Extensive Mid-Oceanic Magma Eruption at the Cretaceous-Paleogene Time Boundary

     The asteroid that hit earth 66 million years ago appears to have caused large amounts of magma to spew out of the bottom of the ocean, a new study of seafloor data finds.

      The discovery, described today in the journal Science Advances, adds to the picture of an extinction event that was as complex as it was deadly.

      For decades, researchers have pointed to a cataclysmic asteroid crashing into the planet as the reason the dinosaurs, and many other species of life on Earth, were wiped out during the Cretaceous-Paleogene (K-Pg) extinction event. That impact, which scientists think left the roughly 110-mile-wide Chicxulub crater in the Gulf of Mexico, would have vaporized living things nearby and sent choking clouds of debris into the air, obscuring the sun.

      But scientists have also pointed to another culprit: the Deccan Traps in present-day India, one of the largest volcanic provinces in the world, which just happened to be very active at the time of the extinction event. The ash and noxious gases from the Deccan Traps are really what killed the dinosaurs, some scientists say, downplaying the asteroid's role.

     "People still argue about which one was actually the primary driver of environmental changes that resulted in the death of dinosaurs," said senior author Dr. Leif Karlstrom, an earth scientist at the U. of Oregon.

     Researchers have also suggested that perhaps the two were connected — perhaps the asteroid triggered Deccan Trap volcanism, producing a brutal one-two punch that ultimately knocked out roughly three-quarters of the earth's plant and animal species. But recent work has shown that the traps started spewing roughly a quarter-million years before the asteroid hit, Dr. Karlstrom said.

     Yet, scientists have wondered if there might indeed be some kind of connection between the two. And lead author Dr. Joseph Byrnes, a geophysicist at the U. of Minnesota, realized something: If the asteroid impact had had a major impact on volcanism at the time, that effect should have shown up in the activity along the Earth's mid-ocean ridges. So he and Dr. Karlstrom went looking for it.

     As we've discussed here at Partial Ellipsis of the Sun before, the mid-ocean ridges are long cracks in the Earth's crust at the bottom of the ocean floor where tectonic plates meet. As the plates pull apart, hot magma rises up between them, flowing out on either side of the crack before cooling, creating new seafloor in the process. With more than 40,000 miles of ridges, this network of cracks forms the longest mountain chain on earth.

   
     Scientists used magnetic data compiled by other researchers and combined it with another data set showing the gravitational field of the surface beneath the ocean. The stronger the gravitational field in a given spot, the more mass there is. 

    "We have a topographic map of the Earth's surface and we have topographic maps of Mars and Venus, but we don't have that for the ocean floor," Dr. Byrnes said. "We have it for places where people have taken ships, but it would take something like 900 years to survey the whole ocean floor. It's just too resource-intensive — so we have to use the gravitational anomalies as a proxy."

     The graph below shows a spike in the creation of new seafloor about 66 million years ago. That's when the Chicxulub asteroid struck the Earth, wiping out the dinosaurs. The impact also instigated the release of massive amounts of magma.

     Sure enough, the scientists found that at the time the asteroid hit the Earth, there was a sudden surge in the magma pouring out of these mid-ocean ridges, which put out on the order of a hundred thousand to a million cubic kilometers of volcanic material. That's not too far behind the estimated several million cubic kilometers or so of magma produced by the Deccan Traps.

     It's possible that the powerful seismic waves produced by the impact triggered the release of reservoirs of magma beneath the surface, Dr. Karlstrom said. And if it affected the mid-ocean ridges this way, it could have played a similar role in the Deccan Traps, triggering even more volcanism than before.

     The mid-ocean ridges, then, could be a bellwether for a similar phenomenon occurring in the already-active Deccan Traps.

       But did that marine magma release do any damage of its own? While it's unclear whether this extra load of ocean floor magma worsened the extinction event, it could potentially have played a role by further acidifying the oceans. Previous work indicates that marine species that were more sensitive to ocean acidification were worse hit by the extinction event. But probing that possibility will take more research, the scientists added.

      "That's what we need to work on next, I would say: trying to tease out what the effects on the environment were of the volcanic activity," Dr. Byrnes said.

Thoughts on this new data? Have you been to the Deccan Traps?
Steph

Speaking of stitches, here's the full quilt my friend made:

     

Bee Bedevilments: Colony Collapse Disorder and More

      Colony Collapse Disorder (CCD) was one of the most striking mysteries in the news 11-12 years ago; honeybee workers were vanishing fast for no clear reason. To this day, that puzzle has never been entirely solved, researchers say.

