On November 21st, 2017 we learned about

Ancient Romans sought out citrus fruit as status symbols more than food

How much would you pay for a fruit that’s mostly rind, doesn’t taste good, and can make you vomit if you eat too much of it? If you were a citizen of ancient Rome, probably a lot. Citrus fruit, originating in east Asia, was hard to come by in the Mediterranean two thousand years ago, and so even something as difficult to enjoy as citron (Citrus medica) made a big impression on people. While most of us would pass over less appealing options like citron in favor of a lime or mandarin orange, Roman elites worked hard to appreciate them, largely thanks to citrus’ scarcity in that part of the world.

If you’ve never eaten a citron yourself, you don’t worry too much. Compared to other citrus fruits, citron are nearly entirely rind, leaving little fruit or meat to eat fresh. Some recipes capitalize on this by cooking with the rind itself, such as pickling it in brine before coating it in sugar to make a candy. Thanks to citrus’ hallmark tricarboxylic, aka citric, acid, the Romans enjoyed citron’s striking scent, both as a breath freshener and moth-repellent in clothing. Some citron was certainly eaten, although consuming the fruit was also tied to the ‘medicinal’ purpose of helping someone vomit up toxins if deemed necessary.

Fruit worth flaunting

There was one more good reason to avoid eating one’s citron fruit, which is the need to display it. Citrons, followed later by lemons, were most prized just because they were hard to come by. They were exotic goods imported through Persia, and owning them was a mark of a family’s wealth. They have been depicted in mosaics and even on coins, and seeds have been discovered in the ruins of wealthier villas around the Mediterranean. Citrus was a great food to have in your home, at least until everyone could have it.

As technology and trade routes modernized, Muslim traders made more citrus fruit available to the western world. However, sour oranges, limes and pomelos just didn’t have the same cache, possibly thanks to this increased availability. Food that was accessible to more people wasn’t worth putting on coins anymore, even if it was probably more worthy of a spot on your plate. As petty as that sounds, it wouldn’t be the last time wealthier people abandoned tasty food over its social status. By the time sweet oranges arrived in Europe in the 15th century, citrus fruits weren’t turning many heads anymore. To fully complete the cycle, when thin-skinned mandarins arrived in Europe in the 19th century, the clout once commanded by ancient citrons was long gone.

Source: In Ancient Rome, Citrus Fruits Were Status Symbols by Natasha Frost, Atlas Obscura

On November 20th, 2017 we learned about

Tracing the origins of turkeys’ supposed stupidity

Nobody wants to be a turkey. Even ignoring the fact that Americans will eat 87 million of these birds on holidays alone, there’s just no glory to be had for these iconic birds. Sure, Benjamin Franklin famously tried to promote their social standing, but today turkeys are solidly associated with incompetence, incoherence, and stupidity. Are they actually a particularly pathetic species, or should we be calling fowl (sorry!) over turkey’s maligned reputation?

To be clear, turkeys are unlikely to really compete with a crow or parrot on an IQ test. They’re not known for being especially cunning birds, but they’re certainly not helpless animals either. Wild turkeys (Meleagris gallopavo) will generally live in social groups of up to 200 individuals, usually composed of hens and their young broods. For protection, they rely on camouflage and the eyes and ears of their flock, like many other social birds. At night, they can overcome their relatively heavy bone structure to fly into trees, staying off the ground where they’d be more easily discovered. To further compensate for their limited flight, they’ve also been known to swim, fanning out their tails to increase buoyancy.

Unwanted associations

The above features were successful enough to see turkeys flourish across North America, but they weren’t enough to really impress humans. Once humans realized that their seed-fed meat was pretty tasty, we started hunting turkeys, taking advantage of their relatively limited mobility. This led to the idea of a “turkey shoot,” as the birds posed little challenge for a well-aimed gun. Limited flight also led to the name “turkey” being used as an insult. In the 1920s, a stage show or movie that performed badly was called a turkey, since sales failed to “take off.” This sense of general failure has probably fed into the idea that turkey’s are stupid, although popular evidence for their poor intelligence is actually a misunderstanding.

Stupidity or neck spasms?

