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6 Pioneering Facts About Mary Leakey

Fossil bones and the earliest footprints of our human ancestors are just a few of Mary Leakey’s groundbreaking discoveries. Get to know the legendary paleoanthropologist, and learn how her serendipitous finds forever altered scientists’ understanding of human origins.

1. MARY LEAKEY WAS A BORN EXPLORER.

Mary Leakey (1913-1996), née Mary Nicol, was destined to be an explorer: Her father, Erskine Nicol, was a landscape painter, and the family traveled extensively through France, Italy, and Switzerland. While staying in a commune in southern France, 12-year-old Mary became interested in archaeology after meeting Elie Peyrony, a French prehistorian excavating a cave. Mary dug through his tiny finds—which included fine points, scrapers, and flint blades—and sorted them into an amateur classification system.

2. FOSSIL HUNTING WAS IN HER BLOOD ...

Leakey’s parents were artists, but hunting for fossils was part of her heritage: Her maternal great-great-grandfather was John Frere, an 18th-century English government official and antiquarian who’s credited with first recognizing Stone Age flint objects as early weapons and tools.

3. ... BUT SHE WASN'T A GREAT STUDENT.

Leakey was intelligent, but she also had a rebellious streak. As a teen, she was expelled from several Roman Catholic convent schools—once for intentionally creating an explosion in a chemistry lab. Figuring she wasn’t cut out for a classroom, Leakey never finished high school, and decided to pursue independent studies in art, geology, and archaeology at the University of London instead. (“I had never passed a single school exam, and clearly never would,” the scientist later wrote in her 1986 autobiography Disclosing the Past.)

4. LEAKEY WAS AN ARTIST WHEN SHE MET HER FUTURE HUSBAND AND RESEARCH PARTNER, LOUIS LEAKEY.

Mary Leakey—who inherited her father’s artistic skills— ended up working as an illustrator for archaeological digs. An archaeologist introduced her to Cambridge University paleontologist Louis Leakey, who needed an illustrator for his book Adam’s Ancestors (1934). The two became lovers, but their union resulted in scandal, as Leakey was still married at the time. The couple married in 1936, after Leakey divorced his first wife.

5. MARY LEAKEY'S FIRST BIG DISCOVERY WAS PROCONSUL AFRICANUS.

Mary Leakey's first major discovery came in 1948 when she found a fossil skull fragment of Proconsul africanus, an ancestor of apes and humans, which later diverged into two separate species. The fossil was thought to be more than 18 million years old.

6. ANOTHER ONE OF MARY LEAKEY'S FAMOUS FINDS CAME COURTESY OF ELEPHANT POOP.

In 1978, Leakey was on an expedition in Laetoli, in Tanzania, when members of her camp engaged in a spirited elephant dung fight. A scientist fell down, and he noticed strange indentations on the ground that had been recently exposed by erosion. They turned out to be tracks made around 3.7 million years prior, from animals that had walked over damp volcanic ash. Examining these prints took several years, but the team's efforts paid off when Leakey noted that one of the prints seemed to be made by a hominin. This discovery showed that early humans began walking upright long before scientists thought they had.

Additional source: Ancestral Passions: The Leakey Family and the Quest for Humankind's Beginnings, Virginia Morell

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The Surprising Reason Why Pen Caps Have Tiny Holes at the Top
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If you’re an avid pen chewer, or even just a diehard fan of writing by hand, you’re probably well acquainted with the small hole that tops off most ballpoint pen caps, particularly those classic Bic Cristal pens. The reason it’s there has nothing to do with pen function, it turns out. As Science Alert recently reported, it’s actually designed to counter human carelessness.

Though it’s arguably unwise—not to mention unhygienic—to chomp or suck on a plastic pen cap all day, plenty of people do it, especially kids. And inevitably, that means some people end up swallowing their pen caps. Companies like Bic know this well—so they make pen caps that won’t impede breathing if they’re accidentally swallowed.

