WEBVTT - BrainStuff Classics: Are Plants Conscious?

0:00:01.920 --> 0:00:06.520
<v Speaker 1>Welcome to brain Stuff production of I Heart Radio. Hey

0:00:06.559 --> 0:00:09.320
<v Speaker 1>brain Stuff, I'm Lauren Vogelbaum, and this is another classic

0:00:09.320 --> 0:00:12.720
<v Speaker 1>episode from our former host, Christian Sager. This one deals

0:00:12.760 --> 0:00:15.160
<v Speaker 1>with a question to which the answer may seem obvious,

0:00:15.200 --> 0:00:23.520
<v Speaker 1>but research has made more complicated. Our plants conscious. Hey,

0:00:23.560 --> 0:00:27.160
<v Speaker 1>brain Stuff, it's Christian Sager. So there's this old episode

0:00:27.160 --> 0:00:29.680
<v Speaker 1>of Star Trek called Wink of an Eye. You may

0:00:29.760 --> 0:00:32.640
<v Speaker 1>have seen it. There's this race of aliens that live

0:00:32.800 --> 0:00:36.680
<v Speaker 1>in hyper sped up acceleration. So when the crew of

0:00:36.680 --> 0:00:39.960
<v Speaker 1>the Enterprise appears to meet up with them, they seem

0:00:40.159 --> 0:00:44.239
<v Speaker 1>so slow that they're unable to move. Now, imagine that

0:00:44.320 --> 0:00:49.199
<v Speaker 1>scenario if you were the aliens, wouldn't you assume humans

0:00:49.240 --> 0:00:54.480
<v Speaker 1>were inert objects with no consciousness. Now let's take this

0:00:54.520 --> 0:00:57.320
<v Speaker 1>and apply it to our relationship with plants. When we

0:00:57.360 --> 0:01:00.400
<v Speaker 1>watch videos of plant life sped up, we see their

0:01:00.520 --> 0:01:05.000
<v Speaker 1>lively movement. But even though plants move and respond to stimuli,

0:01:05.319 --> 0:01:10.080
<v Speaker 1>they're not conscious. Right, Otherwise, every time we ate vegetables,

0:01:10.120 --> 0:01:13.360
<v Speaker 1>we'd be causing them pain. Wait, wait a minute, can

0:01:13.440 --> 0:01:18.199
<v Speaker 1>plants feel pain? Well? Okay, there was this guy once.

0:01:18.319 --> 0:01:20.760
<v Speaker 1>His name was Charles Darwin. You might have heard of him,

0:01:20.880 --> 0:01:25.440
<v Speaker 1>and he once proposed something called the root brain hypothesis.

0:01:25.480 --> 0:01:29.200
<v Speaker 1>He proposed that the tip of a plant's root could

0:01:29.240 --> 0:01:34.080
<v Speaker 1>act like a brain does in some animals, receiving sensory

0:01:34.120 --> 0:01:38.679
<v Speaker 1>input and directing movement. In the years since Darwin made

0:01:38.760 --> 0:01:43.160
<v Speaker 1>this proposal, there's been a growing movement in science called

0:01:43.560 --> 0:01:47.559
<v Speaker 1>plant neurobiology, and it debates the way we think about

0:01:47.600 --> 0:01:53.560
<v Speaker 1>plants and consciousness. Other scientists hate this term, but who cares,

0:01:53.600 --> 0:01:56.760
<v Speaker 1>because here's some of the things we know about plants

0:01:56.800 --> 0:02:02.160
<v Speaker 1>because of this really unusual research. Let's start with plant senses.

0:02:02.600 --> 0:02:06.240
<v Speaker 1>We know that plants have a variety of sense, some

0:02:06.640 --> 0:02:12.639
<v Speaker 1>that can actually act as analogs to our site smell, touch, taste,

0:02:12.760 --> 0:02:16.480
<v Speaker 1>and hearing. In fact, there's evidence that when plants hear

0:02:16.600 --> 0:02:19.639
<v Speaker 1>the sound of a caterpillar chewing on a leaf, they

0:02:19.720 --> 0:02:25.880
<v Speaker 1>respond defensively by producing chemicals like mustard oil. This happens

0:02:26.000 --> 0:02:29.400
<v Speaker 1>even if the sound is a recording and nothing is

0:02:29.440 --> 0:02:35.160
<v Speaker 1>eating the plant. Creepy, right, Plants can also communicate sometimes.

