تدريب Shadowing: Why Pandas Are Impressively Bad at Existing - تعلم التحدث بالإنجليزية عبر الفيديو
جارٍ إنشاء الدرس...
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I think it's easy to look at a panda and forget it's an actual, real animal.
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It's hard to conceive that the incredible forces of evolution that create highly effective, lethal predators would turn one into this?
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And for all the creationists
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that are inevitably frothing to write a comment about how this is proof that animals are created and not evolved,
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why would our Lord Creator create something so terrible?
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This spherical ball of evolutionary mistakes is clinging to existence.
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And while this is very sad, because they are very cute,
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they don't necessarily garner a ton of sympathy when you learn just how bad they are at being animals.
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Pandas have evolved to eat a very narrow range of food, a range so narrow it's basically just one thing, bamboo.
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A plant that has almost no nutritional value and is full of cyanide.
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It's so toxic that pretty much all other animals avoid it, and it's so nutritionally deficient that they have to spend up to 12 hours a day,
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almost all of their waking hours, eating enough of it to survive.
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And for a bear, this makes even less sense.
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They're members of the Ursidae family, related to grizzly bears, polar bears, and black bears.
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Every other species in the Ursidae family eats meat, either as omnivores or as obligate carnivores like polar bears.
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And scientists think that pandas need to eat so much bamboo
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that in the wild they have to keep their distance from one another to get enough.
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This means that they can have a hard time finding a mate.
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This contributes to pandas having an exceedingly low birth rate, which contributes to the fact that they are this close to not existing anymore.
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And on top of this uphill battle that they've already created for themselves, they act as if they have absolutely no survival instincts hardwired into their brains.
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They fall off and get stuck in trees, and just generally act like every day is their first day on earth.
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And on top of this, one of their favorite hobbies is poop.
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They poop over 40 times a day, and given the chance, pandas will absolutely cover themselves in horse poop.
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I am talking head to toe, full body immersion.
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The official term for a group of pandas is an embarrassment of pandas.
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And even if they are lovable, it sure seems like they are an evolutionary accident that maybe came about just for our amusement.
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But as we all know, evolution doesn't work like that.
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Everything evolves for some reason.
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But how is being a clumsy idiot beneficial?
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And why would they evolve to eat the worst thing imaginable?
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And why are they absolutely obsessed with poop?
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Giant pandas are herbivorous bears native to the bamboo forests of south central China.
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And although they are members of the Ursidae family, they have taken a unique evolutionary path.
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Around 40 million years ago, the ancestors of bears split away from the other caniforms.
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Then, around 23 .4 million years ago, the Ursidae family split in two.
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The genus Aeleropoda was all alone on one branch, and this is what pandas evolved from.
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All the other bear species evolved on the other side of that branch.
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And as pandas continued to evolve, they did something truly baffling.
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They evolved to stop eating meat, transitioning to eating almost exclusively bamboo.
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Scientists assume this happened between 6 -7 million years ago, and they make that assumption about the timing
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because of one adaptation they seemed to have gained that allowed for better bamboo manipulation, a pseudo -thumb.
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This is like a whole extra weird little thumb, essentially one of their wrist bones grew extra large so
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that it curves in an opposite direction as the other five of their fingers.
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The thumb isn't as widely useful as a human thumb, but it's perfect for grasping bamboo.
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But at first glance, suddenly adapting to only eat bamboo fundamentally makes no sense.
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And in most ways, pandas still look like the other bears.
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They have sharp claws and sharp canines foods, even their guts still resemble the gut of other carnivores.
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When we look at carnivores vs herbivores, carnivores have much shorter and simpler digestive tracks.
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That's because their high protein diet requires a lot less digestion time to extract all the nutrients they need.
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Herbivores take longer to digest plant foods because there are higher levels of indigestible materials, like cellulose, the main structural molecule in plant cells.
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It's tough and hard to break down, which is why certain herbivores, like cows, have multiple stomach compartments.
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They spend a long time digesting so that they can extract as many carbohydrates and other nutrients as possible.
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But pandas, surprisingly, have a carnivore gut.
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They don't have the multi -chambered stomachs of ruminants, so of their nearly 100 % diet of bamboo, they can only digest around 20 % of it.
