modernprometheusscience

[modernprometheusscience]

Curious about weird #science? Join me and Liv Gaskill on our new #podcast, After School Science Club, where we'll discuss everything from A (for aliens) to Z (for the zombie apocalypse). All 100% "real science" approved!

Now available on Apple Music, Spotify, and Amazon Music. (Google Podcasts coming soon!)

Or visit us at:

https://scienceclubpodcast.substack.com/

[modernprometheusscience]

Unfortunately, I made a great mistake: we began working with this cell line (Hela) and I took the cultural plate with this cells without glovers(((( will I have problems with my health?

Hey, science friends: always use appropriate personal protective equipment in the lab! Whether you’re working with chemicals, biologics, or just glassware that could shatter and hurt you, there’s never a reason not to be safe.

That said, don’t worry too much about an isolated incident, Anonymous. If you touched the outside of a plate without gloves, none of the cell culture medium escaped from the plate, and you washed your hands thoroughly afterward, you’ve probably escaped any major harm.

The bigger danger is the likelihood that you contaminated your cell lines– so keep an eye on them, and if you see anything unusual, bleach them and start over. (To be honest, if you have access to new cells, I would start over with that plate nonetheless, just to be on the safe side. Why jeopardize an experiment that could be important?)

However, this doesn’t mean that it’s okay to touch the outsides of plates without gloves. It’s easy for culture medium to spill, or for a previous chemical or culture spill to contaminate the outsides of your plates in the incubator. Don’t take the risk– wear the gloves (and the lab coat, and the eye protection, and the UV shield, and anything else that’s relevant to your experiments)!

[modernprometheusscience]

Do whales fart?

They do! In fact, almost all mammals, land or sea, are known to pass gas. Generally, the food you eat– or the food a whale or other animal eats– is broken down in the stomach by bacteria and digestive enzymes, and one result of that breakdown is gas. Air can also enter the stomach if you eat or drink too fast, or breathe while you eat.

No matter how it gets there, the end result is that whales, like you, have to get it out again somehow– and that’s where flatulence comes in.

Want to see it for yourself? Of course you do! Click here or see below:

[modernprometheusscience]

There's been a lot of debate lately over whether science fiction needs accurate science – or whether it's even worth discussing the accuracy of science in science fiction. What kind of person expects a science textbook instead of just a fun romp? But as a new essay points out, this is really a matter of suspension of disbelief.

[modernprometheusscience]

Five reflections on an important BMJ paper

I'm sorry I haven't been around much! In plain terms, I've escaped the gilded cage of graduate school, moved overseas, and started working at a dream job (yes, in science and medical writing and editing). It's taken up a lot of time, but I still plan to update Modern Prometheus whenever I can.

Meanwhile, check out this article by Mark Henderson of the Wellcome Trust, talking about how media hype leads to exaggerated or even inaccurate science. The original study is fascinating, despite challenges in defining things like "exaggeration," and it's a note-to-self for me as well.

[modernprometheusscience]

Biologist Mick Schubert talks about the possibility of the Infinity Formula existing in the real world!

A little while ago, I mentioned that I occasionally do some science consulting for Marvel Comics, and I shared a few videos I'd made with them.  Here's another one, about the plausibility of the Infinity Formula and how it might work in a (quasi-)scientifically-accurate manner.  It appeared in Original Sin #6 and I'm pretty blown away because Marvel have made the video look really cool.  Check it out!

[modernprometheusscience]

hello, i love your blog! anyway, this is just a random thing that i was wondering today: so i know more or less what causes halitosis (bacteria build up --> waste products which stink, or the breakdown of amino acids into stinky stuff) but how come it gets worse when one has dry mouth? i would have thought that a moist environment would be most habitable and therefore lead to higher bacteria count, and from there worse breath. or is it as simple as the saliva 'washes' it all away? thanks!

It really is about as simple as that!

You’re absolutely right in that a lot of bacteria, including most of the types living in your mouth, grow best in moist environments.  That’s why mouths are such a great environment for bacterial growth in the first place, and why it’s been suggested that there are actually more bacteria in a single person’s mouth than there are people on the entire planet.

