Category: teded

Why don’t poisonous animals poison themselves?

In fact, how do any toxic animals survive their own secretions? The answer is that they use one of two basic strategies: securely storing these compounds or evolving resistance to them. Snakes employ both strategies – they store their flesh-eating, blood-clotting compounds in specialized compartments that only have one exit: through the fangs and into their prey or predator and they have built-in biochemical resistance. Rattlesnakes and other types of vipers manufacture special proteins that bind and inactivate venom components in the blood.

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Poisonous and venomous animals aren’t the only ones that can develop this resistance: their predators and prey can, too. The garter snake, which dines on neurotoxic salamanders, has evolved resistance to salamander toxins through some of the same genetic changes as the salamanders themselves.

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That means that only the most toxic salamanders can avoid being eaten— and only the most resistant snakes will survive the meal. The result is that the genes providing the highest resistance and toxicity will be passed on in greatest quantities to the next generations.

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As toxicity ramps up, resistance does too, in an evolutionary arms race that plays out over millions of years. This pattern appears over and over again. Grasshopper mice resist painful venom from scorpion prey through genetic changes in their nervous systems. Horned lizards readily consume harvester ants, resisting their envenomed sting with specialized blood plasma. And sea slugs eat jellyfish nematocysts, prevent their activation with compounds in their mucus, and repurpose them for their own defenses.

From the TED-Ed Lesson Why don’t poisonous animals poison themselves? – Rebecca D. Tarvin

Animation by Giulia Martinelli

Hallucinatory experiences are much more closel…

Hallucinatory experiences are much more closely tied to ordinary perception than we once thought.

We know from fMRI studies that hallucinations activate the same brain areas as sight, areas that are not activated by imagination. Many other hallucinations, including smells, sights, and sounds, also involve the same brain areas as real sensory experiences. Because of this, the cerebral cortex is thought to play a part in hallucinations. This thin layer of grey matter covers the entire cerebrum, with different areas processing information from each of our senses. But even in people with completely unimpaired senses, the brain constructs the world we perceive from incomplete information. 

For example, our eyes have blind spots where the optic nerve blocks part of the retina. When the visual cortex processes light into coherent images, it fills in these blind spots with information from the surrounding area. Occasionally, we might notice a glitch, but most of the time we’re none the wiser. When the visual cortex is deprived of input from the eyes, even temporarily, the brain still tries to create a coherent picture, but the limits of its abilities become a lot more obvious. 

By studying hallucinations, we stand to learn a great deal about how our brains construct the world we see, hear, smell, and touch. As we learn more, we’ll likely come to appreciate just how subjective and individual each person’s island universe of perception really is.

For more on the science and research of hallucinations, check out the TED-Ed Lesson What causes hallucinations? – Elizabeth Cox

Animation by Nerdo

Since the time of Homer, ancient stories told …

Since the time of Homer, ancient stories told of fierce warriors dwelling beyond the Mediterranean world, striking fear into the mightiest empires of antiquity. Their exploits were recounted by many epic poets. They fought in the legendary Trojan War and their grand army invaded Athens. Jason and the Argonauts passed by their shores, barely avoiding their deadly arrows. These formidable fighters faced off against the greatest champions of myth: Heracles, Theseus, and Achilles. 

And every single one of these warriors was a woman.

The war-loving Amazons, “the equals of men” in courage and skill, were familiar to everyone in ancient Greece. But were Amazons merely figures of myth, or something more?

Watch the TED-Ed Lesson Did the Amazons really exist? – Adrienne Mayor to uncover the mysteries of these women warriors.

Animation by Silvia Prietov

Football Physics: The Science Behind the Banan…

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In 1997 in a game between France and Brazil, a young Brazilian player named Roberto Carlos set up for a 35 meter free kick. With no direct line to the goal, Carlos decided to attempt the seemingly impossible. His kick sent the ball flying wide of the players, but just before going out of bounds it hooked to the left and soared into the goal.

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According to Newton’s first law of motion, an object will move in the same direction and velocity until a force is applied on it. When Carlos kicked the ball he gave it direction and velocity, but what force made the ball swerve and score one of the most magnificent goals in the history of the sport?

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The trick was in the spin. Carlos placed his kick at the lower right corner of the ball, sending it high and to the right, but also rotating around its axis. 

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The ball started its flight in an apparently direct route, with air flowing on both sides and slowing it down. On one side, the air moved in the opposite direction to the ball’s spin, causing increased pressure, while on the other side—the air moved in the same direction as the spin, creating an area of lower pressure. 

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That difference made the ball curve towards the lower pressure zone. This phenomenon is called the Magnus effect.

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This type of kick, often referred to as a banana kick, is attempted regularly, and it is one of the elements that makes “The beautiful game” beautiful. 

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But curving the ball with the precision needed to both bend around the wall, and back into the goal is difficult. Too high and it soars over the goal. Too low and it hits the ground before curving. Too wide and it never reaches the goal. 

