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Current Biology DOI: (10.1016/j.cub.2016.02.068) // Copyright © 2016 Elsevier Ltd
Current Biology DOI: (10.1016/j.cub.2016.02.068) // Copyright © 2016 Elsevier Ltd

Stuttering in Mice Supports Genetic Theory of Human Speech Disorder

Current Biology DOI: (10.1016/j.cub.2016.02.068) // Copyright © 2016 Elsevier Ltd
Current Biology DOI: (10.1016/j.cub.2016.02.068) // Copyright © 2016 Elsevier Ltd

Speech disorders—like stuttering—are most often treated with behavioral therapy, though a number of potential physical causes have been identified. Some studies have suggested that stuttering may be genetic, and new research appears to support that argument. A report published in the journal Current Biology details a recent study where young mice bred to carry a specific human gene mutation were shown to be more prone to stuttering.

In 2010, researchers found that a mutation in the N-acetylglucosamine-1-phosphate transferase gene (Gnptab) is relatively common in people who stutter, but it's nowhere to be found in people with normal speech patterns. To further investigate whether the mutation actually causes stuttering, a different group of researchers bred the mutation into a generation of laboratory mice.

Many people believe that stuttering is a psychological or emotional problem. In order to eliminate the possibility that their test subjects might be experiencing distress or other issues, the researchers ran the mice through a series of tests. They evaluated the rodents’ motor skills, startle reflexes, sociability, willingness to explore, sense of smell, anxiety, and fear [PDF].

Young mice separated from their families make distress calls known as isolation cries. The researchers took one mouse at a time away from its mother and placed it in a cage designed for sound recording on the other side of the room. When the recording finished, the scientists would weigh the mouse, give it an identifying mark, and snip a little piece of tissue from its tail before returning it to its mother. Later, they tested the tissue samples to determine which mice were carrying the mutated gene.

The hypothesis was confirmed: mice without the mutation seemed to vocalize without trouble. Mice with the mutation, on the other hand, sounded like this:

Audio recording:Barnes et al./Current Biology 2016

Stuttering mice don’t make the same noises as stuttering humans, of course, but when the researchers compared their study subjects’ cries with recordings of people who stuttered, they found similar patterns.

"Many aspects of the vocalizations of our mice with the mutation are normal," researcher Tierra Barnes said in a press statement. "Where they differ is in the timing and temporal sequencing of their vocalizations. Their vocalizations have longer pauses than those of their littermates without the mutation, and there is evidence for more stereotyped repetitions in their vocalizations. These are very similar in some ways to the stuttered speech of humans who carry the same mutation.”

"Stuttering imposes an enormous burden on those that are severely afflicted with the disorder, yet its underlying causes have been very poorly understood," said co-author Dennis Drayna. "While it's surprising that the disorder can, to some degree, be recreated in a mouse, having an experimentally tractable animal model for some aspects of this disorder presents many exciting, new opportunities to move research in this area forward."

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Animals
7 Fun Facts for Elephant Appreciation Day
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Happy Elephant Appreciation Day! Celebrate the occasion with some facts about everyone's favorite gentle giant. 

1. ELEPHANTS CAN RECOGNIZE OTHER ELEPHANT CARCASSES.


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The University of Sussex's Karen McComb told National Geographic that elephants "become excited and agitated if they come across a dead elephant," and, in particular, will investigate skulls and tusks. McComb teamed up with researchers at the Amboseli Elephant Research Project in Kenya to study the behavior, showing wild elephants a range of objects that included skulls. They found that the elephants examined skulls—and tusks in particular—of their own kind twice as long as other skulls, and examined tusks six times as long as they did pieces of wood. They were even able to recognize elephant skulls with the tusks removed, but didn't show preference for certain elephant skulls over others, which suggests they didn't know which skulls belonged to their own relatives. "Animals that are intensely social in life may be most likely to display an interest in their dead," McComb told National Geographic. "But what goes on in their minds while they are doing this is a total mystery."

2. THEY'RE SCARED OF BEES.


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Forget about mice scaring off elephants: When farmers need to keep elephants away from their crops, they should use bees. Researchers in Kenya discovered that even the recorded sound of buzzing bees was enough to make elephants retreat—and cause them to emit a low-frequency sound, inaudible to humans, that warns other elephants of the bees' presence.