But some bacteria don't need much moisture to thrive, and even for the ones that do, a dry mouth isn't enough to kill them.  There's usually enough residual moisture for them to be able to continue living and replicating.  Many types of bacteria even mix with saliva and other components (like food or dead cells) to form a sticky biofilm on your teeth or the inside of your mouth; this biofilm can then act as a safe haven to them when other areas of your mouth are less hospitable.

The bacteria in your mouth can create odours in several ways.  The microbes themselves decompose after death, but that isn't all – they also generate waste as a result of processing the proteins and other chemicals in your food.  Breaking those molecules down results in a wide variety of gases*, all of which contribute to the smell of "morning breath."  Not to mention that oral hygiene is never a perfect process, so you likely also have some tiny particles of the day's food left in the crevices of your mouth and teeth; those can become a part of the odour as well.

During the day, saliva takes care of most of these problems by providing a constant, self-generated mouthwash.  It dilutes the bacterial populations in your mouth, rinses away the ones that are no longer able to adhere (including those that have died), and washes out waste products as well.  At night, though, saliva production decreases dramatically, so there isn't much cleaning going on, and the bacteria are free to generate foul-smelling compounds for hours.  Only in the morning, when you start producing saliva faster again (or when you drink water or brush your teeth), are they removed.

So, in short, your original idea was right!  The saliva "washes away" dead bacteria and waste products.  It also dilutes bacterial populations in the mouth and keeps the environment moist enough to keep down the formation of sticky biofilms (though you still have to actively clean your teeth to effectively eliminate them).  The bad news is that just about everyone gets the same "morning breath" effect for the same reasons (though there are some conditions that can cause dry mouth at other times or make the problem worse).  The good news, though, is that it's usually a quick and easy problem to solve!

* The best-known odour-causing chemicals are the volatile sulphur compounds, or VSCs, which can smell like anything from rotting eggs to human waste.  There are plenty of others, though, including cadaverine and putrescine (chemicals involved in scents of decay), acids, ammonia and related compounds.  In some diseases, uncommon chemicals can lend a characteristic odour to the breath – for instance, diabetes, in which acetone causes a sweet or fruity smell.

[modernprometheusscience]

Hi, I was wondering how we are able to see clouds? If they're a gas, how can we see them? If they're a liquid, how do they not just fall out of the sky without forming clouds at all?

Clouds are actually made up of tiny water droplets or ice crystals suspended in the air.  When they’re in cloud form, they aren’t heavy enough to fall, so they drift – the same effect you see with dust motes in a beam of sunlight.

But why can we see them?  Well, even though they are too small to fall, the water droplets in a cloud are more than sufficient to scatter light.  The average droplet is about ten micrometres in diameter.  The wavelengths of visible light are somewhat smaller (less than one micrometre*), so light is easily interrupted and scattered by the droplets, meaning that the cloud stands out from the background sky and becomes visible.  And, because all of the visible wavelengths of light scatter roughly evenly in all directions, our eyes pick up all of the colours at once, meaning that we see white.

Or rather, we see white most of the time.  Rain clouds, on the other hand, usually look grey – but how?

The even distribution of light by a white cloud is a special type of scattering called Mie scattering, which applies to any situation where the particles doing the scattering aren’t too different in size from the wavelengths of light being scattered (for an example of what happens when the particles are much smaller, check out this earlier post on Rayleigh scattering).

Mie scattering means that the light is scattered in all directions.  As rain clouds build up, though, they become taller and thicker, meaning that light has to pass through more and more layers of suspended droplets in order to reach the ground below.  Because all of these layers will scatter some light off to the sides or back up toward the source, the thicker the cloud, the less light reaches the ground (and the observer’s eye).  That’s what makes storm clouds look grey – and now you also know that the darker the cloud, the thicker it probably is and the more water is up there just waiting to fall!

