Quentin Tarantino vs. Ebola: It Still Isn't Airborne

There are a number of articles making the rounds that claim that there is now an airborne version of the Ebola virus.  I want to set the record straight on this because misinformation tends to spread a lot faster than the actual facts.  The good news is that those articles are all, for lack of a better term, full of shit.  Let me state it in one simple, easy to read sentence with relatively small words:

Ebola is NOT passed on through the air. 

Viruses just don't seem to ever change their primary mode of infection like that.  There has never been a case of this happening and, as I mentioned in a previous post, it is unlikely that this will ever happen.  Ebola is not an airborne virus. 

What is likely happening here is that someone reads a sentence that says, at least in part, "...a germ like Ebola gets passed on via larger, wet droplets..." and they freak right out, completely ignoring the rest of the article which states, in no uncertain terms, that Ebola is not airborne.  They then do some quick "logical" thinking along the lines of:

1.  Ebola virus can be passed through droplets of fluid
2.  Fluid droplets are in the air after someone vomits or coughs
3.  Droplets in the air = airborne virus
4.  Panic

Now, to be fair, it is possible that the people who are writing those articles are simply misunderstanding basic facts. To be even more fair it is possible that they are trying to share their new found knowledge with people in the hopes of making the world a better place.  Both of these things are possible, but, unfortunately, it doesn't really matter.  This is the kind of thing that incites panic rather than makes things better.

For a virus to be airborne it has to be able to form protective little clusters that allow it to survive in the air while it floats around.  Viruses like this totally suck and can be serious problems because simply being in a room with someone who is sick can be enough to infect you.  By contrast, to get infected with Ebola you have to get those fluid droplets into your body which means you have to be within a few feet of an infected person.  Blood and other body fluids don't fly in the air forever.  Just watch the fight scene where The Bride fights all those bad guys in Kill Bill vol 1 (NSFW).  Even when blood is at its most Quentin Tarantino-y, flying through the air in mass quantities, it is still a fluid and thus will obey gravity.  It eventually falls, typically within 3 or 4 feet of the patient, and thus becomes floor-borne.  

Everyone repeat after me:  To get Ebola, you must get body fluids into your body.  Unless you are a health care worker who is actively treating patients with Ebola, your chances of getting the disease hover right around zero.  You would be more likely to be struck by lightening while winning the lottery.

     

Could Ebola Become Airborne?

Yesterday a student came to class freaked out about Ebola.  Again.  He was freaked out this time because he had read an article which quoted Dr. Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota.  In the article, Dr. Osterholm is quoted as saying about an airborne Ebola virus, "It is the single greatest concern I've ever had in my 40-year public health career.  I can't imagine anything in my career - and this includes HIV - that would be more devastating to the world than a respiratory transmissible Ebola virus."

It is important to note that he was not talking about an already existing airborne version of Ebola.  He was talking hypothetically about a possible future airborne Ebola virus.  In fact there has not ever been a case where any virus has shifted its main mode of infection this dramatically.  However this idea - that Ebola could mutate and become airborne - is pants wettingly scary and could result in mass casualties worldwide were it to become a reality.  But how likely is it that this would happen?

The simple answer to this question is "very unlikely, bordering on impossible".  Let's start with an analogy.  You are a quarterback for a football team, and a darned good one.  Last season you were the top passer in the league where you threw over 230 touchdown passes and broke 600 yards of total passing in every game.  It is offensive how good you are.  On top of that you have a natural scent that perfume companies around the world are attempting to copy for their fall scent line.  Lets face it, you are amazing and everyone wants to be you.

You are such an amazing quarterback and all around heckuva guy that your coach decides to throw you in as a defensive lineman for a few plays.  This goes wrong in an almost every possible way.  You are thrown down repeatedly by the larger, more highly trained offensive linemen and manage to get pushed around almost immediately.  You soldier on, however, and on the next play manage to hurt not only yourself but also several of your teammates when your ill advised diving tackle manages to not only miss the running back but takes out 3 of your own players as well.  The overall consensus is that you are amazing on offense with your quick reflexes and the ball in your hand but terrible on defense when size and strength matter more.

Now imagine that you are asked not just to play on a different aspect of a football team, but to play in the French Open tennis tournament.  Sure, it is still a physically demanding activity and you are used to that sort of thing, but it is demanding in an entirely new way that your body is most certainly not trained to handle.  You are used to throwing a ball on a grass field while 11 large men try to kill you.  Tennis requires finesse and years of practice with a racket, not to mention the fact that you are now playing on a slippery clay surface which is difficult even for most pros. With years of time and dedication our star athlete quarterback might be able to make it to the Open, but why would he want to give up his completely successful career to do so?

