On July 17th, 2017 we learned about

The mathematical model that describes how body size sets top speeds

If video games have taught me anything, it’s that bigger characters hit harder, but move slower. This always felt pretty intuitive, to the point where giant characters in fantasy stories are depicted as moving in slow motion compared to human-sized folks. The thing is, movement is tied to our muscle strength, and that strength is (at least partially) due to muscle size, which would suggest that bigger creatures should move faster, not slower. Nobody’s seen an elephant run at 373 miles per hour though, so it looks like reality is siding with video games here, and we finally have the math to prove it.

Fighting physics and fatigue

Myriam Hirt, a zoologist from the German Center for Integrative Biodiversity Research, came up a formula to predict how size influences speed. The first factor is the animal’s mass, which not only dictates the amount of muscle available, but also the amount of inertia that animal has to overcome to start moving. So a large elephant may have some impressively large muscles, but it takes a lot more work to get those legs moving. This is different from weight, which is the influence of gravity on the body’s mass. If you moved an elephant to the Moon, it would weigh less, but still have a lot of inertia since the size of its body didn’t change. The upside of this is that if you did get an elephant moving that fast, it’d be remarkably difficult to then get all that mass to stop.

The second factor is the animal’s anaerobic metabolism, which explains why an elephant isn’t about to do that extra work to break into a swift sprint. Most of the time, a body relies on aerobic metabolism, which uses oxygen to provide energy to your cells, and is used in longer, lower-intensity activities like a long walk. For a quick burst of energy, like sprinting at top speed, muscles use anaerobic metabolism, which burns sugars like glucose directly. This allows for fast twitch activity in muscles, but produces byproducts like lactic acid, putting a cap on long muscles can work this hard. Taken together, the fastest elephants have only been observed hitting 25 miles per hour.

Mutual maximums

In the case of our charging elephant, overcoming the inertia of its mass requires too much anaerobic activity to work. The animal’s large muscles may give it a lot of strength and endurance, but not enough to rocket forward like a cheetah. In fact, across animals moving on land, sea and the air, the same size ratios held true 90 percent of the time. Like a bell curve, small bodies have little inertia to overcome, but lack the muscle to give them much power. Large bodies are too big to get moving before the muscles start to burn out. The sweet spot to maximize speed and size is then in the middle, around the size of a cheetah. Cheetahs have other adaptations that make their bodies even more efficient sprinters, like their super-flexible spines, but the size still matters. A double-sized cheetah wouldn’t be nearly as energy efficient and would like be unable to reach the same 74-mile-per-hour speeds.

This formula does more than confirm the speeds of animals we’re all familiar with. Thanks to it’s high accuracy, it can help us estimate the speed of animals we can’t observe, like dinosaurs. We’re estimating body mass in extinct animals as well, but baring other adaptions to improve performance, it’s fair to assume that a Velociraptor could have run at 34 miles per hour, in contrast to a much bulkier Tyrannosaurus would have only hit 17 miles per hour. Big bodies can provide a lot of power, but physics requires that they also take a lot of work to move around.

Source: Why the Biggest Animals Aren't the Fastest by Stephanie Pappas, Live Science

On July 12th, 2017 we learned about

Muscle strength depends on how well you train your motor neurons

To really achieve your athletic potential, you must strengthen your mind and your muscles. As much as that may sound like a platitude from a motivational poster, it’s actually based on a series of experiments comparing how muscle mass may or may not impact physical strength. Muscles are still the key mechanical actors in these emerging model, but it looks like well-trained motor neurons are the anatomy that can give you access to more of your body’s strength.

Now, nobody is debating the idea that, in general, a larger muscle can do more work than a smaller one. More muscles cells can share the stress of a particular contraction, achieving movement without incurring the damage a smaller muscle would. However, bulky muscles aren’t able to do more work just because they’re big. To get bigger, they’ve presumably been trained along the way, which helps the muscle cells activate simultaneously. Untrained muscles will activate asynchronously, which may protect them from overexertion and damage, but also decrease their effectiveness.

