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Using Nuclear Bombs to Fight Wildlife Poachers

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Getty Images

During the 1950s and '60s, the United States and the Soviet Union tested and showed off their shiny new atomic arsenals by detonating hundreds of nuclear weapons at above-ground sites. After each explosion, residual radioactive material, or fallout, was dispersed into the atmosphere and then spread around the world by the wind. 

Among these radioactive leftovers is an isotope, or variant, of the element carbon known as carbon-14. This same isotope is generated naturally by cosmic rays and normally occurs in small traces, accounting for just one part per trillion of atmospheric carbon. During the Cold War, though, scientists keeping tabs on the isotope’s concentration found a spike—a near doubling—in carbon-14 levels that coincided with the start of the weapons tests, and a slow, steady decline when the tests were moved underground. It was dubbed the “bomb curve.”

Most carbon-14, whether it’s natural or man-made, American or Soviet, oxidizes into carbon dioxide, and then gets taken in by the oceans and by plants. As animals eat these plants and other animals eat those animals, almost every living thing gets a share of carbon-14 incorporated into its teeth or tusks or hair or horns. 

Anyone or anything that was alive during the Cold War got to keep a small souvenir from it inside its body—not enough to do any damage, but enough to date it. If the carbon-14 concentration in some animal or plant tissue is the same as the known level in the atmosphere at a certain date along the bomb curve, that gives you an idea of how old the tissue and the creature it came from is. 

In a study led by doctoral student Kevin Uno, a team of researchers from the University of Utah chased down more than two dozen animal tissue samples that had been collected between 1955 and 2008. Previous studies on bomb curve carbon dating had mostly only looked at tree rings and enamel from human teeth, but Uno and company gathered everything from hair from a blue monkey to teeth from hippos and tusks from elephants to stems from various plants. They measured the carbon-14 levels in these samples and then plotted them along the bomb curve to estimate when the sample was collected (which is usually right around when the animal died). For some of the samples, including tusks from elephants that had died in a zoo and in a national park, they knew the animals’ actual ages, and found their estimations were accurate within a year. 

The Nuclear Response

That the technique worked so well in a variety of tissues might make it a useful forensic tool to battle poachers. 

Every year, an estimated 30,000 African elephants are killed illegally for their ivory tusks. With only some 400,000 animals left in the wild, this kind of slaughter could make the species extinct in just a little over a decade. Poaching and the illegal ivory trade are big business, and those trying to stop it are up against organized and well-armed criminal organizations, corrupt government officials and a quirk in the law. 

International treaties have banned the trade of Asian elephant ivory since 1976, and African elephant ivory since 1989, but the laws allow for some loopholes. In some countries, including the United States, any ivory acquired before ’89 is legal to buy and sell. Trying to distinguish legal, pre-ban ivory from poached, post-ban ivory has been incredibly difficult, and ivory traders can move ill-gotten product by claiming that it’s older than it really is. Carbon dating an ivory sample against the bomb curve, though, can date it and reveal how old and how legal it is. It’s science calling BS on poachers and their marketplace enablers. 

Uno’s work complements research done at the University of Washington, which uses DNA and isotope analysis to locate the origin point of ivory. Working out the “when and where” of confiscated ivory (and other animal parts, like rhino horns) can help shut down individual dealers but also identify poaching hot zones and guide decisions about where to spend conservation funds or send armed rangers to protect animals, and it’s all thanks to the atomic crumbs left over from the Cold War. 

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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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iStock

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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