Transcription
[Music] We usually think of evolution as a process that takes place over thousands, if not millions, of years. While this can be true to an extent, there are traits in both humans and animals that haven't been around for nearly as long as you might think. In humans, traits such as adaptability to altitude and even blue eyes have only existed for a few thousand years. And in the animal kingdom, where favorable mutations can mean the difference between survival and extinction, traits can evolve even more rapidly. Here are 10 animals who have evolved in crazy ways over just the last hundred years.
In a remote region of southern Mexico, there is an indigenous people who practice a ritual involving the fish that dwell in a local cave. Every year, the villagers introduce a toxic plant to the cave's pool, scooping up the resulting bounty of dead fish to take home to eat. The practice has recently been banned by the local government out of concern for the fish population, but they might not have needed to worry. The fish seem to be doing a pretty good job of adapting to the situation themselves. The fish, called Atlantic mollies, make their way underground from the ocean. Scientists were easily able to confirm their hypothesis by exposing some fish from the ocean, who had never been exposed to the ritual, to the toxin alongside their cave-dwelling companions. It was found that the cave dwellers were able to withstand the poison waters for up to fifty percent longer, clear evidence that this local ritual has had a profound effect on the evolutionary trajectory of their sacred fish.
Owls are also feeling the effect of the changing climate, and their evolutionary adaptation has been much easier to spot. The color of an owl's feathers is hereditary, with gray or white plumage typically dominant over brown. But in recent years, the number of brown owls has seen a sharp increase as winter temperatures become more and more mild. An owl's color doesn't change over its lifetime, so it took a nearly 30-year-long study to come to the conclusion that the changing climate is driving this effect. In the winter, white or gray owls have in the past been less visible to predators taking advantage of the snow cover, and were therefore evolutionarily favored. But this is increasingly no longer the case, and if the current warming trend continues, researchers are concerned that white owls may soon vanish altogether. Since previous studies have suggested that brown owls are genetically weaker, with higher metabolisms requiring them to consume more food than their white counterparts, this could have an unforeseen environmental impact.
Salmon migrations are among the most regular events in nature, taking place like clockwork year in and year out for millions of years. But even this process is in danger of being disrupted by global climate change. Thanks to an experiment from the 1970s, researchers have been able to determine that mutated genes are causing some salmon populations to migrate earlier. The 1970s studies selectively bred late-migrating salmon with a mutated marker gene that had no effect on their migratory habits. In this way, late migrators could be identified before migration had even begun. By the 1980s, over 1/4 of the late-migrating populations still carried this mutation, but today it is virtually gone. Its steepest decline was between 1989 and 1993, and it's speculated that it's during this period that late migration began to be an evolutionary liability. It's also noted that stream temperatures in 1989 were the highest yet on record, leading to the hypothesis that once again, climate change is responsible for the sudden shift in migration habits.
Water pollution is absolutely devastating to the environment. It's worse that it can cause dead zones in the ocean that are inhospitable to life, irreversibly damaging entire ecosystems. But it seems that even in the harshest conditions, life will always find a way. In the riverways of New York and New Jersey, some of the most contaminated areas on the planet, there lives a species of fish that has managed to thrive despite living in a toxic soup of dangerous chemicals for 30 years. Up until the late '70s, there was virtually unrestricted dumping of toxic waste into the Hudson River, permanently altering its composition. By 1980, up to 95 percent of the fish in the area had liver tumors, but not all. And the ones that didn't seem to be doing just fine. These survivors gave birth to a new type of fish called the tomcod, that is highly resistant to PCBs, dioxins, and everything else floating around in the noxious soup it calls home. Unfortunately, this causes a bigger problem: the tomcod's higher numbers make them easy prey for bigger fish, who pass all of those toxins right on up the food chain.
Another pest that we humans seem to be stuck with, the tiny household mouse, can cause huge problems. Setting out mouse traps isn't always the best idea because these critters can carry disease, making poison a safe and cheap alternative. Unless, of course, you happen to have an infestation of a new breed of poison-resistant super mice, which agricultural scientists have recently identified. It's thought that this is the result of interbreeding between a rare Algerian breed, which is resistant to toxins due to a mutation, and a more common European breed, passing the poison resistance onto the offspring. The two breeds would likely never have met if not for human agricultural practices, and the overuse of pesticides may have also played a part. Whatever the cause, it may indeed be time for somebody to finally build a better mousetrap.
