1 00:00:01,840 --> 00:00:07,560 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey brain Stuff, 2 00:00:07,600 --> 00:00:13,080 Speaker 1: Lauren Volabon. Here. It's early April as I record this episode, 3 00:00:13,200 --> 00:00:18,080 Speaker 1: and spring is springing. My neighborhood's lawns are growing again, 4 00:00:18,280 --> 00:00:21,439 Speaker 1: which means we're getting close to the long, warm season 5 00:00:21,560 --> 00:00:26,119 Speaker 1: of one of my favorite scents, freshly cut grass. The 6 00:00:26,360 --> 00:00:31,360 Speaker 1: scent is amazing, sweet, bright green, but those clippings would 7 00:00:31,400 --> 00:00:33,920 Speaker 1: not be delicious on top of a salad or in 8 00:00:33,960 --> 00:00:37,680 Speaker 1: the middle of a blt. A grass is both leafy 9 00:00:37,840 --> 00:00:42,159 Speaker 1: and green, like spinach and lettuce, but assuming that you're 10 00:00:42,159 --> 00:00:46,000 Speaker 1: a human, it is not good for you to eat. 11 00:00:47,360 --> 00:00:51,920 Speaker 1: Generally speaking, you can eat grass. It's natural and not 12 00:00:52,080 --> 00:00:55,520 Speaker 1: toxic unless it's been sprayed with pesticides. You just can't 13 00:00:55,560 --> 00:00:59,840 Speaker 1: digest it. A grass has zero of the nutritional value 14 00:00:59,840 --> 00:01:03,360 Speaker 1: for humans that it does for cows, yacks, deer, sheep, 15 00:01:03,480 --> 00:01:08,360 Speaker 1: and other ruminants. Ruminants are mammals that have special digestive systems, 16 00:01:08,440 --> 00:01:11,720 Speaker 1: including a four chambered stomach, that allow them to get 17 00:01:11,720 --> 00:01:16,319 Speaker 1: at the nutrients in grass. But okay, let's back up 18 00:01:16,319 --> 00:01:20,679 Speaker 1: a little. What is grass. Grasses are a family of 19 00:01:20,720 --> 00:01:25,240 Speaker 1: plants that occur on every continent, yes, even Antarctica. There 20 00:01:25,280 --> 00:01:28,960 Speaker 1: are over eleven five hundred species in over seven hundred 21 00:01:29,000 --> 00:01:31,560 Speaker 1: and fifty genera. It's one of the largest families of 22 00:01:31,600 --> 00:01:35,600 Speaker 1: plants on Earth. The family does include lots of plants 23 00:01:35,600 --> 00:01:38,960 Speaker 1: that we humans have domesticated and specialized to use as food. 24 00:01:39,680 --> 00:01:42,600 Speaker 1: Grains like wheat, oats, rice, and corn are all the 25 00:01:42,640 --> 00:01:46,800 Speaker 1: seeds of different grasses. Sugar cane is a tall, sturdy 26 00:01:46,840 --> 00:01:50,040 Speaker 1: category of grass that we press to obtain sweet juice 27 00:01:50,160 --> 00:01:54,680 Speaker 1: that we then process into sugar, molasses, and rum, but 28 00:01:55,040 --> 00:01:58,200 Speaker 1: usually we don't eat the leafy part of the grass itself. 29 00:01:58,960 --> 00:02:02,440 Speaker 1: One exception is young and tender bamboo shoots, though even 30 00:02:02,440 --> 00:02:07,320 Speaker 1: those have to be boiled first. We generally don't eat 31 00:02:07,360 --> 00:02:10,000 Speaker 1: the grass part of grasses because we don't have the 32 00:02:10,040 --> 00:02:15,120 Speaker 1: stomachs for it or the teeth. Leaves of grass contain 33 00:02:15,240 --> 00:02:18,320 Speaker 1: a lot of silica, which is a tough mineral deposit 34 00:02:18,400 --> 00:02:22,360 Speaker 1: that helps give them structural support. A research has shown 35 00:02:22,360 --> 00:02:25,440 Speaker 1: that it also makes grasses more difficult for insect and 36 00:02:25,440 --> 00:02:29,880 Speaker 1: mammalian herbivores to chew and digest. If we tried to 37 00:02:29,919 --> 00:02:32,720 Speaker 1: eat grass over time, it would wear away the enamel 38 00:02:32,760 --> 00:02:35,240 Speaker 1: on our teeth and we only get the one set 39 00:02:35,240 --> 00:02:39,560 Speaker 1: as adults. Ruminants, however, have teeth that are constantly growing, 40 00:02:40,000 --> 00:02:42,880 Speaker 1: so as their teeth wear down, they grow back up again. 