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Autoimmune Diseases May Have a Silver Lining

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The gradual increase in the incidence of autoimmune illnesses like lupus, rheumatoid arthritis, and type 1 diabetes has frustrated researchers for years. Now one group of scientists says they might know why it's happening—and how it might benefit humans in the long run. They shared their findings at the annual meeting of the International Society for Evolution, Medicine and Public Health in Durham, North Carolina.

To be clear: Living with an autoimmune disease can be awful. People with these conditions are literally attacked by their own bodies. We are not arguing that having an illness makes your life better. But like any ecosystem, the human body is a complex and convoluted place. We don’t fully understand how all the elements work or relate to one another, or what happens when one element changes.

Over the last few years, scientists have found some very unexpected relationships within the immune system that remind us that “good” and “bad” are human concepts. The same genetic mutation that causes sickle cell disease, for example, also protects against malaria. And modern day descendants of the Vikings may be more prone to asthma, thanks to a mutation that helped their ancestors fight off parasites. 

Is it possible that other immune disorders have something to offer as well? To find out, researchers investigated immunity in two animals: humans and sheep. 

The sheep came first. Researchers have been tracking the health and biographies of 7000 wild sheep in Scotland for three decades now, watching over them through illness, infection, old age, and the birth of new lambs.  

Image credit: Tomek Augustyn via Wikipedia Commons // CC BY-SA 2.0

Princeton University evolutionary biologist Andrea Graham and her colleagues analyzed blood samples from more than 2000 sheep, looking for what they call self-reactive antibodies—the type that cause autoimmune issues. They found that sheep with higher levels of these antibodies were also more likely to have higher levels of parasite-fighting antibodies. Like the Vikings’ descendants, the sheep’s immune systems fiercely attacked invaders (good!) and themselves (not so good). 

Graham was interested to find out if she could find similar patterns in older adults. She and her team tapped into the data collected by the Social Environment and Biomarkers of Aging Study, which has followed more than 1000 elderly people in Taiwan for the past 27 years. Once again, the research team looked through participants’ blood samples for signs of self-reactive antibodies. And once again, they found an interesting link—but this time it was to longevity. At any given age, participants with high self-reactive antibody levels were 33 percent less likely than their peers to die within a year. They also seemed better protected against viral infections. 

Aaron Blackwell is an evolutionary anthropologist at the University of California, Santa Barbara. Speaking to New Scientist, he said these studies suggest that autoimmune disorders may not be a physiological mistake after all, but a functional adaptation.

The experiments were conducted on very specific populations—Scottish sheep and older humans in Taiwan—but Blackwell is confident that the results are not unique.

“I would expect these results to be applicable across many species and across different human populations,” he says. 

Know of something you think we should cover? Email us at tips@mentalfloss.com.

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Animals
Owning a Dog May Add Years to Your Life, Study Shows
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We've said that having a furry friend can reduce depression, promote better sleep, and encourage more exercise. Now, research has indicated that caring for a canine might actually extend your lifespan.

Previous studies have shown that dog owners have an innate sense of comfort and increased well-being. A new paper published in Scientific Reports and conducted by Uppsala University in Sweden looked at the health records of 3.4 million of the country's residents. These records typically include personal data like marital status and whether the individual owns a pet. Researchers got additional insight from a national dog registry providing ownership information. According to the study, those with a dog for a housemate were less likely to die from cardiovascular disease or any other cause during the study's 12-year duration.

The study included adults 40 to 80 years old, with a mean age of 57. Researchers found that dogs were a positive predictor in health, particularly among singles. Those who had one were 33 percent less likely to die early than those who did not. Authors didn't conclude the exact reason behind the correlation: It could be active people are more likely to own dogs, that dogs promoted more activity, or that psychological factors like lowered incidences of depression might bolster overall well-being. Either way, having a pooch in your life could mean living a longer one.

[h/t Bloomberg]

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Big Questions
Why Don't We Eat Turkey Tails?
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Turkey sandwiches. Turkey soup. Roasted turkey. This year, Americans will consume roughly 245 million birds, with 46 million being prepared and presented on Thanksgiving. What we don’t eat will be repurposed into leftovers.

But there’s one part of the turkey that virtually no family will have on their table: the tail.

Despite our country’s obsession with fattening, dissecting, and searing turkeys, we almost inevitably pass up the fat-infused rear portion. According to Michael Carolan, professor of sociology and associate dean for research at the College for Liberal Arts at Colorado State University, that may have something to do with how Americans have traditionally perceived turkeys. Consumption was rare prior to World War II. When the birds were readily available, there was no demand for the tail because it had never been offered in the first place.

"Tails did and do not fit into what has become our culinary fascination with white meat," Carolan tells Mental Floss. "But also from a marketing [and] processor standpoint, if the consumer was just going to throw the tail away, or will not miss it if it was omitted, [suppliers] saw an opportunity to make additional money."

Indeed, the fact that Americans didn't have a taste for tail didn't prevent the poultry industry from moving on. Tails were being routed to Pacific Island consumers in the 1950s. Rich in protein and fat—a turkey tail is really a gland that produces oil used for grooming—suppliers were able to make use of the unwanted portion. And once consumers were exposed to it, they couldn't get enough.

“By 2007,” according to Carolan, “the average Samoan was consuming more than 44 pounds of turkey tails every year.” Perhaps not coincidentally, Samoans also have alarmingly high obesity rates of 75 percent. In an effort to stave off contributing factors, importing tails to the Islands was banned from 2007 until 2013, when it was argued that doing so violated World Trade Organization rules.

With tradition going hand-in-hand with commerce, poultry suppliers don’t really have a reason to try and change domestic consumer appetites for the tails. In preparing his research into the missing treat, Carolan says he had to search high and low before finally finding a source of tails at a Whole Foods that was about to discard them. "[You] can't expect the food to be accepted if people can't even find the piece!"

Unless the meat industry mounts a major campaign to shift American tastes, Thanksgiving will once again be filled with turkeys missing one of their juicier body parts.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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