Note (12/2015): Hi there! I'm taking some time off here to focus on other projects for a bit. As of October 2016, those other projects include a science book series for kids titled Things That Make You Go Yuck! -- available at Barnes and Noble, Amazon and (hopefully) a bookstore near you!

Co-author Jenn Dlugos and I are also doing some extremely ridiculous things over at Drinkstorm Studios, including our award-winning webseries, Magicland.

There are also a full 100 posts right here in the archives, and feel free to drop me a line at with comments, suggestions or wacky cold fusion ideas. Cheers!

· Categories: Biology, Genetics
What I’ve Learned:

X-linked inheritance: sometimes chromosomes aren't X-actly as they should be.
“X-linked inheritance: sometimes chromosomes aren’t X-actly as they should be.”

We humans have a bunch of chromosomes — balled-up tangles of DNA — lying around our cells. Forty-six of them, in fact, in twenty-three pairs. We get one chromosome of each pair comes from our mother and one from our father — though they may smush together and intermingle during the fertilization process.

(That’s the chromosomes, not our parents. They smushed and intermingled right before the fertilization process, obviously. Also, Barry White was probably involved, which you don’t typically find at the chromosomal level.

Most DNA strands are more into Marvin Gaye.)

The last chromosome pair — the “sex chromosomes” — is special. Males get one copy each of an “X” chromosome and a “Y” chromosome. And females double up on “X” chromosomes, leaving out “Y” altogether.

(The chromosomes get those names because under a microscope, they look a little like the alphabet letters.

To whom, I don’t know. Maybe Elmo from Sesame Street is in charge of naming biological structures.)

Put another way, if a fertilized egg gets the “Y” chromosome from the father (and one of the mother’s “X” chromosomes), the child will be male. If it gets the father’s “X” (and a second “X” from the mother), it’ll be female. Genes on these chromosomes will kick in during development, to determine the sex of the child.

(That’s how it works in humans, anyway, and most other mammals. Some animals have different sex chromosomes — like chickens, where hens have ZW and roosters are ZZ. Or grasshoppers, where females get XX and males get one X, nothing else, and are told to suck it up and stop whining.

Or platypuses, which have ten sex chromosomes, because of course they do. Platypuses are freaking weird.)

The XX versus XY choice has consequences down the line. Many genetic traits are “recessive”, meaning if just one of your two chromosomal copies is defective, you’re fine. Only if both are screwy will you have the trait or disease. For genes on, say, chromosome 3 or 12, that’s okay — everyone’s got two copies, so it’s rare to get both mucked up at once.

But X chromosome genes are trickier. Males only get one copy of X — from their mothers, remember, because to even be male, they had to get a Y from their fathers. If a gene on that lonely X chromosome happens to be horked up, they’re out of luck. There’s no backup, no “chromosome on the cloud” or flash-drive file to recover. One X chromosome, one chance to get all of “X-linked inheritance” right.

Sometimes, it doesn’t happen. If a recessive trait is X-linked and the father has a wonky copy, his daughters will all inherit it — but one bad copy doesn’t hurt. They’ll still get a “normal” X from Mom, and hopscotch happily away. If the mother is affected, all her kids have a 50% chance of catching the bad copy — but again, in girls, it’s covered by a healthy X (this time, from Dad). Only the sons, with mother’s lone mangled chromosome, get dinged by recessive X-linked inheritance.

(Daughters can also get the diseases. But it takes both an affected father and mother — and a bit of bad luck — to be so dinged. It’s like the sperm and egg walked a black cat under a ladder or something.

There’s also “dominant” X-linked inheritance, where even a single defective copy of a gene causes a disease. Females are more likely than males to inherit these conditions, but they’re pretty rare. Overall, X-linked torpedoes still sink males more often.)

So what issues can X-linked inheritance cause? Common recessive disorders include hemophilia, color blindness and certain types of muscular dystrophy. And the rarer stuff includes even nastier syndromes and diseases you wouldn’t wish on your worst newly-fertilized enemy.

So however many X’s you happen to have, be happy that the dice of X-linked inheritance probability didn’t roll snake eyes for you. Unless they did, and then curse the cocked-up chromosomes that combined to mark the mutant-X spot. If only you’d been a platypus, this might not have happened.

Something much weirder, probably. But not this.

Actual Science:
Medline PlusSex-linked recessive
NCBIAn introduction to genetic analysis / human genetics
Science PrimerX-linked inheritance
NHS UKX-linked conditions
Wellcome TrustX-linked diseases

Image sources: Madical School (X-linked inheritance), AllMusic (White ‘n’ Gaye), Aussie Pete II (Elmo [and Norah Jones!] and Y), Try Nerdy (platypus sex [chromosome] appeal)

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· Categories: Biology, Genetics
What I’ve Learned:

Alu element: The crowd's not boo-ing, they're Aluuuuu-ing.
“Alu element: The crowd’s not boo-ing, they’re Aluuuuu-ing.”