More strength from the same muscle

Not all strength training is turning out to be equal. One on hand, many repetitions of lighter weights is being found to be effective as fewer repetitions of heavier weights to build muscle mass. It may take longer, but lifting lighter weights can help you develop larger muscles. The catch is that lifting larger weights seems to not only train muscles, but also motor neurons, which changes how well you can put your quads, biceps or triceps to work.

This relationship was tested in a variety of ways. One test involved electrically stimulating muscles to see if heavy and light weights produced muscles with different limits on their output. Another test asked participants to do a matching task, and found that the muscles trained on heavier weights didn’t need to work as hard to complete it. In every case, matching muscle sizes didn’t matter as much as the way those muscles had been trained. Researchers aren’t sure why heavier weights are more effective at training our motor neurons in this way, but it suggests that lifting weights close to your limit may be more effective at raising what that limit is.

Source: Why Strength Depends On More Than Muscle, Scienmag

On June 21st, 2017 we learned about

How Rebecca Huit heaved a Hummer over her head, plus handled her flaming fingers

Sciencing the Sisters Eight!

Rebecca Huit is one of the younger sisters in The Sisters Eight, but she commands an outsized amount of attention from her siblings, even before gaining her powers. When she does start demonstrating unusual abilities, it’s unclear what’s happening at first, because she manifests both inhuman strength and incendiary fingertips. There’s little reason to suspect these abilities are tied to each other, and so we’ll unpack each power on their own.

More massive muscles

The development of Rebecca’s strength may have two distinct causes. At the opening of Rebecca’s Rashness, we find that Rebecca is vigorously training at all hours of the day, and getting eye-popping results. She’s able to easily support the full weight of her sister, Petal, from one arm with no sign of fatigue, indicating that she’s somehow gotten a lot stronger than the average seven-year-old. The book fails to mention any changes to Rebecca’s appearance, but there’s a chance that she’s suddenly been building muscle mass because her body has stopped blocking its growth.

Many mammals, including humans, cats, cows and dogs, naturally create a protein called myostatin. This protein acts as a regulator on our muscle development, keeping us from building excessive amounts of muscle that might cause a drain on our energy levels without much practical gain from an evolutionary standpoint. When genetic mutations, or a decrease of another protein called follistatin, somehow leave an animal without myostatin, muscles develop to unusual sizes, greatly increasing the creature’s strength. Even newborn babies lacking myostatin will show bulk in their leg muscles, and can lift over six pounds in one hand by the time they’re four and a half. If Rebecca has suddenly dropped her myostatin production, developing enough muscle to lift Petal wouldn’t be a big challenge.

Hoisting the Hummer

Shortly thereafter, Rebecca amazes her family by lifting up an entire Hummer, raising it over her head. Hoisting 6400 pounds into the air is a far cry from supporting an older sister, and even new muscle growth might not account for the amount of strength necessary. Since Rebecca was lifting the Hummer to help her friend Pete, there’s a good chance that she was tapping into what’s known as hysterical strength. This is the strength that people tap into in emergencies to do things like… well, rescuing friends trapped under cars. In real life, these people are usually only lifting a quarter of the car’s weight to free someone, and they’re not actually using more strength than their muscles normally offer— it’s just more strength than the body ever wants to use.

Like the myostatin that keeps our muscle production in check to save resources, our brains normally cap our muscle exertion below their physical limits. This provides a buffer for our safety so that we don’t damage muscles, ligaments, tendons or bone. It also helps us save some calories to get home to recuperate after exertion, rather than leave us completely limp on the ground. Hysterical strength isn’t achieved with boosted muscles then, but by removing the feelings of pain and fatigue that normally keep things in check at around 60% of our potential strength. People who have experienced hysterical strength have sometimes paid a price in self-induced injuries, although they usually don’t notice things like eight cracked teeth until they’ve calmed down after the triggering emergency.

Hot hands

For better or for worse, the flames that later shoot from Rebecca’s fingers aren’t tied to emergency responses, as she can set things ablaze at will. Flames are described as blasting from her fingers, indicating that there’s some sort of pressurized fuel source to push the fire away from her hands, like the pressurized nozzles on a flamethrower. Unlike a flamethrower, we see no sign of a pilot flame though, so some other mechanism must be heating things up enough to burn things down than traditional fuels like propane or butane.

