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[00:01] Welcome to Brain Stuff, a production of IHeartRadio. Hey Brain Stuff, Lauren Vogelbaum here. Goats are the most multipurpose livestock animal that I know of. They can be raised specifically as a food source for their rich, slightly funky meat or milk. When raised for their hair or hide, they produce some of the most luxurious fibers on the market. Angora and cashmere both come from goats. They're also happy to clear land of overgrowth. In lots of places, you can rent goats to essentially mow your lawn. And of course, they can make adorable and entertaining companions. One particular breed of goat, however, is known for a rather different trait, suddenly stiffening up and appearing to faint. Footage of these fainting goats occasionally makes the rounds on social media. Yet, despite all appearances, these goats aren't weak of heart or abnormally prone to fright, and they're not actually fainting. They don't lose consciousness at all during these episodes, they just fall over. This is caused by what's basically a delay in the relaxation of muscles that tense up involuntarily during surprise or other excitement. Think of what happens when you startle, you tense up briefly. What's happening in these goats is that they lock into that tension for several seconds, and if they happened to be on uneven ground when they tensed, they're likely to tip over. This happens due to a genetic medical condition known as myotonia congenita, congenita meaning present at birth. The goats are more properly called myotonic, not fainting. The severity of the condition varies. Some myotonic goats will stiffen up every time they're startled, others less frequently. Symptoms often lessen over time, and some animals are better able to adapt to the condition. Younger goats are more prone to tumble when startled, but as they grow older, many eventually manage to avoid falling down at all during episodes, and may simply trot away on stiffened legs. Older goats also tend to become more secure with their environment and startle less easily. Today, let's talk about this rare breed of goat, and how myotonia affects their lives, including how they even came to be considered a breed, and why anyone would breed for myotonia in the first place. To understand what happens when a myotonic goat startles, first, let's look at what happens under normal conditions. When a goat is surprised by a sudden movement or sound, or maybe if it just saw a farmer friend is really excited about feeding time or getting to play, the animal's eyes and ears relay that startling data to its brain, which then sends an electrical signal to the skeletal muscles, such as those in the leg and neck involving voluntary movement, causing a momentary tensing. This is often referred to as the fight or flight response. Just think of how it feels to be startled or have a friend remind you. You'll find your voluntary muscles contract and tighten for a second. And this is your brain telling your muscles that the time has come to possibly confront or run away from an immediate threat. Though, of course, we experience this in other situations too. You might feel a tense rush when you get up to give a presentation or see someone that you have a crush on. Normally, this tensing is followed by an immediate relaxation of the affected muscles, allowing the typical person or goat to turn and run away from a perceived threat or otherwise respond to the situation. But with myotonia, the muscles stay tensed for maybe five to 20 seconds before slowly relaxing. It's not painful, and the goats seem to recover just fine in the aftermath. What's happening here is that due to differing functions at the cellular level, the voluntary muscles of myotonic animals receive the electric signal from the brain to tense, and then keep tensing instead of releasing. Sort of like a skipping record. This happens because myotonia affects a particular gene called ClCN1 or chloride channel 1. This gene is involved in the production and regulation of proteins, which are vital to the flexing and relaxing of skeletal muscles. Basically, positively charged sodium ions relay the brain's message for the muscle cells to contract. Negatively charged chloride ions, which ClCN1 affects, tell the muscle cells to relax. Myotonia results in an abnormal channel of chloride ions, which throws this relationship out of balance. The muscle cells wind up with more than enough sodium, but not enough chloride, which causes repetitive electrical signals from the brain, such as those associated with being startled, to result in stiffness. The condition does happen in other animals as well, including humans. In people, it's categorized into two types, named for researchers who broke ground in their study, Thompson type and Becker type. Becker type is more common and can be more severe, with symptoms often delayed until a patient is a few years old. Both are highly treatable with physical therapy, exercise, and or medication, though, of course, we have a greater capacity to be frustrated or embarrassed about it. The condition is hereditary and can be either a dominant trait in which the gene only has to be inherited from one parent, or a recessive trait in which the gene is carried by both parents. Where fainting goats differ from other myotonic animals, however, is that they are sometimes bred to encourage myotonia in their offspring. Fainting goats only exist as a breed because humans want them around. It's hard to imagine an animal with myotonia congenita lasting long in the wild. If a predator was to approach, the animal would stiffen up and natural selection would take its course. The strong survive and the weak perish. That is, unless human breeders are there to protect the weaker animals and encourage their traits. While myotonia likely predates recorded history, the encouragement of the trait in goats and the resulting emergence of fainting goats as a distinct breed can be dated back to the early 1880s in Marshall County, Tennessee. Some accounts link the breed to a particular farm worker named John Tinsley, who reportedly brought a number of goats exhibiting symptoms of myotonia down from Nova Scotia, Canada. Over a century later, herds of fainting goats could be found throughout the United States. Humans have always selectively bred animals for two basic reasons. To encourage certain behavioral traits and or to encourage certain physical features. For example, a working farm dog may be bred for hurting instincts or stamina. Pet dogs may be bred for their trainability or their cute little fuzzy faces. Myotonic goats are no different. As pets or additions to a farm that welcomes visitors, myotonic goats are uniquely entertaining and retain the temperament that makes most goats good companion animals. But a thing about goats is that they are natural climbers and jumpers, so they're also natural escape artists when fenced in. Farmers often need to expend extra effort to keep the animals enclosed. But myotonia tends to curb that behavior, and the excitement of climbing and jumping can trigger a spell, so the goats are more likely to stay put. And when they are raised for their meat, all of that excessive muscle tensing can result in greater muscle mass, less body fat, a higher meat-to-bone ratio, and more tender meat than other breeds of goat. Whether food or friend, fainting goats don't seem to be going away anytime soon. Numbering an estimated 4,000 to 5,000 in total, the animals are recognized as an official breed and are raised throughout the US and beyond. Enthusiasts have even established breed standards and regularly show their prize animals at livestock festivals. Today's episode is based on the article How Fainting Goats Work on howstuffworks.com, written by Robert Lamb. Brain Stuff is a production of IHeartRadio in partnership with howstuffworks.com and is produced by Tyler Klang. For more podcasts from IHeartRadio, visit the IHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.