On July 7th, 2015 we learned about

How a seahorse is akin to a theoretical robotic monkey

Seahorses are deviants, let’s just get that out of the way. They’re named after terrestrial quadrupeds for their face, the males defy convention by handling gestation, and now we’ve learned that they don’t agree with just about every other fish that tails are to be used for propulsion. If that weren’t enough, they’ve evolved the world’s first square tail, making them a better match for possible robots than other tail-reliant animals.

These tails aren’t just to look unusual, of course. While they’ve consolidated their locomotion to their fins, these tails are still employed regularly as anchors. Like a monkey or chameleon, they use their tails to wrap around objects like sticks or sea grass. Remaining stationary is a key component to their hunting, which relies on holding still in order to ambush small bits of shrimp and fish floating by in the water. To help master this important grip, their tail seems to have evolved a number of useful specializations.

The tail that makes for a better sea monkey

Replicas of the tail shape were created and found to offer a superior grip than most round, prehensile tails. The squared-off shape allows more surface area to come in contact with the anchoring object, making it more effective. While this tails shape sacrifices some flexibility, a tight grip is obviously more important than fluid movement when you’re trying to hang onto swaying kelp.

For the square shape to be rigid while retaining some flexibility, it had to be segmented, like a series of nested, square beads strung along the animal’s spine. Each segment was found to be very strong and resilient, retaining its shape after being subjected to pressures that would have deformed cylindrical tails. While large enough jaws can obviously overpower this armor, it would be enough to help protect the seahorse from smaller predators.

While humans aren’t looking to stalk shrimp more effectively, the grip and strength of the seahorses tail is of interest to robotics designers. On a large scale, just grips could be of use in dangerous rescue operations. On a small scale, this kind of small but considerable grip may be of use for internal medicine, where small pieces of tissue need to be held in place for surgery. There don’t seem to be plans, however, to replicate the weirdness of the seahorses themselves though.

Source: Why Seahorses Have Square Tails by Rachel Nuwer, Smithsonian

On July 7th, 2015 we learned about

Sussing out what we see in each other’s faces

As social animals, humans love looking at faces. Even objects that vaguely resemble two eyes and a mouth are often anthropomorphized, sometimes with personalities being attributed to the sink, wall socket or headlights in the process. But cues are we looking for when we have these reactions? In an actual human, what are we responding to when we feel that somebody seems nice, just from glancing at them? It seems that some traits are built into the shape of a face, while others are coming what expressions are being made at the time.

Isolating these two influences was not completely simple. Researchers picked a very range of faces and qualities to look for in order to avoid a sprawling web of interconnected traits. On the facial structure side of the coin, they tested if the shape, and more specifically the width of a face, could influence how people saw personalities and physical strength. Strength was selected, because previous studies had found correlations between wider bone structure and higher testosterone, giving this connection a chance to be perceived by test subjects.

The range of expressions was a bit more varied, but the core traits were based around how trustworthy someone might be when they were frowning, scowling, or smiling. Many combinations of the above were compared, even though the initial seeds for these variations were a small batch of men who had had their photos manipulated to accentuate and vary these different attributes.

Sorting through shape and sentiment

The findings are that humans, or at least the humans participating in the study, really are connoisseurs of reading faces. Observers of faces were able to parse different attributes with a fair amount of granularity— nobody was attributing emotional or personality traits to bone structure, while strength was discretely tied to the width of a face. This may seem obvious, but there researchers were curious if an angry, aggressive expression might be perceived as strong, since signs of aggression can sometimes influence us more than we might realize.

So in the end, how people just your personality is, thankfully, under your control. Even if you’re not a fan of your nose, cheek bones or chin, the way to convince people that you’re warm or trustworthy is just to smile.

Source: Your Facial Bone Structure Has a Big Influence on How People See You by Jessica Schmerler, Scientific American

On July 6th, 2015 we learned about

Bird ballads boosted with beak beats

A good song has more than just a catchy melody or clever lyrics. To really be something that makes your audience want to move, your song needs a good rhythm as well, a fact apparently not overlooked by songbirds like the Java Sparrow. While these birds don’t have a metronome or drum kit handy, they have been found to use their beaks to click a beat while they sing, sort of like an avian beatboxer.

The sparrows’ beat clicking, excuse me, beak clicking does follow the beat of their song, indicating that it’s not accidental noise as a bi-product from singing. They also haven’t been found clicking when they weren’t singing, either to themselves or when courting a female. Further reinforcing the sense of intent is that, like the songs themselves, the beats seem to be taught from fathers to their sons. This isn’t to say that percussion is strictly the product of family legacies, as experimental sparrows raised with other species of birds, or by themselves, would occasionally use beak clicks in their songs as well. They just weren’t using any established patterns that would have otherwise been shared with them.