A model for spraying flammable fuels is the African bombardier beetle. When threatened, this beetle can spray a mix of hydrogen peroxide and hydroquinones that combine in mid-air to form oxygen, boiling water and benzoquinones. None of these components aren’t literally combusting during this reaction, but the resulting spray can cause chemical burns, clouds of vapor and intense heat, sometimes as high as 200° Fahrenheit. Potential predators hit this cocktail are likely to be burned and incapacitated, allowing the beetle to escape danger. It’s not going to literally set your drapes on fire necessarily, but if Rebecca was spraying anything like this out of her fingers it would still cause plenty of damage.

Overall, this all leaves Rebecca as a very dangerous, volatile girl, and most people wouldn’t want to risk being near these abilities on the best of days. The combination of extra strength operating at its full capacity, even temporarily, while spraying noxious, burning chemicals is so extreme that Rebecca’s eventual imprisonment really seems like the only rational option for the remaining siblings. As well as the surrounding neighborhood.

Source: The Man of Steel, Myostatin, and Super Strength by E. Paul Zehr, Scientific American

On June 14th, 2017 we learned about

Trip to space seems to have spurred a flatworm to regenerate a second head

It may sound like something out of a 1950’s science fiction story, but spending time in space has apparently spurred a flatworm into growing two heads. Flatworms are actually known for their regenerative abilities, and this particular worm was actually cut in half before heading into orbit on the International Space Station (ISS) in the hope that it would regrow its body. However, regenerating with a second head, along with a number of other abnormal developments, isn’t exactly what scientists were expecting when designing the experiment. The second head doesn’t mean we need to fear radioactive space monsters from outer space, but it does raise concerns over long-term health effects of living away from the Earth.

Altered in orbit

Planarian flatworm (Dugesia japonica) regeneration is usually much more predictable. The tiny creatures regularly handle fission without a problem, and can use it to boost populations. A single worm splits in half, and each half regrows whatever pieces are missing. So usually a tail will regrow a head, and a head will regrow a tail. Researchers have known that a two-headed variation was technically possible, but the Tufts University researchers had never encountered a two-headed worm before, even after 18 years of research. What’s more, the underlying change must have been substantial, as that two-headed flatworm returned from space only to continue making two-headed copies of itself.

The other flatworms have also exhibited changes to their physiology and behavior, although they’re understandably less dramatic than growing a second head. They exhibited an reaction to fresh water when first returning home, becoming temporarily paralyzed when first immersed. They also don’t show flatworms’ normal aversion to light, and will not seek out darker portions of their containers when given the chance.

Changes from flying and floating

It’s not clear what is driving these various changes. A change in the worms’ microbiomes may help explain the temporary reaction to fresh water, and other research has already shown that bacteria notice when they’re in microgravity too. Other influences include a diminished pull from the planet’s geomagnetic field, stress from takeoff and landing, or just issues related to floating in microgravity while on board the space station.

At this point, scientists have a good understanding of what chemical changes could change a flatworm, since those things can all be tested here on the ground. Isolating what are likely mechanical influences from traveling to and in space are a new frontier, but they need to be understood if humans hope to export our lifestyles to other planets. Nobody believes that astronauts will sprout second heads after being in space, but animals like flatworms are still a good way to study the importance of gravity on living systems, partially thanks to their dramatic reactions to that environment.

Source: Flatworm Travels to Space With One Head, Comes Back With Two by Nathaniel Scharping, D-brief

On June 13th, 2017 we learned about

The debates and designs that resulted in the humble rubber reflex hammer

Today, while waiting in the doctor’s office for a checkup, my second grader proudly announced that she recognized the reflex hammer sitting on the counter, and that she’d figured out how to replicate its function with both her hand and lunchbox. When the doctor actually tested my daughter’s patellar ligament, there was a little disappointment that the iconic rubber hammer wasn’t used, as the doctor struck her knee with the rubber edge of her stethoscope instead. The stethoscope was effective at triggering the reflex, maybe even better than a well aimed lunchbox, so how did these hammers end up in doctors’ toolkits in the first place?

