Ten horrifying outcomes of evolution

June 22nd, 2010
By Dave Mosher

You’ve heard evolution is about the “survival of the fittest,”* but fitness doesn’t guarantee beautiful products.

Sometimes, carrying on your genetic legacy means replacing a host’s tongue, eating your neighbors or letting your mate liquefy every part of your body except for (eek!) your gonads.

In short: You might want to grab a barf bag, because we’re about to take a horrifying little stroll through the animal kingdom. And it’s going to get progressively un-pretty.**

10) Fighting giraffes

It’s a giraffe-whack-giraffe world out there.

Competition for females, surging testosterone and perhaps the scorching heat of the savanna drive some male giraffes mad with rage:

In this clip, horrified tourists see lovable giraffes like they’ve never seen them before: whipping around their heads full-force and whacking their opposing broksie’s body.

This is, of course, all for the attention of ladies.

Yet one has to wonder why broken necks didn’t wipe this perplexing behavior from the evolutionary slate.

9) Warm-blooded reptiles

You’re floating in a warm Cretaceous sea at night, minding your own business, when you suddenly see this thing coming at you:

warm-blooded sea reptile ichthyosaur

A gigantic zombie dolphin? Bzzzt.

It’s an ancient ichthyosaur, a dolphin-like creature that lived between 245 million and 90 million years ago.

Unlike their cold-blooded brethren, these giant sea-faring reptiles were warm-blooded. This allowed them to eek out an advantage in cold, deep waters where hordes of otherwise inaccessible meals roamed. And, millions of years later, soil the pants of any human with an active imagination.

brown pit bull mix dog8) Dog STDs

Fluffy’s raunchy dog park behavior may not be as innocent as you might think.

Like any multicellular sexual creature, canines are subject to spreading venereal diseases.

Herpes? Check. Brucellosis? Check. There are even rumors of dog syphilis out there.

But the real shocker is that canines can sexually transmit cancerous tumors — one of only two kinds of transmissible cancer known (see below for the other).

For those distant from the equator, however, odds are Fluffy is safe; the disease makes its home primarily in tropical climates.

Tasmanian Devil facial tumor cancer7) Tasmanian devil facial cancer

Speaking of animals and transmissible cancers…

Tasmanian Devils teeter on the edge of extinction in the wild, courtesy of human colonization (“tastes like veal!” say early Tasmanian settlers) and dingoes.

Delivering perhaps the final blow, however, is a freakish scourge known as Devil facial tumor disease.

This malady is 100 percent deadly within 18 months, and has wiped out about half of the marsupials in less than 20 years. By 2035, if a cure isn’t found, the Devils are expected to vanish completely.

The best idea about its origins? It’s a counterpart to sexually transmitted canine cancer, which made its way from one unusual host to the next, eventually to dingoes and to the Devils (see above).

6) Duck necrophilia

Isabella Rosellini did a fine job illustrating that duck sex is really, really weird:

Yep — ducks rape each other, sometimes males even rape males.

But it gets worse, fellow Cosmopolitanauts… Much worse.

During the mating season, sex-crazed drakes will copulate with just about any ducks they can find — alive or dead.

If the latter, “mating” can go on for hours. Don’t believe me? Read a professional ornithologist’s account.

humpback anglerfish

"Where are you, Mr. Right?"

5) Anglerfish sex

Female spiders and praying mantises often consume their guys during copulation. That’s pretty tacit knowledge, or at least I’d like to think so.

Yet anglerfish give a whole new meaning to the word “consume” when it comes to sex — The Oatmeal artist Matthew Inman describes it best.

Although it’s a silly cartoon, the truth is equally silly (if that’s an appropriate word, after all):
Male anglerfish will do everything they can to latch onto a female and, once they do, dissolve into her body… fins, skeleton, brains and all. The only thing left behind are their gonads, which the female uses to fertilize her eggs.

4) Chimpanzee cannibalism

Chimpanzees cleanly split off from our evolutionary path about 6 million years ago — a blink of the eye in the 3.5 billion-year history of life on Earth.

And the similarity of our genetics? Depending on how you measure — i.e. including DNA that plays a role in gene regulation vs. strict gene-to-gene comparisons — we’re 94% to 98.5% like to chimps.***

In spite of any civilized comparison we’re keen to make from this comparison, some chimps eat one another.

