Category Archives: Our kin

Why isn’t evolution erasing roadkill?

I live in the suburbs, so dodging roadkill on the way to work is a daily fact of life.  I’m also an unbridled dork, so I can’t help but wonder when I pass the poor victims when evolution is going to kick in and give these guys the sense to stand back from the highway, or come up with some other novel deterrent.  Then I put my reasoning cap back on and remember that evolution is a slow and gradual process, grinding out over vast stretches of geologic time, and that even beneficial changes can be diluted in a large population and not take hold. Maybe our vehicular death dealers are just too new on the scene to have yet prodded any progress.

But it’s not like we haven’t observed selection in action, often times resulting from our own deeds.  The easiest example is the adaptation of bacteria to resist certain antibiotics, a topic discussed at length here on WDTM?  Bombing a bug with drugs is really no different than any other environmental pressure, and those bacteria that just happen to be better equipped to weather the medicinal storm are the ones that live to repopulate the world with more robust beasties.  Bacteria aren’t the only creepy crawlies to get a boost from our well-intentioned eradication efforts, as the recent bedbug plagues in New York City and elsewhere demonstrate.  A March study in Scientific Reports observes that 14 protein-coding genes were “overexpressed” in the heartiest populations, preventing or slowing the absorption of pyrethroid, the most common pesticide used against them.

On a macroscopic level, a group of common mice in Germany have become resistant to the poison warfarin as a result of a horizontal gene transfer from the non-native, human-introduced Algerian mouse.  The unintentional poisoning of the Atlantic tomcod thanks to General Electric’s decades of inconsiderate PCB-dumping into the Hudson River has caused the feisty fish to develop a way to keep the chemical from binding to its cells.  And don’t forget the textbook peppered moth example which, despite flaws in the original methodology that have been corrected in later experiments, continues to show that the darkening of tree bark by industrial soot helped the varieties with more melanin blend in better and avoid the notice of predators, drastically decreasing the population of the their lighter colored brethren.

WHAT DOES THIS MEAN?

So what gives, guys?  I know there isn’t camouflage that would conceal certain raccoons from cars, but knowing that major changes can take place within a few generations thanks to our (often unhealthy) influence, where’s the roadkill resistance?  Charles Brown of the University of Tulsa may have found an example!  He describes in a Current Biology paper how his taxidermy hobby led him to notice that fewer and fewer cliff swallows were being hit by cars over the past 30 years, and further research showed that the ones who do meet their untimely ends have longer wingspans, on average, than the rest of the populations.  It might be that shorter wings make the birds more maneuverable, or maybe they’re just smartening up and staying away.

Evasive maneuvers!  From wired.com

In either case, that’s a system working and more evidence that some organisms can adapt rapidly to selective pressure, even when it’s unnaturally introduced by us.  That’s not a reason to continue our bad behavior, though.  For example, the buffed up Atlantic tomcod may be resistant to its surrounding toxins, but the things that eat it (like HUMANS) aren’t and can subsequently still get sick.  Plenty of other fish species in the Hudson have suffered.  Pest resistance obviously isn’t something we want to encourage, either.

You Are the Product of 4 Billion Years of Evolutionary Success…. Or Not

“Dude, you’re a dumb-ass.  I’ve got the perfect meme for you:”

product

Ha, yeah, that’s funny man.  Wait, what am I, the wolf?  Are you the wolf?  I mean, I woulda thought you’d go the “humans are the pinnacle of evolution” route, with our big brains and upright stance and twitter and shit.  But wolves are cool too.  I mean really, so is everything.  When you think about it, each individual organism out there in the world is the “product of 4 billion years of evolutionary success.”  (Well, more like 3.5 billion years, but what’s 13% between friends?)  Innumerable generations through unfathomable ages striving, struggling, eating, fucking; all so that bumblebee can buzz by, or the wolf can chow on that rabbit, or you and I can have this conversation.  Everything alive today is the culmination of an incomprehensibly extensive, geologic-scale lineage.