0:02:35.440 --> 0:02:39.640
<v Speaker 1>Plant chemical production is like a method of communicating with

0:02:39.680 --> 0:02:43.360
<v Speaker 1>other plants. So here's an example. That smell of freshly

0:02:43.400 --> 0:02:46.799
<v Speaker 1>cut grass that we all know that's actually a distress

0:02:46.919 --> 0:02:52.040
<v Speaker 1>call to warn other plants of danger. It's true in gardens,

0:02:52.480 --> 0:02:55.640
<v Speaker 1>no one can hear you scream. Now, when this distress

0:02:55.680 --> 0:02:59.440
<v Speaker 1>call reaches other plants, they will also emit the chemicals

0:02:59.480 --> 0:03:02.640
<v Speaker 1>to warn their neighbors as well, and these calls can

0:03:02.680 --> 0:03:06.480
<v Speaker 1>even work on different species of plant. For instance, a

0:03:06.600 --> 0:03:10.359
<v Speaker 1>sage plant can signal a tobacco plant to emit an

0:03:10.360 --> 0:03:14.639
<v Speaker 1>odor that's not just to animals that are eating the sage.

0:03:15.120 --> 0:03:18.120
<v Speaker 1>All right, So you hear the term plant neurobiology, and

0:03:18.160 --> 0:03:21.600
<v Speaker 1>you say, but plants don't have brains. Well, one of

0:03:21.600 --> 0:03:26.160
<v Speaker 1>the reasons why many scientists hate that term is because

0:03:26.200 --> 0:03:31.960
<v Speaker 1>plants don't have neurons, but they do produce neuroactive chemicals

0:03:31.960 --> 0:03:35.880
<v Speaker 1>that act like those in the human brain. Glutamate receptors

0:03:36.000 --> 0:03:40.080
<v Speaker 1>form memories and humans, and they're also found in plants,

0:03:40.120 --> 0:03:45.520
<v Speaker 1>and some hormones are transported around plants similar to how

0:03:45.560 --> 0:03:51.640
<v Speaker 1>neurotransmitters move through animal brains. Likewise, some plants are vulnerable

0:03:51.680 --> 0:03:56.640
<v Speaker 1>to drugs that disrupt neurotransmitters in the human brain, like

0:03:57.000 --> 0:04:02.360
<v Speaker 1>prozac or meth amphetamines. They eat even produce their own ethylene,

0:04:02.400 --> 0:04:06.640
<v Speaker 1>which is possibly used as an anesthetic when they're stressed out.

0:04:07.120 --> 0:04:10.320
<v Speaker 1>Plants even have a kind of nervous system, and that

0:04:10.720 --> 0:04:16.360
<v Speaker 1>may allow information to travel around the plant via electrical signals.

0:04:16.440 --> 0:04:22.440
<v Speaker 1>So if plants have sort of brains, do they remember stuff? Well? Yeah,

0:04:22.560 --> 0:04:25.440
<v Speaker 1>plants also have their own kind of memory. In fact,

0:04:25.640 --> 0:04:29.200
<v Speaker 1>there's a plant called the Mimosa pudica plant, and it

0:04:29.320 --> 0:04:34.520
<v Speaker 1>closes its leaflets immediately after they're touched. But because this

0:04:34.600 --> 0:04:39.560
<v Speaker 1>requires energy, the plant won't do it if it's unnecessary. However,

0:04:40.040 --> 0:04:45.719
<v Speaker 1>when researchers dropped potted mimosas fifteen centimeters onto foam, the

0:04:45.839 --> 0:04:49.680
<v Speaker 1>plants learned that the fall wasn't dangerous, so they stopped

0:04:49.680 --> 0:04:54.839
<v Speaker 1>closing their leaves. Even crazier, after one month, the plants

0:04:55.120 --> 0:04:58.440
<v Speaker 1>still remember that the drop wasn't dangerous and they wouldn't

0:04:58.480 --> 0:05:02.640
<v Speaker 1>close their leaves in spons So, given what we know

0:05:02.760 --> 0:05:08.960
<v Speaker 1>about plants senses, communication, nervous systems, and memories, should we

0:05:09.080 --> 0:05:13.400
<v Speaker 1>consider them to be either conscious or intelligent? What about pain?

0:05:14.160 --> 0:05:17.320
<v Speaker 1>Does the fact that plants react to danger indicate that

0:05:17.400 --> 0:05:22.200
<v Speaker 1>they feel pain? Well, some scientists argue yes, while others

0:05:22.640 --> 0:05:32.520
<v Speaker 1>loudly say no. Today's episode was written by Christian and

0:05:32.560 --> 0:05:35.200
<v Speaker 1>produced by Tyler Clang. Brain Stuff is a production of

0:05:35.200 --> 0:05:37.240
<v Speaker 1>I Heart Radio's How Stuff Works from more in this

0:05:37.360 --> 0:05:39.680
<v Speaker 1>and lots of other thoughtful topics. Is it our home planet?

0:05:39.760 --> 0:05:42.400
<v Speaker 1>How stuff Works dot com plus for more podcasts for

0:05:42.440 --> 0:05:45.200
<v Speaker 1>my heart radio, is that thy heart radio app, Apple Podcasts,

0:05:45.240 --> 0:05:46.920
<v Speaker 1>or wherever you listen to your favorite shows,