Every human on earth knows not to let the bedbugs bite. But despite our constant vigilance against them, these tiny pests have proven extraordinarily hard to get rid of. Of course, there's a reason for this: bedbugs depend on us to survive, and so have adapted right along with our efforts to exterminate them. It was recently found that dozens of bedbug populations across the United States have begun exhibiting a resistance to pyrethroid, the most common chemical agent used to control them. While this might be expected to an extent, it's not just one avenue of resistance that researchers are seeing. Gene mutations in these populations have resulted in the pest developing some combination of a thick outer shell, which keeps the chemicals from penetrating, outright resistance to the chemical, or both. While bedbug populations are not known to be very mobile on their own, researchers theorize that hitching cross-country rides with relocating families have helped some of these mutations spread to areas other than those they originated from.
There are many different types of bear species, and a lot of them are suited to very different habitats from the others. Most obviously, polar bears are adapted to incredibly cold climates and almost never come into contact with other species of bears, at least not until recently. Warmer climates due to global climate change are forcing some grizzly bears in Alaska and Canada further north, and intermingling between the two species has led to the possible emergence of a new one: a grizzly-polar bear hybrid known as the "pizzly" or the "growler," depending on your preference. While it has the distinctive white coat of the polar bear, the pizzly also has the large brown paws, cranial shape, and shoulder humps of the grizzly. This could be particularly troublesome because, as fearsome as they can be, grizzlies are generally solitary animals that feed mostly on plants. Polar bears, on the other hand, are extremely social and are the largest land carnivores in the world. It's too soon to say whether we're looking at the evolution of a new breed of fearless, carnivorous super-bears, but humanity's environmental track record and the karmic laws of horror movies dictate that this is probably the case.
The peppered moth is one of the most common varieties in all of Britain. It looks like its name implies, being light in color with dark spots peppered throughout. Its color scheme serves as a sort of camouflage, being hard to spot against the light-colored, dark-spotted trees characteristic of England. At least, this was the case before the Industrial Revolution forced it to make a slight change. In the days before environmental regulations, smoke, soot, and dust filled the air over most large industrial areas, and England was no exception. This caused a dramatic change to the color palette of the countryside, and the peppered moth compensated by evolving a different color scheme, which is almost the complete inverse of its natural one. These solid dark moths, flecked with lighter spots, began to appear in the mid-1800s as the Industrial Revolution was kicking into high gear. Just as strangely, once regulations were in place to clean up the land and air, it only took a couple of decades for the lighter-colored version of the peppered moth to start surging in numbers again.
Moscow has long had a problem with feral stray dogs. There are as many as 35,000 of them in the city at any given time, one for every 300 residents, and nobody seems to know how to handle the problem. Nobody, that is, except the dogs themselves. Over the years, these animals have lost some of the friendlier traits—spotted coats, wagging tails, and friendly demeanor—of their domesticated peers, reverting to a more wolf-like appearance. But that's not the really interesting part. These animals have evolved behaviors that have literally never been seen in the animal kingdom before. Specifically, they have tailored their existence to fit in with the human denizens of Moscow. Not only are they able to recognize which humans are most likely to give them something to eat, but they have actually learned how to navigate Moscow's subway system, relying on sights, smells, and sounds like the conductor announcing stops. They have familiarized themselves with how to get around town and where and when they're most likely to get a meal. Even the pack structure of these dogs has evolved. Unlike typical packs, it's not the biggest or strongest dog that's usually the alpha of a Moscow street pack; it's the smartest.
Illegal ivory poaching is probably the single greatest threat to the continued existence of African elephants. It's a shady but profitable business. The tusks of an adult male elephant can weigh up to 250 pounds, with ivory fetching up to $1,500 per pound on the black market. Tusks are nearly as important to elephants as arms are to us; they're used for fighting, digging, bark from trees, and other everyday tasks. Nevertheless, elephants have begun to appear with extremely undersized tusks or no tusks at all at an alarming rate. From an evolutionary standpoint, this makes perfect sense, as elephants with no tusks or tiny tusks will not be poached and will therefore survive to pass on their genes. Since tusks are more important to males as a display of dominance and a call for mating, far more female elephants than males have begun to display this trait. But we can expect this trend not to last, as these females are likely to pass on the tuskless trait to their male offspring.
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