And now, fresh from the pages of peer-reviewed journals unmediated by the filter of popular press or people who want to drink mummy juice, here’s you’re actual ASR for the week.
First up, a little battle-report from the evolutionary war between predator and prey.
Moths generate auditory-illusions to fool bats.
Intent is one of those tricky things when talking about evolution. In this case, as in many others, what looks like clever planning is the result of thousands of generations of refinement — mostly made through the mediation of how individuals who didn’t play this game well got eaten. It’s not that the moths all got together somewhere and plotted this deception. It’s the bats ate the moths who were easy to catch, until you ended up with this incredible development in insect-audio.
The spinning hindwing tails of silk moths (Saturniidae) divert bat attack by reflecting sonar to create a misleading echoic target.
The moths create a false sonar image. These are stealth aircraft, mico-edition, refined and driven by requirements and deadlines much more strict than anything ever laid out by the Defense Department.
And it’s happened more than once. Different species of moths have developed their own different hind-wing architectures, each of which does something subtly different when casting a deceptive sonic shadow. That difference between species is likely a key part of why this continues to work for any species. If every type of moth was generating the same sort of illusion, projected in some way proportionate to speed, position, and path, bats would long ago have worked out a compensating mechanism. But because different moths pull off this trick in slightly different ways, it’s a lot harder for the bats than “aim 10 inches left, and two feet above.”
But that’s not the say bats have not compensated. Of course they have. That’s why there are still bats. For every time you’ve watched a antelope run across the screen with a narrator relaying how it’s life or death, remember that it’s also life or death for the cat on its heels. After all, predators have to predate. So the fight mega-generational squabble between moths and bats has also resulted in increasing sophisticated means of piercing these illusions from the Chiropteran forces.
Not to mention giving these scientists an excuse for what sounds like a really, really fun experiment.
To test the mechanism underlying these anti-bat traits, we pit bats against three species of silk moths with experimentally altered hindwings that created a representative gradient of ancestral and extant hindwing shapes.
Okay, maybe clipping moth wings doesn’t sound like your idea of a fun Saturday evening. But they made high speed video of this aerial combat, with moths throwing illusions and bats trying to suss out reality. That’s just cool.
Let’s go read more science!
Climate
The Atlantic is getting warmer, because turnover is getting weaker.
The Day After Tomorrow is right up there with Armageddon on the list of movies I hate for both screwing up science and for the sheer level of requiring people to do stupid things to move the plot along. But buried in all that idiocy there are a few germs of actual climate science, and one of them is the importance of ocean currents when it comes to regulating climate over land. Just as we’ve become used to the idea of a “strong El Niño year” influencing rainfall patterns and temperatures across the United States, the temperature of ocean water in these great flowing “rivers” can determine hot and cold, wet and dry, calm or stormy for large areas of the planet.
And big changes in ocean temperatures, like the ones we’re seeing now, can cause extreme changes. As seen by researchers at Ocean University of China, they may not be the changes we expect.
Evidence from palaeoclimatology suggests that abrupt Northern Hemisphere cold events are linked to weakening of the Atlantic Meridional Overturning Circulation (AMOC), potentially by excess inputs of fresh water. But these insights—often derived from model runs under preindustrial conditions—may not apply to the modern era with our rapid emissions of greenhouse gases. If they do, then a weakened AMOC, as in 1975–1998, should have led to Northern Hemisphere cooling. Here we show that, instead, the AMOC minimum was a period of rapid surface warming. More generally, in the presence of greenhouse-gas heating, the AMOC’s dominant role changed from transporting surface heat northwards, warming Europe and North America, to storing heat in the deeper Atlantic, buffering surface warming for the planet as a whole.
The heat-storing effects of the AMOC are the biggest factor in the temporary “slowdown” of global warming that climate change skeptics like to point out by very selectively choosing the start and end dates of their measurements. But the AMOC is getting weaker, which means it’s also “burying” less heat. Meaning the surface waters are getting warmer, quickly.
A high-quality look at CO2 in Boston’s air and its sources.
Scientists from, where else, Harvard University have taken a close look at the ups and downs, as well as the sources, of carbon in the atmosphere around Boston.
Continuous atmospheric measurements of CO2 from five sites in and around Boston were combined with a high-resolution bottom-up CO2 emission inventory and a Lagrangian particle dispersion model to determine regional emissions. Our model−measurement framework incorporates emissions estimates from submodels for both anthropogenic and biological CO2 fluxes, and development of a CO2 concentration curtain at the boundary of the study region based on a combination of tower measurements and modeled vertical concentration gradients. We demonstrate that an emission inventory with high spatial and temporal resolution and the inclusion of urban biological fluxes are both essential to accurately modeling annual CO2 fluxes using surface measurement networks.
As the authors point out, with the US withdrawing from the Paris Agreement, many cities and states have expressed a desire to remain a part of the solution. That’s going to require monitoring like this to determine if cities or regions are meeting the goals they set.
Astonomy
How silica forms in space.
Silica — also known as silicon dioxide or SiO2 — is one of the most common substances on Earth. It doesn’t just cover beaches in the form of sand, it’s one of the most common components of the rocks that make up the planet’s crust. So it may be surprising that it’s been tough to spot its origin in space. But thanks to some researchers from Ibaraki University in Japan, that has changed. Their research looks at a specific type of meteorite, called a carbonaceous chrochondrite, to explore the origins of silicates.
And ... that grabs your interest, go take a look, But I'm leaving out the snippet here because terms like “ultrarefractory Calcium-aluminum–rich inclusions” and “amoeboid olivine aggregates” just don’t make the best light reading.
The end of a Big (bang) era.