41 00:02:44,919 --> 00:02:47,800 Speaker 1: Ruminants also tend to chew in a side to side motion, 42 00:02:48,160 --> 00:02:51,480 Speaker 1: not up and down like we do. This helps shred 43 00:02:51,600 --> 00:02:54,960 Speaker 1: tough grass into tiny bits, making it easier to digest 44 00:02:55,000 --> 00:02:59,320 Speaker 1: when it gets to the stomach. Unlike humans, ruminants, like cattle, 45 00:02:59,520 --> 00:03:02,400 Speaker 1: don't have a single past their food before it enters 46 00:03:02,440 --> 00:03:07,680 Speaker 1: their digestive tract. They chew their cud. After swallowing a 47 00:03:07,720 --> 00:03:10,960 Speaker 1: mouthful of grass, it enters a cow's reticulum, which is 48 00:03:11,000 --> 00:03:14,880 Speaker 1: the first chamber in their four chambered stomach. The muscular 49 00:03:14,919 --> 00:03:17,800 Speaker 1: reticulum can push the grass back into the cow's mouth 50 00:03:18,000 --> 00:03:22,079 Speaker 1: for extra chewing. Pieces of grass can pass easily from 51 00:03:22,120 --> 00:03:25,519 Speaker 1: the reticulum into the second chamber, called the rumen after 52 00:03:25,560 --> 00:03:29,239 Speaker 1: which ruminants are named. This is the largest compartment of 53 00:03:29,280 --> 00:03:32,080 Speaker 1: the stomach. In fully grown cattle, it can be the 54 00:03:32,080 --> 00:03:34,760 Speaker 1: size of a fifty five gallon drum that's over two 55 00:03:34,880 --> 00:03:40,200 Speaker 1: hundred liters in the roomin lots of friendly bacteria help 56 00:03:40,280 --> 00:03:43,080 Speaker 1: break down tough parts of plants by eating away at 57 00:03:43,080 --> 00:03:46,000 Speaker 1: them and releasing nutrients that the cow's body can absorb. 58 00:03:46,640 --> 00:03:50,000 Speaker 1: A similar thing happens in human intestines with human safe foods. 59 00:03:51,480 --> 00:03:54,600 Speaker 1: The trick is that the cow's complex stomach keeps the 60 00:03:54,600 --> 00:03:57,720 Speaker 1: grass they are long enough for the process of rechewing 61 00:03:57,920 --> 00:04:01,000 Speaker 1: and the bacteria to really do the work and breaking 62 00:04:01,040 --> 00:04:03,880 Speaker 1: everything down and getting more out of the grass than 63 00:04:04,080 --> 00:04:08,760 Speaker 1: you or I could. There was a period in history 64 00:04:08,840 --> 00:04:11,920 Speaker 1: where a distant and hairer cousin of humans might have 65 00:04:11,960 --> 00:04:14,320 Speaker 1: been able to digest grass around three and a half 66 00:04:14,360 --> 00:04:17,800 Speaker 1: million years ago. But if a human ate grass today, 67 00:04:17,960 --> 00:04:21,480 Speaker 1: it might cause stomach upset, vomiting, or diarrhea as our 68 00:04:21,480 --> 00:04:25,400 Speaker 1: body attempted to deal with this, not food, or at 69 00:04:25,440 --> 00:04:32,120 Speaker 1: best it might just pass through undigested. But okay, the 70 00:04:32,120 --> 00:04:35,640 Speaker 1: digestive systems of dogs and cats are more like humans 71 00:04:35,720 --> 00:04:40,200 Speaker 1: than they are like ruminants, So if they can't digest it, 72 00:04:40,720 --> 00:04:45,680 Speaker 1: why do dogs and cats eat grass? The scientific answer 73 00:04:45,960 --> 00:04:49,360 Speaker 1: is that no one is sure. The common conception is 74 00:04:49,360 --> 00:04:51,920 Speaker 1: that