Why bother with a beat?

Female Java sparrows don’t sing themselves, but they will click their beaks along with a courting male, which may lead to possible explanation for why clicks have become a part of the males’ musical repertoire. As the female syncs up and participates in the beat, the monogamous birds may form a closer bond with each other. Whether or not there’s actual communication happening in these clicks, or simply an important, shared experience, remains to be seen (and probably heard.)

Source: Birds Tap Their Beaks in Rhythm to Songs by Jennifer Viegas, Discovery News

On July 6th, 2015 we learned about

The sound of chewing makes for tastier mustard

Does sound affect plants? Some gardeners swear that playing music for your plants will help them grow, although there’s a troubling lack of consensus about what music causes what effect. For example, 70’s rock music has been labeled a blessing or a curse for a garden, depending on your source. However, a recent experiment did seem to connect a single, specific sound to changes in the plant’s chemistry— the sound of a caterpillar eating leaves.

Specific defense to specific threats

Some Arabidopsis plants, also known as Mousear Cress, were played recordings of a cabbage butterfly caterpillar eating leaves of that species, and then checked for changes in their physiology. After the recording, the plants had measurably increased the amount of mustard oil in their leaves, which is the primary defense plants in the order brassicales have against these insects. Control plants were played a recording of silence, a recording of similarly pitched insect songs, sounds of the wind, or left in actual silence, none of which triggered the same spike in insect-warding glucosinolates. This suggests that not only are the plants sensitive to sound, but they have some sense of discrimination about when to activate this extra defensive measure.

The benefits of being selective with mustard production is really a matter of managing resources. The extra effort and resources would be very draining if the plant upped the mustard oil production every time the wind blew. But waiting for feeling a bite from the caterpillar might be too late, while being sensitive to sound gives the other leaves on the plant a chance to fend off further chomping.

What other sounds count to your garden?

While cabbage butterfly caterpillars and brassicales have been in an evolutionary arms race for millions of years, there’s also a chance that this defense isn’t so narrowly focused that the plant can’t employ it against other herbivores. Or that other plants don’t use a similar concept, although without a dynamic toxin to produce it may not be a universal concept. A rose can only grow thorns so quickly, after all.

Source: Plants Listen for Hungry Caterpillars, First-of-Its-Kind Study Suggests by Emma Weissmann, National Geographic News

On July 6th, 2015 we learned about

Size might not matter when it comes to brain complexity

The size of our brain has been a huge influence on human evolution. Aside from potential gains in intelligence thanks to a shifting brain-to-body ratio, our skulls have even been reshaped to accommodate the extra mass we carry in our heads. It was hypothesized that the evolutionary growth of our brain outpaced the growth of our skulls, forcing the brain to form increasingly complex folds, nooks and crannies (aka, gyri), which further boosted our cognitive abilities. However, a fossilized monkey skull has called that relationship into question, thanks to it’s high complexity but diminutive size.

The brain box of a 15 million-year-old Victoriapithecus was scanned and analyzed in 3D. The brain was found to fit expectations in its size, but defy them in its form. Across its 36 cubic centimeters, it showed an impressive number of gyri and a particularly large olfactory bulb. What’s more, this large odor-processing center didn’t seem to come at the cost of visual centers, which matched the monkey’s contemporaries. This goes against some ideas about some modern primates, which seem to have ‘sacrificed’ some of our olfactory centers for better visual capabilities.

Cause and effect called into question

This complexity also challenges models explaining primate brain evolution. Larger brains might not have predicated density and complexity as previously assumed. This actually supports recent genetic evidence that the genes driving brain size and complexity are actually independent. So rather size driving complexity and sophistication, the reverse seems to have been true for primates like ourselves.

Source: Old World Monkey Had Small But Complex Brain by Bahar Gholipour, Brain Decoder

On July 5th, 2015 we learned about

Sea squirts use their digestive tracts to avoid being digested

A sea squirt is a small, marine invertebrate animal that you could easily confuse for a squishy chunk of a coral reef. The tube-shaped creatures live attached to a fixed surface of some sort, then passively filter-feed on particulate in the water. This is not to say that their life is without drama— when danger is detected, the sea squirt Polycarpa mytiligera can take the concept of elective amputation to a whole new level and eject their digestive tract out at the potential predator, hopefully frightening it away. Or at least making it loose its appetite.

