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Young Marmosets Learn Not to Interrupt

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A pair of black-tufted marmosets. Image Credit: Miguelrangeljr via Wikimedia Commons // CC BY-SA 3.0

Human children aren’t the only primates that are eager to interrupt their parents’ conversations. Baby marmosets do it, too.

Learning to take turns in conversation is an important aspect in the evolution of communication, scientists from the University of California, San Diego argue in a new study. You can’t understand what someone else is saying if you can’t hear them, after all. 

Similar to polite humans, the common marmoset—a pocket-sized monkey species native to Brazil—doesn’t make noise when one of its brethren is talking. But just like in people, this behavior isn’t automatic: it has to be learned in childhood. 

Researchers from UCSD’s Cortical Systems and Behavior Laboratory studied the vocalization patterns of 10 young marmosets (five pairs of twins) and two sets of parents over the first year of the infants’ lives, recording the “conversations” the juvenile marmosets had with their parents when they couldn’t see each other. In the wild, marmosets keep in contact through high-pitched “phee” calls when they are separated

The elder marmosets guided the behavior of their young by responding when they made the right vocalization, and ignoring them when they did something uncouth. When the young marmosets interrupted their parents’ calls, their parents would simply not respond for several seconds, teaching them that that behavior was inappropriate in that context. If the marmosets did not interrupt, they were more likely to receive a response to their call. 

A common marmoset. Image Credit:  Leszek Leszczynski via Wikimedia Commons // CC BY 2.0 

“When a parent produces a vocal response to their child, it provides a potential positive reinforcement, affirming an interest in continuing the vocal exchange,” the researchers write. “The absence or delay of a response would, therefore, communicate that the behavior of the offspring was not appropriate.”

Furthermore, if the young marmosets produced the wrong sound (not a “phee” vocalization) for the context, their parents were more likely to interrupt them, seemingly a corrective measure. 

Interestingly, young marmosets were significantly more likely to interrupt their father than their mother, though there’s not a clear explanation for why. Furthermore, the young marmosets’ “conversations” with their siblings didn’t change as much over time as their vocalizations with their parents did, suggesting that the primates tailor their voices to the social context. 

The researchers were unable to distinguish whether the marmoset parents were aware that they were actively teaching their offspring proper behavior, or if they were exhibiting normal behavior that happened to direct social learning. 

[h/t: Discover]

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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.

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