Why Can't We Eat Grass?

the middle of a blt. A grass is both leafy and green, like spinach and lettuce, but assuming that you're a human, it is not good for you to eat. Generally speaking, you can eat grass. It's natural and not toxic unless it's been sprayed with pesticides. You just can't digest it. A grass has zero of the nutritional value for humans that it does for cows, yacks, deer, sheep,

and other ruminants. Ruminants are mammals that have special digestive systems, including a four chambered stomach, that allow them to get at the nutrients in grass. But okay, let's back up a little. What is grass. Grasses are a family of plants that occur on every continent, yes, even Antarctica. There are over eleven five hundred species in over seven hundred and fifty genera. It's one of the largest families of

plants on Earth. The family does include lots of plants that we humans have domesticated and specialized to use as food. Grains like wheat, oats, rice, and corn are all the seeds of different grasses. Sugar cane is a tall, sturdy category of grass that we press to obtain sweet juice that we then process into sugar, molasses, and rum, but usually we don't eat the leafy part of the grass itself. One exception is young and tender bamboo shoots, though even

those have to be boiled first. We generally don't eat the grass part of grasses because we don't have the stomachs for it or the teeth. Leaves of grass contain a lot of silica, which is a tough mineral deposit that helps give them structural support. A research has shown that it also makes grasses more difficult for insect and mammalian herbivores to chew and digest. If we tried to eat grass over time, it would wear away the enamel on our teeth and we only get the one set

as adults. Ruminants, however, have teeth that are constantly growing, so as their teeth wear down, they grow back up again. Ruminants also tend to chew in a side to side motion, not up and down like we do. This helps shred tough grass into tiny bits, making it easier to digest when it gets to the stomach. Unlike humans, ruminants, like cattle, don't have a single past their food before it enters

their digestive tract. They chew their cud. After swallowing a mouthful of grass, it enters a cow's reticulum, which is the first chamber in their four chambered stomach. The muscular reticulum can push the grass back into the cow's mouth for extra chewing. Pieces of grass can pass easily from the reticulum into the second chamber, called the rumen after which ruminants are named. This is the largest compartment of

the stomach. In fully grown cattle, it can be the size of a fifty five gallon drum that's over two hundred liters in the roomin lots of friendly bacteria help break down tough parts of plants by eating away at them and releasing nutrients that the cow's body can absorb. A similar thing happens in human intestines with human safe foods.

The trick is that the cow's complex stomach keeps the grass they are long enough for the process of rechewing and the bacteria to really do the work and breaking everything down and getting more out of the grass than you or I could. There was a period in history where a distant and hairer cousin of humans might have been able to digest grass around three and a half

million years ago. But if a human ate grass today, it might cause stomach upset, vomiting, or diarrhea as our body attempted to deal with this, not food, or at best it might just pass through undigested. But okay, the digestive systems of dogs and cats are more like humans than they are like ruminants, So if they can't digest it, why do dogs and cats eat grass? The scientific answer

is that no one is sure. The common conception is that dogs and cats do this because they're ill and trying to make themselves vomit, or because they're missing something in their diets, but research doesn't back that up. In two thousand and eight, scientists the University of California Davis tried to cut through the weeds and shed some light on this mystery. They sent out surveys to twenty five dog owning veterinary students. All reported that their canines ate grass.

A nun said that they observed any signs of illness before their dogs chowed down, and only eight percent so that their dogs vomited afterwards. The researchers also surveyed forty seven dog owners who took their pets to the university's teaching hospital for outpatient care. Seventy nine percent that they saw their pets eating plants, mostly grass. Four dogs were

ill beforehand, and only six vomited afterward. The team then opened the survey up to three thousand people who answered a series of online questions, yielding useful data from about one thousand, six hundred people. Of those, sixty eight percent saw their dogs eating plants mostly grass on a daily or weekly basis. Only eight percent showed signs of sickness beforehand,

and some twenty two percent vomited afterwards. In the same study, the researchers found that grass eating is also common in cats and also has nothing to do with upset stomachs or other illnesses. Most cats, like dogs, do not vomit afterward. They found that it's a common behavior in normal cats and dogs, regardless of diet, and they specified that the behavior of vomiting seems to be incidental to grass eating.

So maybe dogs and cats just like the taste or texture of grass, or maybe it's just there and borum snacking can strike us all. Today's episode is based on the articles why do dogs and cats eat grass? And Many animals eat grass, so why don't humans? On how Stuffworks dot Com, both written by John Partano. Brain Stuff is production by Heart Radio in partnership with how Stuffworks

dot Com and is produced by Tyler Klang. Four more podcasts my heart Radio, visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows.