字幕表 動画を再生する 英語字幕をプリント Hi, I'm Emily from MinuteEarth, and under no circumstances would I eat my own baby, but lots of other animals would, and do. Coming up: more about that. But first, three very short stories about the weird stuff we humans eat. Like, for example, spoiled food. Some of our favorite foods are closer to this... than this. That's because coffee, bread, cheese, beer, even chocolate are all home to millions of microbes. In fact, these foods only acquire the tastes, smells, and textures we love because of tiny bacteria and fungi. The vast majority of microbes, about 99%, are actually quite harmless to humans. But the other 1% are nasty enough that our ancestors, and the ancestors of various other mammals and birds, evolved a natural repulsion to stuff that might harbor nasty germs. In general, we think rotten stuff looks and smells disgusting. Which, considering what's at stake, isn't overly cautious. Fortunately, if friendly microbes get to our food first, they can keep the bad guys at bay. Meats left out on the counter provides the perfect conditions for pathogens to florish. It's warm, moist, and protein-rich, just like our bodies. But with some micro-management, adding lots of salt for instance, we can help harmless salt-tolerant microbes outcompete their dangerous but salt-sensitive relatives. A few unrefrigerated months later, we get salami, rather than "salmonelli." Our ancestors stumbled on this kind of controlled spoilage thousands of years ago, either by lucky accidents, or out of serious desperation. And we humans have been intentionally spoiling food ever since. Not only to keep our food safe to eat, but also because the microbes we culture can transform it almost magically into awesome deliciousness. Yeast, for example, gorge on the sugary starch in bread dough, then burp out carbon dixoide that helps give loaves their lift. In a more exotic transformation, bacteria and fungi take turns munching on piles of cacao, mellowing out bitter polyphenols, and helping create the complex and delicious taste of chocolate. And deep in cheese caves, mold spores populate small holes and cracks in soon-to-be blue cheese, digesting big protein and fat molecules into a host of smaller aromatic and flavor compounds that give the final product its smoothness and rich, funky flavor. But to some, stinky cheese is about as appetizing as licking someone's toes. Which isn't that far off, since the bacteria that make some cheeses super stinky are the same ones that cause foot odor. Yum? Even so, these flavors tend to grow on us, not just literally, not also figuratively. The more we're exposed to particular microbial funks, which can even start in the womb, the more we tend to like them. As a result, people around the world have some very different ideas about how to microbify foods. But every culinary culture involves fermentation in one way or another. If we didn't let food spoil just a little bit, we'd have no sauerkraut, soy sauce, pickles, or prosciutto. Not to mention kefir, kimchi, kombucha, koumiss, katsuobushi, and plenty of other delicacies that don't start with "k." What's more, spoiled food may well have changed far more than our tastes. Historical evidence suggests that when our ancestors gave up their wandering ways and settled down to grow grain, it was likely for love of either bread, or beer. Whatever the case, one thing is clear: without the help of friendly fermenting microbes, we humans would be terribly uncultured. So, spoiling our food actually helps keep it good, but we've also come up with another, cleaner way to keep food fresh. Check it out! Food is delicious, not to mention kind of important for life. But food also goes bad. So humans have invented many ways to preserve it to eat later, or far from where it was harvested. Some of these methods require unhealthy chemicals, or degrade the food's nutritional value. But luckily, freezing can preserve food with most of its nutrients, well, frozen in place. The important part is that most chemical and biological processes run slower at lower temperatures. Which means that if you cool food a lot, enzymes and bacteria and fungi in the food get too cold to decompose it. That's why food lasts longer in the freezer than in the fridge than on the counter. Freezing, however, wasn't always an easy task. Especially before fridges were invented. It's not that freezing food is a new idea. I mean, people who live in cold places have done it by default for thousands of years. But things got messy when we started creating artificial winter to freeze food in warmer climates. Early freezers were basically rooms full of salty ice, which, while they could freeze food, took many hours or even days to do so. A slow freeze gives fluid within cells the time to stack up into big ice crystals. Since water expands when it freezes, the sharp edges of these crystals poke holes through the walls of the cells. And when the food thaws, the fluid leaks out. Gross! Even grosser, bird's eyes. Clarence Birdseye, to be precise. An American entrepreneur who lived in Arctic Canada in the 1910s, Birdseye noticed that when Inuit people went ice fishing in −40°, windy conditions, their catch froze almost immediately. When cooked later, the fish tasted fresh. Birdseye realized that the Arctic frozen foods were tasty BECAUSE they froze quickly and formed smaller ice crystals that didn't damage the cells. Inspired, he went on to develop a process to quickly freeze food by pressing small packages between metal plates chilled to 40° below zero. Combined with clever marketing, this allowed Birdseye to bring Arctic winter to the rest of the world, and to almost single-handedly jumpstart the modern market for frozen foods. You probably even have your OWN freezer, a marvellous device cold enough to quick-freeze almost any food you put in it. In other words, the North Pole in your kitchen. Freezers aren't the only food-related gift that northern climes have brought us. They've also given us delicious reindeer meat. So, why don't Americans eat it? In North America, we tend to think of reindeer once a year: as semi-mythical flying creatures that pull Santa's sleigh around the world. Yet not only are reindeer real―if things had gone a little differently, we might be regularly chowing down on Blitzen-burgers! That's because when the United States bought Alaska from Russia in the late 1800s, American entrepreneurs saw an opportunity to replicate Russia's long-established reindeer-herding industry, and started shipping domesticated reindeer over to Alaska. But it turns out that reindeer are kind of naughty! Entire herds disappeared into the vast Alaskan landscape, where they died or ran off with the area's native wild reindeer. Reindeer herders in Europe and Russia had similar problems, but with a 3000-year head start, their experience gave them a keener sense of where their animals might wander. Something else that kept reindeer from taking off in North America was cows. Yes, cows. Despite lots of reindeer product marketing, Americans already had meat that they liked. They bought thousands of times more beef than reindeer each year. Yet the cattle industry still lobbied hard against reindeer, even getting some local laws passed that prohibited its sale entirely. Times were tough for the reindeer industry. And then, the Great Depression struck. As people's incomes plummeted, so too did their interest in trying exotic reindeer meat. Many reindeer herders, unable to recoup their costs, left their animals to wander at will, and within 20 years, over 90% of these reindeer succumbed to overgrazing, predators, and the call of the wild. Today, a very small reindeer-herding industry still exists in far northwest Alaska. But most of the meat is eaten locally, and new challenges, like a warming climate that can trap reindeer food under a thick layer of ice, are making it even tougher to herd the creatures. So, for most of us, reindeer will probably remain relegated to Santa's sleigh. Rudolph with his nose so bright won't be on your plate tonight. Whether or not you think it's weird to eat reindeer meat depends on where you live, and whether or not you think it's weird to eat your own babies largely depends on whether or not you're a hamster. Sometimes, a hamster mom looks at her adorable little babies and is like, I just wanna gobble you up. Except, not in a cute way. More in like a, [devil voice] "I'm actually about to eat you" kind of way. And hamster moms aren't alone. Pigs, bugs, birds, snakes, primates, and fish all occasionally nom on the next generation. Which is... weird! Not just because we humans consider it deeply wrong to eat our own babies, but also because making babies is the primary goal of virtually all life. So eating them, and the genes they carry, seems like the ultimate act of self-defeat. But self-defeating impulses have a pretty straightforward way of dying out. So the fact that species across the animal kingdom occasionally cannibalize their young suggests that it can sometimes be a successful strategy. For instance, hamsters appear to use baby-eating as a form of crowd control. Females with litters of 8 or 9 pups eat 2 of them on average. And when scientists have tried adding a couple pups to the litter, the hamster moms eat 4. But removing a few of the pups the day they're born pretty much stops the cannibalism before it starts, suggesting that a hamster mom might eat her young to keep her litter small enough that she can provide for the survivors and ensure they grow up to pass on their genes. Other critters, like the long-tailed sun skink, chown down on their babies only in emergencies. When predators repeatedly threaten to eat the mother's eggs, she beats them to it and eats them all herself, which actually makes sense. If the eggs are doomed to become someone's lunch, making them HER lunch helps prepare the momma skink for another round of reproduction. And sometimes, kids, you know, get in the way. So, they just have to go. The male sand goby fertilizes eggs from multiple females over a short period of time, and cares for them all together in one nest. In order to mate again, he has to wait for all his eggs to hatch. So, he sacrifices the slow-pokes to free himself up for more baby-making. In short, for critters across the animal kingdom to maximize the resources, energy, and opportunities they need to pass on their genes, sometimes it does make sense to order off the kids menu. That's what I'd call a not-so-happy meal. Thanks for watching!