* The visible light spectrum ranges from about 390-700 nanometres.  The shortest wavelengths are violet and blue (and if you go even shorter, you end up with ultraviolet light), whereas the longest are orange and red (and if you go even longer, you end up with infrared light).

[modernprometheusscience]

regonym asked:

If this hasn’t been asked about already, would you be so kind as to write a general primer on what GFP can and cannot actually do? and then send it to Steven Moffat Because while I love me some fluors, they are commonly mistreated as magical hand-wave-y things in the media, and there are probably still tons of neat things that I have yet to learn about them! Also I feel like the more people who know that glow-in-the-dark rabbits a la Sherlock are completely ridiculous, the less I will potentially be face-palming at fic/shows/the universe in the future. And that would be awesome. <3

Let’s talk about green fluorescent protein!

It’s a staple of science fiction movies – someone walks into a darkened laboratory, only to find a cage of softly glowing green mice (or rats, or rabbits, or cats, or just about anything at this point).  The bright light is an unmistakable sign: These are Science Animals!  They’ve been genetically altered and may well have superpowers!

But that isn’t how GFP works in the real world.  First and most importantly, this protein doesn’t make animals glow in the dark – that’s a misunderstanding perpetuated by generations of sensational science reporting.  What it actually does is allow animals to glow when exposed to certain wavelengths of light, mainly in the ultraviolet (non-visible) range*.  Turning off the lights is not enough to make a genetically engineered “glow animal” fluoresce; you would have to shine a black light on it to see the effect.  (This is where the BBC’s Sherlock went wrong; rather than having the Baskerville rabbit glow in the dark, they could perhaps have written in a blue light source that would have made the scene scientifically plausible.)

Of course, this assumes that the glowing protein is being expressed in the first place.  Usually, when GFP is used for a scientific purpose, it’s to detect something specific – so it’s only present under certain conditions.  For example, sometimes we use the gene for GFP to see whether or not a different gene is being expressed.  To do this, we splice it into the same place as our gene of interest, so that when that gene is read, the GFP gene is as well (this is called tagging).  Thus, if we see the characteristic green glow, we know that the other gene is probably being read as well.  There are a lot of uses for GFP, but this is a common one!

It’s certainly possible to have GFP expressed all the time, so that you can have an animal that requires no specific conditions to glow (other than black light illumination).  All you have to do to get a permanent glow animal is splice the GFP gene into the genome in a place where it is “always on” (that is to say, always being read by the cell’s protein expression machinery).  This is less useful in science, but seems to be quite popular for applications such as “glow pets” or living art.

All right, so “glow-in-the-dark” animals might not be quite as flawlessly engineered as popular fiction indicates; they still need a light source to fluoresce, and permanently-glowing test subjects aren’t all that useful in the laboratory.  But could there be animals engineered to truly glow in the dark, without the need for an external light source?

Absolutely!  After all, jellyfish (the animals from which GFP was originally purified) don’t need to have a light source in order to glow.  Neither do more familiar animals like fireflies.  Many bioluminescent animals make use of a special type of enzyme called a luciferase, which is able to catalyze a chemical reaction to generate light.  Luciferases take a special compound called a luciferin and put it through a series of chemical changes that consume energy and oxygen and emit a photon of light.  If you’d like to know more about how luciferases or bioluminescence in general work, please feel free to ask!

Bioluminescence imaging, the use of these luciferase systems in intact living organisms, is an up-and-coming field.  As far as I know, no one has yet made a “bioluminescent pet,” but the technique has been used to track biological processes, detect bacterial infections, and even to create plants that glow when they’re touched!  So it may be that the technology isn’t quite there yet, or it may simply be that no one has needed to do it, but there’s no conceptual reason why we couldn’t have animals that really do glow in the dark.

For the time being, you may simply have to hand-wave at the “glow-in-the-dark” animals presented in films and on television and either convince yourself that there’s a light source somewhere that simply isn’t being mentioned or that your show is a pioneering example of luciferase-based glowing pets.