Ebola is a lot like this quarterback.  It is amazing at what it does which is infecting people and living in their blood.  For it to become airborne it would be the equivalent of our quarterback playing in the French Open.  Sure, with lots of mutations and some significant changes to its structure it could happen, but why would it do so?  It would have to give up its already excellent infection and transmission pathway in favor of one that is almost completely different.  It would have to abandon the blood stream as its primary hiding/replicating place in favor of the lungs or throat.  Then it would have to mutate to become able to survive in the air or on surfaces which, at present, it doesn't seem to be able to do very well (Piercy, et al 2010).

Let's talk a little science here for a bit.  Not too much, but enough to get through some basics.  Viruses don't just magically attach to cells and infect them.  They have to be able to grab on to the cells and, after they have successfully done that, invade the cell so it can reproduce.  Without getting into a cell a virus is unable to make more copies of itself and without being able to attach to a cell it can't begin to do that.  Ebola is an interesting virus in that, like HIV, it grabs onto little handles (glycoproteins and other receptors) in the cell membrane and tricks the cell into allowing it access.  Studies show that its preferred mode of infection is to grab onto cells involved in the creation of connections between tissue layers (like the connections that hold your skin to your muscles) and some immune system cells.  It basically does the same thing that HIV does only way more aggressively.

The types of cells it prefers to attack are relatively specific cell types and, despite the fact that all of the cells in your body have the same DNA they are not, in fact, all identical.  Many have different glycoproteins (handles) and therefore different attachment points.  There is a reason Ebola doesn't infect your sinuses or your throat and that is because it appears to have difficulty binding to the cells in those areas.

So in order for Ebola to become airborne it would require a whole series of mutations which would allow it to:

1. survive in the air and on surfaces at room temperature for long periods of time.
2. stop attaching to its preferred host cells in the blood and connective tissue
3. begin attaching to a new type of host cell in the lungs and throat
4. stop killing patients so darn quickly

Each of these steps would most likely require several mutations which is the equivalent of our football player picking up a tennis racket and learning to serve the ball like Pete Sampras.  Possible?  Sure. Likely?  Not really.

Last, and probably most importantly, is the evolutionary reason for why this isn't going to happen:  there is no selection pressure.  Selection pressure occurs when an organism finds itself in a difficult situation, environment-wise.  If the environment changes significantly then species have to either adapt or go extinct.  Ebola is not facing any sort of selection pressure at this point.  It is wildly good at what it does and is incredibly successful as a blood/fluid born virus.  Would our hypothetical quarterback switch to playing tennis in the middle of his amazing career if the NFL still exists and is willing to pay him millions of dollars?  Neither would Ebola.

I have purposely simplified the explanations in this post to make it easier to read.  If there are any bits that you feel need some expansion or clarification, let me know!



Piercy, T.J., Smither, S.J., Steward, J.A., Eastaugh, L., Lever, M.S. (2010) The survival of filoviruses in liquids, on solid substrates and in a dynamic aerosol. J Appl Microbiol. 109(5): 1531-9.

Ebola: Should I Start Wetting Myself Now or Wait Until Later?

The thing in the picture above is an Ebola virus, and it has many of my students pooping their pants right now. Well, probably not right this second, but there has been some general loosening of a particular sphincter muscle over the idea that Ebola will come and claim their young lives in a rather horrible way.  In this post I hope to pass on a bit of knowledge that will hopefully help you and others to understand what Ebola is and what it can do.  I'll let you decide when and if you need to begin wetting yourself.

First off, Ebola is a filovirus which simply means that it is shaped like a thread.  It has a characteristic "shepherds crook" at one end which gives it a rather unique look - a rather long, skinny structure with a loopy thing at the end.  It causes a hemorrhagic fever which is a fancy way of saying that it has a relatively disturbing habit of causing a massive amount of bleeding which eventually leads to death.  How it works is sort of fascinating, but I think I'll skip that bit for now and instead talk about other things.

At the top of the list of questions people want answered is "How can I get it?"  or, to put it a different way, "How can I avoid getting it?"  It is actually rather easy to avoid getting it because Ebola is transmitted in a very specific way.  Since this virus tends to hang out in the bloodstream, you generally have to get Ebola laden blood into your bloodstream.  This is often referred to as "blood to blood contact".  It has been shown that Ebola can also be found in the sweat, tears, saliva, breast milk, and semen of infected people and it is therefore possible for it to be passed along through those fluids.  Those fluids still need to get into your body, however, so unless you are touching, cleaning, or otherwise handling a person with Ebola or the body of a person who died from Ebola, you are not going to get it.  And if you are planning on touching, cleaning, or otherwise handling a person with Ebola or the body of a person who died from Ebola, wear protective clothing to avoid getting it.  A good rule to follow in Ebola outbreaks is if it is wet and not yours then don't touch it.  Come to think of it, this is a pretty good rule to follow even when there is not an Ebola outbreak. 