Turkeys are supposedly so stupid that they will stand with their mouth agape, looking up into the sky as it rains, even it it means they drown themselves. Assuming this isn’t evidence of suicidal birds looking for a way out, it does seem fair to criticize animals that can’t be bothered to keep themselves alive. What’s not fair is judging intelligence when the real issue is a genetic condition that causes uncontrollable muscles spasms.

The condition is called tetanic torticollar spasming, and it can be spontaneous, or triggered by external stimuli like loud noises. It can be fatal in hatchlings, as it can interfere with getting food and water, but is more survivable in turkeys with later onset of symptoms. If it seems incompatible with living in the wild, that may be because it’s only associated with domestic turkeys. In manipulating their genomes to maximize muscle growth, humans have helped boost the prevalence of the recessive genes that cause the spasms. These poor birds look stupid because of a disability humans have unknowingly promoted, which for some folks may make eating turkeys a bit easier on their conscience.

None of the above necessarily demands that we completely reevaluate our opinion of turkeys. Domestic turkeys in particular do have a life few would be envious of, but maybe we should start associating them with the pitfalls of being delicious instead of just being dumb. Ok, and maybe a bit weird.

Source: Are turkeys really the dumbest animals? by Valerie Strauss, The Washington Post

On November 20th, 2017 we learned about

Compounds in broccoli found to help your intestines keep themselves healthy

The trope that broccoli is a burden to eat is just so wrong. Sure it’s can sometimes be bitter, but that’s not really a problem since it plays well with everything from Ranch dressing to Sriracha hot sauce. It looks like little trees, but is actually a flower! And it’s ridiculously healthy, feeding you nutrients while simultaneously saving your intestines from toxins and pathogens that can cause colitis or the ominously vague leaky gut syndrome.

That last benefit may not be terribly appealing to think about, but it’s important enough that researchers have been investigating the exact mechanism that helps broccoli protect our guts. Starting with a confirmation that that mice who ate broccoli suffered less from digestive issues related to intestinal distress, researchers started focusing on a chemical receptor in the gut called the Aryl hydrocarbon receptor, or AHR. This receptor helps regulate intestinal lining, the microbiome, immune system responses, and the “host barrier function.” While nothing in that list should be discounted, the barrier function is known to be critical to various diseases, and basically functions a mechanism that allows nutrients to be digested into the body while trapping potentially dangerous items, like pathogens or toxins, in the intestine for eventual expulsion.

A delicious dose of indole glucosinolate

Broccoli helps activate all this positive activity thanks to compounds called indole glucosinolates. As you digest your food, the indole glucosinolates break down, creating indolocarbazole (ICZ) in the stomach. This can then plug into the AHR receptor, keeping your intestines happy and inflammation-free. To confirm this relationship, mice were bred to be either extra sensitive to ICZ, or to block its interaction. As expected, the mice that couldn’t make use of the broccoli-produced ICZ suffered from more gut problems, indicating that compound’s importance to a healthy digestive tract.

If you’re hoping to someday bypass the broccoli and trigger your AHR receptor through some kind of ICZ-laden medication, prepare to be disappointed. Over-stimulating the AHR through a body-wide trigger has been linked to problems, like toxicity. This research bolsters the idea that local stimulation of the AHR, as when eating some broccoli, is the safest option out there. If you really can’t deal with broccoli though, researchers suspect that other veggies like brussels sprouts and cauliflower may please your intestines as well.

Source: Like it or not: Broccoli may be good for the gut by Matt Swayne, Penn State News

On November 19th, 2017 we learned about

Lemurs depend on leaves because their local fruit lacks protein

No matter how delightful a good salad may be, most of us can’t live on leafy greens alone. Primates, including humans, definitely consume plants in our diets, but we eat other items like nuts, fruit or meat to round our our nutritional needs. Lemurs break this pattern though, and skip everything but leaves when they go looking for food. As it turns out, the lemurs might just think that the local produce on in Madagascar just isn’t worth eating in the first place.

