Our genetic code is a stunning miracle of haphazard complexity. On one hand, it works as a blueprint that tells our bodies exactly how many fingers, toes, and kidneys we're supposed to have. But on the other, it is full of scraps from all of the stages of evolution that brought us here. That's why every once in a while you get an abnormality that scientists call an atavism.
This is the means by which suddenly any creature -- humans included -- can sprout physical traits that they thought they had abandoned millennia ago. And so you wind up with ...
If you're familiar with medical oddities, or at least the Jack Black movie Shallow Hal, you know that occasionally a human will be born with a tail. While these individuals can't use their gift to hang from low-lying branches, their tails are more or less as anatomically correct as that of any monkey from your local zoo. Some people can actually move the damn thing (fair warning, this video is incredibly gross).
You might, however, have thought that this was just a freak accident, like being born with a sixth finger or webbed genitals. Actually, all human babies start life with a stubby little tail while they're in the womb -- it's an evolutionary leftover from when we all had tails. In fact, scientists now think that our early ancestors might have been squirrel-like creatures with tails so long that they were mostly tail.
Via Doug Boyer, Duke University
We've all dated someone who looked like that.
Obviously, the no-tail side won the evolutionary battle, presumably because it has to be next to impossible to bone a female squirrel monster with a tail in the way that's longer than your goddamned body. It's hard not to miss it a little bit, though. Sure, it would make driving a car impossible, but do you ever find yourself standing in line at the DMV and wishing you had a giant limb that you could use to smack somebody across the room? That's you subconsciously missing your phantom tail (that's our theory, anyway).
And in some cultures, being born with a tail can earn you some perks. In India, Chandre Oram is believed by many to be the incarnation of the Hindu monkey god Hanuman because of his 13-inch tail. It's a comparison that he encourages by climbing up trees and eating bananas. That's right, buddy, just go with it.
"We bring you these offerings that you might show us mercy, oh god of fruit and poop."
One of the first animal facts you learn in grade school is that whales and dolphins are mammals and actually more closely related to you than to the fish they resemble. They can't even breathe underwater -- they have lungs just like us. What this actually means is that, millions of years after animals first crawled onto land, the whales decided "Screw everything about this," regrew their fins, and slunk back into the ocean, flipping us the middle finger they no longer have.
These days, whales and dolphins are still occasionally born with stubby little legs, like this one that Japanese researchers caught in 2006 (pictured above), an apparent throwback to ancient times when they may have looked like this:
Via Mary Parrish/Smithsonian Institution
You think you're too good for land? We're glad the Japanese keep harpooning you.
You can see not only where they had back legs, but also that their front fins used to be webbed paws like the Creature from the Black Lagoon:
His balls look like a rolled-up armadillo.
Which is kind of terrifying if you're imagining them, you know, whale-sized. In fact, even normal whales have rudimentary leg bones crammed into their backsides, as you can see floating under the lower left of this killer whale skeleton:
"Killer legs, man."
You can also see its freaky "hands" where you thought it just had flippers. That's what their front limbs actually are -- evolved hands (or paws, whatever):
"Gimme five, man."
The pictures only get freakier from there. Here's the giant skeleton hand of a sperm whale:
Via Wolfgang Sauber
"Make one sperm joke. I'm daring you."
And here's a killer whale with both skeleton hands and huge teeth included in the frame so you can imagine it grabbing you by the neck and biting your head off:
Via Wolfgang Sauber
We'd point out how terrifying it would have been to live in an era when killer whales could come flopping out of the ocean to munch on land prey, but we have a feeling the things would have been slow as shit.
Via Matthew Harris
Dinosaurs are every child's introduction to the idea that evolution has no interest in making things more awesome. For instance, the dinosaurs were so huge and terrifying that evolution decided to punish them for their hubris by turning them into birds. It's difficult to imagine now, but the humble chicken once towered over the savannah as a Tyrannosaurus rex. Now we cut off their wings and make women in tiny shorts serve them to us as food.
Sometimes, though, the chickens are granted a nostalgic throwback to their badass past with a little help from modern science. In 2006, mad scientists working on chicken embryos managed to grow chickens with teeth by coaxing their DNA to recall their ancient evolutionary origins.
We didn't say they were good teeth.
After all, there were a lot of steps in between "building-sized lizards with murderous jaws" and "sad lumps of feathers that eat worms." For instance, there was once a time when they looked like this:
Stephanie Abramowicz via Phys.org
Did anyone else make a "duuuuuuhhh" noise when they saw that?
That's Sulcavis geeorum, the 125-million-year-old ancestor of modern birds, which nature wisely saw fit to eliminate from the gene pool and humanity has decided to tease back into existence by way of the world's most non-threatening species. So modifying a chicken embryo to make it grow teeth just involves using a few tricks to bring out the dormant genetic traits that are still hiding in there.
Somewhere, a young writer has already started on his screenplay about hordes of genetically modified dino-chickens descending upon KFC headquarters to exact their violent revenge. And the poster will be a big KFC bucket full of severed human limbs.