Additionally, Ebola cannot be transmitted through the air.  Sure, if someone is violently coughing or vomiting they may spread droplets of fluid into their immediate surroundings - normally no more than 3-4 feet from their body - but the virus still needs to be in a fluid to be transmitted.  So the idea of a single carrier of Ebola on the subway in New York infecting an entire subway car is not going to happen.  Oh, and one more thing, a person is only contagious when they are showing symptoms of the disease, and since Ebola is rather debilitating, it is highly unlikely that someone who is sick with it will be walking around after they start showing symptoms.  So, to sum up, Ebola is rather difficult to catch.

Unless, of course, you aren't aware of what it is or how it is spread.  The main reason it is a problem in Africa is that people are generally unaware of how to avoid getting sick, and when they do get sick the medical facilities are often poor or nonexistent.  Without proper protective clothing the people who are dealing with the sick or dead often become infected themselves.  So when a person who is wearing little or no protective gear transports or handles an Ebola victim they are likely to get the disease themselves.  This is what contributes to the outbreaks in Africa.  People who are unaware of the disease or how to avoid getting it are coming in direct contact with those who have died from it.  They don't know what precautions to take and the virus spreads.  

But what happens when an infected person leaves their country in Africa and travels to the United States?  Aren't we all at risk?

The answer is typically "no".  As mentioned before, if the person is able to walk around he or she is not infectious.  When they do show symptoms they can easily be quarantined in a hospital and treated only by those wearing protective gear.  Anyone that they came in contact with can be monitored to see if symptoms show up and then quarantined should they become sick. It is incredibly unlikely that an outbreak of Ebola would ever cause massive problems here because we are aware of how to avoid getting it and we know what to do with people who have it.  Basically, don't touch a person who is showing symptoms of Ebola and you will be fine.  The only way Ebola could become a problem in the United States is if it became airborne, which, as we will examine in another post, is incredibly unlikely.

So to answer the question in the title of this post, I'd wait a while before you start wetting yourself.

Why do men have nipples? - A great question with a simple answer

Human bodies are amazing things.  You have eyes that enable you to detect sunsets, ears to hear a symphony by Beethoven, touch receptors to register the feel of an exquisite silk, and a nose to detect the awe inspiring smell when your youngest son releases the built up gas from a recent digestive experience.  In addition to those external things, you have organs that are all squished into your body cavities that enable you to do all sorts of amazing things including breathing, moving, and, to continue a train of thought, producing the gas that enables your youngest son to fart.  

The amazing things the human body can do are normally not limited to one sex.  Obviously some things can only be done by women including providing the nourishing space where babies to grow.  Other things are the only available to men like, well, finding humor in fart jokes after their 39th birthday.  Some body processes, like producing milk, are normally reserved for women but can be performed by men should those men have the inclination, money, and access to a willing medical professional.  While not likely, this is entirely possible due to the fact that men and women produce the same hormones in their bodies, just not normally in the same concentrations.  Change the concentration of a few of those hormones and interesting things can happen.

This explains not only the unusual situation of male lactation, but also a few other things as well.  For example, you may have noticed that men have nipples.  Upon noticing this you may have also noticed that, unlike women, they don't feed babies with them (unless, as previously noted, they really want to).  Once you have noticed both of these things (and by the way, congrats on all the noticing) you will probably have asked yourself the age old question of "why are they there if they don't normally serve any function?"

I have heard many different responses to this question ranging from the completely scientific and well researched to the less scientific and more bro-tastic, "Dude - chests would look weird without them so, you know...nipples."  The real reason men have nipples actually quite simple:  because women have them.

That isn't a very satisfying answer, so lets get a little more detailed.  To start with, lets work with an analogy.
My sons have a Lego set that allows them to build 3 different things.  Follow one set of instructions and you get a car, another set and you get a boat, while yet another produces a plane.  All of the pieces for each structure are included in the kit and you simply have to selectively ignore the pieces you don't need.  One of the slick parts of this set is that the first bit of the instructions for all three things is the same.  It is only after page 20 that you are forced to make a decision as to which structure you are going to build.      

The different human sexes are built pretty much the same way as our Lego set.  Lots of individual pieces are assembled and come together to make up a human and males and females are essentially two separate structures built from the same kit.  For the model with the uterus, continue on to page 21.  For the model with the dangly bits and the fart jokes, skip to page 45.

To put it slightly more scientifically, the vast majority of instructions (genes) used to build a male are also found in the female body and vice-versa.  To drive this point home a bit, in the not too distant future it is going to be technically possible to make male and female clones of yourself.  Flip a few genetic switches in the developing embryo and viola, female clones from male donors.            