* While the major excitation peak for GFP (that is, the wavelength of light that is most effective at making the protein glow) is at 395-400 nm, in the ultraviolet range, there is also a minor excitation peak (another wavelength that can induce a glow) at 475 nm in the natural protein or about 488 nm in the most common engineered variant.  This wavelength is in the visible light spectrum and generates blue light, so it is possible that an animal might glow under near-dark conditions where the only remaining light is blue.  However, it wouldn’t glow very brightly; certainly not as much as is shown in most media!

[modernprometheusscience]

What is more eco-friendly, burial or cremation?

This is an interesting question, particularly as people become increasingly aware of the impact they have on the environment and how they might be able to mitigate it.

Readers, please be aware that this post contains discussions of methods for the disposal of a body after death, including brief descriptions of processes (scientific statements only; no details).

Traditional burial involves a number of environmental factors.  There are coffins, of course, which usually require wood, metal, fabric and transportation.  Many cemeteries also require concrete burial vaults to prevent their grounds from collapsing.  There are the resources needed to dig the grave.  Then there are the chemicals used to preserve bodies and make them look presentable (including embalming fluid, which contains formaldehyde, and various types of make-up), not to mention the resources needed to transport the body itself to the gravesite.  Even without factoring in the funeral itself, burial can be very resource-intensive.

Cremation, in the short term, is worse.  The crematorium itself needs power to run, along with heat and fuel for the incinerator.  This tends to involve the consumption of electricity and natural gas – enough to keep the average home running for one to two weeks.  The process of cremation, too, releases pollution into the air, supposedly equivalent to the amount released by driving over 7700 kilometres (or from New York to Detroit ten times!).  Then, most families choose to keep the remains in an urn or other container, the production of which can also consume significant resources.

However, while cremation is the less eco-friendly option in the short term, over a longer period of time, the resource cost of maintaining a gravesite will eventually edge out the cost of cremation.  Thus, in the long term, cremation is actually a better idea.

Neither of these is the best option for an environmentally sound plan, but if you want to pursue one of them, there are ways to make either choice greener.  For burial, you can choose an ecologically-planned cemetery, or any cemetery that doesn’t require a concrete burial vault.  If you must have a vault, try a five-sided one without a bottom or sealer; this supports the ground structure effectively while using fewer resources allowing decomposition to proceed more naturally.  You can also use a compost-friendly coffin made out of paper mulch, raw wood, recycled or locally sourced materials – or no coffin at all.  You can also request the use of an eco-friendly embalming fluid, or none at all.  For cremation, you have fewer options, but there are still many environmentally-conscious urn choices you can make, including ones that can be planted to sprout a tree.

Other ecologically-friendly choices include burial at sea (some companies even allow you to become part of a living reef!), resomation (a process used for the disposal of research cadavers, in which alkaline hydrolysis and steam-heating reduce the body to ash and an organic fluid that makes excellent fertilizer), or promession (in which the body is frozen in liquid nitrogen, powdered and dehydrated; the results of this process are also a good fertilizer).  If your greatest concern after death is your impact on the environment, one of these choices might be better than either burial or cremation.

Update: geneticx said, “Since this question is about environmental friendliness, perhaps you should note that fertilizer isn’t exactly environmentally friendly – it builds up in run-off and is a leading cause of eutrophication in waterways.”

This is true!  I’d be happy to get into the specifics of fertilizer use in another post (some are more environmentally friendly than others, and different types can cause different problems), but not all fertilizers are good for the environment or the ecological systems into which they’re introduced.  And, because these systems are all interlinked, sometimes ameliorating one problem can make another one worse.  It’s all about balance, so research carefully when making plans to try to benefit the environment!

[modernprometheusscience]

So if the sun went dark (for whatever reason) and leaving aside what it would do to the environment... would human beings eventually be able to see in the dark, through evolution?

Maybe!

If the human race were somehow plunged into darkness in a way that didn’t affect anything else, then it’s entirely possible that we might evolve to have good vision in low light.  Of course, this presumes that we still have some light (from the stars, perhaps, or things that glowed in the dark – because I’m presuming that your question rules out artificial light).