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Not wide enough and the defenders intercept it. Too slow and it hooks too early or not at all. Too fast and it hooks too late.

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The same physics make it possible to score another apparently impossible goal—an unassisted corner kick.

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The Magnus effect was first documented by Sir Isaac Newton after he noticed it while playing a game of Tennis back in 1670. It also applies to golf balls, Frisbees and baseballs. In every case the same thing happens: the ball’s spin creates a pressure differential in the surrounding airflow that curves it in the direction of the spin.  

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And here’s a question: could you theoretically kick a ball hard enough to make it boomerang all the way around back to you?  Sadly, no. Even if the ball didn’t disintegrate on impact or hit any obstacles, as the air slowed it, the angle of its deflection would increase, causing it to spiral into smaller and smaller circles until finally stopping. And just to get that spiral you’d have to make the ball spin over 15 times faster than Carlos’s immortal kick. So good luck with that.

From the TED-Ed Lesson Football physics: The “impossible” free kick – Erez Garty

Animation by TOGETHER

Just some facts you can throw out while watching the World Cup this summer.

lea–krawczyk: Last summer i’ve made a co…

lea–krawczyk:

Last summer i’ve made a commissioned film for TED-ed lessons ! What a great experience. It’s about the myth of Prometheus. You can check the film here : https://ed.ted.com/lessons/the-myth-of-prometheus-iseult-gillespie

Here are some color researches !

We love when artists share their behind-the-scenes of TED-Ed Lessons! 

Here, Léa Krawczyk shares her color studies for her beautifully designed animation on the The myth of Prometheus!

Check out Léa’s tumblr for more behind-the-scenes and her other stunning illustration + animation work.

From the TED-Ed Lesson The myth of Prometheus – Iseult Gillespie

Animation by Léa Krawczyk ( @lea–krawczyk )

Are naked mole rats the strangest mammals?

What mammal has the social life of an insect, the cold-bloodedness of a reptile, and the metabolism of a plant? 

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Bald and buck-toothed, naked mole rats may not be pretty, but they’re extraordinary. With a lifespan of 30 years, their peculiar traits have evolved over millions of years to make them uniquely suited to survive harsh conditions, especially long periods without oxygen. 

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In the deserts of East Africa, naked mole rats feed on root vegetables. They dig for the roots with teeth that can move independently, like chopsticks. 

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But even with these special teeth, a single naked mole rat doesn’t stand a chance of finding enough food; the roots are large and nutritious, but scattered far and wide. A large workforce has a much better chance so naked mole rats live in colonies. 

Similar to ants, bees, and termites, they build giant nests. Housing up to 300 mole rats, these colonies feature complex underground tunnel systems, nest chambers, and community bathrooms. Also like insects, naked mole rats have a rigid social structure. 

The dominant female, the queen, and two to three males that she chooses, are the only naked mole rats in the colony who have babies. All the other naked mole rats, male and female, are either soldiers, who defend the colony from possible invaders, or workers. Teams of workers are dispatched to hunt for roots, and their harvest feeds the whole colony.

Living in a colony helps naked mole rats find enough food, but when so many animals live in the same underground space, oxygen quickly runs out. Naked mole rats can thrive in low oxygen in part because they’ve abandoned one of the body functions that requires the most oxygen: thermoregulation. Naked mole rats are the only mammals whose body temperature fluctuates with their environment, making them cold-blooded, like reptiles.

In response to a real oxygen emergency, naked mole rats enter a state of suspended animation. They stop moving, slow their breathing, and dramatically lower their heart rate. This greatly reduces the amount of energy, and therefore oxygen, they need. At the same time, they begin to metabolize fructose, like a plant. Fructose is a sugar that can be used to make energy without burning oxygen. Usually, mammals metabolize a different sugar called glucose that makes more energy than fructose, but glucose only works when oxygen’s available. Naked mole rats are, in fact, the only mammals known to have this ability.

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For more on these weird & cool creatures, check out the TED-Ed lesson Are naked mole rats the strangest mammals? – Thomas Park

Animation by Chintis Lundgren

Cannibalism in the animal kingdom

In the deserts of the American Southwest, spadefoot toad tadpoles hatch in tiny oases. Until they develop into toadlets, they can’t survive outside of water, but these ponds are transient and quickly evaporate. 

The tadpoles are in a race against the clock to grow up before their nurseries disappear. So nearly overnight, some of the brood explode in size. 

They use their jack-o-lantern teeth and huge jaw muscles to devour their smaller pond mates. Nourished by this extra fuel, they develop quicker, leaving the pond before it can dry out. 

The spadefoot toad is far from the only animal to eat members of its own species as a normal part of its life cycle. All of these animals do, too. 

If that surprises you, you’re in good company. Until recently, scientists thought cannibalism was a rare response to starvation or other extreme stress. Well-known cannibals, like the praying mantis and black widow spider, were considered bizarre exceptions. But now, we know they more or less represent the rule.

