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13 Scientific Terms Even Smart People Misuse

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When scientists use these words, they typically mean something completely different than what they do when non-scientists use them. Sometimes our definitions are too narrow or too broad, and sometimes, we use terms interchangeably when they actually shouldn't be. We dug deep into the American Museum of Natural History's website to help set the record straight.

1. and 2. Poisonous and venomous

Though the words poison and venom are often used interchangeably—and although they both describe a toxin that interferes with a physiological process—there is a difference. It’s all about how the substance is delivered: Venom is delivered via an anatomical device like fangs, while poison is usually inhaled, ingested, or absorbed. As Mark Siddall, Curator of Invertebrate Zoology at AMNH, explains in the clip above, both the rough-skinned newt and the blue-ringed octopus produce a powerful toxin called tetrodotoxin. But scientists call the octopus venomous because it delivers the substance through a bite, and consider the newt poisonous because the toxin is in its skin.

3. Microbes

When most people hear the word “microbe,” they think of stuff that they can't see that's going to make them sick. But while some do cause disease, not all microbes, or microscopic organisms, are bad; in fact, some are essential for life. Microbes include bacteria, viruses, fungi, and protozoa, and make up most of the life on our planet. For every human cell in our bodies, there are about 10 resident microbes; only a small percentage are pathogens.

4., 5., and 6. Meteor, meteorite, and asteroid

Although some use these terms interchangeably, meteors, meteorites, and asteroids are all different things. Here’s how to use them correctly: Asteroids are the rocky bodies that orbit the Sun mostly between Mars and Jupiter; they’re much smaller than planets, and they're sometimes pulled out of their orbit by the force of Jupiter’s gravity and travel toward the inner solar system. The vast majority of meteorites—rocks that fall to Earth from space and actually reach the Earth's surface—are parts of asteroids. Like meteorites, meteors are objects that enter Earth’s atmosphere from space—but they’re typically grain-sized pieces of comet dust that burn up before reaching the ground, leaving behind trails that we call “shooting stars” as they vaporize.

7. Theory

When most people use the word theory, they're talking about a hunch or guess. But for scientists, a theory is a well-substantiated—and testable—explanation that incorporates laws, hypotheses, and facts. The theories of gravity and evolution, for example, aren’t mere hunches; they explain why apples fall from trees and how so many very different plants and animals exist, and have existed, on Earth. According to AMNH’s website, “A theory not only explains known facts; it also allows scientists to make predictions of what they should observe if a theory is true.” Scientific theories are also testable; if evidence isn’t compatible with a theory, scientists can either go back to refine the theory, or reject it altogether.

8. Fossil

As Lowell Dingus, a research associate at AMNH, explains in the video above, fossils aren’t just the remains of hard parts like bones, teeth, and shells. Under the right conditions, organisms’ soft parts—like skin impressions and outlines—can also fossilize. Other things that qualify as fossils are traces made by organisms, like footprints, burrows, and nests. Fun fact: By most definitions, in order to qualify as a fossil, the specimen must be more than 10,000 years old. If they’re younger than that, the specimens are called subfossils.

9. Common ancestor

When you use the term common ancestor, you might mean that one creature evolved from another. But that oversimplifies it: Humans didn’t evolve from monkeys, for example, but share an ape-like common ancestor with Old World monkeys. According to AMNH's website, "Overwhelming evidence shows us that all species are related—that is, that they are all descended from a common ancestor. More than 150 years ago, Darwin saw evidence of these relationships in striking anatomical similarities between diverse species, both living and extinct. Today, we realize that most such resemblances—in both physical structure and embryonic development—are expressions of shared DNA, the direct outcome of a common ancestry."

10. Hominins

Homo sapiens are the only remaining descendants of a once-varied group of primates called the Hominini. You’re probably used to using the term hominids to refer to humans and their ancestors, and not long ago, you would have been correct—but recently, the definition of that word has expanded to refer to all great apes and their ancestors. Instead, you should be using the word hominins to describe the group comprised of modern humans, extinct human species, and our immediate ancestors.

The first hominin fossil was discovered in 1856, and since then, many hominin fossils, comprising many different species, have been discovered. These species emerged in different places over the past six or seven million years, and some of them even lived simultaneously, as AMNH’s Dr. Ian Tattersall explains in the video above.

11. Dinosaurs

We typically say that all dinosaurs went extinct 65 million years ago, but that’s not actually the case. In fact, if you look out your window, you might see one right now. Birds descended from the common ancestor of all dinosaurs, and so, "just as humans beings are a kind of primate, birds are a kind of dinosaur," Mark Norell, curator of the Division of Palentology at AMNH, explains in the video above. So go ahead: Tell your friends that pigeon is a dinosaur. They'll never look at those birds the same way again.