This is one of those times when being a baseball fan can help you learn something about science.

(All the other times either involve knuckleballs or an obscure branch of physics dedicated to explaining what the hell has kept C.C. Sabathia’s pants up for most of his career. So this one is the best, obviously.)

Back in prehistoric times, before most anyone was born probably, people were playing baseball. I’m talking way back, like 1960 or so. It was around that time that major league baseball was invaded by the Alou family. First came Felipe, then his brother Matty — and then his other brother Jesus. And just when you thought there were no more, another Alou family member, Felipe’s kid Moises, joined the league. And Felipe stuck around as a manager, after is playing days were over.

Basically, Alous were everywhere in baseball. You could scarcely swing a dead Louisville Slugger around the majors without thwacking an Alou element. Not that anyone did that, of course. It would be unsportsmanlike.

A similar thing happened long ago in our genomes. Tens of millions of years ago, some furry little ancestral critter hiccuped, mutationally speaking, and produced the first Alu element. These Alu elements are short snippets of DNA that got erroneously copied out of a gene, mangled, and jammed back into the genome. The DNA bits couldn’t hit a curveball or shag fly balls, but they did have one major-league talent:

They could make copies of themselves, which could then set up shop in other spots in the genome.

Just like the Alous, who didn’t enter the league at the same time or always play for the same team, the Alu elements gradually spread themselves around. The species in which they first popped up was an ancestor of a set of mammals called Euarchontoglires, or “supraprimates”; these include, among other beasts, rodents, tree shrews and primates — including humans. That means that all these species — again, including humans — have Alu elements hanging out on their genomic rosters. Lots of them.

It’s like the Alous signed on — and then made clones of themselves, until they were everywhere all over the field. Real Bugs Bunny vs. Gas-House Gorillas stuff. Only with less cigar-chomping lunks, and more transposable DNA elements.

In total, Alu elements make up more than ten percent of the human genome, and there are more than a million of them in every person’s DNA right now. A few thousand of those are unique to humans, but most can be found in other animals, like those shrews and monkeys and such mentioned above. That’s how we know Alu elements jumped into the game a long time ago; all of these species still list Alus on the roster.

Most copies of the Alu elements don’t do much, since they’re located in stretches of DNA between genes. By hopping willy-nilly around the genome, Alu elements do increase our genetic diversity — and recent reports suggest they may help defend against toxins and viruses. The many copies can mutate over time, however, and they can insert into some pretty inconvenient places. These buttinski Alu copies have been linked with diseases from hemophilia to Alzheimer’s to type II diabetes to several types of cancer.

Which is where the parallel with baseball breaks down. So far as I know, no Alous ever scrambled anyone’s DNA, or made opposing pitchers more susceptible to developing cancer. Getting sent down to the minors, maybe. But never cancer.

So the Alous and the Alus have a few things in common. They’ve both been around for nearly forever, and there are a zillion of each, all a little bit different. But one is a family of All-Stars and sluggers, while the other is hitching a ride in our DNA like a pack of joyriding genomic gypsies.

No wonder the Alous are the ones on the baseball cards.

Image sources: Genome News Network (Alu element), Suite / Kevin Schindler (Alous, Alous everywhere), Business Insider (so much Sabathia), (Gas-House Clone-rillas)

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· Categories: Biology
What I’ve Learned:

Tumor suppressor: I'm no hero; I'm just doing my job.
“Tumor suppressor: I’m no hero; I’m just doing my job.”

Fighting evil isn’t all it’s cracked up to be.

First of all, it’s hard. Evil is basically everywhere outside of Walt Disney World, so there’s always another battle on hand. Also, evil is fiendishly creative. Just when you think you have it in check, it’ll pop up behind you, tenting its fingers and snarling, “Excellent.”

But the worst part about fighting evil is that you’ll never be recognized for anything else. That must get old for heroes. Sure, Captain America gets medals for thwarting villains — but maybe he writes poetry, too. Nobody talks about that. What if Superman is a great baker? Or Wonder Woman is a two-handicap golfer? Who would even know?

That’s how it is for so-called tumor suppressor genes. These are genes that have perfectly useful functions in normal cells, merrily toiling along, getting their jobs done. But nobody cares about those jobs — outside geneticists, who nose around everything a cell does. Instead, most people focus on one thing:

If these genes are knocked out of a cell — silenced by mutation or deletion or runaway genetic regulation — then the cell may turn cancerous. With tumor suppressors around, no cancer. Without them — watch out.

The thing is, these genes don’t exist to prevent cancer, exactly; the very name “tumor suppressor” is misleading. In their mild-mannered day jobs, these genes get translated into proteins, and those proteins mostly control whether the cell they live in should grow or not. If it’s not time yet, don’t grow. If the cell is damaged, don’t grow. If it’s badly damaged, try and fix it. And if it can’t be fixed, smash it to bits and storm off in a huff of cytoplasm.