When the sea squirt feels like something is about to bite it off its perch, in about 16 seconds it will regurgitate it’s digestive tract out its mouth, possibly into the mouth of the predator. This can include everything from the stomach down to the rectum, leaving the squirt a small, slightly crumpled version of itself. Aside from the startling visual, the guts repel fish because they apparently taste bad, and will be spat out by fish who give them a nibble. Of course, this can only considered a defensive maneuver if the sea squirt’s survival rate goes up as a result, and remarkably, they can survive nearly turning themselves inside out.

Regenerated rectum, intestines, and stomach

After 12 days of a defensive ejection, sea squirts were found to have already grown digestive organs. Not only that, but they seemed to be immediately functional, as feces was already collecting in the new rectum, meaning they had been eating for some time already. There must be some delay, of course, because sea squirts had been known to be occasionally found in a gutless state for many years. The defensive concept was only solidified for researchers after they accidentally triggered ejections when pinching squirts to remove them for study.

Regeneration in marine life isn’t unique to sea squirts like Polycarpa mytiligera. Sea cucumbers can also eject organs on demand. Sea stars have a slightly tangential set of abilities, as they regularly invert their stomachs to eat, although they don’t really amputate them. For actual regeneration, sea stars just regrow limbs.

Source: Nervous Sea Squirts Squirt Out Their Stomachs and Grow New Ones by Elizabeth Preston, Inkfish

On July 2nd, 2015 we learned about

The ptrouble with pteroids and pterosaur flight

A convenient aspect of evolution is that you can usually look at something as part of a progression or sequence. Patterns seen in related plants or animals can provide a starting point when studying a new species. For example, you can look at quadrupeds the world over and compare forelimbs of many creatures and see how limbs ending in digits are the underlying template of many toes, fingers, and even flippers. Pterosaurs, however, have thrown us for a bit of a loop with what seems to be a brand new bone, throwing our usual body-plan references out the window. Further confounding things is that, unlike some other lineages from the Mesozoic, pterosaurs have no surviving descendants to compare against either.

The bone in question is called the pteroid. It was located somewhere on the front of pterosaur wing. The other bones are understood to be specialized wrist and fingers from which the bulk of the wing membrane was attached. The assumption is that the pteroid was then an attachment point on the front of the wing that may have provided a bit of reinforcement and extra control as the pterosaur wiggled it. The questions surround just how it was attached. Did it stick straight out from the wing? Or did it point from the wing back toward the body, more parallel to the rest of the wing bones?

Fossils are not a snapshot of life

While fossilized pteroids have been found more or less in place along wings, orientation is a trickier detail because fossils are almost always jumbled about by the time we find them. This disruption to an animal’s skeleton can happen right after death, thanks to being moved by water, gravity or other animals who want to eat the body. Shifts in geology can also obfuscate a skeleton’s layout if given enough time.  Even the process of decomposing can be disruptive, as different tissues slacken and rot at different rates, moving the body around. This means that even the best preserved skeletons shouldn’t necessarily be trusted to tell us just how such a small bone sat on these creatures’ wings.

Looking from fossils to physics

So one way this can be studied without perfect specimens is to reverse engineer the wing with computer simulations. It’s been found that a pteroid pointing forwards would increase the amount of surface area of the wing enough to measurably increase the amount of lift they could generate. The drawback to this is that that orientation was also found to put much more stress on the bone and related membrane. The membrane would then need to be very flexible, making it a poor material for the leading edge of the wing. An inward facing pteroid, however, was found create a stable leading edge to the wing without adding stress. It also seems to be a better match for a wide variety of pterosaur wings found thus far, and is thus the more attractive answer at this point.

Source: Sciencespeak: Pteroid by Brian Switek, Laelaps

On July 2nd, 2015 we learned about

Brassicales’ made themselves tastier by battling with bugs

My kids don’t like wasabi very much. They’re not keen on mustard either, which is exactly what this family of plants is hoping for. The strong flavors derived from the plants in the order Brassicales, including cabbages, horseradishes, mustards and kale, aren’t supposed to taste good, particularly to cabbage butterflies (pieris rapae). The fact that humans chose to enjoy what was supposed to be a fierce defense system is just a reminder of how narrow a niche some adaptations end up being.

Brassicales’ ‘flavor-as-bug-repellant’ development started over 90 million years ago. Ancestors started growing glucosinolates, chemicals that are toxic to insects. This way the plant could grow without being completely consumed by cabbage butterfly caterpillars. Those hungry caterpillars then had to either find something else to eat, or come up with way to enjoy the dangerous plants.