To be clear, fruit does grow in Madagascar. Studies have named at least 125 native species, and humans have introduced everything from oranges to avocados. With seemingly a number of choices in their habitat, scientists wondered why more lemurs didn’t follow the model of other primates and make these fruits a bigger part of their diets. Scientists wondered if the fruit supply was historically unstable due to events like cyclones, forcing lemurs to shape their diets around more reliable leaves. After all, even the local fruit bats, Eidolon dupreanum, have to switch to eating nectar for portions of the year when their favorite foods are unavailable.

Not enough nitrogen

When scientists started looking closer at what foods were available to lemurs, they started finding that the quality of the fruit was the real issue. While fruit could be found in the lemurs’ habitat, it didn’t seem to provide much protein per bite. To quickly compare the nutritional content of the fruit available to lemurs and other primates around the world, researchers started measuring nitrogen concentrations, since nitrogen is a key ingredient in many proteins. Fruit eaten by various monkeys from around the world was sampled, and all of it had more valuable nitrogen per bite than the fruit available to lemurs in Madagascar.

To make up for this gap in their diets, it seems that lemurs had to learn to skip the fruit and eat more leaves. Leaves don’t always provide a lot of calories per bite though, and so this required further energy-conserving adaptations, like eating leaves around the clock, or hibernating to use less energy in the first place. Now that the importance of leafy-greens is better understood, conservation efforts can be better designed to ensure that critically endangered lemurs have access to the slightly unintuitive foods they’ve come to depend on.

Source: Lemurs are weird because Madagascar's fruit is weird, Phys.org

On November 19th, 2017 we learned about

Analysis of potatoes’ genetic past identifies opportunities for better breeding in the future

Don’t take this the wrong way, but you’re simpler than a potato, at least on a genetic level. A study of the lowly spuds’ genetic history has found not only how complex the modern potato’s genome is, but that it may be overdue for some innovation. This interest in potato evolution isn’t because potatoes are slacking off in meeting their mutation quota, but that potatoes are humanity’s third most important crop worldwide. If nudging the right gene might yield healthier french fries, we might all be better for it.

A modern, cultivated potato has a lot of genetic material to look through, with over 39,000 genes in it’s genome. That’s more than a human’s 20,000 genes, and even more than potatoes own ancestors. Wild potatoes, as ancestors to the potatoes we grow to eat, are much simpler in comparison. They reproduce with what’s known as a diploid genome, with two sets of chromosomes per organism. This can be accomplished with seeds and berries, a feature that has obviously been bred out of their domesticated counterparts.

Taming the tuber

In the last eight- to ten-thousand years, human intervention changed a lot about these starchy members of the nightshade family. A domesticated potato can reproduce asexually, and now sports a tetroid genome, with four sets of chromosomes per individual. To potatoes out of the Andes mountains, we’ve altered everything from their pest resistance to the the plants’ circadian rhythm, as growing outside high mountain ranges meant differing amounts of sunlight per day. These sorts of mutations are among the 2,622 genes that transformed the potato into the staple starch we now find at the grocery store.

While researchers would like to see further change in the potato genome, they’re mostly looking to achieve it the old fashioned way. In the relatively short time since potatoes were first domesticated, farmers have been able to make some significant changes to these plants. With that said, there is concern that more recent breeding efforts have hit a bit of a ceiling, with no major improvements to speak of in the last 100 years. With more specific information about the potato genome, we may be able to make more significant gains via more carefully planned breeding programs. So as much as you may enjoy your mashed potatoes today, farmers may be able to offer an even better option in the not-so-distant future.

Source: Examining Potatoes’ Past Could Improve Spuds Of The Future by Layne Cameron and Robin Buell, MSU Today

On November 16th, 2017 we learned about

Composition of coal deposits suggests that plants benefited from dinosaur defecation

Plants love giant herbivores. It’s not that they are dying to be devoured exactly, but big eaters like a modern buffalo or ancient Diplodocus have historically helped disperse resources that plants need throughout an ecosystem. By eating plants and seeds, these unintentional gardeners break down nutrients in their digestive system, pooping them out on fresh soil in a new location. Plants’ dependency on this fecal fertilization is sometimes obvious, such as with the impossibly large pit of an avocado that evolved in conjunction with huge creatures like the giant ground sloth, Megalonyx. Other aspects of this dynamic, like nutrient distribution, are a bit more elusive, since the only direct record of that process in the herbivore’s poop itself. To study how this relationship may have worked long ago, researchers skipped looking for the poop itself, focusing instead on coal.

