WEBVTT - Why Can't We Eat Grass?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff,

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<v Speaker 1>Lauren Volabon. Here. It's early April as I record this episode,

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<v Speaker 1>and spring is springing. My neighborhood's lawns are growing again,

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<v Speaker 1>which means we're getting close to the long, warm season

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<v Speaker 1>of one of my favorite scents, freshly cut grass. The

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<v Speaker 1>scent is amazing, sweet, bright green, but those clippings would

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<v Speaker 1>not be delicious on top of a salad or in

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<v Speaker 1>the middle of a blt. A grass is both leafy

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<v Speaker 1>and green, like spinach and lettuce, but assuming that you're

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<v Speaker 1>a human, it is not good for you to eat.

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<v Speaker 1>Generally speaking, you can eat grass. It's natural and not

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<v Speaker 1>toxic unless it's been sprayed with pesticides. You just can't

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<v Speaker 1>digest it. A grass has zero of the nutritional value

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<v Speaker 1>for humans that it does for cows, yacks, deer, sheep,

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<v Speaker 1>and other ruminants. Ruminants are mammals that have special digestive systems,

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<v Speaker 1>including a four chambered stomach, that allow them to get

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<v Speaker 1>at the nutrients in grass. But okay, let's back up

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<v Speaker 1>a little. What is grass. Grasses are a family of

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<v Speaker 1>plants that occur on every continent, yes, even Antarctica. There

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<v Speaker 1>are over eleven five hundred species in over seven hundred

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<v Speaker 1>and fifty genera. It's one of the largest families of

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<v Speaker 1>plants on Earth. The family does include lots of plants

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<v Speaker 1>that we humans have domesticated and specialized to use as food.

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<v Speaker 1>Grains like wheat, oats, rice, and corn are all the

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<v Speaker 1>seeds of different grasses. Sugar cane is a tall, sturdy

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<v Speaker 1>category of grass that we press to obtain sweet juice

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<v Speaker 1>that we then process into sugar, molasses, and rum, but

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<v Speaker 1>usually we don't eat the leafy part of the grass itself.

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<v Speaker 1>One exception is young and tender bamboo shoots, though even

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<v Speaker 1>those have to be boiled first. We generally don't eat

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<v Speaker 1>the grass part of grasses because we don't have the

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<v Speaker 1>stomachs for it or the teeth. Leaves of grass contain

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<v Speaker 1>a lot of silica, which is a tough mineral deposit

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<v Speaker 1>that helps give them structural support. A research has shown

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<v Speaker 1>that it also makes grasses more difficult for insect and

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<v Speaker 1>mammalian herbivores to chew and digest. If we tried to

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<v Speaker 1>eat grass over time, it would wear away the enamel

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<v Speaker 1>on our teeth and we only get the one set

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<v Speaker 1>as adults. Ruminants, however, have teeth that are constantly growing,

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<v Speaker 1>so as their teeth wear down, they grow back up again.

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<v Speaker 1>Ruminants also tend to chew in a side to side motion,

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<v Speaker 1>not up and down like we do. This helps shred

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<v Speaker 1>tough grass into tiny bits, making it easier to digest

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<v Speaker 1>when it gets to the stomach. Unlike humans, ruminants, like cattle,

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<v Speaker 1>don't have a single past their food before it enters

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<v Speaker 1>their digestive tract. They chew their cud. After swallowing a

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<v Speaker 1>mouthful of grass, it enters a cow's reticulum, which is

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<v Speaker 1>the first chamber in their four chambered stomach. The muscular

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<v Speaker 1>reticulum can push the grass back into the cow's mouth

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<v Speaker 1>for extra chewing. Pieces of grass can pass easily from

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<v Speaker 1>the reticulum into the second chamber, called the rumen after

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<v Speaker 1>which ruminants are named. This is the largest compartment of

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<v Speaker 1>the stomach. In fully grown cattle, it can be the

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<v Speaker 1>size of a fifty five gallon drum that's over two

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<v Speaker 1>hundred liters in the roomin lots of friendly bacteria help

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<v Speaker 1>break down tough parts of plants by eating away at

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<v Speaker 1>them and releasing nutrients that the cow's body can absorb.

