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Once-Deadly Viruses Evolved To Protect Early Human Embryos

"We are creatures controlled by viruses," Luis Villarreal, a professor of Molecular Biology and Biochemistry at the University of California at Irvine, tells New Scientist. He's referring to the endogenous retroviruses, or ERVs, that make up about 9 percent of the human genome. Throughout human development, these retroviruses would invade our genome, at first causing death and disease—but as our species evolved a resistance or tolerance, these viruses would become woven into the fabric of our evolution. According to the theories of some scientists, this is how certain species diverge from one another. A virus forces an evolution that gets passed down if it proves beneficial in some way. It was largely thought that the effect of these retroviruses ceased to have an impact on our behavior and evolution thousands of years ago.

But a recent discovery is challenging that assumption. While studying the tiny bundles of just eight cells that comprise 3-day-old human embryos, Joanna Wysocka and her colleagues at Stanford University in California found, in addition to DNA from the parents, evidence of HERVK, the most recent ERV to take root in our DNA, likely some 200,000 years ago.

And HERVK isn't lying dormant in these early embryos: Experiments revealed that the virus appears to produce a protein that prevents dangerous viruses like influenza from penetrating the embryo. It also appears to be aiding in translating genetic instructions to the cellular protein factories. What was once a deadly virus has evolved to be crucial to defense and development of our earliest selves. 

Patrick Forterre of the Pasteur Institute in Paris believes that this corroborates the theory that retroviruses are crucial to species divergence, saying, "It shows that the protein products of a relatively 'recent' retrovirus integration are present very early on in the embryo, and could be involved in some critical developmental programmes."

[h/t New Scientist]

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Stradivarius Violins Get Their Distinctive Sound By Mimicking the Human Voice
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Italian violinist Francesco Geminiani once wrote that a violin's tone should "rival the most perfect human voice." Nearly three centuries later, scientists have confirmed that some of the world's oldest violins do in fact mimic aspects of the human singing voice, a finding which scientists believe proves "the characteristic brilliance of Stradivari violins."

Using speech analysis software, scientists in Taiwan compared the sound produced by 15 antique instruments with recordings of 16 male and female vocalists singing English vowel sounds, The Guardian reports. They discovered that violins made by Andrea Amati and Antonio Stradivari, the pioneers of the instrument, produce similar "formant features" as the singers. The resonance frequencies were similar between Amati violins and bass and baritone singers, while the higher-frequency tones produced by Stradivari instruments were comparable to tenors and contraltos.

Andrea Amati, born in 1505, was the first known violin maker. His design was improved over 100 years later by Antonio Stradivari, whose instruments now sell for several million dollars. "Some Stradivari violins clearly possess female singing qualities, which may contribute to their perceived sweetness and brilliance," Hwan-Ching Tai, an author of the study, told The Guardian.

Their findings were published in the journal Proceedings of the National Academy of Sciences of the United States of America. A 2013 study by Dr. Joseph Nagyvary, a professor emeritus at Texas A&M University, also pointed to a link between the sounds produced by 250-year-old violins and those of a female soprano singer.

According to Vox, a blind test revealed that professional violinists couldn't reliably tell the difference between old violins like "Strads" and modern ones, with most even expressing a preference for the newer instruments. However, the value of these antique instruments can be chalked up to their rarity and history, and many violinists still swear by their exceptional quality.

[h/t The Guardian]

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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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