With just a little light, we might well evolve to have more rod cells in our eyes, because those are the photoreceptors (light-receiving cells) that distinguish between light and dark and give us night vision.  We would probably also lose some or all of our cones, which are the cells that give us colour vision and see in high resolution, but which are also much less sensitive and thus not much use in the dark.  Cones come in three types – ones that see blue, ones that see green and ones that see red – so it’s possible that we’d end up with more blue cones , which are currently the least common and have the highest sensitivity, for better vision; red and green cones, however, would likely be lost entirely over time.  The upshot of all this would be that humans would develop significantly better night vision, but lose sharp detail and some or all of our colour vision.

We would probably also develop larger eyes over time.  Not only does this provide more room on the retina for rod cells, so that we could have more total photoreceptors, but it also allows the pupils to be larger and therefore to capture more light.  Another major advantage of large eyes, though, is that they would increase the distance between the lens (near the front of the eye) and the retina (near the back).  Much like moving a projector farther away from the screen, this means that the image projected by the eye’s lens onto its retina could be larger, allowing better overall vision and compensating a little for the lack of sharp detail we would lose by using our rods to see instead of our cones.

A common question asked about night vision is, “Could humans ever evolve to see like a cat or an owl?”  While not strictly impossible, this isn’t nearly as likely as the previous scenarios, because cats and owls both have a tapetum lucidum (a reflective layer at the back of the eye that increases the amount of light available to the photoreceptors).  Humans would have to evolve one of these from scratch, because our evolutionary ancestors lost theirs about sixty million years ago as we became increasingly diurnal.  On the scale of evolutionary challenges, the tapetum lucidum and its variants aren’t actually that difficult; they’ve evolved a number of times in different ways, but it would still be more difficult for us to acquire one than for us to simply adapt what we already have – like the size and shape of our eyes and the rod and cone cells that give us our vision.

There are other possibilities, though.  We might not evolve better night vision at all, especially if we had absolutely no light.  Without light, there’s nothing to see by even dimly, and therefore there’s no evolutionary reason to make our vision better.  And evolution is a “use it or lose it” scenario – everything our bodies make has a cost, so if we don’t need something (like eyes), then it saves resources for us not to make it*.  In a world without any light, humans might eventually lose the pigments that make our photoreceptors work, or we might lose the photoreceptors themselves, or, eventually, we might lose our eyes altogether, much like some blind cave fish species have.  Then, instead of developing better night vision, we might acquire other mutations that allowed us to function better in darkness – for instance, our other senses might improve, either due to higher sensitivity of the organs themselves or by an increase in size and functionality of the appropriate brain regions.  We might end up with better hearing, balance, touch sensitivity, or even a better sense of direction!  Eventually, we might well change the structure or purpose of a body part we already possess (like growing longer, thinner fingers to use for feeling our way around, much like some underground and deep-sea creatures use sensory tentacles).  It’s possible that we could evolve something from scratch, like the tapetum lucidum I mentioned earlier, but this kind of mutation is much less likely and more difficult.

So there you have it!  In a low-light situation, we would very likely evolve better night vision and some other sensory improvements.  With no light at all, we’d definitely have to improve our other senses, but it’s quite likely that we’d actually lose, rather than gain, visual acuity.

* This is a process called economical adaptation.

[modernprometheusscience]

Dino 101: Dinosaur Palaeobiology is a 12-lesson course teaching a comprehensive overview of non-avian dinosaurs. Topics covered: anatomy, eating, locomotion, growth, environmental and behavioral adaptations, origins and extinction. Lessons are delivered from museums, fossil-preparation labs and dig sites.

I'd like to introduce you all to Dino 101: Dinosaur Palaeobiology, a course about everything dinosaur-related.  Are you interested in how their bodies work?  How they evolved?  What they ate?  Where they lived?  How they defended themselves?  What eventually caused their extinction?  How fossils are made?  If anything about dinosaurs fascinates you, this course is free, interactive, and taught by some of the top vertebrate palaeontology researchers in the world.