This behavior has a lot to do with chimps’ bloodthirsty quest for territory. For a great water cooler conversation at work, anthropomorphize the process and tell your colleagues how chimps will eat their neighbors’ kids after killing their parents and stealing their homes.

fish tongue eating parasite cymothoa exigua

"Nom nom nom!"

3) Cymothoa exigua

When I first read about this wondrous little parasite, I couldn’t believe it.

The tongue-eating louse, as the creature is also called, sneaks its way into a fish’s gills when it draws too near (red snapper are its favorite).

Once inside, it will either a) eat the fish’s tongue or b) suck so much blood from the tongue that it will shrivel up and fall off.

The most bizarre part is yet to come…

The louse will settle in where the tongue used to be by latching onto the stub that’s left. From then on, they’re a merry little couple. The parasite munches on fishy mucous and/or the fish’s blood, and the fish carries on as if nothing is wrong.

Moral of the story: The next time you order a red snapper at a restaurant, be sure to take a peek in the mouth.

horse bot fly2) Botflies

I’m not sure horror movie makers have heard of the botfly.

Or perhaps they have, but are just waiting for their genre to exhaust all of its tired memes before releasing *the* horror movie of all time which — of course — would be solely about botflies.

Or maybe the audiences simply couldn’t handle test screenings.

Whatever the case, botflies are nasty. So nasty, in fact, that I’ll have trouble summarizing their nastiness following this sentence.

Ok, here we go…

After a good roll in the hay, botfly females will either lay their eggs directly on a host, or be more covert and capture an unsuspecting vector (e.g. a house fly) then deposit their eggs on it.

Either way, the eggs eventually hatch and beautiful baby botfly larvae — aka maggots — drop onto a warm mammalian host. Home, sweet home!

Want an intestinal nightmare? There’s a botfly for that.
Some of the 150 or so botfly species get into mammalian tummies via their hosts’ grooming behavior (e.g. licking fur). Once inside, the larvae cozy up in the wall of the stomach or intestines, causing ulcers, blood infections and eventually death.

Want worms munching on your butt? There’s a botfly for that.
Livestock in warm, wet climates — especially sheep — are particularly prone to this type of infestation, where females lay eggs in soiled fur/wool near an animal’s caboose. The larvae burrow their way in, causing sores as they tunnel into the skin, eating along the way.

Want creepy crawlies under your skin? There’s a botfly for that.
One species of botfly likes to shack up in people. And it gets better: not only do they munch their way under the skin, but they have sharp spines that can cause excruciating pain when touched. If you happen to get infested, here are a few household remedies:

  1. Duct tape. Apply, rip off, repeat. This, however, can tear up our maggoty friends under the skin, making way for a nasty infection.
  2. Place a slab of meat on the sore. A nice filet mignon could coax out the maggots — if you’re lucky.
  3. Suffocate them with nail polish. Once the maggots perish, enjoy the task of squeezing them out.

If you’re really twisted and want to see images, well, you can go talk to Google.

Me? I want to wrap this up so I can vomit.

1) Parasites in general

Lucky for you, we’ve only scratched the surface here. (No pun intended.)

Parasites are quite easily the most horrific results of evolution, and we didn’t even talk about bed bugs, malaria, or the big kahuna of parasites: worms!

Tape worms, filarial worms, hook worms, flat worms, guinea worms, ascaris worms, and the worms go on.

Check out those links above, or visit one of the many fine mainstream sites about nature’s grossest and most insidious parasites.

Oh, and you’re welcome for the cop-out.

Photos, from top to bottom: Copyright National Geographic News; Copyright Dave Mosher; Wikipedia/PLoS; Wikipedia; Wikipedia/Vianello; courtesy University of Florida

* Note that survival, aka natural selection, is only half of the explanation for how evolution works (randomness in genetics is the other half). Furthermore, as my entomology professor omce put it, it’s more like “survival of the good-enough.” But I digress — you can bone up on evolutionary mechanisms on your own time. We have gross stuff to talk about!

** Huge thanks to Charles Choi and John Timmer for their nasty suggestions. You guys are gross and awesome.

*** At this point, some may stick their fingers in their ears and go la-la-la-la, but the scientific truth is that we’re really, really, really similar to chimps. Yes, we’re also similar to other creatures such as plants… In a weird, remote billions-of-years kind of way. But at the end of the day, our closest relatives — DNA-base-pair-to-DNA-base-pair — appear to be chimps. If this crushes your worldview, please accept my condolences.


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