This isn’t only a Bic requirement, though the company’s Cristal pens do have particularly obvious holes. The International Organization for Standardization, a federation that sets industrial standards for 161 countries, requires it. ISO 11540 specifies that if pens must have caps, they should be designed to reduce the risk of asphyxiation if they’re swallowed.

It applies to writing instruments “which in normal or foreseeable circumstances are likely to be used by children up to the age of 14 years.” Fancy fountain pens and other writing instruments that are clearly designed for adult use don’t need to have holes in them, nor do caps that are large enough that you can’t swallow them. Any pen that could conceivably make its way into the hands of a child needs to have an air hole in the cap that provides a minimum flow of 8 liters (about 2 gallons) of air per minute, according to the standard [PDF].

Pen cap inhalation is a real danger, albeit a rare one, especially for primary school kids. A 2012 study [PDF] reported that pen caps account for somewhere between 3 and 8 percent of “foreign body aspiration,” the official term for inhaling something you’re not supposed to. Another study found that of 1280 kids (ages 6 to 14) treated between 1997 and 2007 for foreign body inhalation in Beijing, 34 had inhaled pen caps.

But the standards help keep kids alive. In that Beijing study, none of the 34 kids died, and the caps were successfully removed by doctors. That wasn’t always the case. In the UK, nine children asphyxiated due to swallowing pen caps between 1970 and 1984. After the UK adopted the international standard for air holes in pen caps, the number of deaths dropped precipitously [PDF]. Unfortunately, it’s not foolproof; in 2007, a 13-year-old in the UK died after accidentally swallowing his pen cap.

Even if you can still breathe through that little air hole, getting a smooth plastic pen cap out of your throat is no easy task for doctors. The graspers they normally use to take foreign bodies out of airways don’t always work, as that 2012 case report found, and hospitals sometimes have to employ different tools to get the stubbornly slippery caps out (in that study, they used a catheter that could work through the hole in the cap, then inflated a small balloon at the end of the catheter to pull the cap out). The procedure doesn’t exactly sound pleasant. So maybe resist the urge to put your pen cap in your mouth.

[h/t Science Alert]

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Big Questions
What Causes Sinkholes?
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Mark Ralston/AFP/Getty Images

This week, a sinkhole opened up on the White House lawn—likely the result of excess rainfall on the "legitimate swamp" surrounding the storied building, a geologist told The New York Times. While the event had some suggesting we call for Buffy's help, sinkholes are pretty common. In the past few days alone, cavernous maws in the earth have appeared in Maryland, North Carolina, Tennessee, and of course Florida, home to more sinkholes than any other state.

Sinkholes have gulped down suburban homes, cars, and entire fields in the past. How does the ground just open up like that?

Sinkholes are a simple matter of cause and effect. Urban sinkholes may be directly traced to underground water main breaks or collapsed sewer pipelines, into which city sidewalks crumple in the absence of any structural support. In more rural areas, such catastrophes might be attributed to abandoned mine shafts or salt caverns that can't take the weight anymore. These types of sinkholes are heavily influenced by human action, but most sinkholes are unpredictable, inevitable natural occurrences.

Florida is so prone to sinkholes because it has the misfortune of being built upon a foundation of limestone—solid rock, but the kind that is easily dissolved by acidic rain or groundwater. The karst process, in which the mildly acidic water wears away at fractures in the limestone, leaves empty space where there used to be stone, and even the residue is washed away. Any loose soil, grass, or—for example—luxury condominiums perched atop the hole in the ground aren't left with much support. Just as a house built on a weak foundation is more likely to collapse, the same is true of the ground itself. Gravity eventually takes its toll, aided by natural erosion, and so the hole begins to sink.

About 10 percent of the world's landscape is composed of karst regions. Despite being common, sinkholes' unforeseeable nature serves as proof that the ground beneath our feet may not be as solid as we think.

A version of this story originally ran in 2014.

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