I have a special fondness for this course because it's hosted at my undergraduate alma mater and led by my former higher vertebrate palaeontology professor and friend, Dr. Phil Currie. whom I guarantee you have heard of at some point or other if you've ever been into dinosaurs.  He's a fantastic teacher and this course is definitely worth checking out – in fact, I'll be taking it myself just for fun!

[modernprometheusscience]

Read all about the "Chromatin: From nucleosomes to chromosomes" conference at the Wellcome Trust Genome Campus. A detailed report written by Michael Schubert.

I know this isn't strictly science consultation, nor is it the answer to a question, but after speaking at a scientific conference recently, I was offered the chance to write a conference report for Abcam.  It's gone live now, and I wanted to share it, as it's quite a privilege to have gotten to do it!  Hopefully, I'll get to do a lot more of this sort of thing in the future...

[modernprometheusscience]

I want to ask about genetics. Let's say a supernatural creatures rarely date or marry outside species and if they were to procreate with humans, their children would only carry the gene for magic but not be able to do magic themselves. Is it probable to make magic a recessive gene and that it will take several generations for the magic to be able to be performed by a mostly human person?

Interesting question – and one with more than one possible response!  I'll just skip ahead to the end before explaining here and tell you that yes, it is entirely possible to have a form of genetic magic that could show up in an otherwise-ordinary person after numerous generations with no sign of it.  Feel free to read on to learn more, though!

It sounds like your question is asking about the simplest form of Mendelian genetics, in which there is only one gene for a trait, with two alleles (“settings” for the gene): either “magic” or “non-magic.”  The way you describe it, someone with two “magic” alleles would be able to do magic themselves; someone with one “magic” and one “non-magic” allele would be able to pass on the gene, but not do magic; and someone with two “non-magic” alleles would neither do magic nor be able to pass the ability on to a child.

Alleles can be dominant or recessive, as you already know.  A dominant allele overpowers a recessive one, so if you get a copy of a dominant allele from one parent and a recessive allele from the other parent, you’ll show the traits of the dominant allele and, in many cases, you won’t even know the recessive allele is there!  So, if the “magic” allele is recessive, then that would mean you needed two copies of it in order to be able to do magic.  Having one copy would mean that your other allele was the dominant “non-magic” version, which would overpower the presence of the recessive one and make you unable to do magic yourself.  (You would, however, still have a copy of the “magic” allele, which would mean you could pass it onto a child even though you couldn’t use it yourself.)

So, here are a few things that might happen:

A child might have two magic parents (meaning that both parents had two copies of the “magic” allele).  In that case, the child would be guaranteed to get two copies of the magic allele, because the parents wouldn’t have anything else to pass on, and the child would be able to do magic.

A child might have one magic parent (with two magic alleles) and one non-magic parent (with two non-magic alleles).  In that case, the child would be guaranteed to get one copy of each kind (one from each parent), meaning that the child wouldn’t be able to do magic, but that he or she would have one copy of the magic allele to pass onto his or her eventual children.  So those children couldn’t do magic, but their children might be able to.

A child might have one magic parent (with two magic alleles) and one non-magic parent (with one of each, like the children I just described).  Let me show you what would happen in this case, using a genetic diagram called a Punnett square:

The letters around the sides of the squares tell you what alleles the parents have.  The magic parent (across the top) has two lowercase "m" alleles, meaning two magic alleles.  The non-magic parent (down the side) has one lowercase "m" magic allele and one capital "M" non-magic allele.  The capital letter tells you which allele is dominant; in this case, the non-magic one.

The letters in the square tell you what alleles the children might have.  In this case, you can see that half of the potential children would be non-magic (because they inherit a magic allele from one parent and a non-magic allele from the other), but all of those children might be able to pass on the magic allele to their children.  The other half of the children would be magic (because they inherit the magic parent's magic allele, and also the recessive magic allele from the other parent).

