The animals with which we share the planet inspire awe and wonder. Discovering the history, physiology, mating rituals, and behavior of all animals can be fascinating, but not all creatures are created equal regarding their evolutionary process.

Some animals have evolved in miraculous ways that enable them to thrive in their environment, and others have…not. Some of the more unfortunate animals seem to be true oddities of nature, fascinating in their unique flaws and attributes.

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So why do these adaptations happen in the first place? Why does the evolution of a species sometimes betray it, weakening its chances to propagate, while others have adapted in ways that help them prosper in their environment? Here are some of the notable examples of the most bizarre and fascinating “mistakes” in the animal kingdom, and how nature and human interference have triggered them.

Giant Pandas

If there’s one animal on our list that seems determined to make their lives difficult, it’s the panda. And one of their main problems is their poor dietary choices. While a vegetarian diet is normally seen as a healthy lifestyle choice, it has a deleterious effect for pandas.

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According to homeschool teacher Faten Awde Pentikis, who has a degree in biology, “Their diet is not good for them. That’s because bamboo, their food of choice, plays havoc on their stomachs—the animals have short digestive systems, which can cause them to move their bowels up to 40 times per day.” This means that the fibrous and nutrient-deficient plant is quite the ill-suited meal.

And their problems extend beyond food. The very act of procreation, which is pretty essential to the survival of a species, is a challenge for the panda. Females are in heat for only 24 to 72 hours each spring.

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Breeding pandas in captivity has proven difficult, and zoos and animal sanctuaries have used elaborate (and sometimes comical) methods, including adult movies and viagra, to try to stimulate male and female pandas to copulate.

Captive pandas often grow up without adequate knowledge of mating behavior as well—in a piece for Discover Magazine, writer Lizzie Buchen notes: “In the wild, panda cubs usually stay with their mothers for about two years; breeding centers in China remove cubs at about six months to a year to make sure the mother ovulates during the next breeding season. Young pandas are thus denied an important period of social interaction and the opportunity to observe appropriate mating behavior.”

Long-Tailed Widowbirds

Whereas the panda is evolutionarily challenged by its lack of interest in mating, Africa’s long-tailed widowbird’s strong desire to mate takes precedence over very perfunctory aviary skills.

While female widowbirds can fly normally, males have some challenges staying gracefully airborne due to their unusually long and striking tail feathers (hence the name).

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Six to eight of the male’s tail feathers grow up to 20 inches, making it hard to fly for long periods. This is understandable, given its rear plumage averages three times larger than the bird’s actual body.

So why would nature give a bird feathers so large it has trouble flying? It all points to procreation: Males use them to woo females, and in this evolutionary instance, size definitely matters.

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Male birds engage in “static displays,” raising their feathers in a hood-like formation to attract female birds, and the males with the longest tails are the most desirable suitors.

According to a 1982 study by the University of Gothenburg, “Males in which the tail was experimentally elongated showed higher mating success than males having normal or reduced tails. …These results suggest that the extreme tail length in male long-tailed widowbirds is maintained by female mating preferences.”

So male long-tailed widowbirds might not be the best at flying, but they use their oversized evolutionary trait to its full advantage.

Honeybees

Anyone who has been stung by a bee will vouch for it being a painful and unpleasant experience (especially for those who are allergic to bee stings). But if you were stung by a honeybee, the bee got the worse end of the deal. Honeybees die after stinging.

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So why can’t honey bees live after injecting their painful barb into a human or animal’s flesh? “When a honeybee stings someone, they lose their stinger. However, they also lose much more—they also leave behind their abdomen, digestive tract, and muscles and nerves,” Pentikis says. “This ultimately results in an abdominal rupture which proves fatal. And the honeybee is the only bee subspecies that can’t survive after delivering their sting.”

In a piece for Forbes, entomologist, organismic biologist, and physiologist Matan Shelomi wrote: “Worker bees seem to be born knowing what to do, and sting instinctively. I doubt they know their stinging will be fatal. All that matters is to get rid of whatever is attacking the colony, and stinging works.”

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This, he said, operates on kin selection, an evolutionary strategy that promotes self-sacrifice to help protect a relative’s reproductive success—in this case, the queen bee. Shelomi wrote, “Queen bees can sting too, but their stinger is not barbed, and they can actually sting you multiple times without dying.”

Speaking of the queen, the only honeybees that can sting you are worker bees, all of which are also female. Male bees, known as drones, serve only one function: to mate with the queen.