Coal is largely made up of carbon from ancient plants, compressed over millions of years into the black rocks we know today. It’s not completely homogeneous though, and significant amounts of other materials from the original plants can still be detected when the coal is analyzed. These data are routinely gathered as part of geological surveys, so when Christopher Doughty from the University of Flagstaff wanted to find out how much over-sized herbivores like dinosaurs impacted their ecosystems, the coal was an attractive data source.

Comparing coal collections

Obviously, nobody can be exactly sure where these huge dinosaurs were dropping their dung, but the fossil record does provide evidence about where dinosaurs were spending their time. Doughty focused his study on two batches of coal deposits, with one being primarily samples from the western United States, dated to the Cretaceous period, and the other coming from Appalachia’s Pennsylvanian subperiod, a time that predated any true dinosaurs by over 40 million years. As expected, the coal, and thus the plants, from the Cretaceous had much higher nutritional levels, with an average of 136 percent more calcium, magnesium, phosphorus and sulfur. These nutrients were also more evenly distributed geographically, indicating that the dinosaurs that were depositing them weren’t congregating for extended periods of time in a single location. Based on the bathroom habits of modern herbivores, Doughty estimates that a multi-ton herbivore was likely to walk between four to 10 miles before taking needing a rest stop, making sure that no single plot of land got all the nutritious feces.

As much as these patterns make sense, it’s hard to be conclusive about this activity. To rule out non-fecal explanations for the differences between the western and Appalachian coal, like erosion or precipitation, aluminum levels were used as a kind of control. Aluminum is naturally occurring but toxic to plants, so if it was also more prevalent in the Cretaceous coal, it might suggest that these elements were added independently of plant growth cycles. However, aluminum levels were very similar from both batches of coal, indicating that changes in geology and the weather were not responsible for the enriched coal. While it’s not the same as finding a massive collection of distributed coprolites, it does look like dinosaur poop made a big difference to plants’ health.

Plants deprived of dung

So if plants seemed to do better when there were huge herbivores spreading nutrients near and far, where does that leave our ecosystems today? Unfortunately, it looks like human development has broken this dynamic, as we’ve purged many habitats of their plant-eating megafauna. Those that remain are also unable to roam as freely as their ancestors did, which is likely creating pockets of nutrition in places where the buffalo still roam, while leaving other areas less inviting to plant life.

Source: Signatures of Dinosaur Poop Found in Cretaceous Coal Seams by Katherine Kornei, Eos

On November 16th, 2017 we learned about

Bacteria swim and sense their surroundings with a single piece of anatomy

To walk down the street, your body employs over 25 muscle groups to control your gait and keep you upright. If you happen to bump into something, your foot has between 100,000 to 200,000 nerve endings in the sole alone to capture an enormous amount of detail about what you just hit. This works for us, but there are simpler ways to get around. After all, even lone bacteria can propel themselves through the world, making due with minimal sensory information. Exactly how that was all done with a single cell actually been a bit of a mystery, but researchers from the University of Basel have finally found how these tiny organisms interact with their environment.

The key feature in bacterial navigation is a long tendril extending from the cell membrane called the flagellum. As long as the bacteria is in some kind of liquid, from saliva to water to mucus, the flagellum spins, pushing the bacterium around like a stringy propeller on an outboard motorboat engine. It’s movement is powered by a stream of protons entering the cell, at least until it hits something.

Sticking a landing

When the bacterium comes in contact with a solid surface, the flagellum reveals its secondary function: a sensory “organ.” When the flagellum hits something, the the wall of your sinuses, the flow of protons is disrupted, which triggers further reactions inside the cell. Aside from the flimsy propeller being slowed down, the change in proton movement tells the bacterium to create an adhesive, which it then uses to anchor itself to that solid surface. In just a few seconds of contact, the bacterium is setting itself up to potentially launch an infection in the tissue it just bumped into.