A child might have two non-magic parents who both have a recessive magic allele.  You can try doing a Punnett square on this yourself, but the ultimate outcome is that one of the squares will have two magic alleles (magic child), one of them will have two non-magic alleles (non-magic child who cannot pass the gene on), and the remaining two squares get one of each (non-magic child who can pass the gene on).

A child might have two non-magic parents, one of whom has two non-magic alleles and the other of whom has one of each.  Again, if you do the Punnett square on this, you'll find that all four of the squares are for non-magic children, but half of the children can pass on the magic allele, whereas half cannot.

Or, finally, a child might have two non-magic parents with no magic alleles.  Obviously, that child would neither be magic nor be able to pass on magic.

And this is just the simplest case!  Genetics, however, is rarely as straightforward as this.  Here are just a few of the things that could make the situation more complicated:

Mutation: A non-magic gene might mutate into a magic one, or vice versa.  Alternatively, a magic gene might be mutated to be slightly less effective, but still magic – or a non-magic gene might be mutated to be just slightly more predisposed to magic.  Over time, mutations can accumulate in the genome, meaning that after a few generations, someone with no "magic" alleles might still be able to do magic, or someone with ordinary "magic" alleles might turn out to be unable to do magic, due to mutations in the copies of the gene.

Multiple genes: You might need several genes all working in specific ways in order to be magical.  Just like there isn't one single gene for height, or hair colour, or how fast your fingernails grow, there might not be one single gene for "magic or non-magic."  It could be that overall magical ability is controlled by several genes, or by several groups of genes.  It could be that different kinds of magic are controlled by different genes.

Epistasis: Sometimes, multiple genes work together in a kind of pathway or "flow."  You might have two genes that control magical ability (let's call them A and B), and you might need to have them both turned on in order to be magical.  If A is turned on and B is on, then you're magical.  If A is turned on and B is turned off, then you aren't.  And if A is turned off, then it doesn't matter whether or not B is turned on because you can't be magical either way.  This control of one gene by another "upstream" gene in the pathway is called epistasis.

Regulatory genes: Some genes in the genome can control whether or not other genes are read, or when they are read, or how much they are read.  These genes can "turn on or off" other genes at various times or under various conditions, or they can help to control how much of a gene's product is present in the system (for instance, if a gene makes a particular protein and it's dangerous for the body to have too much or too little).

Epigenetics: Genes aren't entirely independent.  They're controlled by all sorts of outside factors – how tightly their DNA is packed (which controls access to the genes, which controls whether and how much they work); whether or not the protein machines designed to make them work can bind to them; whether or not there are outside factors interfering with them; all sorts of things that aren't in the genes themselves, but control whether and how well they work.

Of course, as long as this response is, it's just a small taste of what goes on in the genome.  I could keep listing possibilities for ages!  As I said, though, the long and the short of it is that, yes, you can have a recessive (or otherwise hidden or low-grade) inclination toward magic that might show itself in an otherwise-ordinary family line after several generations.  In fact, as you can see, there are even all sorts of different ways to do it!

[modernprometheusscience]

About a year and a half ago, I did some science consultation for Marvel Comics and made a few short videos for the Marvel Augmented Reality app about the real biology of superheroes.  This is one of them, which appeared in Captain America #5 and discusses ways in which the Super Serum might theoretically affect Captain America's body.  (And yes, they did spell my name wrong in it, though they got it right in all the other videos.)

I don't know where all of these videos are embedded in the comics (though I remember doing some for Hulk, the X-Men and the Fantastic Four that I haven't yet found), but here are two more from the Marvel homepage:

The Science Behind Radioactive Blood, which appeared in Superior Spider-Man #7 and talks about what would really happen if your blood were radioactive.

Legion's Biology, which appeared in X-Men Legacy #11 and talks about the way the supervillain Legion might realistically work.

[modernprometheusscience]

I have come to ask some SCIENCE. If you had a system that consisted of a pair of lasers facing away from each other in a total vacuum and both were turned on for some amount of time (until the batteries went flat), would you not then have two light waves moving further apart from each other for eternity? And doesn't that break thermodynamics? Or am I just wrong about that? If I'm not just wrong I am assuming the answer involves curvature of space somehow.