"It's impossible to cover Africa in electric fences," Lucy King, author of the paper, told The Huffington Post. "The infrastructure doesn't exist in many places and it would restrict animals' movement." But something like a bee fence—hives strung on strong wires a certain distance apart that would move when elephants walked into them, disturbing the hives—"could be a better way to direct elephants away from farmers' crops," she said.

3. THEY MIGHT UNDERSTAND POINTING.


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Humans often use pointing as a way to nonverbally get a message across, though not many other animals grasp the concept. But according to a two-month study of 11 tame African elephants, these pachyderms might be able to: When presented with two identical buckets and pointed in the direction of the one containing food, elephants picked up on the cue fairly consistently: Elephants had a success rate of 67.5 percent (1-year-old humans have a success rate of 72.7 percent). But an earlier study of Asian elephants indicated that they don’t notice pointing gestures, which is a bit of a mystery.

4. ONE ELEPHANT CAN "TALK." 


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Koshik, an elephant in a South Korean zoo, developed the ability to imitate the sounds of five words he's heard from his trainer—annyeong (hello), anja (sit down), aniya (no), nuwo (lie down), and joa (good)—by sticking his trunk in his mouth. The scientists who first noticed Koshik’s ability speculate that he learned to “talk” because he was lonely.

5. THEY'RE DIGITIGRADES.


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It's Latin for "finger walking," and what it means is that elephants walk on their toes (there are five of them, as well a sixth false toe). According to the book Mammal Anatomy: An Illustrated Guidemost of the animals' weight "rests on a broad pad of elastic tissue behind the toes" which "acts as a shock absorber and prevents the skeleton from jolting too much when the animals walk. It also allows elephants to move surprisingly quietly despite their size."

6. AN ELEPHANT PREGNANCY LASTS ABOUT TWO YEARS.


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If you thought being pregnant for nine months was a long time, be glad you're not an elephant, which can be pregnant for up to 680 days, according to the BBC. All that time in the oven has a benefit, though: Elephant calves are born with highly-developed brains, capable of learning their herd's complex social structures and ready to put their trunks to use.

7. NINETY-SIX ELEPHANTS ARE KILLED IN AFRICA EVERY DAY.


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Unfortunately, elephant poaching remains a very big problem: An estimated 35,000 elephants are killed annually, their tusks sold illegally in the ivory market. Do the math, and that comes out to nearly 96 elephants every day. Find out what you can do to help elephants and stop poaching at 96Elephants.org.

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Yani Dubin via Flickr Creative Commons // CC BY-ND 2.0
Bumblebees Mark Their Trails With Tiny Scented "Footprints"
Yani Dubin via Flickr Creative Commons // CC BY-ND 2.0
Yani Dubin via Flickr Creative Commons // CC BY-ND 2.0

Bees seem to have an endless number of tricks up their sleeve—and on their feet. Scientists have discovered that bumblebees leave itty-bitty scented “footprints” on every flower they visit, thereby informing other foragers that the bloom’s been recently tapped. The researchers published their findings in the journal Nature Scientific Reports.

Bees are the queens of complex communication. They exchange information with one another and their environments using a dazzling array of sensory input, including electrical impulses, sound, dance, and chemical signals.

Some of those signals flow out into the world through the bees’ delicate little feet. The bottom segment of a bee’s leg, called the tarsus, secretes a scented goo that helps the bee stick to the soft surfaces of flower petals. The chemical profile of each bee’s foot-glue is as unique as a fingerprint.

Previous studies have shown that bees glean important information from one another’s goo, skipping flowers that other bees have already visited. This raised an interesting question: If a bee can "read" another bee’s scent mark, can it also identify that bee?

To find out, researchers planted small clusters of fake flowers in the laboratory and topped some of them up them with sucrose nectar. They then gave bumblebees (Bombus terrestris) free rein to tromp around the blossoms, marking them up and taking in the marks of other bees that had come before.

The bees proved careful and canny readers. Not only did they use other bees’ scent marks to decide which flowers to probe, but they also considered the source of the scent when making that decision. An individual bee could easily differentiate between the smell of its own feet (trustworthy), those of its family members (very trustworthy), and those of strangers (not a reliable source of floral information).

Lead author Richard Pearce is a biologist at the University of Bristol. "Bumblebees are flexible learners and, as we have discovered, can detect whether or not it is they or a different bumblebee that has visited a flower recently. These impressive abilities allows them to be cleverer in their search for food, which will help them to be more successful," he said in a statement.

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