So while a worker bee ends its life after a sting, it’s ultimately a selfless act for the protection of the species (although it can survive stinging other insects, since their exoskeletons aren’t as dense as animal or human skin).

Aye-Aye Lemurs

The world is full of odd-looking creatures that delight and unnerve, but the aye-aye lemur of  Madagascar has an unsightly appearance that affects its very existence.

With its piercing eyes, large incisors, and lengthy claws, the aye-aye is certainly strange-looking. But its middle finger, which is skeletal in appearance ( and used for collecting insect larvae in trees), has made the nocturnal animal hunted by humans who believe them to be a threat.

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According to conservationist and world traveler Jme Thomas of Travel with Jme & Bryan, “The native people believe them to be a sign of bad luck. …The poor thing is really hated and feared—and even now, the superstition in the country is very strong.”

This has led to disturbing folk legends, such as the belief that if the lemur points its middle finger at a person, it curses them to lose their life. Thomas adds that even the name speaks to superstition: “There is a theory that the name actually came from making sounds to replace their actual name—because they are so feared and evil, in the native cultures [it is believed that] calling them by name will ‘summon’ them.

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“Because of this, animal sacrifices seem to be the ‘cure all’ for everything, from blessings for good luck to curing illness. …It is hard to break those traditions. Perhaps as technology slowly infiltrates the country, this may change, but being a very poor country … things are not changing quickly in regard to the aye-aye, and many people there feel it’d be better if they did go extinct, so conservation efforts are difficult.”

In fact, due to being hunted and slain, aye-ayes were believed to be extinct in 1933 but were rediscovered in 1957. They are still listed as endangered by the IUCN Red List of Threatened Species. One can only hope that education and conservation efforts can eventually stem the tide and help protect these misunderstood animals.

Can nature really make mistakes?

So now that we’ve covered examples of evolutionarily challenged animals, one has to wonder—are these freak errors of nature? Or is there a method to their genetic madness? And what part do we play in the process?

According to science teacher Jamie Jones, “Evolution can’t really make mistakes because evolution itself is random. Every mutation is, by definition, a mistake. Some of those mistakes end up conferring an advantage, which is how they stick around in the population. So in the wild, every adaptation, even if its advantage is unknown, must be conferring one or it would die out.”

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As far as human’s impact upon animal evolution, Jones states, “That changes when breeding becomes directed or intentional. The animals I would consider most challenged by evolution are absolutely those with human interference, especially dog breeding. Most bulldogs, for example, suffer from arthritis and respiratory issues and have shorter life spans than other breeds. This is because of mutations that give them their flattened faces and bowed legs and stocky build. In the wild, those mutations would expire because they confer disadvantages, but humans artificially keep them in the gene pool.”

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Pentikis adds: “Some factors driven by humans are hunting and commercial fishing. Hunting is an action by humans that can influence evolution. When hunters seek out larger prey, they are leaving behind the smaller animals to reproduce. Same goes for commercial fishing. If we continue to fish for the larger fish, we are removing larger fish and causing more small fish to pass on their genes. …Another way humans influence evolution is when we intentionally select animals based on the qualities we want, we end up changing the animal’s genetics from their ancestors.”

Humans don’t get off easy, either.

Humans aren’t immune to evolutionary challenges. In fact, one could argue we have some strong disadvantages and some physical traits that no longer serve much purpose.

“Are humans keeping disadvantageous genes in our own gene pools? Definitely,” says Jones. “Mostly because of medical intervention like reproductive treatments for infertility, for example. In the wild, people with low fertility rates would be less likely to reproduce and pass on genes, so those genes would diminish in the population. We are interfering with that, no doubt.”

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“We have an appendix, which results in little consequence if removed,” Pentikis adds. “Our pinky toes and wisdom teeth no longer serve the same purpose they did for our ancestors. Males have larger Adam’s apples, yet size plays no factor in the protection of our vocal cords.”

The American Association for the Advancement of Science held a 2013 conference called The Scars of Human Evolution, which discussed how a mix of biology and behavior led to various health problems including foot and leg issues like plantar fasciitis, Achilles tendonitis, shin splints, and broken ankles. High infant mortality rates were also brought about by walking upright. As one panel speaker said, “Evolution doesn’t act to yield perfection. It acts to yield function.”

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In other words, what may seem like an evolutionary mistake ultimately serves a purpose, even if it seems ridiculous on the surface. Science aims at explaining these strange behaviors and physiological issues to see how we can help all species thrive and survive to their full potential.