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Design, Naturally: Wasps take the sting out of brain surgery

By Anwen Bowers

“I cannot persuade myself that a beneficent & omnipotent God would have designedly created the Ichneumonidæ with the express intention of their feeding within the living bodies of caterpillars …”

This statement from Darwin is often quoted in discussions about his changing relationship with religion as he developed his theory of evolution. 150 years later, the ichneumonidae in question are taking a step towards shedding their demonic reputation by inspiring a new approach to neurosurgery.

| Image: Sean McCann
Pretty deadly. We could look at ichneumonidae ALL DAY.| Image: Sean McCann

The ichneumonidae are a subfamily in possibly the largest group of animals in the world – the parasitoid wasps. Estimates of the total number of ichneumonidae species alone reach up to 100,000 – more than all the vertebrate species in the world. The wasps gain their name because they brutally kill their host species, as opposed to parasites which drain the resources of an organism without causing significant harm. Indeed, life histories of the parasitoid wasps are close to the stuff of nightmares.

The extremely high diversity of ichneumonidae has arisen because each species of wasp has evolved to target just a single type of prey, and to do it as efficiently as possible. Each species is distinguished by its specialised weaponry or tactics that allow them to tackle their prey in their niche habitat or lifestyle. For example, Lasiochalcidia igiliensis’ chosen host is the antlion larva, a ferocious predator in its own right with vicious jaws that it uses against a range of arthropod prey, even spiders.

antlionlarva
A badass Antlion larva clearly has only one thing to fear. Fear of L. igiliensis itself. | Image: Larah McElroy

The seemingly fearless L. igiliensis has been observed to bait the antlion larva, encouraging it to attack the wasps itself. At the point of attack, the wasp will use its powerful legs to prise the jaws of the antlion open, whilst simultaneously depositing an egg into the antlion larvae’s throat. There the egg will incubate, feeding on the antlion from the inside, until the time for metamorphosis comes. At this point the wasp will burst out from the antlion, not unlike the infamous scene from Alien.

Strategies in other species include a fibrous mesh that traps air allowing the wasps to dive down and reach caddis fly in their underwater habitat, and a hormone invisibility cloak that allows the wasps to live within an ants nest, even up to adulthood, without detection. These guys are the Q Branch of the insect world.

M. macrurus prepares to drill. | Image: Evan Kean
M. macrurus prepares to drill. Just look at that ovipositor. Stunning, and inspiring… | Image: Evan Kean

Here at Rising Ape we can vouch from experience that great ideas happen when you put a bunch of scientists from different backgrounds in a room, and maybe give them a bottle of wine. This seems to be what happened in the case of Dr Ferdinando Rodriguez y Baena, a medical engineer who found himself inspired by a serendipitous dinner party conversation with zoologist and biomimetics expert Julian Vincent.

Vincent described how the parasitoid wasp species Megarhyssa macrurus, is able to use her egg laying tube to drill down into tree bark, where she deposits her eggs onto the larvae of the pidgeon tremaz horntail (how did this come up as a topic?! Over dessert?). This is possible thanks to a complex structure of three tubes that can bend and flex as the wasp drills, allowing her to position her eggs with pinpoint precision.

needlepic_imperial
The three parts of this needle echo the ovipositor of the drilling wasp and give it unparalleled flexibility. | Image: UCL

This elegantly specialised structure gave Baena the idea for a new style of needle that mimics the ovipositor. The design allows surgeons to control and manoeuvre the needle inside the patient, navigating around sensitive and fragile parts of the brain. This minimally invasive surgical procedure could even allow surgeons to deliver drugs to very specific areas in the brain, potentially treating diseases such as brain tumours and Parkinson’s. By saving lives for a change, the ingenious ichneumonidae wasps could be about to improve their reputation.  Who knows, even Darwin may have approved.

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Design, Naturally: Sharkskin V Superbugs

By Anwen Bowers

Antimicrobial resistance is one of the biggest challenges faced by the healthcare industry. The evolution of superbugs such as MRSA is evidence that the arms race between antibiotics and bacteria is not a sustainable strategy for preventing infection and keeping patients healthy. Bacteria are able to make infinite changes to their DNA, but there isn’t an infinite supply of new drugs available to target them. Scientists looking for alternative methods to tackle the spread of disease causing bacteria have turned to the natural world for inspiration.

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Opens doors, spreads diseases, can be opened by velociraptors. | Image: Public domain

Bacteria in hospitals spread through contact. If a person touches a surface that hosts bacteria, they can pass it along next time they touch a piece of equipment, or a patient. So could making surfaces inherently resistant to bacteria be an effective way of stopping the transfer and spreading of disease?

Traditional approaches to keeping surfaces sterile involve using some sort chemical agent, for example treating socks with silver to keep smelly feet at bay (equally effective against vampires). The disadvantage of chemical treatment is that protection is short lived, and needs constant renewal. Research suggests that silver nanoparticles in socks last not much longer than a few washes, as the silver is rinsed out into the environment where it becomes a poisonous threat to wildlife.