12. Pterosaurs

Chances are, you probably haven't been using this word much at all. That's because most of us grew up thinking that pterosaurs like the pterodactyl were dinosaurs, and that's what we called them. But these animals weren’t dinosaurs, and they weren’t birds, either. They were actually flying reptiles, cousins to the dinosaurs that evolved on a separate branch of the reptile family tree. Pterosaurs were the first animals after insects to evolve powered flight by flapping their wings to generate lift; you can find out more about pterosaurs from the video above.

13. De-extinction

You probably understand what de-extinction is, but you might not understand what kinds of animals we can bring back—and you have Hollywood to thank for that. Despite what you saw in Jurassic Park, scientists will never be able to resurrect non-avian dinosaurs from extinction; any DNA that might be found is just too old to be used. But for other species, science might find a way in the not-too-distant future. In fact, in 2003, researchers implanted a goat egg with genes from an extinct Spanish mountain goat and used a goat-ibex as a surrogate; the resulting animal lived for just a few minutes, but the experiment proved it could be done.

Scientists expect that technological breakthroughs—and genetic data gathered from specimens—will provide ways to revive recently extinct species (think passenger pigeons, and maybe even wooly mammoths). It sounds cool, but de-extinction comes with a number of thorny scientific and ethical questions, as Museum Curator Ross MacPhee explains in the video above.

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What Pop Culture Gets Wrong About Dissociative Identity Disorder
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From the characters in Fight Club to Dr. Jekyll and Mr. Hyde, popular culture is filled with "split" personalities. These dramatic figures might be entertaining, but they're rarely (if ever) scientifically accurate, SciShow Psych's Hank Green explains in the channel's latest video. Most representations contribute to a collective misunderstanding of dissociative identity disorder, or DID, which was once known as multiple personality disorder.

Experts often disagree about DID's diagnostic criteria, what causes it, and in some cases, whether it exists at all. Many, however, agree that people with DID don't have multiple figures living inside their heads, all clamoring to take over their body at a moment's notice. Those with DID do have fragmented personalities, which can cause lapses of memory, psychological distress, and impaired daily function, among other side effects.

Learn more about DID (and what the media gets wrong about mental illness) by watching the video below.

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Scientists Reveal Long-Hidden Text in Alexander Hamilton Letter
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Age, deterioration, and water damage are just a few of the reasons historians can be short on information that was once readily available on paper. Sometimes, it’s simply a case of missing pages. Other times, researchers can see “lost” text right under their noses.

One example: a letter written by Alexander Hamilton to his future wife, Elizabeth Schuyler, on September 6, 1780. On the surface, it looked very much like a rant about a Revolutionary War skirmish in Camden, South Carolina. But Hamilton scholars were excited by the 14 lines of writing in the first paragraph that had been crossed out. If they could be read, they might reveal some new dimension to one of the better-known Founding Fathers.

Using the practice of multispectral imaging—sometimes called hyperspectral imaging—conservationists at the Library of Congress were recently able to shine a new light on what someone had attempted to scrub out. In multispectral imaging, different wavelengths of light are “bounced” off the paper to reveal (or hide) different ink pigments. By examining a document through these different wavelengths, investigators can tune in to faded or obscured handwriting and make it visible to the naked eye.

A hyperspectral image of Alexander Hamilton's handwriting
Hyperspectral imaging of Hamilton's handwriting, from being obscured (top) to isolated and revealed (bottom).
Library of Congress

The text revealed a more emotional and romantic side to Hamilton, who had used the lines to woo Elizabeth. Technicians uncovered most of what he had written, with words in brackets still obscured and inferred:

Do you know my sensations when I see the
sweet characters from your hand? Yes you do,
by comparing [them] with your [own]
for my Betsey [loves] me and is [acquainted]
with all the joys of fondness. [Would] you
[exchange] them my dear for any other worthy
blessings? Is there any thing you would put
in competition[,] with one glowing [kiss] of
[unreadable], anticipate the delights we [unreadable]
in the unrestrained intercourses of wedded love,
and bet your heart joins mine in [fervent]
[wishes] to heaven that [all obstacles] and [interruptions]
May [be] speedily [removed].

Hamilton and Elizabeth Schuyler married on December 14, 1780. So why did Hamilton try and hide such romantic words during or after their courtship? He probably didn’t. Historians believe that his son, John Church Hamilton, crossed them out before publishing the letter as a part of a book of his father’s correspondence. He may have considered the passage a little too sexy for mass consumption.

[h/t Library of Congress]

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