Two things of note before we continue.  First, all humans have 46 chromosomes - half come from mom and half from dad.  Due to some interesting genetic and evolutionary issues that are well beyond the scope of this post, the half that come from mom are pretty much identical to the half that come from dad.  This means that both moms and dads carry around instructions for how to build nipples.

Second, all babies start out female and it is only with a well timed release of testosterone that the baby begins its transformation into a little dude.  So to go back to the Lego analogy, the first 20 pages of instructions for human babies includes building the basic body parts and setting the stage for a little female baby.  Everyone, even Dwayne "The Rock" Johnson, started off as a little girl.   

"What does this have to do with nipples?" you might ask.  Should you ask that question I would respond, "Everything."

You see, ever since mammals evolved to produce milk from modified sweat glands, nipples have been a fairly important part of the body plan for most of them.  And because half the genes to produce those nipples come from mom and half from dad, this means that dads had to carry around nipple genes whether they wanted to or not.  Since the dads had these nipple genes and it seems the nipple building directions were in the first 20 pages of our instruction manual, they built nipples even though they were not going to produce any milk.

These genes and their nipple instructions are only part of the reason men have them.  The other part is evolution.  To oversimplify a relatively complex concept, evolution works by natural selection.  This means that those critters that are well adapted and have no major physical issues will survive better and make more babies than those with severe problems.  In the grand scheme of things, nipples are not really that detrimental to the male who has them which means that he is still going to survive and he is still going to get to mate and have babies.  If he survives and has babies, his babies will then also have nipples.

To sum up a bit, human embryos are basically identical until 8-9 weeks of development.  At this time the genes that determine maleness will turn on in males and those same genes will stay off in females.  During this initial 8-9 weeks of development the basic body shape happens including two arms, two legs, head, heart, internal organs, skin (nipples), etc.  It is only after this part that embryos branch off to become male or female.  So men have nipples because they have genes that produce them and these genes and their resulting superfluous nippleage don't seem to get in the way of survival or mating.

By the way, "Superfluous nippleage" would make a great name for a punk band.  

As a quick aside, a few other interesting things can happen due to the similarities in hormones and genetics. One of the most common issues is male breast tissue.  This normally develops during puberty and can come as quite a shock to boys who were not exactly expecting breasts, even if they are super small.   No one expects this because no one ever tells boys that this is even a possibility.  The sex talk in 6th grade and health class in high school often tell you that you will develop a deeper voice, hair in several novel places, and muscles due to hormone surges.  They inconveniently leave out the whole, "you might get small breasts" thing, probably because no one wants to tell a 14 year old boy that he and his 11 year old sister are experiencing something in common.

The male breast tissue (normally called "breast buds") is often sensitive and can be painful if you happen to be a goalkeeper and someone hits a soccer ball into your chest at approximately 400 miles an hour.  That may or may not have happened to me in high school, but here's a hint:  It definitely did.  Typically you will notice a is a small lump under one or both nipples which is completely unnoticable by everyone except, of course, the young man in question.  They develop because during puberty the normally delicate balance of hormones can be thrown out of whack resulting in a little bodily confusion.  Your male body recieves a dose of some hormones and thinks to itself, "Hey - I've got these nipples here, may as well do something with them."  After a few weeks, months, or years, the hormomes will go back to normal and the breast tissue will disappear leaving only fond memories.

Human bodies are amazing, strange little things, aren't they? 
    

Untrue Science Fact #1

Not sure where this is from, but I thought it was funny.

More Memes. Inspired by True Events.

I gave the final exam in my night class tonight which gave me both inspiration and lots of time.  Here are a few more memes inspired by true events. 

My thoughts while copying the test:

Walking into the room:

 After a few minutes in the room:

Me, talking to friends after the exam:

And we all have students like this from time to time:

Science Teacher Memes

I spent some time recently putting together a few memes to help my students understand concepts like lab safety and science process.  Here are a few of my favorites.

 These memes and over 30 others can be found in my Teachers Pay Teachers store.

ALL Dinosaurs had feathers?

Image credit: Andrey Atuchin

           

We all know that Tyrannosaurus rex was an enormous theropod dinosaur with huge teeth that, were it alive today, would cause serious pants wetting problems in all who happened across one.  Also, it had feathers and was probably adorable as a baby.  Admittedly the adorableness is pure speculation on my part, but the feathers are fairly well documented and, although mind blowing, significantly less speculative.   

 A few newly discovered fossils suggest an even more mind blowing idea, namely that ALL dinosaurs had feathers.  That's right.  The new findings suggest that all dinosaurs - not just the cute and cuddly ones like T. rex - might have been feathered.  Significant research still needs to be done to confirm this, but if this is true then the special effects in the new Jurassic Park movie are going to need a serious redo.