Medical grade rubber hammers were originally designed to look for fluid built up in people’s chest cavities. After seeing innkeepers thump the side of wine casks to hear how full they were, Dr. Leopold Auenbrugger suggested hitting chests with a percussion hammer to see how hollow they sounded. The idea caught on, but the design was criticized and reworked from all corners. Potential replacements looked like everything from a battle axe to a magic wand. Rubber wasn’t locked down as a material either, as doctors considered whacking their patients with ebony, whale bone, brass, lead and velvety yarn.

Knocking knees for nerves

It wasn’t until 1875 that Drs. Heinrich Erb and Carl Friedrich Otto Westphal noticed what’s been fascinating my daughter— tapping a tendon or ligament can cause the associated muscles to automatically flex and relax. The patella ligament under your knee, for instance, sends a signal through your spine to your alpha motor neuron, which then activates your quadriceps in your thigh. This response is normally used by the body to automatically maintain posture and balance without worrying about it, but for doctors it’s a handy way to diagnose an array of possible maladies. When a knee is jerked more or less than expected, it can help reveal where in the body other symptoms might be stemming from.

The iconic triangular, rubber hammer you’re likely to see at the doctor’s office was developed by Dr. John Madison Taylor in 1888. The design hasn’t changed a lot since then, but it’s not the final iteration of reflex hammers at doctors’ disposal. If the nervous response of other parts of the body are to be tested, a variety of more specialized hammers are available, such as the Krauss hammer that was designed by Dr. William Christopher Krauss. Some have large round heads for knees, small balls for biceps, and thinner structures for stimulating the skin. Of course, if all else fails, a good thump from a thumb might still do the trick as well.

Source: Digital Schmigital: After 130 Years, Reflex Hammer Still Going Strong by Bret Stetka, KQED Future of You

On May 30th, 2017 we learned about

Light-licking mice reveal which taste receptors can actually taste water

Lab mice have been trained to drink light. This involved a bit of work, but the motivation wasn’t so hard since the mice were convinced they were drinking water. The trick was just engineering them to have tongues that could mistake a stream of photons for an actual sip of H2O, which is neat since most of us can barely describe what water tastes like in the first place.

Which cells sense water?

Backing up a bit, researchers were looking for the physiological mechanisms that tell an animal when it’s drinking water versus some other, less hydrating liquid like oil. Our sense of taste informs us about most of the food we put in our mouths, although that requires distinct flavors and smells, which isn’t something we associate with (clean) water. Neurological evidence suggested that our brains have a distinct response to water in our mouths, but to figure out what triggers that activity, researchers started messing with mouse tongues.

Mice were bred with various alternations to the genes governing their taste receptors on their tongues. With a type of receptor disabled, the mice were offered water or similarly clear, tasteless silicon oil to see if they noticed any difference. The mice that lacked receptors normally associated with sour, acidic flavors took longer to notice the difference, so researchers targeted those cells for the next phase of experimentation.

Light instead of liquids

The next step was to raise mice with optogenetic taste receptors on their tongues. Optogenetics is a research technique that makes specific types of cells sensitive to light. Often used in studies of the brain, researchers can then target and activate the genetically engineered cells to prove their role in a particular process. In this case, the sour-sensing taste receptors were made sensitive to light, so that light on the mouse’s tongue would be perceived as a normal food or liquid stimulus, like water. Using a water bottle rigged to emit light, the mice lapped away at the light, eagerly attempting to quench their thirst even though no actual liquid was present.

At this point, the sour-sensing taste receptors appear to be central to how mice, and presumably other mammals, taste water on our tongues. Researchers suspect that drinking water normally washes saliva out of our mouths, changing the acid levels on our tongues to activate these cells. However, the light-drinking mice also revealed that further mechanisms must be at play when getting a drink. As much as the mice were convinced they were lapping up water, they never acted sated by the activity. It seems that the tongue may help indicate when we have water in our mouths, but some other mechanisms were waiting for a real liquid to indicate when to stop drinking.

