[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:07.11,0:00:10.17,Default,,0000,0000,0000,,Humans know the surprising prick\Nof a needle,
Dialogue: 0,0:00:10.17,0:00:12.54,Default,,0000,0000,0000,,the searing pain of a stubbed toe,
Dialogue: 0,0:00:12.54,0:00:14.97,Default,,0000,0000,0000,,and the throbbing of a toothache.
Dialogue: 0,0:00:14.97,0:00:19.60,Default,,0000,0000,0000,,We can identify many types of pain\Nand have multiple ways of treating it.
Dialogue: 0,0:00:19.60,0:00:21.85,Default,,0000,0000,0000,,But what about other species?
Dialogue: 0,0:00:21.85,0:00:26.07,Default,,0000,0000,0000,,How do the animals all around us\Nexperience pain?
Dialogue: 0,0:00:26.07,0:00:28.23,Default,,0000,0000,0000,,It's important that we find out.
Dialogue: 0,0:00:28.23,0:00:29.85,Default,,0000,0000,0000,,We keep animals as pets,
Dialogue: 0,0:00:29.85,0:00:31.46,Default,,0000,0000,0000,,they enrich our environment,
Dialogue: 0,0:00:31.46,0:00:33.63,Default,,0000,0000,0000,,we farm many species for food,
Dialogue: 0,0:00:33.63,0:00:37.78,Default,,0000,0000,0000,,and we use them in experiments\Nto advance science and human health.
Dialogue: 0,0:00:37.78,0:00:39.83,Default,,0000,0000,0000,,Animals are clearly important to us,
Dialogue: 0,0:00:39.83,0:00:44.46,Default,,0000,0000,0000,,so it's equally important that we avoid\Ncausing them unnecessary pain.
Dialogue: 0,0:00:44.46,0:00:47.11,Default,,0000,0000,0000,,For animals that are similar to us,\Nlike mammals,
Dialogue: 0,0:00:47.11,0:00:50.28,Default,,0000,0000,0000,,it's often obvious when they're hurting.
Dialogue: 0,0:00:50.28,0:00:52.52,Default,,0000,0000,0000,,But there's a lot that isn't obvious,
Dialogue: 0,0:00:52.52,0:00:56.20,Default,,0000,0000,0000,,like whether pain relievers that work\Non us also help them.
Dialogue: 0,0:00:56.20,0:00:58.12,Default,,0000,0000,0000,,And the more different \Nan animal is from us,
Dialogue: 0,0:00:58.12,0:01:01.20,Default,,0000,0000,0000,,the harder it is to understand \Ntheir experience.
Dialogue: 0,0:01:01.20,0:01:03.80,Default,,0000,0000,0000,,How do you tell whether \Na shrimp is in pain?
Dialogue: 0,0:01:03.80,0:01:05.13,Default,,0000,0000,0000,,Snake?
Dialogue: 0,0:01:05.13,0:01:06.69,Default,,0000,0000,0000,,A snail?
Dialogue: 0,0:01:06.69,0:01:09.27,Default,,0000,0000,0000,,In vertebrates, including humans,
Dialogue: 0,0:01:09.27,0:01:12.48,Default,,0000,0000,0000,,pain can be split \Ninto two distinct processes.
Dialogue: 0,0:01:12.48,0:01:16.56,Default,,0000,0000,0000,,In first, nerves and the skin sense\Nsomething harmful
Dialogue: 0,0:01:16.56,0:01:19.20,Default,,0000,0000,0000,,and communicate that information\Nto the spinal cord.
Dialogue: 0,0:01:19.20,0:01:21.78,Default,,0000,0000,0000,,There, motor neurons activate movements
Dialogue: 0,0:01:21.78,0:01:24.68,Default,,0000,0000,0000,,that make us rapidly \Njerk away from the threat.
Dialogue: 0,0:01:24.68,0:01:28.32,Default,,0000,0000,0000,,This is the physical recognition of harm\Ncalled nociception,
Dialogue: 0,0:01:28.32,0:01:29.58,Default,,0000,0000,0000,,and nearly all animals,
Dialogue: 0,0:01:29.58,0:01:32.30,Default,,0000,0000,0000,,even those with very simple \Nnervous systems,
Dialogue: 0,0:01:32.30,0:01:33.76,Default,,0000,0000,0000,,experience it.
Dialogue: 0,0:01:33.76,0:01:36.75,Default,,0000,0000,0000,,Without this ability, animals would be\Nunable to avoid harm
Dialogue: 0,0:01:36.75,0:01:39.74,Default,,0000,0000,0000,,and their survival would be threatened.
Dialogue: 0,0:01:39.74,0:01:43.46,Default,,0000,0000,0000,,The second part is the conscious\Nrecognition of harm.
