We have a lot to thank evolution for, but we can’t help being a little resentful of the ways it’s done us Earthlings wrong.
10 Worst Adaptations in the Animal Kingdom
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* We have a lot to thank evolution for. (Bacteria that help us digest food! Solvent mucus that lets us smell pleasant things! Skin!) But we can’t help being just a little resentful the ways that evolution has done us Earthlings wrong, animal and human alike.
* [The Sloth Stomach:] Sloths have to live a seemingly lazy lifestyle because their metabolism is so slow. Yes, a sloth’s stomach may be its most, um… slothenly feature. They can take an entire month to digest one meal. Sloths have a low body temperature, but if they get too cool, their gut bacteria will stop working. That means that even if a sloth just ate enough food to fill its belly for a month, it could starve to death if it gets chilly, because the food would just sit there, undigested.
* [Banana Slug Mating:] Slugs are hermaphrodites, meaning they have both male and female sexual reproductive organs. In some ways, it’s an adaptation that makes life easy – everyone can breed with everyone! But in the case of banana slugs, it can get a little weird. When banana slugs mate, they both insert their penises into each other. But when they’re done, sometimes one – or both, simultaneously – will chew the other’s penis off. Why? Slugs do bite each other as part of their mating ritual, but this goes beyond kink. Some researchers think they just get stuck, or that it’s a competitive behavior to prevent their partner from impregnating other slugs. And no, the penis doesn’t seem to grow back. But good news, everyone! They can still use their female reproductive organs and carry on.
* [Human Pinky Toes:] Humans do not need their pinky toes. Without ‘em, you could walk. You could run. You could probably be a prima ballerina. In a study published in The Journal of Bone and Joint Surgery, 160 subjects all put the least amount of pressure on their pinky toes while walking and standing. Their big toes withstood 3 times as much pressure. However, we do use the metatarsal bone that connects the pinky toe to our ankle. Without it, our feet couldn’t properly distribute our weight and we might not be able to stand upright.
* [Tiny Little T. Rex Arms:] Tyrannosaurus rex wasn’t a dinosaur to be trifled with. It had 4-foot-long jaws filled with serrated teeth. But, almost as if nature were trying to even the odds for its prey, T. rex’s arms were so tiny that it couldn’t use them to grab stuff, let alone put food in its mouth. And T. rex only had two fingers on each hand – most dinosaurs had three, which makes grabbing a lot easier. Evolution might’ve slowly been phasing out T. rex’s arms, relying on the animal’s strong jaw to pick up and tear prey. Some researchers even propose that if the dinosaur had stuck around another million years or so, those arms would’ve adapted right into oblivion.
* Note: We’re technically uncomfortable calling any adaptation “bad.” The fact that animals developed and kept these traits implies that the benefits (no matter how invisible) outweigh the costs (no matter how inconvenient… or yicky).