In a paradigm shift in strategy, scientists have proposed a new mechanical approach to keeping surfaces clean. Taking inspiration from the sea, they want to develop a texture that prevents bacteria from spreading by discouraging microbes from settling in the first place.

dirty boat hull
Hull is filthy. The boat’s hull that is. | Image: Glenn Batuyong

Place almost anything underwater and it won’t be long before a thin film of green slimy phytoplankton will start to settle. This plankton is the trigger for a chain reaction of settlement, as larvae of adhesive animals such as anemones and barnacles will soon follow. This has long been a problem for the shipping industry as fouling like this on ship’s hulls creates a huge amount of drag, slowing down the vessel and adding fuel costs. Even whales, despite their constant movement, will succumb to the nuisance of barnacles and parasites.

But scientists observed that sharks remain clean and crust free, even into old age. For a long time it was thought that sharks move too quickly through the water to give anything any time to settle. Closer inspection of the surface of their skin provided an alternative answer. Sharks are covered in specialised scales called dermal dentacles.

Denticles.jpg
Sharks: Creating the worst place for bacteria to hang out for 100 million years | Image: Pascal Deynat/Odontobase

Dentacle means “small tooth”, a name derived the dentine tissue from which they’re made and the same found in your teeth. Dermal dentacles are highly textured, and when meshed together they form an extremely complex surface, full of micro mountains and canyons. This surface appears to be too unstable for any bacteria to settle and establish a community effectively.

Without the base layer of microscopic organisms, the bigger problem of larger, fouler organisms cannot develop, and the shark remains clean and smooth. This evolutionary advantage then helps the seas’ top predators move swiftly through the water in pursuit of their prey.

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‘Phelps who? Bet I’m cleaner and faster.’ | Image: Mark Conlin

Shark skin is already well studied, and has inspired a range of products, famously the Olympic grade swimwear that can reduce drag and shave milliseconds of a swimmer’s time. To use it as a surface for hospitals was the idea of Anthony Brennan, founder of the company Sharklettm , who have trademarked a textured pattern based on the structure of sharkskin. The company claims that Sharklettm surfaces harbour 94% less bacteria than standard worktops and equipment.

Installed in places such as drawer handles and even surgical equipment, Sharklettm could be a cost effective way of reducing the spread of bacteria, as well as use of antiseptic and not to mention the time staff spend cleaning surfaces. What has evolved over millions of years could be a solution to a very pressing 21st century issue.

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Y is for You!

It’s been 25 weeks since we started this epic journey through the alphabet together, and sadly we are nearing the end.  At this critical juncture, just one letter away from the finality of zed, I thought I would bestow my Pharaoh powers on to you, dear readers.

Comment below with your burning science questions, and I will answer them all next week in my final ABCs of Interesting Things post.

Thank you for reading.  I leave this quest in your very capable hands.

357px-Uncle_Sam_(pointing_finger)
I want YOU to ask me questions

For those still aching for some interesting science facts, how about these “you” facts:

There are more bacterial cells in and around you than human cells.

All of the atoms in your body were made inside stars, as the great Carl Sagan said the 1980 TV Series Cosmos: “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies, were made in the interiors of collapsing stars.  We are made of starstuff.”

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X is for Xenophobia

By Jonathan Farrow from the Thoughtful Pharaoh

A lot happened in the summer of 1954.  The world’s first atomic power station opened in Russia, Alan Turing committed suicide, the CIA set up a coup in Guatemala, food rationing finally ended in the UK, and the first edition of Sports Illustrated was published.  Some pretty big world events, right?

You know what else happened?  22 white, middle class boys boarded a bus to a Boy Scouts of America camp in Oklahoma.  And I’m going to tell you why you should care that they did.

The Robber’s Cave Experiment

On one (presumably sunny) day in 1954, two busses each picked up eleven 11-year-old children who had been screened to be “normal” (Remember, this was 50s America, so that meant white, protestant, middle class, two parents, above-average test scores) and who didn’t know each other.  The busses drove their “normal” boys to a summer camp called Robber’s Cave and deposited them on opposite sides, each group not knowing that the other existed.

For about a week, under the careful surveillance of psychologists posing as counsellors and camp staff, they participated in group bonding activities.  [In some ways, ethics boards have made psychology a lot more boring.  At the same time, it’s probably better that we now consider it unethical to Truman-show 22 pre-teens].

They camped out, played baseball, went swimming, and generally got to know each other.  They even came up with a name for their groups and emblazoned insignia on their t-shirts and caps.  One group killed a snake by a river and dubbed themselves the Rattlesnakes, the other group decided to be patriotic and called themselves the Eagles.

Then came the interesting part.

The experimenters introduced the groups to each other.

The Eagles and the Rattlesnakes were pitted against each other in a series of competitions – baseball, touch football, tug-of-war, and a treasure hunt.  The key aspect of these games was that one group always won and the other lost.  They were zero-sum games.

The result was a little bit scary.  The groups started to hate each other.  It started off with names like “sneak”, “cheat”, and “stinker” but soon developed into cabin raids, flag-burning, and even one Eagle telling another to brush the “dirt” of his clothes after bumping into a Rattler.  There was some serious xenophobia (fear or disgust for the “other” or “alien”).  The experimenters stopped the activities for fear of escalation to serious violence and started to think about how they might eliminate this extreme prejudice.

