’s team is cultivating 17 species for microfragmentation in large troughs on land, with seawater running through them. He is focused on the top six slow-growing massive species that create the foundation of the reef. Some can live for centuries, mounded into boulders the size of a truck.
The Florida researchers plunged their first 200 microfragments into the ocean three years ago, at two sites in a nearshore coral reef off Big Pine Key, Fla. The colonies are now six to eight times as large as they were at planting and have begun to fuse together into areas about the size of a 5-gallon bucket lid. Since then, Vaughan and Page have planted close to 10,000 microfragments in the wild. “People were looking for some glimmer of light,” Vaughan says. “And restoration is turning out to be that in a big way.”

Seeds of reefs
Fragmentation and the newer microfragmentation are both time- and labor-intensive, and therefore very expensive. And, Harrison says, they rely on cloning.

When one coral is broken into fragments, to be fattened up and then planted around a reef, each chunk is genetically identical. All those pieces have the same DNA blueprint to fight infection and to deal with stress. Unlike natural reefs, where individuals are genetically distinct and have different vulnerabilities, cloned corals share the same weaknesses.

“People have spent years growing coral gardens only to have them wiped out by the next bleaching event,” Harrison says. With more diversity, he adds, some of those corals might have survived. In a warmer world where bleaching and disease will probably become more common, “genetic diversity equals resilience.”

To address the diversity issue, Vaughan and Page are raising 20 to 30 genetic variants of each coral species, to be planted around the reef. They are also collecting eggs and sperm from wild colonies of four coral species to grow on Summerland Key.

Harrison has been thinking about genetic diversity ever since the early 1980s, when he saw corals spewing sperm and eggs into the ocean. Few of the resulting larvae would survive. Many would drift away and most would die. All while Harrison saw reefs in decline.

What if, he wondered, scientists could take millions of those diverse coral larvae and help them settle onto reefs to replenish ailing ecosystems?

Other researchers asked themselves the same question. In the late 1990s and from 2007 to 2009, two teams, in Australia and Palau, released coral larvae onto healthy reef areas in mesh tents pitched over the seabed. In both studies, thousands of larvae settled under the tents, many more than scientists would have seen naturally.

But those early results may have been misleading. Most of the early settlers in Palau died within 30 weeks. Flooding the reef with larvae didn’t make a lasting difference in coral numbers. Maybe, the researchers speculated, settlers were too crowded, which meant swamping reefs with larvae made no sense.

Harrison wasn’t ready to give up. Even though most of the new settlers had died, those studies were done on healthy reefs, he says. In battered areas, where some baby corals might naturally drift in, but not enough for the reef to self-heal, a flush of larvae could be a shot in the arm.

The idea was to find a badly damaged reef, where the worst problems, such as blast fishing, had stopped. Harrison would bring a few of the reef’s mature, sexually active corals to the lab, persuade them to release sperm and eggs in aquarium tanks, and then take more than a million of their larvae back out to the reef. The plan was to saturate the environment with settling babies, as adult corals would have done in healthier days.

In 2013, Harrison’s team, led by graduate student Dexter dela Cruz, began a small pilot experiment in the Philippines at a reef called Magsaysay, where nearly two decades of fishing with explosives had taken a toll. Blast fishing is “like hitting the reef with a sledgehammer,” Harrison says. Magsaysay’s large foundational corals were blown to bits. A once-vibrant city was now a wasteland.
By 2013, the blast fishing had stopped, but Magsaysay wasn’t recovering on its own. So Harrison’s team brought in larvae from a species of fast-growing, purple-tipped coral, called Acropora tenuis, collected from a nearby healthier reef. The scientists released more than a million larvae into floorless mesh tents pitched under-water over the reef. After five days, Harrison’s team removed the mesh enclosures.

Over the next six months, most of the tiny coral settlers died. But, by the nine-month mark, the remaining populations had stabilized. Scientists expected more of the juvenile corals to die, but “incredibly and extraordinarily,” Harrison says, none have. At 3 years old, the juvenile corals have reached sexual maturity and are now the size of dinner plates. In June, dela Cruz presented the findings in Honolulu.