Source: Scientists discover a sixth sense on the tongue—for water by Emily Underwood, Science Magazine

On May 24th, 2017 we learned about

Air pressure’s power to halt horses and carry cardboard, without pulverizing people

At first, my kids referred to what they were seeing as a “trick,” like it was part of a magic show. It was actually a well-known, kitchen-science demonstration about air pressure, but it was new and wondrous to them in a way that elicited furrowed brows and excited disbelief. I was simply holding a cup full of water upside-down, with a piece of cardboard “floating” or “sticking” underneath it. My daughter was surprised at how much the cup of water weighed, because, somehow, neither it nor the cardboard was falling all over the kitchen. “It’s like a suction cup,” she finally ventured, although it would be a bit longer before she could explain why that idea made sense.

“Wait, would this work on the Moon? With no air?”

Even though my demonstration may not seem like magic anymore, it’s good to keep in mind that for huge swaths of recorded history, most people wouldn’t have been able to really explain why my cardboard wasn’t falling away from the inverted cup. The idea that atmospheric air pressure was even “a thing” wasn’t easily tested until it could be experimentally removed by comparing normal conditions to a vacuum. Since Aristotle, people accepted the idea that “nature abhors a vacuum” to mean that vacuums just couldn’t really exist. So when German scientist Otto von Guericke visited Holy Roman Emperor Ferdinand III in 1654 for a demonstration of his new invention, nobody in the audience had any way to predict what they were about to see.

Von Guericke arrived with a 20-inch, hollow, bisected sphere and his new vacuum pump. The two halves of the sphere were placed so they touched, but their point of contact was smooth, with just a bit of grease between them. If the intersection was an equator, the “poles” of the sphere had a valve to pump out air, plus hooks that would be used later. The pump was hooked up to pump all the air out of the sphere, at which point teams of horses were hooked up on either side to try and pull the two halves apart. They couldn’t do it.

“So, there was nothing inside, but…”

Not only had von Guericke demonstrated making a vacuum inside his copper sphere, he also showcased the power of the Earth’s atmosphere. The air on the outside of the sphere was pushing the two pieces together so hard it outmatched the strength of the pulling horses. If it had been supported vertically, the bottom half of the sphere would have stayed in place even with over 4,000 pounds hung underneath it- around the weight of an adult rhinoceros. The demonstration was understandably a sensation, and the sphere was even named a Magdeburg sphere, after von Guericke’s home town. And of course, it’s basically the same concept that was holding my cardboard against my cup.

“Carrying a car?”

All that said, it was still hard for my kids to accept that the invisible air that we basically ignore all day could somehow exert so much force. We don’t see it happening, and we don’t even feel it, which seems weird, considering it’s like we’re supporting a Honda Civic all day. We don’t feel the rhino-toting power of the air all the time because unlike the Magdeburg sphere, we normally have air molecules pushing us from all directions, and they balance each other out to a degree, unless it’s windy of course.

Secondly, organisms on Earth have had millions of years to adapt to living with the air pressure here. The 2,204 pounds of pressure you can ignore coming down on your head is balanced and accommodated by the internal pressure of the various fluids that make up your body. Your blood, muscles and lungs are all full of substances pushing outwards, and they’re tuned to expect external pressure from the air pushing back. Without the right amount of pressure pushing on our bodies, things get ugly pretty fast.

At this point, my second grader seemed like the pieces were fitting together. We talked about popping ears on airplanes, the feeling of water pressure under a pool, and watching bags of chips puff up at high altitudes where there’s less air pressure. Hopefully she stays content with the cardboard demonstration, although if not, at least further tests won’t require access to a team of horses.

Source: Storm in a Teacup: The Physics of Everyday Life by Helen Czerski, Transworld Publishers Limited, 2016, p.15

On May 14th, 2017 we learned about

How researchers traced degenerative convulsions to ritual cannibalism in Papua New Guinea

The traditional beliefs of the Fore people of Papua New Guinea describe a living world, guarded by ancestors and stirred by sorcery. Everyone is believed to have five souls, with the ama, aona and yesegi passing on blessings, talents and power to a person’s family after they die. Unfortunately, the rituals to help those souls transition from life could also pass an unusual disease that would cause convulsions, dementia and eventually death. Known as kuru, or “shivering,” this illness defied explanation for decades, as it wasn’t caused by normal pathogens like bacteria, viruses or fungi. Fortunately, the source of the infections was identified, and what was once an epidemic blamed on sorcery is now eradicated from Fore society.