Thanks to IFLScience for the story.

How and Why did Fish Start Walking? A Short Evolutionary History of Limbs.

So, let’s say that you are a fish.  You have gills which work amazingly well for taking oxygen out of the water and helping you not die, and you have fins which help you swim around and avoid predators, also helping you not die.  Your body is streamlined and quite good at cruising through the water and you have paired fins at your head end and tail end which help you change direction quite easily.  These are amazing adaptations which came about through millions of years of evolution, and they are still very helpful to those critters that didn't head off down the path to living on land. 

If we travel back in time to the end of the Devonian period (around 385 million years ago) we would find that there were two types of fish.  One group, the ray finned fish, was very popular and had thin, beautiful fins which were very helpful for swimming in the open water.  They are still the most common type of fish.  The second, much smaller group, were called lobe finned fish, and they spent most of their time hanging out on the floor of lakes, rivers, and streams rather than cruising open bodies of water.  Despite being fish, these lobe finned critters had adapted to a life of bottom feeding and were not nearly as good at hunting or evading predators in the open water.  Their bodies were less streamlined and more flattened because flat is good if you are a bottom feeder.  The lower your profile the less likely you are to be eaten, and being eaten is never good.  

Eusthenopteron (right), a critter that lived about 385 million years ago, is a great example of this flat, lobe-finned critter.  It had a low profile and tended to spend all its time hanging out in shallow seas.  Its fins were still somewhat adapted to swimming, but it is currently thought that it had the ability to "crawl" along the underwater rocks.  The bones of its fins are the blueprint for the bones of your arms and legs and are thought to be the start of the evolution of all tetrapods, or 4 limbed animals.  You can see the pattern in the picture at the top of this post with one bone (pink) attaching at the shoulder of the fish, 2 bones (blue and yellow) attaching to the pink one, and lots of little bones below those two which would be similar to the fingers of later tetrapods. 

Tiktaalik (left), discovered by a team from the University of Chicago led by Neil Shubin, is a 375 million year old critter which is even more amphibian-like.  Shubin sometimes jokingly refers to it as a "fishapod" because it still has characteristics of fish but is well on its way to having 4 limbs like a tetrapod.  It is a great example of a transitional fossil.  It is more flattened than Eusthenopteron and spent most of its time in the shallow rivers during the late Devonian period.  The bones of its limbs have evolved to become more arm- and leg-like, but the main difference between it and its other, more fishy relatives, is that it had the ability to rotate the lower bones in the fin like a wrist.  And, based on the fact that it has a sturdy shoulder structure, this critter definitely used these limbs to support its weight.  Another aspect of this fishapod is that it could move its head from side to side and up and down, something that fish cannot do but is a characteristic of tetrapods.

Following on the heels of Tiktaalik comes another of the transitional critters that helped pave the way for tetrapods to take over land.  Acanthostega (right) lived about 365 million years ago and was, most would agree, more salamander-like than fish.  It had definite limbs - no fins for this one - but due to the structure of the bones it was unable to put any major weight onto those limbs.  It was still, like Tiktaalik, mostly aquatic, but the size and strength of the shoulder bones and the fact that its pelvic (hip) bones were attached to the spine instead of free floating suggest that it relied entirely on these limbs for movement.  Baically, it "walked" along the bottoms of the rivers and streams, only occasionally venturing out of the water. 

Around 360 million years ago, Ichthyostega (left), came around.  At a little over 4 feet in length, this is one of the largest of the transitional critters we are going to discuss.  It was one of the first of the transitional tetrapods to be discovered and for quite a while it was the only transitional tetrapod we had.  It has a fishy tail but everything else about it is amphibian.  It had lost its gills, and its tail fin is significantly smaller than would be necessary for swimming.  The bones in the front and rear limbs show the "one bone, two bones, little bones, fingers" pattern that is characteristic of all tetrapods, and its shoulder, pelvis, and backbone are so robust that scientists agree that this thing definitely spent quite a bit of time on land.  It most likely only used its front two limbs to walk around.  It is still not considered an amphibian, but it is the most amphibian-like of all the transitional critters we have seen so far.

Eventually, around the same time Ichthyostega was cruising around, the amphibians - the first true tetrapods - evolved.  

Based on the evidence, it is obvious that all land based animals with 4 limbs started out in this manner.  We, along with dogs, cats, squirrels, whales (yes, whales), dinosaurs, birds and other animals with 4 limbs owe our existence to a group of critters that, for some reason, left the water and invaded land.  Why would this happen?  Wasn't the water full of things to eat and places to live and other fishy things to mate with?  Yes, it was - that isn't the problem.  The real problem is that, from time to time, the "things to eat" category included fish that would rather not be eaten.  Predators were everywhere and some of them, like the armored Dunkleosteus (right), were massive and not terribly picky about what they ate.  