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This means they have to eat a lot of bamboo, up to 35 kilograms per day.
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Which is also why they poop 40 times per day.
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The food stays in their guts a little longer than most carnivores, but still, this seems wildly inefficient.
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And not only do pandas have a digestive tract that looks like that of a carnivore, their gut microbes also match the pattern of carnivores.
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Gut microbiome diversity is highest in herbivores, then omnivores, with carnivores coming in last.
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You'd think that millions of years of only eating bamboo would introduce a bit of diversity into the panda's gut bacteria, but that's not the case.
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In fact, once panda cubs are weaned off their mother's milk and transition to eating bamboo, the diversity of their gut bacteria decreased.
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As the scientists write in their paper on the subject,
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a carnivorous digestive system fed with a bamboo dominated diet is not a typical feature of evolution.
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But as dumb as this seems, there's usually a reason behind long -standing animal adaptations.
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And in this instance, starting to eat bamboo kind of made sense for pandas, sort of.
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Bamboo may be low in energy, but in southern China, when this adaptation came about, it was abundant.
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Plus, it grows exceptionally quickly.
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Bamboo is one of the world's fastest growing plants, plants, with one species growing more than one meter per day,
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and reaching its maximum height of 20 meters in just under two months.
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And the highest diversity of species of bamboo is in southern China, and as it so happens,
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it perfectly overlaps the limited territory that giant pandas exist in, even though they probably lived over a much wider range in the past.
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Bamboo is such a dominant species, that in a bamboo forest, almost no other plant life grows.
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And not many other animals eat bamboo.
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So for any animal that can evolve to consume it, bamboo provides a bounty of food unlike anything else.
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But it does seem particularly weird for a meat eater to
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suddenly be okay going from eating delicious succulent meat to poisonous sticks.
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But scientists think pandas underwent another strange adaptation to make them fine with this, an adaptation that is as weird as it is sad.
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Around 4 .2 million years ago, pandas lost the function of their T1R1 gene, which is what's involved in detecting umami flavors in meat,
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which are driven by L -glutamate.
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L -glutamate is an amino acid present in high quantities in protein, so it signals that something is especially full of calories and nutrition.
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And suddenly, pandas could no longer detect it, which probably made meat a lot less enticing, at least going by flavor.
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What a curse.
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Likely at first, pandas just adapted to eat a little bit of bamboo due to its abundance, and then after a long time,
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they gradually lost their ability to enjoy meat, and thus lost most of their hunting instincts.
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They might have still People eaten fruit for a while, and even today they'll eat fruit if you give them some, but almost no fruit grows in a bamboo forest.
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Given all of these factors, some scientists think that pandas were probably eating nothing but bamboo as far back as 2 .4 million years.
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But regardless of when it happened, a carnivore evolving to eat only bamboo is unprecedented evolutionarily speaking.
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In fact, anything eating only bamboo is kind of unthinkable.
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Because even if there is a bounty of bamboo, it's still toxic.
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Bamboo is full of cyanide, in quantities high enough that eating it raw would kill most mammals.
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In fact, there have been numerous cases of poisoning among humans who accidentally ate raw bamboo or prepared it incorrectly badly.
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Other herbivores have a way to detoxify cyanide using an enzyme called mitochondrial rodanese,
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because many plants use cyanide as a defense mechanism and herbivores encounter it in small doses over their lifetime.
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But pandas have far less of this detoxification enzyme than normal herbivores.
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And yet these pandas are consuming up to 66 mg of cyanide every day, close to a fatal dose for humans, and they seem just fine.
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It might seem like they are too stupid to realize they're supposed to die.
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but it turns out they actually have a way to get
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around this poison that's different from the way most herbivores do it.
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When researchers looked more closely at the panda's gut bacteria, as diverse as it wasn't,
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they found an abundance of one unique and powerful bacteria, Pseudomonas fluorescens.
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This bacteria helps degrade cyanide compounds, which seems to completely protect the pandas.
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Plus, pandas are strategic in what parts of the bamboo they eat.
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Depending on the species of bamboo and time of year, the pandas may target different parts of the plant to avoid the highest dose of cyanide.
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This targeted feeding is also the case when it comes to nutrients.
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In fact, although 99 % of the pandas diet is bamboo, a recent study found that they're actually eating the same amount of protein as carnivores.