Looking for patterns with no pathogens

Most of the world didn’t know about the Fore people until 1930, and by 1950 there was growing concern about the disease that could cause everything from a loss of motor function to uncontrollable laughter. At that point, there were some symptoms that warned of its onset, such as headaches and joint pain that would usually be overlooked, followed by the more ominous difficulty walking. Clearly something was attacking people’s nervous systems, but no bacteria, virus or fungus could be identified as the culprit. Environmental contaminants were ruled out. Genetic conditions were targeted, but after mapping the family trees of victims, there was no pattern that suggested any particular lineage was in more danger than another.

Thankfully, a pattern did emerge among the victims. Adult women and children were more likely to contract kuru than men, and those women often knew each other. Eventually, it was determined that the women weren’t carrying a contagion themselves, but they were sharing the infection through their traditional duties during funerary rituals. In order to free and care for some of a dead relative’s souls, women prepared and ate the dead body. The women’s bodies were thought to protect and tame souls of the deceased, although in the preparation process they sometimes gave portions to attending children as well. This cannibalism would have probably been safe in most cases, but it proved to be the perfect transmission point for kuru when the deceased had already been infected.

Poisoned by proteins

As these patterns were brought to light, researchers still couldn’t explain what the cause of the disease was on a physiological level. Sometimes the full explanation isn’t completely necessary to help people though, and experiments on chimpanzees proved that eating an infected body did indeed cause kuru. Even infected brains that had been preserved in formaldehyde for years could cause an infection, making it clear that the ritual cannibalism was putting people at risk. With this information, traditions were changed, and infection rates dropped off, with the last death being reported in 2009, probably after years of incubation in the victim’s body.

The last bit of good news is that the underlying mechanism causing this debilitating condition was also identified. Nobody had been wrong in their earlier exclusion of bacteria or viruses, as the infections were driven by misfolded proteins called prions. Rather than fold into the necessary shape to perform normal functions in the body, these proteins somehow start folding into clumps, collecting more protein mass along the way. The prions mostly amassed in the brain and nervous system, eating away at people’s lives until they had no control over their own bodies anymore. We still don’t know exactly how prions get started, but with the outbreak of bovine spongiform encephalopathy, or Mad Cow disease throughout the 1990s among cows fed other cows, there does seem to be a connection to even inadvertent cannibalism. At the very least, it seems that you should be very sure about what meat you eat, and what that meat may have eaten when it was alive.

Source: When People Ate People, A Strange Disease Emerged by Rae Ellen Bichell, The Salt

On May 3rd, 2017 we learned about

Tardigrades secure their cells’ structures with glassy proteins when water runs scarce

One of the problems with living in a droplet of water is that it can dry up in a hurry. Even a puddle or pond isn’t terribly reliable, which naturally causes havoc for the various flora and fauna trying to make the most of their watery home. Some bacteria and fungi can ride out the dry spells by making a special sugar called trehalose, which protects delicate structures inside their cells until their environment is rehydrated. Tiny tardigrades, also known as water bears, were thought to employ this sugar as well, but it turns out that that would be too mundane a solution for animals famed for their extreme survival abilities. Instead, it looks like tardigrades survive with unique proteins all their own: tardigrade-specific intrinsically disordered proteins (TDPs).

Saving their cells

When a tardigrade’s environment is drying up, they’ll face problems with mobility and finding food, but the immediate concern is that the lack of water will destroy individual cells in their bodies. Water is a key component to life on Earth, helping house sensitive organelles in our cells, like mitochondria or ribosomes. When water isn’t there to help support the cytoplasmic fluid inside each cell, membranes crack and delicate proteins lose their shape and become entangled in a biologically useless mess. At the center of the cell, DNA will begin to break apart as well, all of which kills the cell and larger organism.

