Abbreviated Science Round-up: Even older art, eye needles, elephants evolve away their tusks

Nature: Genetics showed that America’s first residents were highly mobile.
Ewen Callaway

An analysis of genomes from dozens of ancient inhabitants of North and South America, who lived as long ago as 11,000 years — one of the largest troves of ancient DNA from the region studied so far — suggest that the populations moved fast and frequently. …

“These early populations are really blasting across the continent,” says David Meltzer, an archaeologist at Southern Methodist University in Dallas, Texas, who co-led the Science study.

The studies also suggest that prehistory of the Americas — the last major land mass to be settled — was just as convoluted as that of other parts of the world.

Fascinating data published in a pair of papers is going to take some time to map out, but tells a terrific story of early settlers who moved in, and just kept on moving and mixing. It also suggests a continent that was more fully populated and interconnected than earlier evidence may have indicated.

Biology

Science: More evidence that a common pesticide is bad for bees.
J. Crall, C. Switzer, et. al

Neonicotinoid pesticides can negatively affect bee colonies, but the behavioral mechanisms by which these compounds impair colony growth remain unclear. Here, we investigate imidacloprid’s effects on bumblebee worker behavior within the nest, using an automated, robotic platform for continuous, multicolony monitoring of uniquely identified workers. We find that exposure to field-realistic levels of imidacloprid impairs nursing and alters social and spatial dynamics within nests, but that these effects vary substantially with time of day. In the field, imidacloprid impairs colony thermoregulation, including the construction of an insulating wax canopy. Our results show that neonicotinoids induce widespread disruption of within-nest worker behavior that may contribute to impaired growth, highlighting the potential of automated techniques for characterizing the multifaceted, dynamic impacts of stressors on behavior in bee colonies.

By performing long term, real time monitoring of hives, the authors determined not just that neonictonoids may be a large factor behind an increase in failing bee hives, but have a better understanding of the mechanisms of hive collapse.

National Geographic: Elephants are evolving to lose their tusks.
Dina Maron

The oldest elephants wandering Mozambique’s Gorongosa National Park bear the indelible markings of the civil war that gripped the country for 15 years: Many are tuskless. They’re the lone survivors of a conflict that killed about 90 percent of these beleaguered animals, slaughtered for ivory to finance weapons and for meat to feed the fighters.

Hunting gave elephants that didn’t grow tusks a biological advantage in Gorongosa. Recent figures suggest that about a third of younger females—the generation born after the war ended in 1992—never developed tusks. Normally, tusklessness would occur only in about 2 to 4 percent of female African elephants.

This can be thought of as the same kind of selective pressure that Darwin pointed out as shaping pets and farm animals. Just in a larger, more horrific form.

Climate

Science: Extreme summer weather events to increase by 50 percent or more.
M. Mann, Stefan Rahmstorf, et. al.

Persistent episodes of extreme weather in the Northern Hemisphere summer have been associated with high-amplitude quasi-stationary atmospheric Rossby waves, with zonal wave numbers 6 to 8 resulting from the phenomenon of quasi-resonant amplification (QRA). A fingerprint for the occurrence of QRA can be defined in terms of the zonally averaged surface temperature field. Examining state-of-the-art [Coupled Model Intercomparison Project Phase 5 (CMIP5)] climate model projections, we find that QRA events are likely to increase by ~50% this century under business-as-usual carbon emissions, but there is considerable variation among climate models.

Extreme summer events include both increased seasonal drought and the related wildfires. What’s happening in California right now can be expected to increase over the next decades, as can similar events in other areas. So can widespread drought and extreme heat waves.

Science: Measuring 350,000 years of rain and drought by looking in a cave.

Here, we present a 350,000-year record of past water table fluctuations in Devils Hole 2 cave that are driven by variations in recharge amount to the local groundwater flow system. Because of the unprecedented length and precision of our record, we can observe variations in regional moisture availability over the last three glacial-interglacial cycles at a millennial-scale resolution. The timing of past water table rises and falls (>9 m in amplitude) closely coincides with the expansion and reduction of Northern Hemisphere ice volume, which in turn influences the position and intensity of westerly winter storms on orbital time scales. Superimposed on this long-term trend are millennial-scale highstands recorded during the last glaciation that coincide with North Atlantic Heinrich events. Earlier millennial-scale highstands provide the first evidence of multiple short-lived wet periods in the SW United States linked to coeval cooling intervals in the North Atlantic during marine isotope stages 6 and 8. The Devils Hole 2 water table record is currently the longest independently dated paleomoisture record in the SW United States and thus provides a critical testbed to examine the controls on regional moisture availability over larger time scales.

Some of the wet periods mapped by this study seem to correspond to expansion of past civilizations in the Southwest, who were then caught out by extended drought when that damp period ended.

Medicine

Ars Technica: Delivering medicine to the eye with needles. Tiny needles.
Kiona Smith

Getting drugs into the eye is a challenge. The most effective solutions tend to be unpleasant and involve actual injections into the eyeball. If doctors deliver the injection in a less horrifying part of the body, it can take a dangerously high initial dose to ensure that enough of the drug actually reaches the eye. Eye drops tend to wash out, and they’re surprisingly inefficient: the eye only absorbs about five percent of the drug most of the time. For some patients, these tradeoffs lead to a choice between needles and blindness.

As someone who has probably had 10,000 drops of that eye-scalding pupil enlargement fluid squirted in my eyes over my lifetime, it certainly can be unpleasant. But this … somehow doesn’t sound better.

Some recent ideas … have involved microneedles: pyramid-shaped needles just a few hundred micrometers long. Microneedles have been increasingly popular as a less-painful way to get drugs through a patient’s skin without an injection—they’ve been used to deliver vaccinations, local anesthetics, and anti-diabetic medications.

Hmm. 

Discover Magazine: Can we beat the themodynamics trap of air conditioning?
Chelsea Gohd

As people search for solutions to the climate change crisis on Earth, scientists are working to create renewable energy sources as alternatives to fossil fuels. Now, scientists at Stanford University hope to offer a new solution as they are developing a single device that collects solar energy and shoots radiation out into space – acting as both a heater and air conditioner.

Normal air conditioners simply move heat around, and in the process actually create more heat. They’re also a long way less than 100 percent effective. Nothing ever is. So to make an air conditioner that doesn’t ultimately cause the planet to warm, requires getting some of that heat off the planet.

The device is made up of a solar absorber on top of a radiative cooler, which is composed of layers of nitride, silicon and aluminum. These layers are then vacuum-sealed to prevent heat loss. The device takes in solar energy and reflects infrared radiation in the cooler back to outer space. The device is still in development, but the researchers behind it claim that it can warm the surrounding area up to 75 degrees Fahrenheit (24 degrees Celsius) and cool the surrounding area up to 84 degrees Fahrenheit (29 degrees Celsius). The team also asserts that, since the solar absorber blocks the radiative cooler, it improves its performance.

Astronomy

NBC News: Earth may have a pair of “ghost moons.”

Astronomers in Hungary say they’ve detected a pair of what some call “ghost moons” orbiting our planet not far from the moon we all know.

The hazy clouds of dust — tens of thousands of miles across but too faint to be seen with the naked eye — were first detected almost 60 years ago by a Polish astronomer, Kazimierz Kordylewski. But the patches of light he found were too indistinct to convince some scientists that the clouds were really there, and the existence of the “Kordylewski clouds” has long been a matter of controversy.

Image

The image this week, as in many weeks, is from Andy Brunning at Compound Interest. Visit the site for a larger, easier to read version.

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