Researchers hope that by understanding how bacteria initiate infections, we may be able to develop the means to disrupt them. This study was done with harmless Caulobacter bacteria, but the method of propulsion and mechanical sensitivity is probably used by many species of bacteria, including those that cause health problems in humans. With any luck, further research will allow us to prevent or at least slow this anchoring process, offering new forms of treatment as an alternative to our weakening library of antibiotics.

Source: Bacteria have a sense of touch

On November 15th, 2017 we learned about

Oceanic noise pollution poses serious problems for fish’s reproductive success

When submerged in water, human communication often gets reduced to hand-gestures, like a vague game of slow-motion charades. Without specialized equipment, it’s the best we can do in an environment that doesn’t accommodate our air-based speech. This limitation for our species has led to a lot of ignorance about how other species click, chirp and sing in the water, but new investigations are now discovering the importance of sound to the denizens of the sea. Scientists are now finding that aural communication is much more widespread than headline-grabbing whales and dolphins, extending all the way to the ocean’s floor with mating songs of the humble goby.

Gobies like Pomatoschistus microps are small fish that live usually don’t live more than a year. They live in shallow, coastal areas around Europe, and are mostly preyed up on by larger fish like cod. The sand goby (Pomatoschistus minutus) spends most of its time sitting motionless on the sea floor, waiting to grab passing invertebrates to eat. They perk up a bit in the summer though, when the males will commandeer an empty clam shell, sitting under it while courting local females with song. If the song catches the ear of a female, she’ll spawn her eggs under the male’s shell where he will fertilize and guard them until they hatch.

Sefloor seranade

The goby’s song itself probably won’t sound much like a good Barry White album to a human ear, but experiments have found it to be crucial to reproductive success. To test the role of the male’s song, researchers subjected two female and one male goby to the sound of a motorboat engine, simulating the kind of noise pollution that has become common in today’s oceans. When the humble “purring” (or in case of the common goby, “woodpecker-like”) sounds of the male goby had to compete with sounds of human activity, there was very little interaction between the male and female fish. In the cases where the fish did mate, the eggs seemed to somehow be affected by the noise as well, with half the eggs dying before hatching, and the surviving eggs taking longer to gestate. While slower courtship is likely explained simply by noise drowning out the male’s song, researchers aren’t sure why the eggs also suffered once they’d been fertilized.

This sensitivity to noise is a mounting problem for our oceans, where ships of all sizes, as well as undersea drilling and mining, are making more and more noise each year. However, this study also suggests that noise may be a consideration on small scales as well. The scientists behind this study worry that labs that work with fish need to take greater care to keep noise to a minimum, as fish in aquariums may be reacting to sound and skewing research results more than researchers have commonly been accounting for.

Source: Female fish like males who sing by University of Gothenburg, Science Daily

On November 15th, 2017 we learned about

Climate models that explain colder conditions on dwarf and exoplanets

As the Earth struggles with atmospheric warming, scientists are finding mechanisms that are actually cooling more distant worlds. Unfortunately, they’re not systems that we could reproduce to deal with our greenhouse gas problem on Earth, but understanding what chills the atmospheres of these distant bodies will likely help with the search for habitable worlds in other solar systems.

Pluto is colder than we calculated

Everybody knows that Pluto is cold, but the dwarf planet still surprised scientists with just how cold it really was. Remote measurements of the elements in Pluto’s atmosphere suggested that the Sun should warm its surface to around -343° Fahrenheit, but that isn’t what the New Horizons spacecraft measured when it flew by in 2015. Instead, more direct measurements found that the atmosphere was a frosty -397° Fahrenheit. Over the last two years, researchers have been looking through the collected data to see what could account for this temperature difference.

The current hypothesis is built around the size of the particles in Pluto’s atmosphere. Most atmospheres are made of gas, meaning the atoms and molecules suspended in the sky are tiny and fairly energetic. Pluto seems to have some larger hydrocarbon particles in the mix though, suspended as solid crystal structures instead of gases. Even though these particles are small enough to be measured in nanometers, they’re big enough to interact with heat from the Sun in an unusual manner. Instead of trapping heat against the dwarf planet’s surface like a greenhouse gas, they’re likely absorbing heat from the Sun and surrounding atmosphere, then radiating that heat back into space. This means that the heat is essentially reflected before it has a chance to warm Pluto up.