The crazy part is that these were all “normal” boys who didn’t know each other beforehand and had no reason to hate each other besides that their groups (that had also only been formed weeks ago) were in direct competition.

The experimenters tried to bring the groups together at mealtimes and for positive evening activities, but that only served to escalate the hatred.  They hurled food at each other at dinner time and jostled to be first in line.

What the experimenters tried next was pretty genius.  They got the groups to try and work together to solve problems that affected everyone.  One night the truck that was supposed to deliver food “broke down” so they all teamed up and pulled it out of the ditch with their tug-of-war rope.  Another day, the water supply pipeline broke and they all worked together to find the leak. These superordinate (larger than the group) goals brought the Rattlers and Eagles together.

Inter-group relationships built because of these events and at the end of the camp, some campers asked to mix up the busses and one group that had won $5 in a competitive contest offered to buy milkshakes on the ride home for the whole group.  How nice.  They had been reconciled as easily as they had been set against each other.

A 1997 study showed how this sort of reconciliation can be contagious.  It isn’t just people who have friends in other groups who will be more likely to be empathetic.  If you know someone who has friends in another group, you will be more likely to be nice to people in that group.  Sounds a bit complicated, but basically if you have a friend who is a clown, it’s not only you who will be more likely to not hate clowns, but also all of your friends.  As soon as a few Rattlers got to thinking that maybe the Eagles weren’t so bad, the positive feelings probably spread pretty quickly.

Chemical Basis for Xenophobia

But what was going on in their brains to make this happen?

Don’t worry, the kids weren’t lobotomized to find out.

A 2010 Dutch study out of the University of Amsterdam showed that Oxytocin, the “cuddle chemical”, might have something to do with it.

Research subjects who had ingested some Oxytocin were more “ethnocentric” than their placebo-munching counterparts.  People with a bit of extra Oxytocin in their systems were more likely to say they would sacrifice the lives of many outgroup members to save the life of one ingrouper and associated more positive, human words with ingroupers and more negative, dehumanizing words with outgroupers.

The Robber’s Cave Experiment was one of the first field experiments in social psychology.  It inspired Philip Zambardo’s Stanford Prison Experiment and Stanley Milgram’s Obedience Experiment.  It pushed people to consider why they acted in bigoted ways and showed how easy it can be to both turn people on each other and bring them back together.  When we mistreat people who belong to different racial/social/economic groups, are we really being any more than rational than the Eagles and Rattlers? No, we aren’t.

To find out more about the Robber’s Cave experiment, read this summary article by the leader experimenter, Muzafer Sherif, and this webpage.

Muzafer Sherif is also famous for a series of studies using an interesting phenomenon known as the autokinetic effect.  he showed that people will create group norms and stick to them even when the group is taken away.

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W is for Wasps

It’s summer time.  And you know what that means? Sure, summer means picnics, barbecues, and sun.

But it also means the coming of the most dreaded outdoor villains: wasps.

Some people freeze up when they see the stripey serial stingers, others try to wave them away.  I prefer the stoic strategy of a short, sharp yelp followed by a crazed hand-waving motion.  It’s not a conscious decision, nor one that I am proud of, but the wasps seem to get the idea that I don’t want them around.

What is a wasp?

Wasp_morphology.svg
Image by Stannered

In taxonomic terms, a “wasp” is any member of the suborder Apocrita that isn’t a bee or an ant.  While that may help useful for biologists, it doesn’t really tell us anything about the creatures.

Wasps are a varied group of hairless, six-legged flying insects that measure anywhere from to 1mm (Fairy Wasp) to 4.5cm (Japanese Hornet).  There are thousands of species of wasp, many of which are specially adapted to feed on and parasitize insects we would regard as pests.

Parasitism

And the way they parasitize those pests can be cruel indeed.  Some parasitoid wasps lay their eggs inside their prey, only to have the eggs hatch a few weeks later, letting their young eat their way out of the unsuspecting caterpillar that has been feeling a strange itch recently.

Other wasps lay their eggs inside plants, genetically modifying a plant’s seeds to suit the wasp’s needs.

Still other inventive wasps have figured out that they can lay their eggs in the nests of other wasps and trick another queen into raising their young.

It seems there is nothing a wasp won’t lay its eggs in.

Fighting Wasps

Not all wasps are content merely laying eggs in unusual places.  Some have acquired a taste for honey.

Meet the Japanese Giant Hornet.

While European honeybees haven’t developed defenses, asian honeybees have discovered a way to fry invaders.

So while you may just think of them as a nuisance when you’re trying to enjoy your picnic, remember that with wasps, there is more than meets the eye.

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V is for Vitruvian Man

VitruvianThis drawing, of a man contained within a circle and a square, is one of the most recognizable in the world.  It seems to fascinate people and has a way of transcending time and space to connect with its viewers.  It also is really easy to parody.