For more cannibalistic creatures, check out the TED-Ed Lesson Cannibalism in the animal kingdom – Bill Schutt

Animation by Compote Collective

Why do we dream?

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In the 3rd millennium BCE, Mesopotamian kings recorded and interpreted their dreams on wax tablets. In the years since, we haven’t paused in our quest to understand why we dream. And while we still don’t have any definitive answers, we have some theories. Here are seven reasons we might dream.

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1. In the early 1900’s, Sigmund Freud proposed that while all of our dreams, including our nightmares, are a collection of images from our daily conscious lives, they also have symbolic meanings which relate to the fulfillment of our subconscious wishes.  Freud theorized that everything we remember when we wake up from a dream is a symbolic representation of our unconscious, primitive thoughts, urges and desires. Freud believed that by analyzing those remembered elements, the unconscious content would be revealed to our conscious mind, and psychological issues stemming from its repression could be addressed and resolved.

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2. To increase performance on certain mental tasks, sleep is good, but dreaming while sleeping is better.  In 2010, researchers found that subjects were much better at getting through a complex 3D maze if they had napped and dreamed of the maze prior to their second attempt. In fact, they were up to ten times better at it than those who only thought of the maze while awake between attempts, and those who napped but did not dream about the maze. Researchers theorize that certain memory processes can happen only when we are asleep, and our dreams are a signal that these processes are taking place.

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3. There are about ten thousand trillion neural connections within the architecture of your brain. They are created by everything you think, and everything you do.  A 1983 neurobiological theory of dreaming, called “reverse learning,” holds that while sleeping, and mainly during REM sleep cycles, your neocortex reviews these neural connections and dumps the unnecessary ones. Without this unlearning process, which results in your dreams, your brain could be overrun by useless connections, and parasitic thoughts could disrupt the necessary thinking you need to do while you’re awake.    

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4. The “Continual Activation Theory” proposes that your dreams result from your brain’s need to constantly consolidate and create long term memories in order to function properly. So when external input falls below a certain level, like when you’re asleep, your brain automatically triggers the generation of data from its memory storages, which appear to you in the form of the thoughts and feelings you experience in your dreams. In other words, your dreams might be a random screensaver your brain turns on so it doesn’t completely shut down.   

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5. Dreams involving dangerous and threatening situations are very common, and the Primitive Instinct Rehearsal Theory holds that the content of a dream is significant to its purpose.  Whether it’s an anxiety filled night of being chased through the woods by a bear, or fighting off a ninja in a dark alley, these dreams allow you to practice your fight or flight instincts and keep them sharp and dependable, in case you’ll need them in real life. But it doesn’t always have to be unpleasant; for instance, dreams about your attractive neighbor could actually give your reproductive instinct some practice too.

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6. Stress neurotransmitters in the brain are much less active during the REM stage of sleep, even during dreams of traumatic experiences, leading some researchers to theorize that one purpose of dreaming is to take the edge off painful experiences to allow for psychological healing. Reviewing traumatic events in your dreams with less mental stress may grant you a clearer perspective and an enhanced ability to process them in psychologically healthy ways. People with certain mood disorders and PTSD often have difficulty sleeping, leading some scientists to believe that lack of dreaming may be a contributing factor to their illnesses.   

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7. Unconstrained by reality and the rules of conventional logic, in your dreams your mind can create limitless scenarios to help you grasp problems and formulate solutions that you may not consider while awake. John Steinbeck called it “the Committee of Sleep” and research has demonstrated the effectiveness of dreaming on problem solving. It’s also how renowned chemist August Kekule discovered the structure of the benzene molecule, and it’s the reason that sometimes the best solution for a problem is to “sleep on it”.

And those are just a few of the more prominent theories. As technology increases our capability for understanding the brain, it’s possible that one day we will discover the definitive reason for them; but until that time arrives, we’ll just have to keep on dreaming.

From the TED-Ed Lesson Why do we dream? – Amy Adkins

Animation by @clamanne

Happy Birthday to Sigmund Freud today!

teded: May the Fourth be with you. From the T…

teded:

May the Fourth be with you.

From the TED-Ed Lesson The hidden meanings of yin and yang – John Bellaimey

Animation by TED-Ed

teded: As comets move close to the Sun, they d…

teded:

As comets move close to the Sun, they develop tails of dust and ionized gas. Comets have two main tails, a dust tail and a plasma tail. The dust tail appears whitish-yellow because it is made up of tiny particles — about the size of particles of smoke — that reflect sunlight. The plasma tail is often blue because it contains carbon monoxide ions. Solar ultraviolet light breaks down the gas molecules, causing them to glow. Plasma tails can stretch tens of millions of kilometers into space. 

The more you know…

For more on plasma, watch the TED-Ed Lesson Solid, liquid, gas and … plasma? – Michael Murillo

Animation by Tomás Pichardo Espaillat