But yeah, human beings are clearly the most successful species on Earth.  Right?  How do you define “success?”  Is it sheer complexity?  We got that down (#awesome).  Okay, so what?  Remember what Stephen Jay Gould pointed out in his book Full House about the “Drunkard’s Walk” (which is also the title of a Leonard Mlodinow book about statistical randomness).  Imagine you get hammered and stumble two steps out the door of the bar.  You’re soused, so you don’t know where you’re going; you’re equally as likely to take a step forward as you are backward.  You can’t go too far back or you’ll hit the wall of the bar.  That’s like the lower limit on complexity.  So you stagger around and eventually, just by chance, you’ll end up way over at the next building, the upper limit of complexity.  Is that an achievement, you fucking lush?  Or was it just that enough time elapsed that you were able to cover all the possibilities?

No, asshole, I’m not saying that evolution is random.  Individual mutations are random, but the ones that best adapt an organism to their particular environment are the ones that get selected for.  “Particular” being the important word there.  To oversimplify, wooly coats won’t help at the Equator and wings do you no good underground.  So is any one trait “better” than another?  Depends on where you are.  Sometimes complexity even hurts you.  Snakes ditched their limbs because they likely hindered burrowing and cavefish traded their eyes for other weapons (unrelated to the Stonecutters’ machinations).  And what if the other guy is ramping up the fitness as fast as you are?  Gazelles get faster, so lions get faster, so gazelles get nimbler, etc., etc.  That doesn’t sound like progress or success.  That sounds a lot like running in place.

All right, forget about success, how about DOMINANCE! We are EVERYWHERE!  And there’s a lot of us!  Seven billion big animals running around.  We’ve filled ecologic niches from the rainforest to the tundra, but bacteria and even simpler forms of life have found ways to withstand the pressures at the bottom of the ocean and the scalding conditions in thermal springs.  They’ve obviously got us beat on pure numbers, but our big bodies don’t compare to their overall biomass, either.  Bacteria globally outweigh us by somewhere around 5,000 times.

But we win because we are FINISHED!  At the peak of our evolution, no more changes!  WRONG!  In addition to simple genetic drift, studies suggest that skin and eye colors are still changing, as well as our tolerance for lactose and wheat.  In fact, human evolution may be happening faster than ever.

WHAT DOES THIS MEAN?

Biologists actually have a very precise definition of success, and it has to do with a quantifiable value of fitness.  The upshot is that to be truly successful, an organism has to pass on its genes to future generations, and spread them as far as possible.  So in that case, I can think of at least one 4 billion year end-product that’s not successful.  Cause as long as you keep chucking stupid internet memes at people, you’re never getting laid.

 

Mighty Marvels of Regeneration: Could We Heal Like Comic Book Characters?

The best science fiction and fantasy is rooted in reality.  Arthur C. Clarke’s classic 2001:  A Space Odyssey showed what could happen if our current computers developed human-like intelligence and emotion.  Michael Crichton’s Jurassic Park captured the imaginations of kids and the young-at-heart with a seemingly plausible parable on how to resurrect long-extinct dinosaurs (look for a post on this possibility in the future).  And as in Marvel’s Fantastic Four comics, the universe’s planets are often threatened with consumption by a peckish giant in a purple skirt.

Okay, maybe scratch that last one, but what about some of the superhuman feats of our more grounded champions?  Comic characters get beat up a lot, yet they always seem to come back for more merely a month later.  While a healthy suspension of disbelief is required to account for most of that, some of our favorites have built-in mechanisms to explain their near-miraculous recoveries.  How realistic are these regenerative capabilities?  Might they even translate to human applications?