dogs and cats do this because they're ill and 75 00:04:51,960 --> 00:04:55,239 Speaker 1: trying to make themselves vomit, or because they're missing something 76 00:04:55,240 --> 00:05:00,240 Speaker 1: in their diets, but research doesn't back that up. In 77 00:05:00,279 --> 00:05:03,480 Speaker 1: two thousand and eight, scientists the University of California Davis 78 00:05:03,520 --> 00:05:05,760 Speaker 1: tried to cut through the weeds and shed some light 79 00:05:05,800 --> 00:05:09,400 Speaker 1: on this mystery. They sent out surveys to twenty five 80 00:05:09,480 --> 00:05:14,120 Speaker 1: dog owning veterinary students. All reported that their canines ate grass. 81 00:05:14,839 --> 00:05:17,160 Speaker 1: A nun said that they observed any signs of illness 82 00:05:17,200 --> 00:05:21,000 Speaker 1: before their dogs chowed down, and only eight percent so 83 00:05:21,160 --> 00:05:26,360 Speaker 1: that their dogs vomited afterwards. The researchers also surveyed forty 84 00:05:26,400 --> 00:05:28,920 Speaker 1: seven dog owners who took their pets to the university's 85 00:05:28,920 --> 00:05:33,120 Speaker 1: teaching hospital for outpatient care. Seventy nine percent that they 86 00:05:33,160 --> 00:05:36,840 Speaker 1: saw their pets eating plants, mostly grass. Four dogs were 87 00:05:36,839 --> 00:05:42,920 Speaker 1: ill beforehand, and only six vomited afterward. The team then 88 00:05:43,000 --> 00:05:45,920 Speaker 1: opened the survey up to three thousand people who answered 89 00:05:45,960 --> 00:05:49,400 Speaker 1: a series of online questions, yielding useful data from about 90 00:05:49,440 --> 00:05:54,000 Speaker 1: one thousand, six hundred people. Of those, sixty eight percent 91 00:05:54,080 --> 00:05:57,200 Speaker 1: saw their dogs eating plants mostly grass on a daily 92 00:05:57,440 --> 00:06:01,840 Speaker 1: or weekly basis. Only eight percent showed signs of sickness beforehand, 93 00:06:02,120 --> 00:06:07,000 Speaker 1: and some twenty two percent vomited afterwards. In the same study, 94 00:06:07,040 --> 00:06:09,760 Speaker 1: the researchers found that grass eating is also common in 95 00:06:09,839 --> 00:06:13,640 Speaker 1: cats and also has nothing to do with upset stomachs 96 00:06:13,760 --> 00:06:18,359 Speaker 1: or other illnesses. Most cats, like dogs, do not vomit afterward. 97 00:06:19,400 --> 00:06:22,040 Speaker 1: They found that it's a common behavior in normal cats 98 00:06:22,080 --> 00:06:25,359 Speaker 1: and dogs, regardless of diet, and they specified that the 99 00:06:25,360 --> 00:06:28,799 Speaker 1: behavior of vomiting seems to be incidental to grass eating. 100 00:06:30,720 --> 00:06:33,800 Speaker 1: So maybe dogs and cats just like the taste or 101 00:06:33,920 --> 00:06:38,000 Speaker 1: texture of grass, or maybe it's just there and borum 102 00:06:38,000 --> 00:06:45,960 Speaker 1: snacking can strike us all. Today's episode is based on 103 00:06:46,000 --> 00:06:48,520 Speaker 1: the articles why do dogs and cats eat grass? And 104 00:06:48,720 --> 00:06:51,320 Speaker 1: Many animals eat grass, so why don't humans? On how 105 00:06:51,360 --> 00:06:55,239 Speaker 1: Stuffworks dot Com, both written by John Partano. Brain Stuff 106 00:06:55,279 --> 00:06:57,680 Speaker 1: is production by Heart Radio in partnership with how Stuffworks 107 00:06:57,680 --> 00:07:00,360 Speaker 1: dot Com and is produced by Tyler Klang. Four more 108 00:07:00,400 --> 00:07:04,240 Speaker 1: podcasts my heart Radio, visit the iHeartRadio app, Apple Podcasts, 109 00:07:04,360 --> 00:07:06,239 Speaker 1: or wherever you listen to your favorite shows.