The original document, pictured above and created by Leonardo Da Vinci, has two major components: the drawing itself, and two paragraphs of writing.  Both deserve some attention, because while this image is rather commonplace in our culture, most people don’t realize how many layers there are.

Vitruvius

First off, why is the drawing even called the “Vitruvian Man”?  Is Vitruvius a place or something?

That was my first thought, but it turns out that Vitruvius was a man.  Vesuvius = volcano, Vitruvius = man.

Vitruvius was a roman architect whose ten-part treatise on architecture, De architecura, was the only document about architecture to survive from antiquity.  This means we owe much of our knowledge of the theory behind Roman aqueducts, central heating, and water pumps to this book. It is also the source of the (possibly apocryphal) story of Archimedes, his discovery in a bathtub, and his shout of “Eureka!”.

Vitruvius held that the three basic elements of good architectural design were strength, functionality, and beauty.  These elements are so important that they remain mainstays of modern architectural theory.  He was also especially interested in proportion.  He believed that ‘beautiful’ proportions were those based on nature.  And what more perfect example of nature was there than Man?

He believed that a perfect male body would fit the following conditions and that these proportions could be used to design perfect buildings.

For if a man be placed flat on his back, with his hands and feet extended, and a pair of compasses centred at his navel, the fingers and toes of his two hands and feet will touch the circumference of a circle described therefrom.

And just as the human body yields a circular outline, so too a square figure may be found from it. For if we measure the distance from the soles of the feet to the top of the head, and then apply that measure to the outstretched arms, the breadth will be found to be the same as the height, as in the case of plane surfaces which are perfectly square.

-Vitruvius’ De architectura

And then his writings were lost for more than a thousand years.

They were re-discovered in the 1400s in Italy and gained traction amongst Renaissance artists.

The drawing

And which Renaissance artist should be more intrigued by the challenge of drawing Vitruvius’ man than Leonardo Da Vinci, the namesake of everyone’s second favourite Ninja Turtle?

It's ok Leonardo, you may be my second favourite Ninja Turtle, but you'll always be my favourite Renaissance painter.
It’s ok Leonardo, you may be my second favourite Ninja Turtle, but you’ll always be my favourite Renaissance painter.

Da Vinci realized that in order for Vitruvius’ description to work, the centre of the square needed to be lower than the navel.  This lateral thinking separated Leonardo from other artists whose attempts to keep the same centre for both shapes made their men look strange.

cesariano-vitruvius-1 De_Architectura030

The other thing that separates Da Vinci’s Vitruvian Man is the dual positioning.  It gives a sense of movement to the piece as if it is an early kind of animation.  One unfortunate consequence of this is that the drawing doesn’t render very well in 3D and looks kind of like an alien:

An alien through the trees!  Image by Matt Brown
An alien through the trees! Image by Matt Brown

The writing

The drawing itself certainly draws a lot of attention, but few take the time to look at the writing.  This is partially because it is in illegible script, and the script is triply illegible to me.  First of all, I’m just bad at reading old, faded cursive script.  Second, it’s in Italian and I don’t understand Italian. Third, and most interestingly in my opinion, it’s written in mirror writing.  Why he did this is unknown, but it might have helped him avoid smudging as he wrote with his left hand.

The content of the paragraphs describe all of the proportions present in the drawing.  For Da Vinci (and Vitruvius), the distance between the tip of the fingers and the elbow is called one cubit and it is exactly six times the width of a palm and one quarter the height of a person.

There are 15 such proportions below that I encourage you to try out.  How do you measure up to the Vitruvian Man?

  • the length of the outspread arms is equal to the height of a man
  • from the hairline to the bottom of the chin is one-tenth of the height of a man
  • from below the chin to the top of the head is one-eighth of the height of a man
  • from above the chest to the top of the head is one-sixth of the height of a man
  • from above the chest to the hairline is one-seventh of the height of a man.
  • the maximum width of the shoulders is a quarter of the height of a man.
  • from the breasts to the top of the head is a quarter of the height of a man.
  • the distance from the elbow to the tip of the hand is a quarter of the height of a man.
  • the distance from the elbow to the armpit is one-eighth of the height of a man.
  • the length of the hand is one-tenth of the height of a man.
  • the root of the penis is at half the height of a man.
  • the foot is one-seventh of the height of a man.
  • from below the foot to below the knee is a quarter of the height of a man.
  • from below the knee to the root of the penis is a quarter of the height of a man.
  • the distances from below the chin to the nose and the eyebrows and the hairline are equal to the ears and to one-third of the face.

To learn more about this topic, watch this BBC documentary (part 1, part 2) on the subject that inspired this post.

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U is for Ununoctium and the Island of Stability

Quick, without looking it up: how many elements are there on the periodic table?

If I had asked that question before the first hydrogen bomb exploded in 1952, the answer would have been 98.   In that year, humans succeeded in synthesizing the first element that the crucibles of stars and supernovae hadn’t supplied to Earth: Einsteinium.

Boom.  Image public domain
Boom. Image public domain

Since then, we’ve been busy bees, building bigger atoms by smashing protons and neutrons together.  63 years after the first atoms of Einsteinium were made off the coast of an atoll in the Pacific and according to the International Union of Pure and Applied Chemistry (IUPAC), there are 114 official, named elements.  Those 16 additional elements were not easy to make, but we’re far from done.