(So basically, tumor suppressors are like eight year old children building a Lego set. “Evil fighters”, my ass.)

The “smash it to bits” part is kind of important. If certain tumor suppressors are working properly — but the rest of the cell isn’t, the bum — they can trigger a process called programmed cell death, also known as apoptosis. This is pretty much what it sounds like — slapping a proverbial “KILL ME!” sign on the wall of the cell, and letting the body rip it limb from limb.

Gruesome, maybe — but better than having a mutated cell grow out of control, and eventually form a tumor. Any good horror movie will tell you: better to off yourself in an emergency than to join the mutant zombie horde. All that shambling around is exhausting, and who wants brain stuck between their teeth?

Anyway, tumor suppressors are very important genes; they’re just not named especially well. Fighting evil — or tumors — gets so much attention that the real everyday jobs these genes naturally do barely gets recognized. Instead, they’re known for a function they serve almost by default.

It’s like labeling a butt plug a “poop suppressor”; technically true, but not really what the thing is actually used for. Which, as any Parisian can tell you, is a giant Christmas tree.

I bet that thing would suppress the shit out of some tumors. Ho ho ho.

Image sources: CISN (crash into cancer!), Government Executive (Burns, tenting), Sparkles and Crumbs (sweet-tooth Superman), HugeLOL (apoptosis, post mortem), BoingBoing (Parisian Christmas tree art, aka “O Pluggenbaum”)

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· Categories: Biology, Genetics
What I’ve Learned:

The punctuated equilibrium of Tatiana Maslany in Orphan Black
“Properly-punctuated equilibrium: Ten million ellipses, then a whole bunch of exclamation points.”

Punctuated equilibrium sounds like something you get when you perforate an eardrum. Like there should be PSAs about it, with scary pictures of death metal bands and Beats headphones with blood on the cans.

Luckily, it’s not that. No one’s coming to tear the Dethklok from your cold, deaf hands.

Instead, punctuated equilibrium is an evolutionary biology concept that made a big splash in the 1970s. It’s been desplashed a little since then, but it’s still pretty important. Plus Stephen Jay Gould helped think it up, and mostly everybody liked him. So there’s that.

The idea is this: in (at least) some cases, the pressure on organisms to evolve and adapt and squirt out a bunch of funky new species isn’t constant over time. When there’s plenty of food and the water is fine and everybody owns their own TiVo, then it doesn’t matter much if your individual set of genes makes you three percent hardier than your neighbor.

Oh, sure, you might get off your deoxyribonucleic ass and mutate up another leg or some gills or an enzyme to digest styrofoam. But let’s face it: you’ve got a pizza coming, and you’re still catching up on last season’s Orphan Black. Who has the time to speciate? And frankly, why bother?

This could go on for millions, or tens of millions of years.

(Well, Orphan Black won’t, of course. Tatiana Maslany is terrific and all, but she’s going to be too old for this thing at some point. I don’t care how many gills she grows.)

Things get interesting, says punctuated equilibrium, when the going gets tough. If the resources dry up, individuals die out. Small groups get separated from others; exploitable niches become more important. The quickest — and perhaps most radical — to adapt will ultimately thrive. Like the guy who brings a flask to the keg party, in case the beer runs out.

Or something less alcoholic. If you must.

It’s during these periods of ecological pressure and isolation that many new species are born. In between, all the old fern and finch and crocodile species sit around getting fat on Cheetos. And often each other.

But introduce a little hardship, and nature blossoms with adaptation to take advantage. That’s why an oceanful of brine shrimp will remain boring dumb brine shrimp forever. They want for nothing; they’re little trust fund crustaceans, born with silver… um, tiny handled eating utensils that rich baby shrimps would use… in their mouths.

(Or gills. Or whatever. Look, there’s no “aquatic face anatomy” tag on this post, all right? You get the idea.)

However! Scoop a small colony of shrimp out of the sea, stuff them in an envelope and shove them in the mail — now that’s an ecological challenge. And it’s enough to turn them into a whole new species: Sea Monkeys, with legs and fingers and brains and disturbingly human lips and what appear to be testicles growing on stalks out the tops of their heads.

And how does it work? Through the science of punctuated equilibrium.

So far as you know, unless you happen to own any of Stephen Jay Gould’s work. Or a freshman biology book. Or Sea Monkeys.

Stupid Sea Monkeys.

Actual Science:
Princeton UniversityPunctuated equilibrium
Evolution 101 / BerkeleyMore on punctuated equilibrium
National Center for Science EducationThe origin of species by punctuated equilibria
Shaking the Tree / Google BooksPunctuated equilibrium comes of age
Astrobiology MagazineLife after catastrophe

Image sources: BioNinja (evolution models), NeatoShop (poorly punctuated), BioNinja, The Mary Sue, io9 and Huffington Post (Tatiana Maslany clone evolution), She’s Fantastic! (Sea Monkeys)

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