Tardigrades survive this decomposition by preventing it before the damage is done. The TDPs normally float around in kind of formless blobs when they’re not needed, but as water molecules become scarce, special genes kick up their production so they can go to work. The TDPs begin to solidify into a glassy structure that’s less orderly than your usual solid crystal, but firm enough to to lock delicate cellular structures in place. Instead of breaking and folding into each other, the inside of the cells are encased and thus inert, waiting for water to be reintroduced to the tardigrade’s body.

Protection outside the organelles

On a larger, Ok– 1.5mm, scale, the tardigrade will follow a similar pattern. As it begins to lose water, it will fold itself up into a more compact ball, called a “tun” state, so it can wait for water with less risk to its anatomy. This involves retracting their head and limbs into the body, leaving the resulting lump looking a bit like a microscopic raisin. This response is also seen when tardigrades are in extreme cold, as they end up losing nearly all of the water in their bodies.

The genes to create TDP have been isolated, which means they might not be unique to tardigrades much longer. Researchers successfully engineered yeast and bacteria to make use of TDP genes, at which point those organisms were also able to survive dehydration. The hope is that these proteins might someday help protect everything from corn to vaccines, all of which currently rely on more costly freezing processes for preservation.

My second grader asked: Is this how tardigrades survive freezing too?

It seems like it should be? Tardigrades have been thawed out after 30 years in deep freeze storage, where they were in their compact tun state which would suggest they had deployed their TDPs. It’s assumed that a lot of their durability, including some seperate mechanisms to repair DNA damage, evolved to deal with dehydration and just happened to be great at everything else. The only catch is that any water that could somehow freeze might damage cells by forming sharp ice crystals, but prehaps the glassy TPDs can contain any stray H20 as well.

Source: Tardigrades turn into glass to survive complete dehydration by Andy Coghlan, New Scientist

On April 30th, 2017 we learned about

‘Hunger’ hormone may help the brain make new memories

You want the best for your kids, but sometimes it’s not clear what that is. Nutrition for a growing body is important, and you want them to get the nourishment they need to grow, from their skeleton to their brain… and four-year-olds with low blood-sugar are awful to be around. On the other hand, a bit of hunger may have some benefits, at least as far as memory performance goes. Scientists are getting closer to pinpointing the exact mechanisms at work, but it looks like a hormone from a hungry tummy get your body to make more brain cells.

The hormone in question is called ghrelin, and it’s secreted when the stomach is empty. When ghrelin reaches your brain, it triggers a sense of hunger and gastric acid production, basically setting you up for meal time. Once your stomach stretches out a bit, presumably from being filled with food, the ghrelin production drops off and a different hormone, leptin, heads up to the brain to let you know to relax and stop eating.

Boosting brain growth

Longer-term exposure to ghrelin may have some other effects on the brain though. Animals on low-calorie diets that presumably leave them feeling a bit peckish seem to do better on cognitive tasks than their well-fed peers. Mice given injects of extra ghrelin probably felt a bit of the munchies, but also performed better on learning and memory tests. In the most direct test of this relationship, mouse neurons in a petri dish were bathed in ghrelin, it stimulated more growth of new brain cells. In an actual mouse, those new cells would likely help the mouse form new memories, explaining what’s boosting their test scores.

While mice might be ready to learn when they want a snack, this hasn’t been tested directly in humans. Lower calorie diets have been found to offer some health benefits, but most discussions of fasting for memory-boosts are anecdotal at this point. Intermittent fasting does raise ghrelin levels in the body, but we don’t know if this offers the same benefits to people as it does to mice. In the mean time, researchers are looking at ghrelin as a way to help trigger brain cell-growth in people with Parkinson’s disease, so we may soon settle how being hungry helps your brain (or doesn’t.) In the mean time, hangry kids are a big enough incentive from my perspective to avoid keeping them too hungry on purpose.

My second grader asked: So if I have a spelling test should I skip my lunch so I remember things better?

Nope. Some studies have found that being hungry impairs cognition in humans. If ghrelin does pan out promote brain cell growth, it also wouldn’t work on such a short timescale. The new brain cells need time to grow and put into use, and even then are more about making it easier to build new memories, not retrieve the memories you already have.

Source: Hungry stomach hormone promotes growth of new brain cells by Clare Wilson, New Scientist