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An ancient piece of chewing gum offers surprising insights into the human genome
All this from a wad of gum?
- Researchers recently uncovered a piece of chewed-on birch pitch in an archaeological dig in Denmark.
- Conducting a genetic analysis of the material left in the birch pitch offered a plethora of insights into the individual who last chewed it.
- The gum-chewer has been dubbed Lola. She lived 5,700 years ago; and she had dark skin, dark hair, and blue eyes.
Five thousand and seven hundred years ago, "Lola" — a blue-eyed woman with dark skin and hair — was chewing on a piece of pitch derived from heating birch bark. Then, this women spit her chewing gum out into the mud on an island in Denmark that we call Syltholm today, where it was unearthed by archaeologists thousands of years later. A genetic analysis of the chewing gum has provided us with a wealth of information on this nearly six-thousand-year-old Violet Beauregarde.
This represents the first time that the human genome has been extracted from material such as this. "It is amazing to have gotten a complete ancient human genome from anything other than bone," said lead researcher Hannes Schroeder in a statement.
"What is more," he added, "we also retrieved DNA from oral microbes and several important human pathogens, which makes this a very valuable source of ancient DNA, especially for time periods where we have no human remains."
In the pitch, researchers identified the DNA of the Epstein-Barr virus, which infects about 90 percent of adults. They also found DNA belonging to hazelnuts and mallards, which were likely the most recent meal that Lola had eaten before spitting out her chewing gum.
Insights into ancient peoples
The birch pitch was found on the island of Lolland (the inspiration for Lola's name) at a site called Syltholm. "Syltholm is completely unique," said Theis Jensen, who worked on the study for his PhD. "Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal.
"It is the biggest Stone Age site in Denmark and the archaeological finds suggest that the people who occupied the site were heavily exploiting wild resources well into the Neolithic, which is the period when farming and domesticated animals were first introduced into southern Scandinavia."
Since Lola's genome doesn't show any of the markers associated with the agricultural populations that had begun to appear in this region around her time, she provides evidence for a growing idea that hunter-gatherers persisted alongside agricultural communities in northern Europe longer than previously thought.
Her genome supports additional theories on northern European peoples. For example, her dark skin bolsters the idea that northern populations only recently acquired their light-skinned adaptation to the low sunlight in the winter months. She was also lactose intolerant, which researchers believe was the norm for most humans prior to the agricultural revolution. Most mammals lose their tolerance for lactose once they've weaned off of their mother's milk, but once humans began keeping cows, goats, and other dairy animals, their tolerance for lactose persisted into adulthood. As a descendent of hunter-gatherers, Lola wouldn't have needed this adaptation.
A hardworking piece of gum
A photo of the birch pitch used as chewing gum.
These findings are encouraging for researchers focusing on ancient peoples from this part of the world. Before this study, ancient genomes were really only ever recovered from human remains, but now, scientists have another tool in their kit. Birch pitch is commonly found in archaeological sites, often with tooth imprints.
Ancient peoples used and chewed on birch pitch for a variety of reasons. It was commonly heated up to make it pliable, enabling it to be molded as an adhesive or hafting agent before it settled. Chewing the pitch may have kept it pliable as it cooled down. It also contains a natural antiseptic, and so chewing birch pitch may have been a folk medicine for dental issues. And, considering that we chew gum today for no other reason than to pass the time, it may be that ancient peoples chewed pitch for fun.
Whatever their reasons, chewed and discarded pieces of birch pitch offer us the mind-boggling option of learning what someone several thousands of years ago ate for lunch, or what the color of their hair was, their health, where their ancestors came from, and more. It's an unlikely treasure trove of information to be found in a mere piece of gum.
A new study finds that dogs fed fresh human-grade food don't need to eat—or do their business—as much.
- Most dogs eat a diet that's primarily kibble.
- When fed a fresh-food diet, however, they don't need to consume as much.
- Dogs on fresh-food diets have healthier gut biomes.