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<v Speaker 1>A similar thing happens in human intestines with human safe foods.

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<v Speaker 1>The trick is that the cow's complex stomach keeps the

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<v Speaker 1>grass they are long enough for the process of rechewing

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<v Speaker 1>and the bacteria to really do the work and breaking

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<v Speaker 1>everything down and getting more out of the grass than

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<v Speaker 1>you or I could. There was a period in history

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<v Speaker 1>where a distant and hairer cousin of humans might have

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<v Speaker 1>been able to digest grass around three and a half

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<v Speaker 1>million years ago. But if a human ate grass today,

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<v Speaker 1>it might cause stomach upset, vomiting, or diarrhea as our

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<v Speaker 1>body attempted to deal with this, not food, or at

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<v Speaker 1>best it might just pass through undigested. But okay, the

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<v Speaker 1>digestive systems of dogs and cats are more like humans

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<v Speaker 1>than they are like ruminants, So if they can't digest it,

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<v Speaker 1>why do dogs and cats eat grass? The scientific answer

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<v Speaker 1>is that no one is sure. The common conception is

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<v Speaker 1>that dogs and cats do this because they're ill and

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<v Speaker 1>trying to make themselves vomit, or because they're missing something

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<v Speaker 1>in their diets, but research doesn't back that up. In

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<v Speaker 1>two thousand and eight, scientists the University of California Davis

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<v Speaker 1>tried to cut through the weeds and shed some light

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<v Speaker 1>on this mystery. They sent out surveys to twenty five

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<v Speaker 1>dog owning veterinary students. All reported that their canines ate grass.

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<v Speaker 1>A nun said that they observed any signs of illness

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<v Speaker 1>before their dogs chowed down, and only eight percent so

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<v Speaker 1>that their dogs vomited afterwards. The researchers also surveyed forty

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<v Speaker 1>seven dog owners who took their pets to the university's

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<v Speaker 1>teaching hospital for outpatient care. Seventy nine percent that they

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<v Speaker 1>saw their pets eating plants, mostly grass. Four dogs were

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<v Speaker 1>ill beforehand, and only six vomited afterward. The team then

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<v Speaker 1>opened the survey up to three thousand people who answered

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<v Speaker 1>a series of online questions, yielding useful data from about

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<v Speaker 1>one thousand, six hundred people. Of those, sixty eight percent

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<v Speaker 1>saw their dogs eating plants mostly grass on a daily

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<v Speaker 1>or weekly basis. Only eight percent showed signs of sickness beforehand,

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<v Speaker 1>and some twenty two percent vomited afterwards. In the same study,

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<v Speaker 1>the researchers found that grass eating is also common in

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<v Speaker 1>cats and also has nothing to do with upset stomachs

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<v Speaker 1>or other illnesses. Most cats, like dogs, do not vomit afterward.

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<v Speaker 1>They found that it's a common behavior in normal cats

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<v Speaker 1>and dogs, regardless of diet, and they specified that the

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<v Speaker 1>behavior of vomiting seems to be incidental to grass eating.

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<v Speaker 1>So maybe dogs and cats just like the taste or

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<v Speaker 1>texture of grass, or maybe it's just there and borum

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<v Speaker 1>snacking can strike us all. Today's episode is based on

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<v Speaker 1>the articles why do dogs and cats eat grass? And

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<v Speaker 1>Many animals eat grass, so why don't humans? On how

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<v Speaker 1>Stuffworks dot Com, both written by John Partano. Brain Stuff

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<v Speaker 1>is production by Heart Radio in partnership with how Stuffworks

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<v Speaker 1>dot Com and is produced by Tyler Klang. Four more

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<v Speaker 1>podcasts my heart Radio, visit the iHeartRadio app, Apple Podcasts,

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