Heavy snowfall on a hot planet

While Pluto’s hydrocarbon haze may be an effective heat shield, the exoplanet Kepler-13Ab uses similar mechanisms in even more extreme circumstances. The giant planet has a close orbit around its star, Kepler-13A, and thus doesn’t doesn’t rotate like the Earth does on a daily basis. This leaves one side of the so-called “hot Jupiter” in constant daylight, raising temperatures as high as 5,000° Fahrenheit. The night side is then left in permanent darkness, with temperatures dropping appropriately.

Kepler-13Ab was found to have titanium oxide (TiO) in it’s atmosphere, which by itself isn’t unusual for a gas giant planet. Usually this leads to higher temperatures in a planet’s upper atmosphere, as the TiO acts like a greenhouse gas more or less, collecting and emitting heat. Kepler-13Ab changes that formula thanks to its immense gravity, which is six-times greater than Jupiter’s. So instead of remaining in the sky as gases, the planet is pulling some TiO down on its cold, night side as larger particles, almost like a form of snow. As the snow gets pulled down, it takes some heat away with it, lowering the maximum temperature in the upper atmosphere. Without Kepler-13Ab’s intense gravity, the particles would be more likely to recirculate in the atmosphere again, redistributing heat.

Nobody is planning to visit Pluto or Kepler-13Ab any time soon, but these extreme climates will help us as we search for more temperate planets. Being able to understand all the variables that can influence a planet’s climate, including less obvious factors like gravity and particulate size, will make it easier to identify the more subtle conditions that could make some planets pleasant place for life to take root.

Source: Astronomers discover sunscreen snow falling on hot exoplanet, Phys.org

On November 14th, 2017 we learned about

Ancient otter had a bite big enough to put mollusks, mammals, birds and turtles on its menu

Paleontologists may have identified the most dangerous, and by extension, cutest, otter to ever live. Siamogale melilutra is estimated to have grown to 110 pounds in size, possibly acting as the apex predator in its local environment. This assessment isn’t just based on the otter’s wolf-sized body though, as researchers have also simulated its jaw strength, suggesting that this fuzzy critter could have probably munched just about any animal it got it’s mouth on.

S. melilutra lived around six million years ago in what is now southwestern China. It would have been a wet, swampy area with thick plant growth with plenty for an otter to eat, assuming these carnivores ate similarly to their modern river otter cousins. That’s a wide range of possibilities, as modern otters are known to eat everything from plants to rodents to clams. Once researchers factored in how the size of S. melilutra must have influenced its bite strength, they had to expand the possibilities to include thick-shelled mollusks, birds and even the local turtles if it felt like it.

Baby-faced with big bites

Otter bites are generally pretty impressive, being driven by large muscles in their face that also lead to the cute cheeks people find so adorable. To create a more detailed picture of S. melilutra’s bite, researchers scanned fossilized jaws with computed tomography (CT), getting a picture of the ancient bones inside and out. They calculated the range of the jaw’s movement and how much force it could exert on a crunchy snack, then compared that to similar calculations based on modern otters to see if the results fit with better known otter-anatomy. The overall trend was that smaller otters tend to have smaller, sturdier jaws than their larger kin. However, S. melilutra broke that trend as it’s jaws were six-times stronger than you’d expect for it’s size. Basically, it’s bite was even bigger than it’s already large body.

While calculating the physical forces a skull can exert is helpful, otters tend to complicate matters with their behavior. Most animals’ bites are correlated with the food they need to break apart more than their overall size. If this were strictly true in otters, clam-eating sea otters would have even more enormous jaws than they already do in order to break open hard shells. By using rocks, the otters have come up with an alternative to bigger teeth and jaws, and so their anatomy doesn’t need to match their diets so closely, allowing for the closer correlations with body size. Even allowing for this otter-specific weirdness, the fact that S. melilutra had both larger and stronger jaws still suggests that it was a top predator, as its powerful bite would have put just about everything in it’s environment on the menu, even without figuring out how to break shells with stones.

Source: A giant, prehistoric otter's surprisingly powerful bite by Charlotte Hsu, University of Buffalo News Center