Why Are There No More Dinosaurs?

CHLOE EFFRON / DINOSAURS: ISTOCK
CHLOE EFFRON / DINOSAURS: ISTOCK

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Actually, there are still dinosaurs: Birds! But let’s talk about that a little later. Scientists have found clues in rocks and fossils that tell us that by 65 million years ago, the climate (CLY-met), or usual weather, of the Earth had changed a lot, becoming cooler and drier. That was hard on the heat-loving dinosaurs. But that’s not why almost all of the dinosaurs became extinct, or disappeared forever. Scientists think a terrible event occurred that killed them off.

In 1991, scientists discovered a huge 110-mile-long crater, or hole, in the Gulf of Mexico. They think this crater was made by a giant, fiery, 6-mile-wide asteroid (AST-er-oyd) from space that smashed into the Earth about 65 million years ago. The impact was more powerful than any bomb we have ever known. Scientists believe this event killed most plant and animal life—including the dinosaurs. The asteroid probably caused shockwaves, earthquakes, fireballs, wildfires, and tidal, or really big, waves. It also sent huge amounts of dust and gas into the atmosphere, which is like a big blanket of air that surrounds the Earth. That was really bad for the planet.

The dust blocked sunlight, making the planet very cold and dark. Then, over time, the gases trapped heat, causing the Earth to get even hotter than it was before the asteroid hit. This change was deadly for most dinosaurs, and they became extinct. But birds survived. Many millions of years earlier, they had evolved (ee-VOL-ved), or changed slowly over time, from one group of dinosaurs. And when the dinosaurs disappeared, mammals diversified (die-VERSE-uh-fide), or changed, into many different kinds of animals—including us, many millions of years later. So the next time you see a bird swoop by, wave hello to the little flying dinosaur!    


Alcohol-Producing Gut Bacteria May Harm Livers—Even if You Don't Drink

itakdalee/iStock via Getty Images
itakdalee/iStock via Getty Images

Teetotalers might think their liver is safe from the damaging effects of alcohol consumption, but new research is hinting that even non-drinkers and light drinkers might have cause for concern. It turns out a type of gut bacteria is capable of producing alcohol—and enough of it to potentially cause some pretty serious health consequences, including liver disease.

A study led by Jing Yuan at the Capital Institute of Pediatrics in Beijing, China and published in the journal Cell Metabolism offers details. After evaluating a patient with auto-brewery syndrome (ABS), a rare condition brought on by consumption and fermentation of sugary foods that leaves a person with high blood alcohol levels, researchers made an intriguing discovery. Rather than finding fermenting yeast that may have led to the condition, the patient’s stool contained Klebsiella pneumonia, a common gut bacteria capable of producing alcohol. In this subject, K. pneumonia was producing significantly more alcohol than in healthy patients.

The patient also had nonalcoholic fatty liver disease (NAFLD), characterized by fatty deposits in the liver. While many cases of NAFLD are relatively benign, too much fat can become toxic. Examining 43 other subjects with NAFLD, scientists found that that K. pneumonia was both present and potent, pumping out more alcohol than normal in 60 percent of participants with NAFLD. In the control group, a surplus was found in only 6.25 percent.

To further observe a correlation, scientists fed the bacteria to healthy, germ-free mice, who began to see an increase in fat in their livers after only one month. While not conclusive proof that the bacteria prompts NAFLD, it will likely trigger additional research in humans.

It’s not yet known how K. pneumonia acts in concert with the bacterial profile of the gut or what might make someone carrying stronger strains of the bacteria. Luckily, K. pneumonia can be treated with antibiotics. That’s good news for people who might never touch a drink and still find themselves with a damaged liver.

[h/t Live Science]

5 Hilarious Discoveries from the 2019 Ig Nobel Prize Winners

andriano_cz/iStock via Getty Images
andriano_cz/iStock via Getty Images

Each September, the Ig Nobel Prizes (a play on the word ignoble) are given out to scientists who have wowed the world with their eccentric, imaginative achievements. Though the experiments are usually scientifically sound and the results are sometimes truly illuminating, that doesn’t make them any less hilarious. From postal workers’ scrotal temperatures to cube-shaped poop, here are our top five takeaways from this year’s award-winning studies.

1. Left and right scrota often differ in temperature, whether you’re naked or not.

Roger Mieusset and Bourras Bengoudifa were awarded the anatomy prize for testing the scrotum temperatures in clothed and naked men in various positions. They found that in some postal workers, bus drivers, and other clothed civilians, the left scrotum is warmer than the right, while in some naked civilians, the opposite is true. They suggest that this discrepancy may contribute to asymmetry in the shape and size of male external genitalia.

2. 5-year-old children produce about half a liter of saliva per day.

Shigeru Watanabe and his team nabbed the chemistry prize for tracking the eating and sleeping habits of 15 boys and 15 girls to discover that, regardless of gender, they each produce about 500 milliliters of spit per day. Children have lower salivary flow rates than adults, and they also sleep longer (we produce virtually no saliva when we sleep), so it seems like they may generate much less saliva than adults. However, since children also spend more time eating than adults (when the most saliva is produced), the average daily levels are about even—at least, according to one of Watanabe’s previous studies on adult saliva.

3. Scratching an ankle itch feels even better than scratching other itches.

Ghada A. bin Saif, A.D.P. Papoiu, and their colleagues used cowhage (a plant known to make people itchy) to induce itches on the forearms, ankles, and backs of 18 participants, whom they then asked to rate both the intensity of the itch and the pleasure derived from scratching it. Subjects felt ankle and back itches more intensely than those on their forearms, and they also rated ankle and back scratches higher on the pleasure scale. While pleasure levels dropped off for back and forearm itches as they were scratched, the same wasn’t true for ankle itches—participants still rated pleasurability higher even while the itchy feeling subsided. Perhaps because there’s no peace quite like that of scratching a good itch, the scientists won the Ig Nobel peace prize for their work.

4. Elastic intestines help wombats create their famous cubed poop.

In the final 8 percent of a wombat’s intestine, feces transform from a liquid-like state into a series of small, solid cubes. Patricia Yang, David Hu, and their team inflated the intestines of two dead wombats with long balloons to discover that this formation is caused by the elastic quality of the intestinal wall, which stretches at certain angles to form cubes. For solving the mystery, Yang and Hu took home the physics award for the second time—they also won in 2015 for testing the theory that all mammals can empty their bladders in about 21 seconds.

5. Romanian money grows bacteria better than other money.

Habip Gedik and father-and-son pair Timothy and Andreas Voss earned the economics prize by growing drug-resistant bacteria on the euro, U.S. dollar, Canadian dollar, Croatian luna, Romanian leu, Moroccan dirham, and Indian rupee. The Romanian leu was the only one to yield all three types of bacteria tested—Staphylococcus aureus, Escherichia coli, and Vancomycin-resistant Enterococci. The Croatian luna produced none, and the other banknotes each produced one. The results suggest that the Romanian leu was most susceptible to bacteria growth because it was the only banknote in the experiment made from polymers rather than textile-based fibers.

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