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How?
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Because young bamboo shoots roots actually have a lot of protein in them, and so do the leaves at certain points in their life cycle.
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And pandas target these to get as much protein as wild cats do.
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In the end, their bamboo diet is 61 % protein energy, 23 % carb energy, and 16 % fat.
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This is even reflected in panda milk, which has a higher ratio of protein than the milk of herbivorous mammals.
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So at first, I'm kind of impressed that pandas found a way to cheat the system and turn a crappy food source into something usable.
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But this feeling doesn't last long.
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Because even if pandas can technically get enough nutrients out of bamboo, they still have to eat an ungodly amount of it to get enough nutrients,
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spending pretty much their entire life doing nothing else but gorging on it.
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To cope with this, their metabolism has adapted to slow way down, and they can't afford to move around that much.
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They are fairly sedentary animals trying to hold on to every ounce of energy that they can.
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And while this is a somewhat effective evolutionary reaction, it doesn't solve all of their problems.
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The winters in China can be brutally cold, and unlike other bear species that can pack on fat and hibernate for the winter,
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pandas can't afford to ever stop eating.
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So they just have to endure it, meaning they have to spend even more energy using thermoregulation to maintain a stable internal temperature.
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Eating bamboo became a positive feedback loop requiring them to eat more and more bamboo, and it might also explain why they're so clumsy,
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or at least why they appear to be.
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Pandas look clumsy in part because they're always looking for the lowest energy way to get around, and sometimes the easiest way to get somewhere is to fall there.
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And their round shape just lends itself to rolling.
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Scientists think they might partly do this just for fun.
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So at this point in the panda story, it seems like they've found a sort of novel way to get enough nutrients,
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something they don't have to compete with other species for and is readily abundant.
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Which is sort of an evolutionary win as long as they can eat enough of it.
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But there are still even more problems with this plan.
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Although they don't have to compete with other species much for bamboo, they still sort of have to compete with each other.
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And because they need to eat so much of it, each wild panda keeps a large territory to themselves.
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They live solitary lives, using their sense of smell to avoid each other as best as they can.
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Male pandas tend to have territories that are around 6 .5 square kilometers, while female territories are usually about 4 .5 square kilometers.
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This isn't a problem in itself.
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They don't seem to mind living solitary lives.
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However, it becomes a big problem when it's time to mate.
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Pandas only seek out other pandas in spring for mating.
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And female pandas have a fertility window of just two to seven days per year.
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And conception has to be timed exactly.
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Like, come on guys, I'm actually just getting annoyed at this point.
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So when it's getting close to time to mate, pandas leave scent messages for one another by rubbing their scent glands on trees, rocks, and grass, and they just hope
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that other pandas get the message in time to hike miles over mountainous terrain to mate in the minuscule two -day window.
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If they succeed, which they rarely do, female pandas are pregnant for five months before giving birth to a tiny cub about 1 800th of their size.
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Half of panda pregnancies result in twins.
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Awesome.
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Except for the weaker of the two cubs is often abandoned.
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Pandas can typically only care for one infant at a time, because the tiny cubs need constant and careful attention.
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I get that this happens in many animals, but this just seems like yet another way pandas are begging to go extinct.
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Their evolutionary path is just kind of an impossible one.
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But what about the poop thing?
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Could this maybe be the secret to their ongoing survival?
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Giant pandas in central China's Foping National Nature Reserve have been seen absolutely smearing horse poop all over their entire bodies,
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really focusing on their face and necks.
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Is this fun?
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Or is this some other weird adaptation that somehow helps them?
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Recently scientists think they made a breakthrough in this horse poop mystery.
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They noticed that the pandas seemed to do this most when it was cold outside.
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Could it somehow be a way to keep them warm?
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Because pandas are fiercely protected, scientists rarely get access to do direct experiments with them.
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So for this scientific question, the researchers used mice.
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They covered the mice in the poop compounds of interest, and found that poop -treated mice walked on cold surfaces more readily, and huddled together for warmth less.
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And what the researchers realized was that these poop compounds inhibit cold receptors in mice, and also in pandas.
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Some experts argue that this could be a way for the pandas to endure those brutally cold winters while forgoing hibernation.
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But while it might be a coping mechanism, it seems like it could be an incredibly bad one.
