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Ancient Poop Reveals Extinction Event Inside Humans

ancient-p-oop, Utah, petroglyph

Scientists studying ancient poop discovered that inside, we’re not as diverse as we used to be.

Mass extinction is happening across the planet, triggered largely by human activities, but a new study revealed extinctions inside humans. Using new techniques, researchers studied 1,000-2,000-year-old ancient poop called paleofeces and found that dozens of species in the human gut became extinct. 

In the large intestine, a microbiome of fungi, bacteria, and viruses helps digest food, regulate the immune system, and fight disease. Thus, losing these microbes probably had a deleterious effect on human health. As with extinct animals and plants, when they are gone, they don’t return.

“These are things we don’t get back,” said lead author, Harvard Medical School microbiologist Aleksandar Kostic. “When they’re gone we’re missing a key piece of what makes us us,” he said.

Ancient Poop Time Machine

Another biologist studying the samples, also called coprolites, said it was like using a “time machine.” 

The coprolites were found in rock shelters in Utah and Mexico, where people lived a millennium ago. Due to the arid conditions, the ancient poop was “exquisitely preserved,” Kostic told CNN.

By studying bits of food in the samples, they found that people were eating beans and maize. However, samples from Utah indicated people were struggling to survive during a famine. Consequently, they were eating things like grasshoppers and prickly pears.

Later, as humans began eating processed foods and using antibiotics, the bacterial ecosystems living inside became less diverse. As a result of lower diversity, humans began experiencing more diseases, allergies, diabetes, and obesity.

Interestingly, modern industrialized sanitation practices may have also contributed to an extinction event in our microbiomes.

Related: Scientists Sequence Ancient Bear Genetic Code from Dirt

Dozens of Previously Unknown Species 

According to Science, the researchers found dozens of unknown species, a surprisingly high percentage no longer living inside humans. 

“In just these eight samples from a relatively confined geography and time period, we found 38% novel species,” Kostic said.

In all of the ancient samples, they found a bacteria called Treponema. Today, the bacteria is rare and only occasionally found in people living in nonindustrial lifestyles, although their microbiome more closely matches the ancients.

Consequently, the microbiologist believes it indicates factors other than diet alone caused the extinction. 

As humans rapidly moved to industrial lifestyles, our bodies may not have had time to adapt to such an internal extinction. Some of the extinct microbes were likely helpful. However, further research might guide commercial efforts to “reshape modern microbiomes,” suggested geneticist Keolu Fox. 

Strangely, the ancient poop could prove quite valuable to reseed people with ancient microbes.

“It’s supposedly waste, but it contains DNA and profiles of microbial diversity. Maybe that poop is literally gold,” Fox says. “We’re getting into a whole new gray area.”

As CNN reported, the microbes may help in the fight against chronic illnesses like diabetes. Already, research is moving forward which requires FDA approval to study fecal microbic transplants in animals.

New Microbes Found on Early Humans and Neanderthals 

Another new study from some of the same scientists explored bacteria found on Neanderthals’ teeth. In both Neanderthals and early modern humans, they found DNA from previously unidentified microbes.

The study also found bacterial evidence that Neanderthals ate a carbohydrate-rich diet, along with early humans. Their microbiomes included a genus of bacteria called oral streptococci, which developed to consume sugars. As their brains grew larger, they needed a higher energy food source like glucose to maintain it.

“The findings suggest both our human ancestors and Neanderthals acquired these bacteria prior to their splitting off from a common ancestor; an event that would’ve occurred approximately 600,000 years ago. Which means both humans and Neanderthals would’ve relied on a diet including starch-rich foods before their split. And that they both had growing brains with significant energy demands,” reported Yahoo!

Molecular archaeologist Christina Warinner says the findings are evidence both Neanderthals and humans cooked their food, before the practice of agriculture

To this day, modern nonindustrial genomes have more genes to digest complex carbohydrates compared to people in modern industrial areas.

Although we can’t reintroduce extinct microbes in our guts, Kostic recommends eating more fiber, complex carbs, exercising, and “coming into contact with soil and animals” to boost diversity.

Related: Scientists Discover a Switch Causing a Gorilla’s Brain to Grow More Like a Human’s

More on the subject from SciShow:

Featured image: Native American petroglyph by Norm_Bosworth via PixabayPixabay License

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