Four diets were tested<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1MS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NjY0NjIxMn0._w0k-qFOC86AqmtPHJBK_i-9F5oVyVYsYtUrdvfUxWQ/img.jpg?width=980" id="1b1e4" class="rm-shortcode" data-rm-shortcode-id="87937436a81c700a8ab3b1d763354843" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: AntonioDiaz/Adobe Stock<p>The researchers tested refrigerated and fresh human-grade foods against kibble, the food most dogs live on. The <a href="https://frontierpets.com.au/blogs/news/how-kibble-or-dry-dog-food-is-made" target="_blank">ingredients</a> of kibble are mashed into a dough and then extruded, forced through a die of some kind into the desired shape — think a <a href="https://en.wikipedia.org/wiki/Food_extrusion" target="_blank">pasta maker</a>. The resulting pellets are sprayed with additional flavor and color.</p><p>For four weeks, researchers fed 12 beagles one of four diets:</p><ol><li>a extruded diet — Blue Buffalo Chicken and Brown Rice Recipe</li><li>a fresh refrigerated diet — Freshpet Roasted Meals Tender Chicken Recipe</li><li>a fresh diet — JustFoodforDogs Beef & Russet Potato Recipe</li><li>another fresh diet — JustFoodforDogs Chicken & White Rice Recipe.</li></ol><p>The two fresh diets contained minimally processed beef, chicken, broccoli, rice, carrots, and various food chunks in a canine casserole of sorts. </p><p>(One can't help but think how hard it would be to get finicky cats to test new diets. As if.)</p><p>Senior author <a href="https://ansc.illinois.edu/directory/ksswanso" target="_blank" rel="noopener noreferrer">Kelly S. Swanson</a> of U of I's Department of Animal Sciences and the Division of Nutritional Sciences, was a bit surprised at how much better dogs did on people food than even refrigerated dog chow. "Based on past research we've conducted I'm not surprised with the results when feeding human-grade compared to an extruded dry diet," he <a href="https://aces.illinois.edu/news/feed-fido-fresh-human-grade-dog-food-scoop-less-poop" target="_blank">says</a>, adding, "However, I did not expect to see how well the human-grade fresh food performed, even compared to a fresh commercial processed brand."</p>
Tracking the effect of each diet<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNTU5ODI1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY3NjY1NTgyOX0.AdyMb8OEcjCD6iWYnXjToDmcnjfTSn-0-dfG96SIpUA/img.jpg?width=980" id="da892" class="rm-shortcode" data-rm-shortcode-id="880d952420679aeccd1eaf32b5339810" data-rm-shortcode-name="rebelmouse-image" data-width="1440" data-height="960" />
Credit: Patryk Kosmider/Adobe Stock<p>The researchers tracked the dogs' weights and analyzed the microbiota in their fecal matter.</p><p>It turned out that the dogs on kibble had to eat more to maintain their body weight. This resulted in their producing 1.5 to 2.9 times the amount of poop produced by dogs on the fresh diets.</p><p>Says Swanson, "This is consistent with a 2019 National Institute of Health study in humans that found people eating a fresh whole food diet consumed on average 500 less calories per day, and reported being more satisfied, than people eating a more processed diet."</p><p>Maybe even more interesting was the effect of fresh food on the gut biome. Though there remains much we don't yet know about microbiota, it was nonetheless the case that the microbial communities found in fresh-food poo was different.</p><p>"Because a healthy gut means a healthy mutt," says Swanson, "fecal microbial and metabolite profiles are important readouts of diet assessment. As we have shown in <a href="https://academic.oup.com/jas/article/92/9/3781/4702209#110855647" target="_blank">previous studies</a>, the fecal microbial communities of healthy dogs fed fresh diets were different than those fed kibble. These unique microbial profiles were likely due to differences in diet processing, ingredient source, and the concentration and type of dietary fibers, proteins, and fats that are known to influence what is digested by the dog and what reaches the colon for fermentation."</p>
How did kibble take over canine diets?<p>Historically, dogs ate scraps left over by humans. It has only been <a href="https://www.thefarmersdog.com/digest/the-history-of-commercial-pet-food-a-great-american-marketing-story/" target="_blank">since 1870</a>, with the arrival of the luxe Spratt's Meat Fibrine Dog Cakes—made from "the dried unsalted gelatinous parts of Prairie Beef", mmm—that commercial dog food began to take hold. Dog bone-shaped biscuits first appeared in 1907. Ken-L Ration dates from 1922. Kibble was first extruded in 1956. Pet food had become a great way to turn <a href="https://www.dogfoodadvisor.com/choosing-dog-food/animal-by-products/" target="_blank">human-food waste</a> into profit.</p><p>Commercial dog food became the norm for most household canines only after a massive marketing campaign led by a group of dog-food industry lobbyists called the Pet Food Institute in 1964. Over time, for most households, dog food was what dogs ate — what else? Human food? These days more than half of U.S. dogs are <a href="https://www.nytimes.com/2014/08/03/magazine/who-made-that-dog-biscuit.html" target="_blank">overweight or obese</a>, and certainly their diet is a factor.<span></span></p><p>We're not so special among animals after all. If something's healthy for us to eat—we're <em>not</em> looking at you, chocolate—maybe we should remember to share with our canine compatriots. Not from the table, though.</p>
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Eating veggies is good for you. Now we can stop debating how much we should eat.
- A massive new study confirms that five servings of fruit and veggies a day can lower the risk of death.
- The maximum benefit is found at two servings of fruit and three of veggies—anything more offers no extra benefit according to the researchers.
- Not all fruits and veggies are equal. Leafy greens are better for you than starchy corn and potatoes.