Imagine that you are a small lobe-finned fish living about 380 million years ago.  Even though your large fins are constantly mocked by the other, more svelt and popular ray-finned fish in the area, you are perfectly content living near the edge of the water, crawling around on the rocks, searching for food.  You come across a tiny shrimp and are about to dig in to what will most likely be the best meal of your young life when out of the corner of your eye you see a shadow.  This shadow might be nothing, a piece of floating wood or one of those ray-finned meanies, but it might be one of those massive predators that the Devonian is so chock full of.  You decide not to chance it and run away, but since you are so small compared to the predator you won't get far before your latest meal becomes your last meal and you are killed and eaten in some horrible way.  What does a small lobe-finned fish do?  The only thing that you can do - scamper into shallower water to avoid this predator.  

You scoot to your left to begin the hopefully life-saving journey away from the predator, but NO!  It has seen you!  Crawl little lobe-fin, crawl!  So you put on a little burst of speed and pull out your trump card.  Your stronger fins - the ones the other fish make fun of  because they are so large and weird - allow you to leave the water to avoid being lunch.  You scamper up out of the shallow water and onto land just as the predator makes its move, and due to the fact that you are no longer in the water the predator makes a quick change of direction and eats one of the ray-finned fish that were unable to get out of the way.  You perch on the rock for a second to gloat and make sure the predator is gone and then dive back in, ready to resume your search for a little shrimpy snack.

This predator avoidance strategy is one of the more likely reasons for tetrapod evolution.  If you are not in the water you are not going to be eaten by anything in there.  As it turns out, until amphibians evolved and truly started hanging out on land, most land animals were more like millipedes and other insects and therefore were not really something the first tetrapods needed to worry about.  At this time, land was the safest place to be if you could get there.

This is just part of the story of how our ancestors got up and changed the world.  I'll do a post on lung evolution in the future to help round out the major transformations needed for life on land.  

You are Awesome. A Quick Evolutionary History of Your Accomplishements.

You are a winner.  I'm not just saying that to garner your affection, although I am not against that, but rather because it is the truth.  You are a winner because, to begin with your most recent amazing achievement, as a sperm you beat out an estimated 300,000,000 other sperm for the coveted title of being you.  This race was long and arduous and, while other sperm made fateful errors and turned the wrong direction at the fallopian tubes or were ensnared by the vaginal mucous before even reaching the uterus, you persevered and ended up fertilizing that egg.  So you got that going for you, which is nice.

Additionally, even before you won the sperm race, you were descended from winners.  Your direct ancestors were all strong enough and fast enough to be able to survive until it was time to mate, and when it was business time they were attractive enough to actually get a mate.  Had even one of your ancestors been a bit of a dud with less than adequate skill in the survival department you wouldn't be here now.  You are the product of over 3.8 billion years of evolution.

But this planet of ours, where that evolutionary process happened and continues to happen, seemed, at times, to be downright antagonistic to the squishy things that were attempting to flourish on it.  From volcanos belching lava and tiny bacteria spewing forth nasty toxic gasses to meteors impacting the surface and making life significantly more interesting than it already had been, there have been times when it was incredibly difficult to be a living thing.

Life, and therefore your ancestors, almost come to an abrupt end on five different occasions in the past.  It was during these Mass Extinction events that your ancestors survival skills were really put to the test.  The first of these occurred about 450 million years ago and wiped out 60-70% of all species.  The second, around 370 million years ago, resulted in the deaths of about 70% of all species.  The third, the Permian extinction event, is the subject of the rest of this post and will be discussed in detail in a bit.  The fourth occurred around 200 million years ago and wiped out 70-75% of all species including many of the competitors of the dinosaurs, helping them rule the land for another 140 million years or so.  The fifth happened about 65 million years ago and is the one most people know about.  It was responsible for not only the deaths of all of the non-avian (not birdlike) dinosaurs but also the extinctions of around 75% of all species.

The third event, the Permian extinction, occurred around 250 million years ago and is known as the Great Dying due to the fact that almost 95% of all species went extinct. Your great-great-great (x140 million or so) grandparents, the reptiles, had evolved only about 70 million years prior and were attempting to make a go of it on this crazy death planet.  The reptiles almost immediately split into two main types, the synapsids and the diapsids.  These were sort of like sibling groups in that while they were similar in a lot of ways, there were also some key differences, the most obvious of which, assuming you have access to these things, is the number of skull holes (or, should you wish to impress people at a tea party, temporal fenestra) each had.  As in all sibling rivalries there was some competition, and there was a winner and a loser.  The winner, at first, were the synapsid reptiles which grew to fairly decent sizes and were essentially the kings and queens of the Permian period.  Some, like Dimetrodon, could reach 15 feet in length with a massive sail-like crest on its back that allowed it to regulate its body temperature.  These huge reptiles are often mistaken for dinosaurs because of the large size and scary teeth, but they predated dinosaurs by around 70 million years.