For slower-growing corals, Harrison’s approach will take extra patience. But for fast-growers like A. tenuis, reseeding larvae could be a quick and affordable way to help severely damaged reefs bounce back.

Winning corals
Getting more larvae onto damaged reefs is the first step, Harrison says. But some individuals are stronger and more stress-tolerant than others. As they grow up, these “winners” distinguish themselves by surviving.

Across the Pacific from Magsaysay, biologist Gates is studying winners. Rows of indoor and outdoor aquariums gurgle in her lab on Coconut Island, off Oahu’s windward shore. Those tanks are full of Montipora capitata, a local and fast-growing coral collected from the patchy reefs surrounding the island.

In 2014 and 2015, unusually warm water hit Hawaii. Under stress, many corals rejected their symbiotic algae, then blanched from a healthy brown to white; some died.

Gates’ team patrolled the reefs around the island during and after the bleaching, in search of hardy M. capitata individuals that stayed brown, even in hot water. The scientists are also interested in M. capitata that bleached, but then recovered. Gates equates the work to professional sports scouting, “out at high schools, looking for the best athletes.”
When she finds top performers, Gates brings them to her lab to run them through their paces, exposing each pro-performer to different temperatures and pH levels in seawater tanks. Some conditions re-create today’s oceans, while others mimic future warm and more acidic seas.

Today, Gates is breeding the strongest corals (her first batch of babies was born in June). She hopes that top performers will have “extremely talented kids” that inherit their parents’ strengths. It’s too soon to tell how the new corals will do once they’re planted out on the reef.

“We’re trying to give corals a leg up,” she says. Reefs healthy enough to survive without human intervention are the ultimate aim. In the next five years, the researchers plan to branch out from M. capitata to look for super corals of all five species found in the bay surrounding Coconut Island.

It would be ideal to find those super corals before the next big bleaching event. But for that, the researchers need another sign of resilience. That sign, Gates says, could be hidden in the way corals glow.

Some coral animals, and their symbiotic algae, are loaded with fluorescent proteins that absorb incoming light, then spit it back out by glowing. It’s unclear what fluorescent proteins do for corals; they may be a kind of sun block, protecting corals from the intense light in shallow seas, or a form of camouflage or part of the immune system.

Stress affects corals’ glowing proteins and changes their fluorescence patterns. In the Pacific and Indian Ocean species Acropora yongei, for instance, researchers reported in 2013 in Scientific Reports that the concentration of green fluorescent protein fell with temperature stress before bleaching and the coral glowed less intensely. In an earlier study, prolonged high temperatures changed the ratio of green to orange fluorescence in the endangered Caribbean coral Orbicella faveolata.

Gates expects that under stress, super corals will keep their healthy fluorescence patterns much longer than corals that are bleaching. One next step, Gates says, is to stress out tiny pieces of coral and watch what happens under a very powerful laser scanning confocal microscope. She’ll expose nubbins of coral to acidifying water or increasing temperatures in a petri dish. The microscope will pick up the fluorescence of the nubbins and may indicate which corals will stay healthy the longest.
Once scientists can identify the hardiest corals, they can combine selective breeding with other rehab techniques. Approaches like microfragmentation could help super colonies mature super fast. Then, Gates says, “we would have a strategy to get the reef producing its own offspring quite quickly.”

No two approaches to saving reefs are the same, which is probably a good thing. Coral fragmentation, reseeding and selective breeding each have their pros and cons.

“The assumption that one size will fit all is completely flawed,” Gates says. What might work on the Florida coast wouldn’t necessarily work in the Pacific. Like far-flung cities, each reef has different needs and priorities. Their communities of coral vary as do the threats they face. Some problems, like warming oceans, are global in scope. Others, like pollution from roads and agricultural runoff, overfishing and dynamite fishing, are often more localized. Rehabilitation approaches will vary, depending on the type and severity of damage, and how the mosaic of coral species might respond.

Across the globe, “will the things that we do be different?” Gates asks. “Absolutely.”