Caterpillar countermeasures

The caterpillars that started producing a glucosinolate-defusing protein lead the next charge in this little arms race. The advantage was two-fold: they could not only eat Brassicales again, but they were the only insects left to do so, meaning they now had them as their own private buffet. So the plants had scared off most insects, but intensified their value to these caterpillars all the more. The response was new branches in the plant family tree, using different amino acids to make the caterpillars’ defensive-proteins obsolete.

This cycle continued over and over, leading to new, specialized species along the way. In response to their local caterpillar threats, plants ended up creating new flavors along the spectrum of “bitter” and “burning.” These defenses technically work on humans too, since that’s the source of the flavors we enjoy when eating these plants, but in application they’re not actually a threat to us.

Enjoying our position from the sidelines

My kids may still fall for kale or wasabi’s trick, and feel like it’s not safe to eat (often along with a resounding “yuck!” or “it’s spicy!”). Despite my enjoyment of these foods, I have to allow for these reactions to an extent, since bitterness is generally associated with toxins. But once you get past that, you can discover that these defensive plants have really just made themselves more delicious. Thankfully, our ability to selectively breed crops at this point should save us from the caterpillar’s struggles with potentially toxic wasabi down the line.

Source: Why You Should Thank A Caterpillar For Your Mustard And Wasabi by Jessie Rack, The Salt

On July 1st, 2015 we learned about

Stifled rats solve mazes while they slumber

You know that dream, where you’re walking down a hallway, and suddenly there’s an intersection, and you turn left and then there’s this pile of food just waiting for you? No? Well, maybe if you were a lab rat this would seem more familiar. Rats have been found to not only to replay experiences they’ve had while they sleep, but also to imagine aspirational changes in those memories.

Researchers have been tapping into rodents’ thoughts for a while now, and have a decent working model for where to look for different kinds of thought processes when they’re plugging electronic sensors into rat brains. They know that when the rat experiences a new location, certain parts of their brain are activated as they map out that space. It’s specific enough that when the rat is sleeping later, they can confirm what location the rat is remembering as it rests. The next question was if the rats could conceptualize a space they had observed but not actually experienced.

Confirming the accuracy of rats’ dreams

The rats where tested by being put in a simple, T-shaped maze. At the intersection, food was visible down one path, but it wasn’t accessible. Later, when the rats brains were going over these memories, their internal mental maps seemed to extend the experience, as if the rat was imagining moving past the barriers, into the space with the food that they had not been able to visit that day. The next day, the rats were allowed to revisit the maze without the barriers, and the mental map that had been plotted the night before matched their eventual experience in the maze.

The rats put a lot of mental energy into this task while they slept, although at first blush it’s not clear that there were any immediate benefits to it (ie, they weren’t clearly faster in the maze the next day). Further tests will look into how this mental energy pays off, but for now it’s interesting just to confirm that rats would have a dream like this in the first place. It may mean that some of our dreams’ importance during sleep is not just to reencode memories, but to actually try to do a bit of abstract problem-solving before reengaging with the task later.

Source: Rats Dream About the Places They Want to Explore by Kiona Smith-Strickland, D-Brief

On July 1st, 2015 we learned about

Metallic hair helps ants beat extreme desert heat

Hair is usually employed by the animal kingdom for insulation. Some famous examples include species with so much fur they’re named for it, like a woolly mammoth. This is only one side of the insulation story though, as Saharan silver ants prove hair’s utility in staying cool as well. This is important, as they often find themselves out looking for food in temperatures of up to 158º Fahrenheit.

The hair works in two ways, reflecting sunlight and helping remove heat from the ants’ bodies. The distinctive silver coloring of their tiny hairs acts like a layer of tin-foil, reflecting visible sunlight as well a near-infrared light when the ants venture outside. Aside from the color, the shape of the hairs help too. Rather than round shafts, each hair is shaped like a tall, triangular prism. They also have a hard bend in them, so that they don’t lay flush against the ant’s carapace. Instead, they leave a then layer of air that helps circulate air around each hair, helping to draw heat off of it, and therefore off the ant. It’s similar to heat sinks used in cooling computer components, only on an amazingly compact scale.

The combination of these two pieces of biological engineering make a huge difference. Properly hairy ants have their temperature reduced by as much as 50º F, which is good since the ants die at 128.48º F, leaving them a bit of a buffer when they go out searching for food. All together, this system allows the ants to actually take advantage of these extreme temperatures. Even though they only risk exposure for 10 minutes at a time, the environmental heat helps keep predators away. Since they’re the animal with the air-conditioning, it makes mid-day savaging much saver than dusk or at night, when most desert animals are more active.

Source: These ‘silver’ ants use special hairs to survive the harshest desert heat by Elahe Izadi, Speaking of Science