This sibling rivalry lasted, with the synapsids in the ascendency, until the Permian Extinction event.  The synapsids, and indeed almost everything else, were basically wiped out during this time, and this opened up the door to their rivals, the diapsids.  The diapsids had bided their time while their synapsid relatives dominated, staying small and inconspicuous.  After the Great Dying the diapsid reptiles began their dominance, leaving the synapsids to the fate of small stature and inconspicuity, assuming that is even a word.  Spell check doesn’t have a problem with it so I am leaving it in.  

The diapsid reptiles eventually went on to evolve into such hit animals as the pterosaurs, crocodiles, dinosaurs and, eventually, birds.  The synapsids hung back and began the process of evolving to survive.  They stayed small and adapted to the cooler, darker night conditions.  They developed hair to insulate themselves and assist in temperature regulation.  They developed more refined jaw bones and modified ear bones to aid in hearing.  They began to produce milk from glands on their stomach to feed their young, and when the time was right, roughly 65 million years ago after the Cretaceous mass extinction event, evolved into all of the groups of mammals that we have today.  Dogs, cats, platypuses, squirrels, elephants, whales, primates and eventually you - all of them descended from that one group of reptiles that refused to die when almost everything else did.  

And that is why you are a winner.  Your ancestors survived everything that this cranky old Earth and solar system could throw at them and came out on top.  You are #1.  

Or, to put it like one of my college biology professors:

Secondary Science Resources

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Genomic Revolution

One of my favorite sites to find short, interesting videos that I can use to spice up class is TED.com.  I feel a bit like a crack dealer here by providing the first taste, but if you have never been there before, check it out and be prepared to spend the rest of the day doing nothing but clicking on video after video.  The one below is on the Genomic Revolution.  Click the video below to learn about how your life is going to change thanks to the genomic revolution.

  

Your 3.5 Billion Year Old Family Tree

One of the coolest bits about teaching students evolution is that they get to learn that they are related to every living thing.  For example, Dunkleosteus, the critter pictured above, is your 185 millionth great-grandparent.  If you take your family tree even further back you can find that you and that oak tree outside share an ancestor from about 1.4 billion years ago. 

More Climate Change Leads To Less Guacamole

For those of us who live in the midwest, the reality of Climate Change can be a bit of a tough sell.  Just yesterday, in fact, while I was in the locker room at my gym, a whole group of severely underdressed men placed one leg up on the benches and proceded to scandalize the rest of us not only with body parts that should not be as obviously displayed as these were, but also with comments like, "Where's this 'global warming' I keep hearing so much about, and "Man - I'd take a little of that so called 'global warming' those scientists are always yammering on about."

Without a decent understanding of the facts of climate change, these comments are to be expected.  This is primarily due to the fact that, unlike other parts of the country, our recent weather has been somewhat mild.  I say that having just lived through what is most likely a climate change induced polar vortex for the past several months, but for some reason cold weather doesn't really conjur up images of climate change in most people's minds.  Our relatively cool summers and, until recently, the warmish winters have not given most midwesterners a good dose of what the rest of the planet has been experiencing.  The term "Global Warming" is still commonly used and, although it is true that many places on the planet will warm up, not all changes will be in the form of higher temperatures.  Some of the changes are going to be in the form of more severe weather, some in the form of droughts, and some in the form of colder than normal temperatures, at least for a while.

And if you are a fan of the fast food-ish restaurant Chipotle, some of the changes will hit us a little closer to home.

Chipotle recently announced that, “Increasing weather volatility or other long-term changes in global weather patterns, including any changes associated with global climate change, could have a significant impact on the price or availability of some of our ingredients.”  What this is basically saying is that certain staples from the restaurant like guacamole or salsa might not be available should the price of those ingredients increase too much.  For the full story, check out Think Progress or Time  

***Update***

Chipotle is not saying that there will be a shortage of avocados this year due to climate change.  This statement made by Chipotle was part of a regular risk disclosure statement to the SEC.  All companies do this, and in these statements, companies disclose all of the possible risk factors that might affect business.  The Chipotle statement is unique in that it is the first to explicitly state climate change as a viable risk factor that could affect business.        

Evolution as a Story - Part 1

I love studying evolution.  There are many reasons for this, but one of the most compelling is that it is the story of how we, as humans, came to be.  It is a story of adaptation and extinction, success and failure, and if told correctly it can help students to a greater understanding of just how cool this whole evolution thing is.  I mean, we are related to fish and oak trees for crying out loud.  How cool is that?  I plan on writing about how I tell the story of our evolution in a future post or two, but for right now I'd like to share a few things I have made which help me tell this story to my classes.

