Author: TED-Ed - Gifs worth sharing

teded: Despite what many may think, handedness…

teded:

Despite what many may think, handedness is not a choice. It can be predicted even before birth based on the fetus’ position in the womb. So, if handedness is inborn, does that mean it’s genetic? 

Well, yes and no. Identical twins, who have the same genes, can have different dominant hands. In fact, this happens as often as it does with any other sibling pair.

From the TED-Ed Lesson Why are some people left-handed? – Daniel M. Abrams

Animation by TED-Ed

Happy Left Hander’s Day!

Proud to be a lefty? Grab yourself a Left Hand, Best Hand t-shirt, designed by TED-Ed! 

Poison dart frogs have evolved a resistance to…

Poison dart frogs have evolved a resistance to their own toxins. These tiny animals defend themselves using hundreds of bitter-tasting compounds called alkaloids that they accumulate from consuming small arthropods like mites and ants. One of their most potent alkaloids is the chemical epibatidine, which binds to the same receptors in the brain as nicotine but is at least ten times stronger. 

An amount barely heavier than a grain of sugar would kill you. So what prevents poison frogs from poisoning themselves? Think of the molecular target of a neurotoxic alkaloid as a lock, and the alkaloid itself as the key. When the toxic key slides into the lock, it sets off a cascade of chemical and electrical signals that can cause paralysis, unconsciousness, and eventually death. But if you change the shape of the lock, the key can’t fit. For poison dart frogs and many other animals with neurotoxic defenses, a few genetic changes alter the structure of the alkaloid-binding site just enough to keep the neurotoxin from exerting its adverse effects.

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

Animation by Giulia Martinelli

teded: Happy Book Lover’s Day! Get lost in a …

teded:

Happy Book Lover’s Day! Get lost in a good book. Need some ideas?

31 great books for students, chosen by students

40+ books recommended by our educators

From the TED-Ed lesson The contributions of female explorers – Courtney Stephens

Animation by @lizziakana

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

An elderly woman named Rosalie was sitting in …

An elderly woman named Rosalie was sitting in her nursing home when her room suddenly burst to life with twirling fabrics.

Through the elaborate drapings, she could make out animals, children and costumed characters. Rosalie was alarmed, not by the intrusion, but because she knew this entourage was an extremely detailed hallucination. Her cognitive function was excellent, and she had not taken any medications that might cause hallucinations. Strangest of all, had a real-life crowd of circus performers burst into her room, she wouldn’t have been able to see them: she was completely blind.

Rosalie had developed a condition known as Charles Bonnet Syndrome, in which patients with either impaired vision or total blindness suddenly hallucinate whole scenes in vivid color. These hallucinations appear suddenly, and can last for mere minutes or recur for years. We still don’t fully understand what causes them to come and go, or why certain patients develop them when others don’t.

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

Animation by Nerdo

teded: Did you know that dogs smell in stereo?…

teded:

Did you know that dogs smell in stereo? The ability to smell separately – with each nostril – helps them determine from what direction smells come. This is just one of the many ways that dogs’ wonderfully developed noses make them so scent-savvy.

From the TED-Ed Lesson How do dogs “see” with their noses? – Alexandra Horowitz 

Animation by Provincia Studio

teded: “Life moves pretty fast. If you don’t s…

teded:

“Life moves pretty fast. If you don’t stop and look around once in a while, you could miss it.” – Ferris Bueller

From the TED-Ed Lesson Would you opt for a life with no pain? – Hayley Levitt and Bethany Rickwald

Animation by Avi Ofer

Fun Fact Friday!

Fun Fact Friday!

Did you know that only one in four folks smell something funky in their pee after eating asparagus? Are you part of that unlucky 25%?

From the TED-Ed lesson How do we smell – Rose Eveleth?

Animation by Igor Coric

teded: “For to be free is not merely to cast o…

teded:

“For to be free is not merely to cast off one’s chains, but to live in a way that respects and enhances the freedom of others” -Nelson Mandela

Join us in celebrating Nelson Mandela’s birthday today!

From the TED-Ed Lesson The philosophy of Stoicism – Massimo Pigliucci

Animation by Compote Collective

Today would have been Nelson Mandela’s 100th birthday!