Rather than competing, Gates, Vaughan and Harrison are working toward a common goal: to find the right mix of approaches to support the reefs so they no longer need human help.

Eyes offer window into brain’s timekeepers

The eyes may reveal whether the brain’s internal stopwatch runs fast or slow. Pupil size predicted whether a monkey would over- or underestimate a second, scientists report in the Nov. 2 Journal of Neuroscience.

Scientists knew that pupils get bigger when a person is paying attention. They also knew that paying attention can influence how people perceive the passage of time. Using monkeys, the new study links pupil size and timing directly. “What they’ve done here is connect those dots,” says neuroscientist Thalia Wheatley of Dartmouth College. More generally, the study shows how the eyes are windows into how the brain operates. “There’s so much information coming out of the eyes,” Wheatley says.
Neuroscientist Masaki Tanaka of Hokkaido University School of Medicine in Japan and colleagues trained three Japanese macaques to look at a spot on a computer screen after precisely one second had elapsed. The study measured the monkeys’ subjective timing abilities: The monkeys had to rely on themselves to count the milliseconds. Just before each trial, the researchers measured pupil diameters.

When the monkeys underestimated a second by looking too soon, their pupil sizes were slightly larger than in trials in which the monkeys overestimated a second, the researchers found. That means that when pupils were large, the monkeys felt time zoom by. But when pupils were small, time felt slower.

The differences in pupil size were subtle, but Tanaka and colleagues think these changes are meaningful. Pupil size, the results suggest, offers a readout of the brain as it keeps track of passing milliseconds.

This pupil readout may reflect a specific type of signaling in the brain. As a chemical messenger called noradrenaline puts the brain into a heightened state of alertness, pupils get bigger, previous research has shown. That link is why this study makes sense, Wheatley says. Attention is known to make time fly, a distortion that would lead a monkey to think a second has elapsed sooner than it has. The opposite is also true. When the brain is a little more sluggish or not paying attention, time ticks by slower and seconds stretch out.

By finding that the eyes hold clues to how the brain perceives time, Tanaka says that the study may motivate further research into how brain cells actually make this split-second calculation (SN: 7/25/15, p. 20).

Too many stinkbugs spoil the wine

How many stressed-out stinkbugs does it take to spoil a batch of wine? More than three per grape cluster, new research says.

Stinkbugs are a pest among vintners because of the bugs’ taste for wine grapes and namesake foul smell. When accidentally harvested with the grapes and fermented during the wine-making process, the live insects can release their stink and ruin the wine (SN: 5/5/07, p. 285). The newly determined threshold is three per cluster of grape, researchers from Oregon State University in Corvallis report in the Journal of Agricultural and Food Chemistry. More stinkbugs produced red wine that tasted musty, as judged by a consumer panel. Quality tanked with rising levels of the stress compound, (E)-2-decenal, which smells like coriander.

White wine lovers can rest easy; stinkbugs don’t seem to affect its flavor because white is processed differently than red.

Cassini’s ring dive offers first close-up of Saturn’s cloud tops

Cassini has beamed back stunning images from the spacecraft’s daring dive between Saturn and its rings.

The first closeup pictures of the planet’s atmosphere reveal peculiar threadlike clouds and puffy cumulus ones, plus the giant hurricane first spotted on Saturn in 2008 (SN: 11/8/08, p. 9). Released April 27, the images of Saturn’s cloud tops are a “big step forward” for understanding the planet’s atmosphere, says Cassini imaging team member Andy Ingersoll, an atmospheric scientist at Caltech.
“I was pretty struck by the prevalence of the filamentary type of clouds,” he says. “It’s as if the long threads of clouds refuse to mix with each other.” Studying the interactions of these clouds and the cumulus ones will reveal what’s going on in Saturn’s skies.

During its dive, Cassini swooped to within 3,000 kilometers of the planet’s atmosphere and 300 kilometers of the innermost edge of the rings at 124,000 kilometers per hour. Slamming into even tiny particles from the rings could have damaged the spacecraft. To protect Cassini, mission scientists used the spacecraft’s 4-meter-wide antenna as a shield, putting the spacecraft temporarily out of contact with NASA.