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If their bodies no longer feel the sensation of cold, this could prevent them from seeking shelter, and would actually be incredibly dangerous.
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Because of this, some scientists aren't convinced, and they think the pandas just really like poop for fun.
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So at best, this behavior is weird and gross, and at worst, it's downright stupid and maybe suicidal.
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Horse poop is probably not the secret sauce to their unlikely ongoing survival.
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I know I'm kind of joking about all of this, but it really looks like pandas are just simply bad at surviving.
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It looks like they exploited the environmental niche of bamboo, but at a great cost, basically dooming themselves.
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Because of all of this, certain simulations make some scientists think that pandas have been on the decline for thousands of years or even longer.
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Some argue that if humanity had never existed, the panda would still go extinct in the very near future.
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It's undeniable that they are slow to adapt, and that their very specific niche puts them at a disadvantage if any single thing in that environment changes.
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But humans are really, really good at changing the environment.
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So even if pandas have been declining without humans, humans have undoubtedly made it worse.
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Panda population decline accelerated rapidly in the 1700s, when agriculture and human civilization expanded rapidly in central China.
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And ever since then, panda habitat has been wildly fragmented.
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Dams, roads, and railways divide panda habitats, making it even more difficult for them to find each other to mate,
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and reducing the amount of bamboo forests needed for them to get enough food.
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This along with poaching absolutely slashed panda numbers.
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Today, only around 1800 pandas are left in the wild.
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Regardless, if we don't intervene, pandas would absolutely go extinct.
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Captive breeding programs have saved pandas from the brink of oblivion,
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and now humans are working to create corridors between forest reserves to link up wild pandas once again.
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Do we as humans spend a ridiculous amount of money trying to keep an animal
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that seems to want to go extinct alive?
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Yes.
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But is it maybe our responsibility to try?
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Also yes.
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Evolution did them dirty, but so did we.
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Sometimes we just have to take care of the idiots amongst us.
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My favorite part of studying biology is looking at these evolutionary questions.
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The big causes and effects that shape every animal on earth.
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How competitive pressure and genetic mutations led to the supremely weird bamboo diet for pandas.
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How a drying climate caused ants to become fungus farmers.
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How becoming upright animals allowed us to become extremely smart animals.
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The path to higher intelligence in humans is unlike anything else in the animal kingdom.
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And it's something I've explored in depth in a five -part Nebula original mini -series called Becoming Human.
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In this series, I explore the major steps in human evolution, from toolmaking, to hunting, to long -distance running,
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to language, to the birth of consciousness as we know it.
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Nebula is the streaming platform we built for exactly this reason.
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To create original content that takes a little longer, has a higher production value, and explores areas that we want to take a deep dive into,
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things that don't always work on YouTube.
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And right now for the holiday period, we're offering gift cards to Nebula for you to give to your friends or family members.
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This is a great last minute gift idea, and one that doesn't add to the pile of stuff stuff, that Christmas so often brings.
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Or to give your friend or family member access to everything Nebula will ever have to offer, you can gift a lifetime subscription for $300.
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This is a great gift for the people who lament having to pay for
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With this option, you can buy once and never pay again.
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Lifetime subscriptions, whether it's for yourself or as a gift, help fund original series like Becoming Human and so many others.
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And I know that there are thousands of you who got access to Nebula earlier through an old bundle deal,
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There are so many amazing original shows and films on Nebula, like Tom Nicholas's new feature length Boomers documentary,
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المفردات وملاحظات التحدث لهذا الدرس
يحتوي هذا الفيديو على 226 جملة و3509 كلمة للتدرب على الترديد. مدة الكلام 22:28. يتكلم المتحدث بسرعة طبيعية، نحو 156 كلمة في الدقيقة، قريبة من المحادثة اليومية. 78% فقط من الكلمات ضمن أكثر 3,000 كلمة شيوعًا في الإنجليزية، فالمفردات صعبة نسبيًا.