     And perhaps it never will be. Colony collapse disorder has faded in recent years as mysteriously as it began. It’s possible the disappearances could start up again, but meanwhile bees are facing other problems.

     CCD probably peaked around 2007 and has faded since, says Dr. Jeff Pettis, who during the height of national curiosity was running the Beltsville, MD, honeybee lab for the U.S. Department of Agriculture. Five years have passed since Dennis vanEngelsdorp, who studies bee health at the University of Maryland  has seen a “credible case” of colony collapse (see below in the lower part of the image.)

     Beekeepers still report some cases, but Dr. Pettis and Dr. vanEngelsdorp aren’t convinced such cases really are colony collapse disorder, a term that now gets used for a myriad of things that are bad for bees. To specialists, colony collapse is a specific phenomenon. An apparently healthy colony over the course of days or a few weeks loses much of its workforce, while eggs and larvae, and often the queen herself, remain alive. Also food stores in collapsing colonies don’t get raided by other bees as a failing colony’s treasures usually do.

      “I think I know what happened,” says Dr. Pettis, now in Salisbury, MD, consulting on pollinator health. His proposed scenario for CCD, like those of some other veterans of the furor, is complex and doesn’t rest on a single exotic killer. But so far, no experiment has nailed a proof.

     Looking back, Pettis realizes he had heard about what might have been early cases of CCD, described as colonies “just falling apart,” for several years before the phenomenon made headlines. Then in November 2006, Pennsylvania beekeeper David Hackenberg, as usual, sent his colonies to Florida for the winter. They arrived in fine shape. Soon after, however, many buzzing colonies had shrunk to stragglers. Yet there were no dire parasite infestations and no dead bee bodies in sight.

      “It was, ‘OK, something weird just happened,’ ” remembers Dr. Jay Evans of the USDA’s honeybee lab in Beltsville. “It looked like a ‘flu,’ something that kind of swept through miraculously fast.”

      No single menace, however, could be tightly linked to every sick colony, or only to sick colonies. Varroa mites, small hive beetles, Nosema fungi, deformed wing virus, unusual signs of pesticide exposure, for instance —screening techniques at the time just weren’t picking up a clear pattern in any of these bee bedevilments.

     Entomologists were hounded by the press, not to mention leaned on by politicians and pursued by would-be entrepreneurs. “For me, what made it rewarding,” Dr. Pettis says, “was that people were learning about the value of pollination.”

      A Columbia University researcher who had identified pathogens in mysterious human disease outbreaks looked at the problem. Dr. Ian Lipkin had never worked with bees, but he and his lab collaborated with entomologists and other bee specialists to search for any genetic signature of a pathogen appearing only in collapsing colonies. The approach of searching through mass samples, with their messy traces of gut microbes and random parasites, is now familiar as metagenomics. At the time, this way of searching for pathogens was groundbreaking, says collaborator Diana Cox-Foster, then at Penn State U. The resulting paper, in Science, pointed to several viruses, especially the previously obscure Israeli Acute Paralysis Virus, or IAPV. That emphasis on IAPV, which got a lot of attention at the time, hasn’t held up well. “It’s not 100 percent ruled out,” Evans says. But the explanation’s main problem is shared by other threats proposed as a single cause of CCD. After finding IAPV or another presumed single menace in sick bees in one place, he says, “you could go to other apiaries that were collapsing and not find it, or you could find it in healthier colonies.”

      As an apiary inspector for Pennsylvania at the time, vanEngelsdorp monitored for signs of collapse in over 200 hives. “We tried to watch it happen but we couldn’t,” he says. None collapsed. Even finding the sickest bees in collapsing colonies was a challenge. Doomed bees presumably flew off in multiple directions, and birds or other scavengers usually found the bees before scientists could.

     Dr. Pettis now sees the disaster as a two-step process. Various stressors such as poor nutrition and pesticide exposure weakened bees so much that a virus, maybe IAPV, could quickly kill them in droves. Evans, too, sees various stressors mixing and matching. When pressed for his best guess, he says “all of the above.”

       Dr. Cox-Foster has managed to re-create part of the process, the vanishing effect that marked the end for stressed bees. When she infected honeybee colonies in a greenhouse with a virus, the sick bees left the hive but were trapped by the greenhouse walls before dispersing too far to be found. (Of course, this experiment doesn’t demonstrate how colonies with no sign of a virus died.

     That tendency for sick bees to leave hives, Dr. vanEngelsdorp proposes, could have developed as a hygiene benefit. “Altruistic suicide,” as social-insect biologists call it. Flying away from the colony could minimize a sick bee’s tendency to pass disease to the rest of the hive.