Cassini reestablished contact with mission control early on April 27 and started to send back data minutes later. Shots of the rings and other features will be available in the coming days, and more stunning views are expected when the spacecraft shoots through the gap between Saturn and its rings again on May 2. It will ultimately orbit 20 more times before plunging into the planet’s atmosphere on September 15 (SN Online: 4/21/17).

This sea snake looks like a banana and hunts like a Slinky

With its bright hue, this snake was bound to stand out sooner or later.

A newly discovered subspecies of sea snake, Hydrophis platurus xanthos, has a narrow geographic range and an unusual hunting trick. The canary-yellow reptile hunts at night in Golfo Dulce off Costa Rica’s Pacific coast. With its body coiled up at the sea surface, the snake points its head under the water, mouth open. That folded posture “creates a buoy” that stabilizes the snake so it can nab prey in choppy water, says study coauthor Brooke Bessesen, a conservation biologist at Osa Conservation, a biodiversity-focused nonprofit in Washington, D.C. In contrast, typical Hydrophis platurus, with a black back and yellow underbelly, hunts during the day, floating straight on calm seas.
The newly described venomous snake has been reported only in a small, 320-square-kilometer area of Golfo Dulce. After analyzing 154 living and preserved specimens, the researchers described the reptile’s characteristics July 24 in Zookeys. The scientists hope that the subspecies designation will enable the Costa Rican government to protect the sunny serpent, which they worry is already at risk from overzealous animal collectors.

Skeleton ignites debate over whether women were Viking warriors

Viking warriors have a historical reputation as tough guys, with an emphasis on testosterone. But scientists now say that DNA has unveiled a Viking warrior woman who was previously found in a roughly 1,000-year-old grave in Sweden. Until now, many researchers assumed that “she” was a “he” buried with a set of weapons and related paraphernalia worthy of a high-ranking military officer.

If the woman was in fact a warrior, a team led by archaeologist Charlotte Hedenstierna-Jonson of Uppsala University in Sweden has identified the first female Viking to have participated in what was long considered a male pursuit.
But the new report, published online September 8 in the American Journal of Physical Anthropology, has drawn criticism from some researchers. All that’s known for sure, they say, is that the skeleton assessed in the new report belonged to a woman who moved to the town where she was interred after spending her youth elsewhere.

“Have we found the Mulan of Sweden, or a woman buried with the rank-symbols of a husband who died abroad?” asks archaeologist Søren Sindbæk of Aarhus University in Denmark. There’s no way to know what meanings Vikings attached to weapons placed in the Swedish grave, Sindbæk says.

Although the new paper dubs the long-dead woman “a high-ranking female Viking warrior,” other interpretations of her identity are possible, Hedenstierna-Jonson acknowledges. But she notes that the Viking woman “was an exception in a sphere dominated by men, either if she was an active warrior or if she was ‘only’ buried in full warrior dress with a complete set of weapons.”

Excavations in the late 1800s at Birka, a Scandinavian trading center from the 700s to around 1000 (SN: 4/18/15, p. 8), uncovered the woman’s grave. Remains of Birka lie on the island of Björkö, about 30 kilometers west of present-day Stockholm. About 1,100 of more than 3,000 graves that encircle Birka have been unearthed.

Excavators noted that the body lay among a warrior’s gear. This equipment included an ax, a spear, arrows, a large knife, two shields and two horses. Playing pieces found in the grave, apparently for some type of board game, suggest the woman may have been a high-ranking officer with knowledge of military tactics and strategy, Hedenstierna-Jonson’s team speculates.
Researchers have typically assumed that Viking-era graves with weapons contain male warriors. Curiously, though, many skeletons in these graves, including that of the Birka woman, display no battle injuries.

Biological anthropologist Anna Kjellström of Stockholm University, a coauthor of the new study, reported at a meeting in 2013 that the Birka individual was a woman, based on pelvic shape and bone sizes. DNA from the Birka skeleton now confirms its female status and reveals many genetic similarities to present-day northern Europeans.

