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Entrance to the archaeological site of Vindija Cave, Croatia.
Entrance to the archaeological site of Vindija Cave, Croatia.
MPI f. Evolutionary Anthropology/ J. Krause

Scientists Extract Neanderthal DNA From Cave Dirt

Entrance to the archaeological site of Vindija Cave, Croatia.
Entrance to the archaeological site of Vindija Cave, Croatia.
MPI f. Evolutionary Anthropology/ J. Krause

Researchers have developed a new DNA sequencing technique that allows them to identify a site’s prehistoric inhabitants, even in the absence of fossils or bones. The team reported their results in the journal Science.

The Ice Age was a turbulent time. Archaeologists would love to know more about how and where proto-humans like Neanderthals and Denisovans lived back then, but the two groups left very little of themselves behind. Today, their remains are scarce.

For a long time, the absence of bones or other fossil evidence meant the absence of information. But research technology is getting more versatile, more expansive, and more incisive every day. Thanks to high-powered telescopes, microscopes, and advanced medical imaging, we can see things now that we never could before. And the same holds true for DNA sequencing technology.

Our DNA is not concentrated in our blood or our bones. It’s all over us. And we’re constantly shedding it, in the form of hair, skin cells, urine, and feces, just as prehistoric peoples did thousands of years ago.

Evolutionary geneticist Viviane Slon of the Max Planck Institute (MPI) and her colleagues wondered if technology had advanced enough to spot fragments of long-ago-shed DNA. They collected soil and sediment samples from 85 different sites in Europe and Russia, all of which were known Neanderthal or Denisovan hangouts. They then combed through these samples, looking for any trace of mammalian mitochondrial DNA, Neanderthal, DNA, or otherwise.


Becky Miller sampling sediment for genetic analyses at the archaeological site of Trou Al’Wesse, Belgium. Image Credit: Monika V. Knul

What they found overwhelmed them. “It’s on the order of trillions of DNA fragments in a sample the size of a teaspoon,” co-author Matthias Meyer of MPI told Science reporter Lizzie Wade in a separate article. Most of those fragments were non-human. They belonged to woolly mammoths, woolly rhinos, spotted hyenas, and a whole host of other Ice Age animals.

But there were signs of ancient hominin life, too. Samples from four caves turned up Neanderthal DNA. Denisovans had left their genetic mark in another. Teeny-tiny pieces of their loose genetic material—teeny-tiny traces of their lives—had hung on, resting in the dirt, for all these years.

Chris Stringer is an anthropologist at the Natural History Museum in London. He was not part of the research team, but told Science that their findings represent “a great breakthrough. Anyone who’s digging cave sites from the Pleistocene now should put [screening sediments for human DNA] on their list of things that they must do.”

Primary image credit: MPI f. Evolutionary Anthropology/ J. Krause

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Entrance to the archaeological site of Vindija Cave, Croatia.
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The Surprising Link Between Language and Depression
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Skim through the poems of Sylvia Plath, the lyrics of Kurt Cobain, or posts on an internet forum dedicated to depression, and you'll probably start to see some commonalities. That's because there's a particular way that people with clinical depression communicate, whether they're speaking or writing, and psychologists believe they now understand the link between the two.

According to a recent study published in Clinical Psychological Science, there are certain "markers" in a person's parlance that may point to symptoms of clinical depression. Researchers used automated text analysis methods to comb through large quantities of posts in 63 internet forums with more than 6400 members, searching for certain words and phrases. They also noted average sentence length, grammatical patterns, and other factors.

What researchers found was that a person's use (or overuse) of first-person pronouns can provide some insight into the state of their mental health. People with clinical depression tend to use more first-person singular pronouns, such as "I" and "me," and fewer third-person pronouns, like "they," "he," or "she." As Mohammed Al-Mosaiwi, a Ph.D. candidate in psychology at the University of Reading and the head of the study, writes in a post for IFL Science:

"This pattern of pronoun use suggests people with depression are more focused on themselves, and less connected with others. Researchers have reported that pronouns are actually more reliable in identifying depression than negative emotion words."

What remains unclear, though, is whether people who are more focused on themselves tend to depression, or if depression turns a person's focus on themselves. Perhaps unsurprisingly, people with depression also use more negative descriptors, like "lonely" and "miserable."

But, Al-Mosaiwi notes, it's hardly the most important clue when using language to assess clinical depression. Far better indicators, he says, are the presence of "absolutist words" in a person's speech or writing, such as "always," "constantly," and "completely." When overused, they tend to indicate that someone has a "black-and-white view of the world," Al-Mosaiwi says. An analysis of posts on different internet forums found that absolutist words were 50 percent more prevalent on anxiety and depression forums, and 80 percent more prevalent on suicidal ideation forums.

Researchers hope these types of classifications, supported by computerized methods, will prove more and more beneficial in a clinical setting.

[h/t IFL Science]

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There's a Train Full of New York City Poop Stranded in Alabama—Here's Why.
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Residents of Parrish, Alabama probably aren't too fond of New Yorkers right now. That’s because the town is currently home to a full trainload of poop courtesy of the Big Apple, as Bloomberg reports. Some 200 shipping containers of treated sewage have been stuck in Parrish for more than two months while the town takes landfill operators to court.

New York City doesn't keep its own sewage sludge to itself, and it hasn't for decades. In the 1980s, New York City was dumping its "biosolids"—the solids left over from sewage treatment, i.e., your poop—into the Atlantic Ocean, where it settled on the bottom of the sea floor in a thick film stretching over 80 square nautical miles. When the government banned the practice of dumping waste straight into the ocean, the city had to get creative, finding a way to get rid of the 1200 tons of biosolids produced there every day.

Enter the poop train. As a 2013 Radiolab episode taught us (we highly recommend you listen for yourself), treated sludge was eventually shipped out to other states to use as fertilizer in the 1990s. After farmers in Colorado began noticing better growth and fewer pests in the fields they grew with New York City's finest sewer sludge, growers in other states began clamoring to take the big-city poop by the train-full, too. That tide has turned, though, and now no one wants the city's poop. Because of the cost of running the program, the train to Colorado stopped in 2010.

Now, biosolids are instead shipped to landfills upstate and in places like Georgia, Ohio, and Pennsylvania, according to The Wall Street Journal. And Alabama. For more than a year, the Big Sky landfill near Parrish has been accepting New York City biosolids, and the locals who have to deal with trainloads of rotting waste aren’t happy.

Normally, the sludge would be loaded onto trucks and then driven the last stretch to get to the landfill. But Parrish and its nearby neighbor of West Jefferson aren't interested in playing host to those messy poop transfers anymore. As the two towns take the landfill operators to court over it, the trains are stuck where they are, next to Parrish's Little League baseball fields. The trainload of sludge is blocked from either being sent to the landfill or back to New York City. While the city has stopped shipping more waste to Big Sky, it essentially said "no takebacks" regarding what they've already sent south. Short of a legal decision, that poop isn't moving.

Needless to say, the residents of Parrish would really, really like to resolve this before summer hits.

[h/t Bloomberg]

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