I want to tell you the story of the outer reaches of the periodic table. The tale involves magic (no, seriously… there’s an important concept called magic numbers) and a legendary island in the midst of a terribly unstable sea (again, not just metaphors here… Chemists have theorized of an island of stability that lies in the midst of a sea of instability), but the edge of the chemical world is dark and full of terrors.  Before making our way to the brink, I need to prepare you with the tools you need to wade out into the sea of instability to find the island of stability.

Always have to be careful in the world of chemistry.  Image by Eliot Phillips
Always have to be careful in the world of chemistry. Image by Eliot Phillips

So what is an “element” anyways?

Atoms, the basic building blocks of matter, are made up of electrons whizzing around in clouds around central nuclei.  A nucleus is made of positively charged protons and neutrons without a charge. An atom is said to be a particular element because of the number of protons it has.  If an atom has one proton, it will be called hydrogen.  A hydrogen with extra neutrons or electrons will still be hydrogen, but as soon as another proton is introduced, you’ve gone and made yourself a helium.

A cartoon of an atom with electrons in black, neutrons in blue, and protons in red.
A cartoon of a Lithium atom with electrons in black, neutrons in blue, and protons in red.

In that sense, atoms are just like me with breakfast: change up the cereal or the fruit but touch the coffee and I turn into a whole different person.

At this point you might be asking yourself what the point of neutrons or electrons is if they have no effect on the name of an atom.  The utility of electrons is pretty obvious: the tiny, whizzing balls of negative charge allow atoms to bind together and, because atoms are mostly empty space, their mutual repulsion is what gives matter the illusion of being solid.

Neutrons and Why We Need Them

The role of neutrons is a little bit less obvious.  They have almost all the same properties as protons (same mass, same size, made up of quarks) but lack a charge.  This similarity but lack of charge keeps them subject to the strong nuclear force, just like protons, but avoids the electromagnetic force.  The strong force acts only at very short distances and, like its name suggests, is very strong.  The electromagnetic force, like Paula Abdul suggested in the 80s, acts to keep like charges apart and opposite charges together.

That means protons have a problem if they want to live together in a nucleus.  Protons are by definition positively charged and would be repelled by each other if it were up to the electromagnetic force alone.  This is where neutrons come in.

Neutrons act like nuclear glue: they exert extra strong nuclear force pressure to keep protons together without any electromagnetic effects.  Small nuclei don’t need much glue: Helium has 2 protons, 2 neutrons; Lithium has 3 protons and 4 neutrons.  Bigger nuclei need a lot more glue (e.g. gold – 79 protons, 118 neutrons, lead – 82 protons, 126 neutrons).

Charting the Nuclear Waters

The question soon became: how big can we go?

It has long been known that any element with more than 82 protons (anything past lead on the periodic table) will be inherently unstable.  It will decay radioactively by shedding protons and neutrons until a stable configuration is reached.

Radioactive elements are still elements, though.  They just don’t stick around for as long.  Typically, heavier atoms are less stable.  Just ask Livermorium, whose atoms have a half-life of only 60 milliseconds.

If you start to graph the stability of atoms according to their number of protons and neutrons, it quickly becomes apparent that larger nuclei need proportionally more neutrons to be stable.

asd
The black line at 45 degrees shows when proton numbers = neutron numbers. The black dots are stable nuclides. Past 82 protons (lead), there are no more permanently stable nuclides.  Image by Sjlegg

Some scientists think there could be as many as 7000 different nuclides (combinations of protons and neutrons) that would be stable enough to observe, if only for a fraction of a second.  We currently know of 3000.

Another trend that scientists noticed is that there appears to be particular numbers of neutrons or protons that make for unusually stable atoms.  Those numbers, as of 2007, are 2, 8, 20, 28, 50, 82, and 126.  They have been dubbed “magic numbers”.  Atoms with a magic number of protons and a magic number of neutrons, like Helium (2 and 2) or Calcium (20 and 20) are said to be “double magic”.

The Island of Stability

In the 60s, it was suggested that beyond the current range of the periodic table lies a set of theoretical atoms that could be very large and very stable.  With a “magic” number of protons and neutrons, the atomic components could be arranged in just such a way as to maximize the glueyness of neutrons and spread out the repulsion of protons.

The fabled island itself.
The fabled island itself.  Image by InvaderXan

The metaphor was so vivid that it soon became adopted and has been used ever since.  Scientists even talk of landing on the shores of the island, but its oases still lie undiscovered and unspoilt.

Ununoctium

Before they were confirmed to be synthesized in the lab, the edges of the periodic table were given temporary names according to a set of naming conventions.  These rules are a strange hybrid of greek and latin roots for the element’s number.

The most recent transition from lati-greek to English and official additions to the periodic table were Flerovium (element 114, previously ununquadium – quad is latin, tetra would be greek) and Livermorium (element 116, previously ununhexium – hex is greek, sex would be latin).