أهم المفردات في هذا الفيديو
15 كلمة من الفيديو تستحق التعلّم، مع النطق والمعنى:
| الكلمة | النطق | المعنى |
|---|---|---|
| bamboo اسم | /bæmˈbu/ | خَيْزَرَان, خَيْزُرَان |
| poop اسم | /ˈpuːp/ | بُرَاز, كَاكَا |
| evolution اسم | /ˌiːvəˈluːʃ(ə)n/ | تَطَوُّر |
| subscription اسم | /səbˈskɹɪpʃən/ | اِشْتِرَاك |
| diversity اسم | /daɪˈvɜː(ɹ)sɪti/ | تَنَوُّع, تَعَدُّدِيَّة |
| mouse اسم | /maʊs/ | فَأْرَة, فَأْر |
| thumb اسم | /ˈθʌm/ | إِبْهَام |
| compete فعل | /kəmˈpiːt/ | تَنَافَسَ, تَبَارَى |
| researcher اسم | /ˈɹiˌsɝ.t͡ʃɚ/ | بَاحِث, بَاحِثَة |
| sharp صفة | /ʃɑɹp/ | حَادّ |
| argue فعل | /ˈɑɹ.ɡju/ | جَادَلَ, حَاجَّ |
| rarely ظرف | /ˈɹɛəɹli/ | قَلِيلًا, قَلِيلًا مَا |
| narrow صفة | /ˈnæɹəʊ/ | ضَيِّق |
| contribute فعل | /kənˈtɹɪb.jut/ | سَاهَمَ |
| documentary اسم | /ˌdɒk.jʊˈmɛn.tɹi/ | وَثَائِقِيّ, شَرِيطٌ وَثَائِقِيّ |
القواعد في هذا الفيديو
أكثر التراكيب التي يستخدمها المتحدث، مع العبارات نفسها من الفيديو:
| التركيب | في الفيديو |
|---|---|
| الجمل الشرطية if + جملة، will/would + فعل — شرط ونتيجته | if we don't intervene, pandas would absolutely |
| المضارع التام have/has + اسم المفعول — حدث ماضٍ ما زال له أثر الآن | have evolved · they've already created · have taken |
| المبني للمجهول be + اسم المفعول — التركيز على ما يحدث لا على من يفعله | are created · are weaned · are driven |
| جمل الوصل who / which + جملة — معلومة إضافية عن شخص أو شيء | down, which is · gene, which is · milk, which has |
نطق يحتاج إلى انتباه
يستخدم المتحدث 33 من الصيغ المختصرة، مثل don't, they're, doesn't. انطقها بصيغتها القصيرة كما تسمعها.
- أصوات “th”: thumb /ˈθʌm/, sympathy /ˈsɪm.pəθ.i/, lethal /ˈliː.θəl/
- أصوات “sh” و“zh”: evolutionary /ˌiː.vəˈluː.ʃən.ɛɹ.i/, evolution /ˌiːvəˈluːʃ(ə)n/, subscription /səbˈskɹɪpʃən/, adaptation /ˌæd.æpˈteɪ.ʃən/, sharp /ʃɑɹp/
- الكلمات الطويلة — انتبه لموضع النبر: evolutionary /ˌiː.vəˈluː.ʃən.ɛɹ.i/, evolution /ˌiːvəˈluːʃ(ə)n/, adaptation /ˌæd.æpˈteɪ.ʃən/, diversity /daɪˈvɜː(ɹ)sɪti/, incredibly /ɪŋˈkɹɛdɪbli/
كيف تتدرب بهذا الفيديو
- استمع إلى الفيديو كاملًا مرة واحدة دون أن تتكلم، ودوّن الكلمات التي لا تعرفها.
- ابدأ بسرعة 0.75×، وردّد جملة جملة، ثم عُد إلى السرعة العادية عندما يصبح الأمر سهلًا.
- سجّل صوتك وقارنه بالأصل، مع الانتباه إلى كلمات مثل bamboo, poop, evolution.
ما هي تقنية التظليل الصوتي؟
التظليل الصوتي (Shadowing) تقنية تعلم لغة مدعومة علمياً، طُورت أصلاً لتدريب المترجمين الفوريين المحترفين. الطريقة بسيطة لكنها قوية: تستمع لصوت إنجليزي أصلي وتكرره فوراً بصوت عالٍ — كظل يتبع المتحدث بتأخير 1-2 ثانية. تُظهر الأبحاث تحسناً كبيراً في دقة النطق والتنغيم والإيقاع وربط الأصوات والاستماع والطلاقة.