A big era in space-based astronomy has closed with the final maps from ESA’s Planck Telescope. As reported in Nature, these final images give astronomers their best look yet at the Cosmic Microwave Background (CMB) left behind by the Big Bang resulting in the “most precise measurements yet of the age, geometry and composition of the cosmos.”
But these final images are also … final. The CMB has been studied intensely with a series of more powerful, more accurate instruments. But now, there are no more such instruments coming down the line. The last days of Planck represent the end of new data in this area for some time to come.
So, for scientists who have spent years or decades pouring over an ever-sharpening picture of the universe’ first moments, it’s time to move on. Or at least, move later. Even if that means using devices less sophisticated than the one they’re now putting to rest.
Many scientists who worked on the mission have already moved on to other project. Silvia Galli became part of Planck in 2013 after her PhD and is one of the few dozen scientists left on the mission, and helped to lead the latest study. Now, she says she will probably join many of her colleagues who are working on Euclid, a major European mission that will map the Universe’s galaxies on an unprecedented scale and is preparing for launch in 2021. Euclid is an old-fashioned optical telescope, not a microwave detector, which makes it a technically different kind of mission requiring different skills. On a personal level, it is exciting to move on to new endeavours, she says.
Anthropology
The origins of equine dentistry.
Sometimes the title alone is enough to let you know that an article is going to be worth your time. And really, what could beat “the origins of equine dentistry.” Dentists? But for horses? No, really, how did that get started?
We report the earliest evidence of equine dentistry, from the Mongolian Steppe, at 1150 BCE. Key shifts in equine dentistry practice through time can be linked first to the emergence of horseback riding and later to the use of metal bits that enabled better control of horses. The maintenance of horse health through dentistry underwrote the key role of horses in cultures and economies around the world.
I already knew that the Mongols were among the first to use a stirrup that gave them improved stability for their horse-mounted archery. But I’d be willing to bet that something as apparently simple as paying attention to how the bridle affected their horse’s teeth, played a large role in providing them with mounts that could be used more frequently, and over a longer period. More experienced, smarter, healthier, and happier horses equals one more successful rapacious horde.
And it seems their practices still live on.
Although free-range grazing on gritty forage mitigates many equine dental issues, contemporary Mongolian horsemen nonetheless practice some forms of dentistry, including the removal of problematic deciduous teeth and the vestigial first premolar (“wolf tooth”).
The culture that eats together … forms a pretty impressive civilization.
The University of South Florida led this research that look at how a culture called the Paracas formed in southern Peru. And they did it by looking at a marker of how the culture pulled together from individual small groups and families, into a larger cooperative group — big cook-outs.
We demonstrate that one classic ethnographic mechanism of cooperative social organization, the hosting of feasts, was used in an early complex, nonstate society in the south coast of Peru ∼2300 B.P. We likewise demonstrate that the catchment zone of the people and goods that participated in the feast was extensive. These data support a cultural evolutionary model of early state formation as one of a network strategy. That is, key areas across a large landscape were initially integrated into a cooperative group as opposed to a strategy of local consolidation and subsequent aggregative growth.
Getting people together in a large group to exchange goods and share a meal seems like an important step on the ladder to forming a more organized society. And not a bad measure for how “civilized” any area is: How often do you get together with people around you to share a meal?
Researchers looked at how you could gauge the development of a culture not just through evidence that people came together to celebrate a feast, but how more “exotic” items appearing at that feast demonstrated that the culture was growing more extensive in its reach and trading network.
Medicine
Triggering calorie burning in brown fat.
Brown fat has something of a magical reputation among people who are watching their weight. But how this material gets signaled to burn calories has been poorly understood, and the subject of a thousand theories put forth in diet books by people whose primary interest has been more about lightening wallets and tightening belts.
But a team led by researchers from Harvard Medical School has discovered that a single substance seems to play a key role in signalling brown fat to light the metabolic furnace. Which does seem to suggest that there really could be an effective “diet pill” or at least, some form of weight-loss treatment, down the line.
We show that substantial and selective accumulation of the tricarboxylic acid cycle intermediate succinate is a metabolic signature of adipose tissue thermogenesis upon activation by exposure to cold. Succinate accumulation occurs independently of adrenergic signalling, and is sufficient to elevate thermogenic respiration in brown adipocytes. Selective accumulation of succinate may be driven by a capacity of brown adipocytes to sequester elevated circulating succinate. Furthermore, brown adipose tissue thermogenesis can be initiated by systemic administration of succinate in mice.
Succinate, or succinic acid, is generated within cells by those tiny engines of the metabolism, mitochondria. The tricarboxylic acid cycle (TCA) in mitochondria splits sugars like glucose and fat to generate energy. A side process to this cycle throws off extra protons, and in brown fats those protons hit a protein that generates heat. So, indirectly, brown fat takes sugars and regular fats and expends them as heat energy, rather than storing them up in the body. (and yes, I simplified that, because while I once could draw a diagram of every step in TCA down to molecular structure, that was circa 1978).
But the part of this that is sure to make the news is this: Early research shows that adding succinate succinate to the drinking water of mice prevented obesity, even when the mice were fed a diet that got other mice fat.
There are two key words here: Mice. And early. Whether this effect would also be seen in humans, and whether adding sizable amounts of succinate (and these mice seemed to get pretty good slugs of the stuff) over a long period would be safe … is pretty unclear. Note that the description up there of TCA is down to the level of protons. That’s how basic this mechanism is. Fiddling with it may not be nearly so simple as succinate in, fat off. But, if you must, both broccoli and beets have a fair amount of the stuff.
Image
As usual, today’s image comes from Andy Brunning at Compound Interest. Check his site for the original image, which is larger and easier to read.