The world famous Wolverine, star of the breakthrough X-Men movies as well as his own solo venture (with a sequel on the way), is the king of stitching himself back together.  His mutant healing factor rapidly regrows enormous amounts of tissue, at one point in his serial even regenerating an entire body around his metallic skeleton after the explosive villain Nitro seared away his flesh.  After his amazing ability was supercharged, he was even able to bring himself back from a single drop of blood!

wolverine skeletoncover image of Wolverine (Volume 3) #48

Such stunts will never be within our grasp, but the concept itself is not unheard of.  Planarians, commonly called “flatworms,” are simple critters less than an inch long that typically live in ponds and rivers.  They themselves are famous for coming back from extreme situations, spawning multiple complete organisms when cut into pieces.  In one mind-blowing study, a planarian was irradiated so that none of its cells could reproduce and it would slowly die.  A single, solitary c-Neoblast (an undifferentiated unit akin to stem cells) was transplanted from a donor into the victim’s tail, and subsequently grew all the former tissues back to create a new, functional animal!  Too bad people are not planarians.

Sure, coming back from a single cell or a little bit of blood is literally incredible.  How about something simpler?  Like, I don’t know, decapitation?  Wolverine’s final foe in the X-Men:Origins film was the regeneratin’ degenerate known as Deadpool, a product of the same super secret government program and perhaps the only dude bad enough to rival our hero in the healing department.  The creep’s head was shown to still be conscious after being removed from his body, a fate the comic book counterpart has suffered on numerous occasions, proving it to be little more than a minor inconvenience.

deadhead

The many-headed, mythologic Hydra would regrow two heads for every one lopped off, and the tiny creature for which it’s named is not far behind.  Composed of a basal disc used to adhere, a tubular body and a mouth opening surrounded by thin tentacles, the bitty beast will actually regrow its “head” when lost, thanks to constant mitosis (cell reproduction) in the body.  If a hydra is chopped up in a blender (who came up with that experiment?), a centrifuge can be used to reaggregate it and bring it back to life, much like Deadpool returned from being smashed to bits by the sinister Iceman in “Uncanny X-Force #16″.  I wouldn’t try this one at home.

All right, all right, no one’s expecting that we’ll ever be able to regrow a head or our entire musculature, but something like limb regeneration seems just feasible enough.  So much so that Dr. Curt Connors, an ordinary scientist, tried to restore his departed right arm with a serum inspired by reptilian recuperative tactics.  The treatment succeeded, but side effects included skin irritation, spontaneous tail appearance and a beatdown from the Amazing Spider-Man.

the-amazing-spiderman-movie-lizard-poster

Similar to a scene in the cinematic adaptation of 2012, there are lizards called skinks whose tails snap off when grabbed by predators, allowing the animal to escape.  Amphibians are better known for regrowing limbs, but the potential for human use recently took a less optimistic turn.  It has long been thought that such recuperation was a skill developed early in evolution, and that the ability had been “switched off” in mammals and birds.  New studies of the red-spotted newt, however, show that many of the newt’s RNA transcripts that code for proteins used in the process are unique to the organism, i.e. not found in other things like us.  That innate ability may just not be there for people, and no magic potion is likely to instill it.

WHAT DOES THIS MEAN?

You should take any story of human regeneration with a grain of salt.  In 2008, hobby store owner Lee Spievack claimed to regrow a lost fingertip by applying a powder derived from pig bladders, an assertion called “junk science” by University of Leeds professor Simon Kay, adding that, “If you could regenerate body parts like this, your first port of call would be a serious science journal like Nature because it would be a Nobel prize winning revolution.”  A similar if not as spectacular story was reported by Californian Deepa Kulkarni, but closer examination suggests it was the proper dressing of the wound to prevent the growth of scar tissue that restored the finger’s appearance, and not a sprinkling of “pixie dust.”

But perhaps the cause is not completely lost.  African spiny mice were found in 2012 to have brittle skin that tears off when attacked; skin they can regenerate complete with hair follicles and sweat glands.  The regrowth begins from a clump of cells comparable to the blastemas employed by salamanders.  People aren’t mice, either, but at least mice are closer cousins than a minuscule, glorified gut tube.  The precedent is now there in mammal physiology, so that one day we may learn how to become superhuman.  Ya know, like a lizard.