First, I have a short textbook that I wrote for use in my Zoology class which focuses on the evolutionary story of the major groups of organisms including invertebrates, fish, amphibians, reptiles, birds, and mammals.  Each 4-6 page chapter deals with a particular group of animals and explains the main points of their evolution in what I hope is a humorous yet educational manner.  This book is available for sale as a digital download at my Teachers Pay Teachers store should you be interested.  There you can download a free sample to see what it is like as well as purchase either individual chapters or the entire textbook, should you feel so moved.  And because I am such a stand-up kinda guy, for a limited I am giving away the evolution chapter of my textbook for free!    

To supplement the textbook I put together graphic organizers for the chapters on Reptiles, Birds, and Mammals.  I give these out to the students so they can use them to take notes while we discuss these topics.  Click the links to go to my store to download free higher resolution copies of these organizers.  (The images below are just JPEGs because I am relatively new to blogger.com and haven't figured out if it is possible to link files to posts.)  

Finally, I have made Prezis which use the graphic organizers as the main focal point to help the students follow the story we are discussing.  The links to the Prezis are below.  If you are a regular user of Prezi, feel free to make a copy of these presentations for use in your classroom.  If you are not a regular user of Prezi, it is an amazing, free, online presentation tool that I can't recommend highly enough.

Reptile Evolution Prezi Link

Bird Evolution Prezi Link

Mammal Evolution Prezi Link

New Video Series from PBS - Your Inner Fish

I am more excited than I probably should be for this new series from PBS.  "Your Inner Fish" is one of my favorite evolution books and now PBS and the author, Neil Shubin, have teamed up to make a 3 part series on the subject.  It is slated to start on April 9 at 10pm Eastern/9pm Central.  Check out the website for more information and a few videos.  

Boy, wouldn't this be terrible?

Major Transformations - Jaw Evolution

I like my jaws.  They are, perhaps, my favorite thing to use when I am chewing stuff.  They are also incredibly helpful in the whole talking department, and given that I am a teacher this is a fairly important adaptation for me to have.  Jaws are really swell.

But how did we come to have these neat little chompers anyway?  It turns out that the story of jaw evolution is fairly simple.  You see, once upon a time about 530 million years ago, there lived a group of critters named the Agnathans.  These were a strange sort of organism what with their long bodies and sucker faces and no paired fins, but they were some of the first fish to grace our fair ocean and for this we have to give them credit. 

They were a happy sort of fish (I assume) and lived their lives happily filtering their breakfasts, lunches, and dinners through their happy little sucker mouths.  The water would flow in through their open face hole and then out again through the gills.  This provided them with both food and oxygen which are good things to have if you want to not die.  And not die they did.  Or didn't.  Or didn't not do.  Or whichever combination of words means that they survived for quite a long time and can, in fact, be found alive today.  The relatively gross Lampreys and the downright vile Hagfish are both examples of Agnathan (jawless) fish.

Those little gills that they used to pull oxygen from the water are all feathery and frilly and, if taken out of the water, will collapse in a little less than frilly pile.  To combat this, these jawless fish used special cartilage bars called Gill Arches to give the gills a bit of backing.  These gill arches served the purpose remarkably and kept those little frilly gills open and extracting oxygen, but the relative stiffness of these gill arches could also be viewed as a bad thing.  Since they couldn't flex too much the fish had to rely on continuous movement or the occasional currents to keep water flowing over their gills.  

This constant motion was a major energy drain and could have been a bit of a problem for these early critters.  No matter how streamlined you are, constant movement is going to require more energy than simply hanging out.  If you will allow me a bit of gross oversimplification, after a bit of time a mutation or series of mutations in the genes that regulate the formation of these gill arches came about and, quite literally, changed the world.  The gill arches became hinged so that they could be a bit more flexy.  This added flexibility gave those critters with these mutations an advantage over their less flexy peers.  They could now pump their gill arches like a bellows and bring flowing water over the gills without having to move around much.

So now we have flexible gill arches.  You might be asking, What does this have to do with my ability to eat a cow?  Actually, it has everything to do with your ability to eat a cow, or celery, or anything else for that matter.  You see, it was these flexible gill arches that eventually became the jaws.

In another gross oversimplification, over time the front gill arches became more flexible and pushed forward a bit.  The flexible gill arches in the front linked up with the mouth and gave the fish a tool for trapping food.  Now the fish could flex the rear arches to bring water into the mouth and over the gills, and it could flex the front gill arches to snap completely shut to catch other critters for food.  The jaw was now basically complete - an apparatus for taking oxygen out of the water was turned into a weapon.

For a more complicated version of these events complete with fancy science words and a lot more detail, go here.