     Colony losses each year are still running higher than beekeepers say would be acceptable (gray bar in the image below). Even though hives can be split so numbers eventually build up again, the slowdown and expense raise the costs of pollination.

      Today, hive losses remain high even with CCD waning or gone, according to national surveys by the Bee Informed Partnership, a nonprofit bee health collaboration. Beekeepers typically note that they either expect or can tolerate annual losses between 15 and 20 percent of their total number of colonies. Yet from April 2016 until March 2017, losses across the United States ran at about a third of hives. And that was a so-called good year, the second-lowest loss in the seven years with data on annual losses.

      Classic CCD may not be as much of a threat these days, but the “four p’s” — poor nutrition, pesticides, pathogens and parasites — are, says Dr. Cox-Foster, now at a USDA lab for pollinating insects in Logan, Utah. Coping with the four p’s may not fire the imaginations of armchair entomologists. But it’s more than enough of a challenge for the bees.

       Answer? Choose B (but it's still a confounding mystery.)

Bee well,
Steph

2017: 74 Interesting Science, Technology, and Health Links

     Here are 74 interesting science, technology, and health stories in this 2017 year-end article from The Atlantic. Enjoy all the links from how flamingos easily stand on one leg (#2). . .

in formation. . .

to a large waterfall in Antarctica where the Nansen Ice Shelf meets the sea (#19). . .

to the way hummingbirds drink nectar using tongues that are so long that, when retracted, they coil up inside the birds’ heads, around their skulls and eyes (#59). . .

to genetically distinct uptown versus downtown rats in New York City (#60). . .

to the oldest rocks on earth (4 billion years old having fossil traces in them in the Torngat Mountains in Canada (#67) to. . . wherever the links take you.

      Which links were most intriguing for you? Which did you skip past quickly (#13 for me)?

      I'll leave the mole rats and their oxygen needs for you to discover (#74).

All the best for a healthy, happy, and scientifically stimulating 2018!

Steph

Something to Crow About: Happy Hooking, a Relatively New Tool Skill

      New Caledonian crows are the only species besides humans known to manufacture hooked tools in the wild. These birds produce these remarkable tools from the side branches of certain plants, carefully 'crafting' a crochet-like hook that can be used for snagging insect prey.

      The study, published in Current Biology on December 7, 2017, reveals how crows manage to fashion particularly efficient tools, with well-defined 'deep' hooks.

      The hook is widely regarded as one of humankind's most important innovations, with skillful reshaping, a useless piece of raw material is transformed into a powerful tool. While our ancestors started making stone tools over 3 million years ago, hooks are a surprisingly recent advance; the oldest known fish hooks are just 23,000 years old.

         Project leader Dr. Christian Rutz has conducted field research on New Caledonian crows for over a decade. His team recently noticed that crows' hooked tools vary considerably in size and shape. While some tools only exhibit a small extension at the tip, others have deeper hooks.

     Dr. Rutz explains: "We suspected that tools with pronounced hooks are more efficient, and were able to confirm this in controlled experiments with wild-caught crows. The deeper the hook, the faster birds winkled (to extract with difficulty) bait from holes in wooden logs."

     This finding raised the intriguing question of what it takes to make such well-formed hooks. The researchers started planning their study by imagining how humans would approach a comparable task. "When a craftsperson carves a tool from a piece of wood, two things ensure a quality product: good raw materials and skill," Dr. Rutz said.

      Researchers found that the same, apparently, applies to New Caledonian crows. The researchers discovered that the depth of the hook was influenced by both the properties of the plant material, and the technique crows used for detaching branches. When birds made controlled cuts with their sharp bills, the resulting hooks were significantly deeper than when they used a 'sloppier' alternative method of simply pulling off branches. Careful cutting may leave more wooden material at the tip of the stick from which the hook can subsequently be 'sculpted'.

     Surprisingly, adult crows, which are expected to have considerable tool-making experience, did not produce the deepest hooks and regularly employed the 'quick-and-dirty' manufacture technique. Dr. Rutz notes that making very deep hooks may not be the best strategy in the wild: "It probably takes more time and effort to make such tools, and experienced birds may try to avoid these costs. It is also possible that deep hooks break more easily when inserted into narrow holes and crevices."

      Dr. Christophe Boesch, a world-leading chimpanzee expert and Director of the Max Planck Institute of Evolutionary Anthropology in Leipzig, Germany, comments: "We have recently discovered that chimpanzees routinely use naturally-hooked stems to fish for algae, but they don't actively craft these hooks. The crows can reshape plant material with their pointed bills, which act like 'precision pliers', but this would be very difficult for chimpanzees with their large fingers."