A comparison of two forms of radioactive strontium in teeth from the Birka woman, 15 other individuals excavated at Birka and pre-Viking age people from several parts of Sweden indicated that the woman moved to the trading center as a teenager or young woman. Humans absorb strontium from local rock formations through water and plant foods, leaving a chemical signature in teeth that approximately maps where these people grew up. The researchers estimate the woman was at least 30 years old when she died.

Findings in the new paper don’t demonstrate that the Birka woman was a Viking warrior, writes archaeologist Judith Jesch in a Sept. 9 post on her Norse and Viking Ramblings blog. Perhaps all alleged warriors in Viking-era warrior graves who lack serious wounds didn’t actually fight, contends Jesch, of the University of Nottingham in England. Hedenstierna-Jonson’s group provides no evidence that the Birka woman’s bones contain traces of strenuous physical activity expected from a warrior adept enough to avoid severe injuries, she writes.

“A certain amount of confusion” surrounds the original locations of bones excavated at Birka and then bagged for storage, including those of the proposed woman warrior, Jesch adds. Sloppy excavation practices at Birka more than 100 years ago sometimes accidentally lumped together bones from different graves, she says in her post.

Women could have been warriors during the Viking age, whether or not the Birka woman fought alongside men, says archaeologist Marianne Moen of the University of Oslo. Research over the past 30 years shows that Viking women were landowners, farmers, merchants, traders and participants in legal proceedings. Graves of two other Viking-era women, both in Norway, contain various weapons.

What’s important is not to hold women to a different standard than men when assessing comparable weapons placed in their graves, Moen asserts. The Birka find “was a warrior grave until it was sexed as female,” she says. “Now a lot of people would like to call it something else. That is where the danger lies here.”

Photons are caught behaving like superconducting electrons

Light is a fan of the buddy system. Photons, or particles of light, have been spotted swapping energy with partners. This chummy behavior resembles how electrons pair up in materials that conduct current without resistance, known as superconductors, researchers report in a paper accepted in Physical Review Letters.

Although the photons exchange energy like electrons do, it’s unknown whether the particles are actually bound together as electrons are, and whether photons could produce an effect analogous to superconductivity. “This is a door that is opened,” says study coauthor Ado Jorio, a physicist at the Universidade Federal de Minas Gerais in Brazil. Now, he says, the questions that must be addressed are, “How far can we push this similarity? Can we find with photons incredible results like we find for electrons?”
In certain solid materials cooled to extremely low temperatures, electrons form partnerships called Cooper pairs (SN: 6/13/15, p. 8), which allow superconductivity to occur. Although the negatively charged particles typically repel one another, two electrons can bind together by exchanging phonons, or quantum packets of vibration, via the lattice of ions within these materials. This alliance coordinates the electrons’ movements and thereby eases their passage through the material, allowing them to flow without resistance. Superconductivity’s potential technological applications — which include energy-efficient power transmission, superstrong magnets and levitating trains — have attracted heaps of scientific interest in the phenomenon.

Now, Jorio and colleagues have shown photons behaving similarly to superconducting electrons. When the researchers shined a laser on water, pairs of photons that emerged from the liquid at the same time tended to have complementary energies. While one photon had lost a little energy, another had gained the same amount of energy, indicating that they were exchanging quantum vibrations. The effect appeared in a variety of transparent materials, says Jorio, and it was observed at room temperature, unlike electron pairing in superconductors.

The team also showed that the exchanged quantum vibrations were “virtual” — appearing only for fleeting moments — just like the vibrations exchanged by electrons. The theory that explains the interaction “is exactly the same as for the electrons,” Jorio says.

Scientists already knew that photons can lose or gain energy via vibrations, but the similarity with Cooper pairs is a new and interesting way of thinking about the effect, says physicist Ian Walmsley of Oxford University, who was not involved with the research. “It’s a field that has not yet been explored.”
It is still too early to know how far the analogy with superconducting electrons extends, says physicist Ben Sussman of the National Research Council of Canada in Ottawa, who was not involved with the research. But the connection seems worth investigating: “This is an interesting rabbit hole indeed.”