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Speaker 1: Welcome to brain Stuff from How Stuff Works. Hey, brain Stuff,

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Speaker 1: it's Christian Seger. So there's this old episode of Star

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Speaker 1: Trek called Wink of an Eye. You may have seen it.

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Speaker 1: There's this race of aliens that live in hyper sped

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Speaker 1: up acceleration. So when the crew of the Enterprise appears

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Speaker 1: to meet up with them, they seem so slow that

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Speaker 1: they're unable to move. Now, imagine that scenario. If you

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Speaker 1: were the aliens, wouldn't you assume humans were inert objects

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Speaker 1: with no consciousness. Now let's take this and apply it

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Speaker 1: to our relationship with plants. When we watch videos of

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Speaker 1: plant life sped up, we see their lively movement. But

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Speaker 1: even though plants move and respond to stimuli, they're not conscious. Right, Otherwise,

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Speaker 1: every time we ate vegetables, we'd be causing them pain. Wait,

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Speaker 1: wait a minute, can plants feel pain? Well? Okay, there

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Speaker 1: was this guy once. His name was Charles Darwin. You

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Speaker 1: might have heard of him, and he once proposed something

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Speaker 1: called the root brain hypothesis. He proposed that the tip

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Speaker 1: of a plant's root could act like a brain does

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Speaker 1: in some animals, receiving sensory input and directing movement. In

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Speaker 1: the years since Darwin made this proposal. There's been a

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Speaker 1: growing movement in science called plant neurobiology, and it debates

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Speaker 1: the way we think about plants and consciousness. Other scientists

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Speaker 1: hate this term, but who cares, because here's some of

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Speaker 1: the things we know about plants because of this really

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Speaker 1: unusual research. Let's start with plant senses. We know that

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Speaker 1: plants have a variety of sense some that can actually

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Speaker 1: act as analogs to our site smell, touch, taste, and hearing.

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Speaker 1: In fact, there's evidence that when plants hear the sound

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Speaker 1: of a caterpillar chewing on a leaf, they respond defensively

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Speaker 1: by producing chemicals like mustard oil. This happens even if

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Speaker 1: the sound is a recording and nothing is eating the plant. Creepy, right.

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Speaker 1: Plants can also communicate sometimes. Plant chemical production is like

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Speaker 1: a method of communicating with other plants. So here's an example.

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Speaker 1: That smell of freshly cut grass that we all know

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Speaker 1: that's actually a distress call to warn other plants of danger.

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Speaker 1: It's true in gardens, no one can hear you scream. Now,

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Speaker 1: when this distress call reaches other plants, they will also

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Speaker 1: emit the chemicals to warn their neighbors as well. And

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Speaker 1: these calls can even work on different species of plant.

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Speaker 1: For instance, a sage plant can signal a tobacco plant

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Speaker 1: to emit an odor that's not just to animals that

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Speaker 1: are eating the sage. All right, So you hear the

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Speaker 1: term plant neurobiology and you say, but plants don't have brains. Well,

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Speaker 1: one of the reasons why many scientists hate that term

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Speaker 1: is because plants don't have neurons, but they do produce

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Speaker 1: neuroactive chemicals that act like those in the human brain.

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Speaker 1: Glutamate receptors form memories in humans, and they're also found

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Speaker 1: in plants, and some hormones are transported around plants similar

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Speaker 1: to how neurotransmitters move through animal brains. Likewise, some plants

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Speaker 1: are vulnerable to drugs that disrupt neurotransmitters in the human brain,

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Speaker 1: like prozac or meth amphetamines. They even produce their own ethylene,

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Speaker 1: which is possibly used as an anesthetic when they're stressed out.

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Speaker 1: Plants even have a kind of nervous system, and that

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Speaker 1: may allow information to travel around the plant via electrical

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Speaker 1: sick mills. So if plants have sort of brains, do

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Speaker 1: they remember stuff? Well, yeah, plants also have their own

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Speaker 1: kind of memory. In fact, there's a plant called the

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Speaker 1: Mimosa pudica plant, and it closes its leaflets immediately after

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Speaker 1: they're touched, but because this requires energy, the plant won't

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Speaker 1: do it if it's unnecessary. However, when researchers dropped potted

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Speaker 1: mimosas fifteen centimeters onto foam, the plants learned that the

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Speaker 1: fall wasn't dangerous, so they stopped closing their leaves. Even crazier,

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Speaker 1: after one month, the plants still remember that the drop

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Speaker 1: wasn't dangerous and they wouldn't close their leaves in response. So,

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Speaker 1: given what we know about plants, senses, communication, nervous systems,

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Speaker 1: and memories, should we consider them to be either conscious

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Speaker 1: or intelligent? What about pain? Does the fact that plants

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Speaker 1: react to danger indicate that they feel pain? Well, some

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Speaker 1: scientists argue yes, while others loudly say no. Check out

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Speaker 1: the brainstuff channel on YouTube, and for more on this

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Speaker 1: and thousands of other topics, visit how stuff works dot

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Speaker 1: com