The synthesis of element 117, Ununheptium, was announced in 2014, but IUPAC is still reviewing the findings.  The chemistry world continues its search for Ununoctium and speculation about its properties varies from unusually stable to unusually reactive.

One thing is for certain: when it is synthesized, it won’t last long.

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T is for Tardigrade

By Jonathan Farrow from the Thoughtful Pharaoh 

Boil ’em, mash ’em, stick ’em in a stew.  They’re versatile!

No, I’m not talking about taters.  I’m talking about tardigrades: quite possibly the most durable creatures on Earth.

They might also be the strangest combination of cute and terrifying anybody has ever seen looking through a microscope.

Cute and terrifying.  Image by Abribus
Meet the water bear.  Strange combination of cute and terrifying. Image by Abribus

Tardigrades, also known as water bears, evolved 500 million years ago.  They have survived on a diet of moss and lichen since around the time the first fish evolved and shortly after animals evolved at all.  While their basic body plan hasn’t changed much, they haven’t been evolutionarily idle.  They’ve developed some pretty neat adaptations (some of which will be discussed below) and diversified into over 1000 unique species. One thing all of these species has in common is size: all species of tardigrade measure between 0.1-1 millimetre (comparable to the size of a single salt crystal).

The amazing thing about these itty-bitty balls of chitinous cuticle is that they can withstand pretty much every type of extreme we can cook up.  They’ve been boiled to over 150 degrees celsius without breaking a sweat.  They’ve been frozen to -250C and didn’t need tiny parkas.  They’ve been dipped in acid, shot into space, dried out, and zapped with thousands of times the lethal radiation dose for a human and they just kept chugging.

Why won't you die!? Image by Frank Fox
Why won’t you die!? Image by Frank Fox

Why are we being so cruel to these tiny creatures?  Because they keep surviving.  Things that terrify us and would kill almost any lifeform barely even faze them.  Tardigrades have expanded the notion of habitable environments and understanding their indestructibility has profound implications for both earthbound medicine and for life on other worlds.

I think tardigrades are pretty darn cool.  This is likely due in no small part to the fact that the lab where I did my thesis in undergrad was home to a healthy colony of moss-eating tardigrades.  Up on the third floor of the Life Science Building at McMaster University, my former supervisor, Dr. Stone (or Doc Roc as he likes to be called) has been testing tardigrade tolerances with Taru, his PhD student.

“Ewww, you can see all of its insidey bits” – Me, the first time I looked at a tardigrade through a microscope. Image by Daniel Adrian Ciobanu, Krzysztof Zawierucha, Ioan Moglan, and Łukasz Kaczmarek.

I got in touch with Doc Roc this week to ask him a few questions about tardigrades.  To give you an idea of the kind of (awesome) professor he is, one of his research goals was to publish a one-sentence paper.  He accomplished that goal with the help of quite a number of semi-colons.  As you’ll see below, I think he likes that useful but oft-forgotten punctuation mark.

Thoughtful Pharaoh (TP): Where do you find tardigrades?

Doc Roc (DR): Tardigrades are found the world over, literally on all continents and in all bodies of water; they inhabit all systems, marine, freshwater, terrestrial; they occur terrestrially on moss.

[They’re everywhere!]

TP: What have you done to test the limits of tardigrades?

DR:  We have tested their tolerance to temperature (cold), radiation, desiccation, pH, g-forces (simulated), and red food dye (I think that you know the tale); we have witnessed complete revival from -80 degrees Celsius for up to 6 months (but they can tolerate -250 K); 4000 Gy radiation (6 Gy kills humans); completely drying out inside an evaporating water droplet (tales in the literature purport over 100 years in a desiccated state); over 16000 g (Earth atmosphere being 1 g – meteoritic impact being an order-of-magnitude greater, however); and sensitivity to red food dye.

[The tale of the red food dye: In one of many discussions of tardigrades in that lab, I was asking if these incredible creatures had any weaknesses.  Doc Roc told me about a curious incident that happened when he tried to stain tardigrades to see them better.  He tried putting some red food colouring onto the plate and they changed colour and were easy to spot, but they also all died. Green and blue food colouring did nothing, but red colouring stressed the tardigrades to death.  Strange that such an indestructible creature could be undone by food colouring.]

TP: What is the most interesting thing about tardigrades, in your opinion?

DR: I think that understanding how their tolerance and reproductive modes (e.g., parthenogenesis) evolved are the most interesting topics for tardigrade research.

[Tardigrades don’t need males to reproduce.  Females can lay unfertilized eggs which will hatch as clones, genetically identical to the mother.  The advantage of this is that they don’t need to waste time looking for mates. The disadvantage is low genetic diversity.]

TP: What do you want to do next?

DR: We plan to investigate how they tolerate the high radiation doses (e.g., their DNA repair mechanisms).

[McMaster has a small nuclear reactor on campus, which has been used in recent years to expose tardigrades to high levels of radiation.  After thousands of times a lethal radiation dose for humans, the tardigrades were fine and in some cases the irradiated ones did better than their lab-housed control counterparts.  How they can survive and continue to reproduce remains a mystery but it almost certainly involves some incredible DNA repair.]