Technically, the answer to this question is that it doesn’t matter whether or not you have two light waves moving farther apart for eternity.  There are some complex calculations that can be done to determine whether or not the light waves continue to move apart the way you describe*, but it isn’t really important because either way, it doesn’t actually break thermodynamics.  (It had better not, because every star in the universe is essentially doing the same thing as those two lasers, but on a much larger scale.)

About fifteen years ago, scientists discovered that the universe is not only expanding, but doing so at an ever-accelerating rate.  Everything is not only moving farther away from everything else, but it’s moving away faster and faster all the time.  Taken to its logical conclusion, this means that, eventually, everything will be moving away from everything else at the speed of light, or ultimately at an even greater speed than that**.

Where you might be running into trouble is in your interpretation of the second law of thermodynamics.  It does state that “the entropy of an isolated system [in this case, your two light waves] never decreases.”  It even goes on to further state that “systems are always evolving toward thermodynamic equilibrium,” which means that they are moving toward a balance in which there is no flow of energy from any part of the system to any other.  None of this means, though, that your lasers necessarily break the law.  The most basic mathematical statement of the second law is this:

where S = entropy of the system and t = time.  (So, to put this equation into words, “the change in entropy of the system over the change in time is greater than or equal to zero.”)  Or, in plain English, “over time, the total amount of entropy in the system has to either stay the same or increase.”

So what this means is that it’s actually okay for the entropy of the system never to increase, as long as it isn’t decreasing.  Your interpretation of the second law assumes that everything in the universe will eventually be “perfectly mixed,” or that the entropy of everything will eventually be the same – which isn’t true.

* You would have to know the starting distance of the lasers from one another and from the edge of the universe, and then correlate the speed of light (299,792 km/s) with the acceleration of expansion of the universe (74.2 km/s/Mpc) in order to see whether the light waves continued moving directly away from one another and if so, for how long and how fast.

** This might seem to violate special relativity (which postulates that speeds greater than that of light cannot be observed), but in fact it doesn’t, because the universe is also expanding, so nothing is actually moving through the universe at a relative speed greater than that of light.

[modernprometheusscience]

Hey Mick, why does it sometimes hail even when it's not that cold? How does liquid rain skip straight to solid ice without turning first into snow?

Aha!  You’ve asked two separate questions here, so I’ll answer them each independently.

First, hail is actually often a product of warmer weather.  Typically, what happens is that a raindrop will form within a cloud that features strong up- and downdrafts within it.  Before the drop can fall, it gets caught in an updraft and carried to the top of the cloud, which is usually very cold (in fact, the more severe the weather, the colder the cloud tops often are).  If the air is cold enough and the drop travels high enough, the water will freeze, yielding a small hailstone.  This hailstone will begin to fall again, but if the updrafts are strong enough, it can be carried up again and again, acquiring a new layer of ice each time until it is so large and heavy that the air currents can no longer support it.

Though it isn’t always necessary to have warmer weather in order to form hail, it is quite common, especially as high humidity also increases the probability of hail.

As to snow, that forms by quite a different process and doesn’t come from rain at all.  What happens with snow is that a tiny particle called a “condensating nucleus” or a “seed” allows water to condense around it and, if the temperature is at or below freezing, the water forms tiny, feathery ice crystals instead of heavy droplets.  More ice crystals can accumulate as long as the seed remains in the condensing environment (that is, the cloud), and when the accumulated ice becomes heavy enough, it falls.  If the air temperature is at or below freezing all the way to the ground, the ice remains in its snowflake form; that’s snow.  However, if the air is warmer lower down, the snowflake will melt into rain, and if there are alternating warmer and colder layers, it will melt into water and then re-freeze into hail!  It’s quite common for snowflakes to undergo changes and become other forms of precipitation on their way down, but a snowflake cannot form from another type of precipitation after falling from the clouds.

I hope that clears things up for you!