     The present study is the first to examine in a non-human animal what factors determine the morphology of crafted tools, and as a consequence, their foraging efficiency. Paleo-anthropologists try to understand how our ancestors produced relatively complex tool shapes from basic raw materials, such as wood, bone or seashell, but they face the challenge that the manufacture process cannot be directly observed.

      The New Caledonian crow, with its remarkable ability to fashion hooked tools from plant stems, provides a fascinating window into humans' evolutionary past.

Hooked on Crows,
Steph

Where All the Women Are Strong: Bone Strength Comparison

     A new study comparing the bones of central European women who lived during the first 6,000 years of farming with those of modern athletes has shown that the average prehistoric agricultural woman had stronger upper arms than living female rowing champions.

     Researchers from the University of Cambridge's Department of Archeology say this physical prowess was likely obtained through tilling soil and harvesting crops by hand, as well as the grinding of grain for as much as five hours a day to make flour.

      Until now, archeological investigations of past behavior have interpreted women's bones solely through direct comparison to those of men. However, male bones respond to strain in a more visibly dramatic way than female bones.

     The Cambridge scientists say this has resulted in the systematic underestimation of the nature and scale of the physical demands borne by women in prehistory.

     "This is the first study to actually compare prehistoric female bones to those of living women," said Dr. Alison Macintosh, lead author of the study published this month in the journal Science Advances.

     "By interpreting women's bones in a female-specific context we can start to see how intensive, variable and laborious their behaviors were, hinting at a hidden history of women's work over thousands of years."

     The study used a small CT scanner in Cambridge's laboratory to analyze the arm (humerus) and leg (tibia) bones of living women who engage in a range of physical activity: from runners, rowers and footballers to those with more sedentary lifestyles.

     The bone strengths of modern women were compared to those of women from early Neolithic agricultural eras through to farming communities of the Middle Ages.

     "We can forget that bone is a living tissue, one that responds to the rigours we put our bodies through. Physical impact and muscle activity both put strain on bone, called loading. The bone reacts by changing in shape, curvature, thickness, and density over time to accommodate repeated strain," said Dr. Macintosh.



      "By analyzing the bone characteristics of living people whose regular physical exertion is known, and comparing them to the characteristics of ancient bones, we can start to interpret the kinds of labor our ancestors were performing in prehistory."

      Over three weeks during trial season, Macintosh scanned the limb bones of the Open- and Lightweight squads of the Cambridge University Women's Boat Club, who ended up winning this year's Boat Race and breaking the course record. These women, most in their early twenties, were training twice a day and rowing an average of 120 kilometers a week at the time.

      The Neolithic women analyzed in the study (from 7400-7000 years ago) had similar leg bone strength to modern rowers, but their arm bones were 11-16% stronger for their size than the rowers, and almost 30% stronger than typical Cambridge students. {Bone scan is at left, above, vs. x-ray to the left}.

     The loading of the upper limbs was even more dominant in the study's Bronze Age women (from 4300-3500 years ago), who had 9-13% stronger arm bones than the rowers but 12% weaker leg bones.

     A possible explanation for this fierce arm strength is the grinding of grain. "We can't say specifically what behaviors were causing the bone loading we found. However, a major activity in early agriculture was converting grain into flour, and this was likely performed by women," said Dr. Macintosh.

      "For millennia, grain would have been ground by hand between two large stones called a saddle quern. In the few remaining societies that still use saddle querns, women grind grain for up to five hours a day." {The mano and metate is a variety of saddle quern used for nixtamalization or grinding.}

     "The repetitive arm action of grinding these stones together for hours may have loaded women's arm bones in a similar way to the laborious back-and-forth motion of rowing."

     However, Macintosh suspects that women's labor was hardly likely to have been limited to this one behavior.

     "Prior to the invention of the plough, subsistence farming involved manually planting, tilling and harvesting all crops," said Dr. Macintosh. "Women were also likely to have been fetching food and water for domestic livestock, processing milk and meat, and converting hides and wool into textiles.

     "The variation in bone loading found in prehistoric women suggests that a wide range of behaviours were occurring during early agriculture. In fact, we believe it may be the wide variety of women's work that in part makes it so difficult to identify signatures of any one specific behavior from their bones."

     Dr. Jay Stock, senior study author added: "Our findings suggest that for thousands of years, the rigorous manual labor of women was a crucial driver of early farming economies. The research demonstrates what we can learn about the human past through better understanding of human variation today."

Where all the women are strong,
Steph (former member of Smith College Crew)