TP: Do you ever name the tardigrades?

DR: The student who studies them is named Taru, which seems an appropriate name for one; given that we work with a parthenogenetic species, I would name them Tarugrade 1, Tarugrade 2, …

[Seems reasonable to me.]

TP: If they’re so invincible, why haven’t tardigrades taken over the world?

DR: Organisms are limited in their resources, so populations can grow unchecked only to the extent that living materials are available (populations crash thereafter); predators additionally can reduce population sizes.

[In other words, tardigrades can still starve and get eaten.  Just like every other creature.]

TP: What can studying tardigrades tell us about life on other planets?

DR: Studying tardigrades can inform us about the limits to which organisms can survive, helping researchers to identify which extreme environments are viable and whether organisms could be transported between planets.

[The theory that life arrived here from another planet (called panspermia) is not as crazy as it sounds.  I wrote a bit about it a while ago.]

Thanks Doc Roc!

If you have any other tardigrade questions, feel free to comment below and be sure to share this with your friends. Spread the water bear word and let us not be frightened of our tardigrade overlords!

Tardigrade 1
This guy looks like he’s ready to partygrade. Image by the Goldstein lab.

If you want to learn more:

  • The BBC recently published a pretty comprehensive article about these resilient little critters here
  • TARDIS was a European mission in 2007 to see how well they survived in space
  • A (bearded!?) Hank Green produced a video about them for SciShow in 2012.
0

S is for Simple Rules

By Jonathan Farrow from the Thoughtful Pharaoh

Consider the following: schooling fish, roundabouts, segregation, and human consciousness are all examples of the same fundamental property of the world.  It may seem crazy to suggest that roundabouts may be interesting in some sense, but bear with me.

The property in question, and this week’s topic, is emergence.  In each case individual entities, by following simple rules, can create complex patterns of behaviour.  What makes these patterns special is that they can’t be predicted based on the simple rules alone.

Swarms

If you’ve ever seen a murmuration of starlings, you have probably found yourself wondering how that many birds (upwards of 100,000) can all fly so quickly in such close proximity without hitting each other.  For those of you uninterested in ornithology (the study of birds), there are also plenty of examples of swarms in entomology (the study of insects) and ichthyology (the study of fish), and even chiropterology (study of bats).

Image by SteveD
Image by SteveD

In each case, the animals are unaware (and frankly, uncaring) of the beautiful shapes their swarms make.  They aren’t even trying to swarm.  They are trying to survive and their instinct tells them to follow a few simple rules.  Since the advent of computers, scientists have been trying to find out what those rules are.

One of the most famous computational models of swarming behaviour was proposed by Craig Reynolds in 1986.  In his Boids program, simulated birds had to follow three rules:

  1. Separation: Don’t crash (steer away from nearby boids).
  2. Alignment: Get with the program (steer towards the average heading of nearby boids)
  3. Cohesion: Don’t get lost (steer towards the average location of nearby boids)

This model is actually a really good model for the behaviour we observe in birds and fish.  Recent studies have also shown this alignment rule is especially important for bats.

Locusts, on the other hand, seem to have a much simpler set of rules.  Locusts just want to avoid getting their backsides eaten.  When approached from behind, locusts will tend to fly forward for fear of cannibalism.  This creates an overall tendency to move forward and can lead to giant swarms.

Image by CSIRO
Image by CSIRO

Roundabouts

If you’ve ever been to Swindon (and, from what I hear, you’re not missing much if you haven’t), you might have come across quite possibly the most offensive piece of civil engineering in the UK.

That's right.  A giant roundabout.  Image in the public domain
That’s right. A giant roundabout. Image in the public domain

As a North American, I cringe at the thought of even a tiny roundabout but Swindonians apparently hate everything that is good in this world.

They built the Magic Roundabout.  A terrifying series of 6 small roundabouts encircling a larger roundabout that goes the other way.  If that sounds confusing, it’s because it is.

The more confusing part, however, is that hundreds of thousands of cars pass through it unscathed.  While there is certainly a lot of anxiety about it, there have been only 14 major accidents in 25 years.

Hell for North Americans.  Image from the BBC
Hell for North Americans. Image from the BBC

The vast majority of people pass through fine, despite there being 5 different entry and exit points and many conflict points (places where streams of traffic cross).  This happens because of a few simple rules:

  1. Follow the lines
  2. Give way to cars coming from the right
  3. Drive to where you want to go
  4. Don’t crash

Apparently it’s actually an effective way to move cars through an intersection, but my North American sensibilities just can’t handle it.

For more information on this piece of crazy road engineering, visit this explanatory page and watch this video.

Segregation

Choosing who you associate with based on a singular trait has been known to lead to a lot of issues in the past.  As a dog person, I’ve lost a lot of friends to cats (and their parasites).  Despite my friendly demeanour and my ability to put up with a fairly large proportion of cat-lovers in my immediate vicinity, at a certain point I start to feel uncomfortable and want more fellow dog-lovers.

