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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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History
The Queen of Code: Remembering Grace Hopper
By Lynn Gilbert, CC BY-SA 4.0, Wikimedia Commons

Grace Hopper was a computing pioneer. She coined the term "computer bug" after finding a moth stuck inside Harvard's Mark II computer in 1947 (which in turn led to the term "debug," meaning solving problems in computer code). She did the foundational work that led to the COBOL programming language, used in mission-critical computing systems for decades (including today). She worked in World War II using very early computers to help end the war. When she retired from the U.S. Navy at age 79, she was the oldest active-duty commissioned officer in the service. Hopper, who was born on this day in 1906, is a hero of computing and a brilliant role model, but not many people know her story.

In this short documentary from FiveThirtyEight, directed by Gillian Jacobs, we learned about Grace Hopper from several biographers, archival photographs, and footage of her speaking in her later years. If you've never heard of Grace Hopper, or you're even vaguely interested in the history of computing or women in computing, this is a must-watch:

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science
Why Are Glaciers Blue?
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The bright azure blue sported by many glaciers is one of nature's most stunning hues. But how does it happen, when the snow we see is usually white? As Joe Hanson of It's Okay to Be Smart explains in the video below, the snow and ice we see mostly looks white, cloudy, or clear because all of the visible light striking its surface is reflected back to us. But glaciers have a totally different structure—their many layers of tightly compressed snow means light has to travel much further, and is scattered many times throughout the depths. As the light bounces around, the light at the red and yellow end of the spectrum gets absorbed thanks to the vibrations of the water molecules inside the ice, leaving only blue and green light behind. For the details of exactly why that happens, check out Hanson's trip to Alaska's beautiful (and endangered) Mendenhall Glacier below.

[h/t The Kid Should See This]

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