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When Did Women Start Shaving Their Pits?

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Earlier this week, Ethan Trex taught us the history of shaving. Several readers left comments inquiring about when women started shaving their legs and underarms, so we cracked open the mental_floss book In the Beginning: The Origins of Everything. Here's what we learned:

Underarms
American women had no need to shave their underarms before about 1915 "“ after all, who ever saw them? Even the word "underarm" was considered scandalous, what with it being so near certain other interesting body parts. Then came the sleeveless dress. An ad in the fashion mag Harper's Bazaar decreed that to wear it (and certainly to wear it while participating in "Modern Dancing"), women would need to first see to "the removal of objectionable hair." They didn't need much convincing, and by the early '20s, hairy underarms were so last decade, at least in America.

Legs

The '20s fashion was risqué on the bottom half, too, but most women of the era didn't seem to feel the need to shave their legs, and when hemlines dropped again in the '30s, the point became moot. The '40s, however, brought even shorter skirts, sheerer stockings, and the rise of leggy pin-ups such as Betty Grable. "The removal of objectionable hair" suddenly applied to a lot more surface area.

Naughty Bits
Was it porn actresses who started this one? GIs concerned about disease? The Brazilians? Nah. For hundreds of years, the bikini wax has been a common practice among a group more often associated with extreme modesty: Muslim women. In much of the Middle East and North Africa, brides-to-be remove all their body hair before the wedding night. Yes, all of it. Frequently, they stick with the aesthetic after marriage "“ and some men do likewise.

You can pick up a copy of 'In the Beginning' in the mental_floss store.

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How Michael Jackson's Dancing Defied the Laws of Biomechanics
Phil Walter, Getty Images
Phil Walter, Getty Images

From the time he debuted the moonwalk on broadcast television in 1983, Michael Jackson transcended the label of "dancer." His moves seemed to defy gravity as well as the normal limits of human flexibility and endurance.

Now we have some scientific evidence for that. Three neurosurgeons from the Postgraduate Institute of Medical Education and Research in Chandigarh, India, recently published a short paper in the Journal of Neurosurgery: Spine that examines just how remarkable one of Jackson's signature moves really was.

In the 1988 video for "Smooth Criminal" and subsequent live performances, Jackson is seen taking a break from his constant motion to stand in place and lean 45 degrees forward. Both he and his dancers keep their backs straight. Biomechanically, it's not really possible for a human to do. And even though he had a little help, the neurosurgeons found it to be a pretty impressive feat.

An illustration of Michael Jackson's 'Smooth Criminal' dance move.
Courtesy of 'Journal of Neurosurgery: Spine.' Copyright Manjul Tripathi, MCh.

Study co-author Manjul Tripathi told CNN that humans can't lean forward much more than 25 or 30 degrees before they risk landing on their faces. (He knows, because he tried it.) Normally, bending involves using the hip as a fulcrum, and erector spinae muscles to support our trunk. When Jackson leaned over, he transferred the fulcrum to the ankle, with the calf and Achilles tendon under strain. Since that part of the body is not equipped to support leaning that far forward without bending, the "Smooth Criminal" move was really a biomechanical illusion. The act was made possible by Jackson's patented shoe, which had a "catch" built under the heel that allowed him to grasp a protruding support on the stage. Secured to the floor, he was able to achieve a 45-degree lean without falling over.

But the neurosurgeons are quick to point out that the shoes are only part of the equation. To achieve the full 45-degree lean, Jackson would have had to have significant core strength as well as a strong Achilles tendon. An average person equipped with the shoe would be unable to do the move.

How does this apply to spinal biomechanics research? The authors point out that many dancers inspired by Jackson are continuing to push the limits of what's possible, leading to injury. In one 2010 paper, researchers surveyed 312 hip-hop dancers and found that 232 of them—almost 75 percent of the cohort—reported a total of 738 injuries over a six-month period. That prevalence could mean neurosurgeons are facing increasingly complex or unique spinal issues. The surgeons hope that awareness of potential risks could help mitigate problems down the road.

[h/t CNN]

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Scientists May Have Pinpointed How Much Exercise Your Heart Needs to Stay Healthy
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There’s really no limit to the benefits of exercise, from cognitive improvement to increased cardiovascular capacity to more energy. But one of the biggest reasons to maintain a fitness regimen is to ward off chronic conditions. For example, exercise helps keep arteries from stiffening as we age, which lowers our risk of heart disease.

"Get some exercise," however, isn't exactly specific advice. Is twice a week good enough? Three times a week? Five? And for how long each time?

Researchers in Dallas, Texas may have found an answer. According to Newsweek, a study by staff at the Institute for Exercise and Environmental Medicine and area hospitals looked at 102 people, aged 60 and over, who self-identified as either sedentary, casual, committed, or master-level exercisers. They worked out anywhere from almost never to daily. The researchers found that casual exercise (two to three times weekly, 30 minutes each session) was associated with keeping the mid-sized arteries, like those found in the head and neck, from aging prematurely. But four to five sessions per week helped stabilize the larger central arteries, which send blood to the chest and abdomen. The research was published in the Journal of Physiology.

The study did not look at the type of exercise performed or other lifestyle choices that may have affected the participants' arterial health. But when it comes to moving your body to keep your arteries limber, it seems safe to say that more is better.

[h/t Newsweek]

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