Tensions flare.  Image by Peretz Partensky
Tensions flare. Image by Peretz Partensky

In 1971, Thomas Schelling set out to model this behaviour and came out with a somewhat surprising and scary result.  Even when people are fine with being in the minority, if they are dissatisfied when surrounded by a large majority of “others”, they will tend towards segregation.  The model followed a few simple rules:

  1. If you are surrounded by a certain percentage (e.g. 30%) of similar people, you are satisfied
  2. If you are surrounded by a certain percentage of different people (e.g. 70%), you are dissatisfied
  3. If you are dissatisfied, move to somewhere where you are satisfied.

Within a few rounds, there is very little diversity left as people tend to move towards those who are similar.  This, despite the fact that no individual is saying they outright dislike the other group or couldn’t live with members of the other group.  This model helps to explain why segregation is so hard to eliminate.

Interestingly, this tendency towards segregation can be reversed if a maximum of similar people rule is added:

4. If you are surrounded by a certain percentage of similar people (e.g. 90%) you are dissatisfied

Again, complex patterns and simple rules.

To learn more about the model, go here.

Conciousness

There are approximately 100 billion neurons in an adult human brain.  These neurons are connected in intricate ways to create an estimated 100 trillion connections.

Now that's a lot of connections!  Image from Wikimedia
Now that’s an impressive set of connections! Image from Wikimedia

Somehow (and to be honest we’re not really sure how yet), these connections lead to all of our brains’ activities from thought to imagination and memory.  The abilities of the system (the brain) couldn’t possibly be known from the rules that neurons abide by.  All that a neuron does is pass on its signal according to a set of rules.  We still don’t know what those rules are.

We do know that when a neuron is activated (whether by electrical or chemical stimulation), it activates other neurons.  The precise number and location of these other neurons is still a big mystery in neuroscience, but it must be activating both nearby neurons and neurons on the other side of the brain.  This dual activation of long- and short-distance connections is what creates the sustained patterns we observe in fMRI scans.

Human Connectome Project
The Human Connectome Project, kind of like the Human Genome Project before it, is setting out to map all of the brain’s 100 trillion connections to better understand how it works.  Image by Xavier Gigandet et al.

While I don’t mean to suggest that everything in life can be boiled down to simple rules, I think it’s pretty incredible the patterns that emerge from individual actors all playing their parts.

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R is for Ratzilla

An excerpt from my favourite scene in the 1987 film, the Princess Bride:

Westley: Rodents of Unusual Size? I don’t think they exist. [R.O.U.S. attacks Westley] Westley: Ahhhh!!!

Why is that my favourite scene?  Because I laugh every time I watch it. The R.O.U.S. is just so ridiculous-looking and shows up right after Westley disbelieves its existence.

For the devoted readers out there, you’re maybe wondering what my obsession with R.O.U.S.es is, because I’ve written about them before, but somehow they capture my imagination unlike any other strangely-proportioned creature.  I think it has something to do with the comedic effect of reversing the expectation of something cute.

Rodents of Unusual Size: They do exist. Image from the Princess Bride
Rodents of Unusual Size: They do exist. They are definitely not cute.  Image from the Princess Bride

The R.O.U.Ses from the Princess Bride have come to set the standard for overgrown rodents, but sometimes reality is stranger than fiction.

The largest discovered member of the rodent family (membership to which depends on having a pair of razor-sharp, ever-growing incisors), Josephoartigasia monesi is estimated to have been the size of a bull.

.

Reconstruction of head
A reconstruction of J. monesi’s skull based on the bones that were recovered. Image by Andres Rinderknecht & Ernesto Blanco

Since only its skull was discovered, the  weight of this creature has been debated.  The original discovery paper pegged the mass of the monstrous mulch muncher at 1211kg on average with a maximum of 2584kg. To put that into perspective, that’s anywhere from 1 to 4 dairy cows.  A more recent study, however, showed that depending on the part of the skull you use to predict the mass of the full creature, J. monesi could have weighed from as low as 356kg (half a cow) to 1534kg (back up to the 2-cow range).  Even if the creature was as small as 356kg, that still makes it nearly 6 times heavier than the current rodent heavyweight champion of the world, Floyd Mayweather the capybara.

In any case, it’s definitely big enough for a recent Science Magazine article to correctly use the term “Ratzilla”.

Rodents of Unusual Size: They do exist.  Image from the Princess Bride
RATZILLA!!!  Image by James Gurney

Ratzilla’s bite force was recently estimated up to 4000N, enough to outperform modern crocodiles and tigers.  It was definitely a herbivore though, and is thought to have used its teeth as elephants use their tusks: to dig around for tasty treats.

Luckily for us, Ratzillas (Ratzillae?) no longer roam the plains of South America.  They went extinct about 2 million years ago, after 2 million years of rodent dominance.  Interestingly, that makes them the contemporaries of terror birds, sabre-toothed cats, and giant ground sloths. Their size and sharp teeth probably made them tough prey items.

Just like the R.O.U.Ses in the Princess Bride though, they were probably susceptible to fire jets and swords.

And with this rodent rant written, I promise to not write about any more Rodents of Unusual Size for the remainder of this ABCs series.