Dialogue: 0,0:01:43.46,0:01:46.59,Default,,0000,0000,0000,,In humans, this occurs when the sensory\Nneurons in our skin
Dialogue: 0,0:01:46.59,0:01:51.40,Default,,0000,0000,0000,,make a second round of connections\Nvia the spinal cord to the brain.
Dialogue: 0,0:01:51.40,0:01:57.02,Default,,0000,0000,0000,,There, millions of neurons in multiple\Nregions create the sensations of pain.
Dialogue: 0,0:01:57.02,0:02:01.15,Default,,0000,0000,0000,,For us, this is a very complex experience\Nassociated with emotions like fear,
Dialogue: 0,0:02:01.15,0:02:02.08,Default,,0000,0000,0000,,panic,
Dialogue: 0,0:02:02.08,0:02:03.21,Default,,0000,0000,0000,,and stress,
Dialogue: 0,0:02:03.21,0:02:05.73,Default,,0000,0000,0000,,which we can communicate to others.
Dialogue: 0,0:02:05.73,0:02:08.48,Default,,0000,0000,0000,,But it's harder to know exactly\Nhow animals experience
Dialogue: 0,0:02:08.48,0:02:10.59,Default,,0000,0000,0000,,this part of the process
Dialogue: 0,0:02:10.59,0:02:13.89,Default,,0000,0000,0000,,because most them can't show us\Nwhat they feel.
Dialogue: 0,0:02:13.89,0:02:18.54,Default,,0000,0000,0000,,However, we get clues from observing\Nhow animals behave.
Dialogue: 0,0:02:18.54,0:02:22.49,Default,,0000,0000,0000,,Wild, hurt animals are known\Nto nurse their wounds,
Dialogue: 0,0:02:22.49,0:02:24.67,Default,,0000,0000,0000,,make noises to show their distress,
Dialogue: 0,0:02:24.67,0:02:27.03,Default,,0000,0000,0000,,and become reclusive.
Dialogue: 0,0:02:27.03,0:02:31.15,Default,,0000,0000,0000,,In the lab, scientists have discovered\Nthat animals like chickens and rats
Dialogue: 0,0:02:31.15,0:02:35.63,Default,,0000,0000,0000,,will self-administer pain-reducing\Ndrugs if they're hurting.
Dialogue: 0,0:02:35.63,0:02:39.18,Default,,0000,0000,0000,,Animals also avoid situations where\Nthey've been hurt before,
Dialogue: 0,0:02:39.18,0:02:42.38,Default,,0000,0000,0000,,which suggests awareness of threats.
Dialogue: 0,0:02:42.38,0:02:45.20,Default,,0000,0000,0000,,We've reached the point that research\Nhas made us so sure
Dialogue: 0,0:02:45.20,0:02:47.12,Default,,0000,0000,0000,,that vertebrates recognize pain
Dialogue: 0,0:02:47.12,0:02:51.63,Default,,0000,0000,0000,,that it's illegal in many countries\Nto needlessly harm these animals.
Dialogue: 0,0:02:51.63,0:02:56.05,Default,,0000,0000,0000,,But what about other types of animals\Nlike invertebrates?
Dialogue: 0,0:02:56.05,0:02:58.31,Default,,0000,0000,0000,,These animals aren't legally protected,
Dialogue: 0,0:02:58.31,0:03:02.23,Default,,0000,0000,0000,,partly because their behaviors\Nare harder to read.
Dialogue: 0,0:03:02.23,0:03:04.44,Default,,0000,0000,0000,,We can make good guesses\Nabout some of them,
Dialogue: 0,0:03:04.44,0:03:05.27,Default,,0000,0000,0000,,like oysters,
Dialogue: 0,0:03:05.27,0:03:06.10,Default,,0000,0000,0000,,worms,
Dialogue: 0,0:03:06.10,0:03:07.32,Default,,0000,0000,0000,,and jellyfish.
Dialogue: 0,0:03:07.32,0:03:09.88,Default,,0000,0000,0000,,These are examples of animals\Nthat either lack a brain
Dialogue: 0,0:03:09.88,0:03:12.22,Default,,0000,0000,0000,,or have a very simple one.
Dialogue: 0,0:03:12.22,0:03:16.13,Default,,0000,0000,0000,,So an oyster may recoil when squirted\Nwith lemon juice, for instance,
Dialogue: 0,0:03:16.13,0:03:18.82,Default,,0000,0000,0000,,because of nociception.
Dialogue: 0,0:03:18.82,0:03:20.72,Default,,0000,0000,0000,,But with such a simple nervous system,
Dialogue: 0,0:03:20.72,0:03:24.52,Default,,0000,0000,0000,,it's unlikely to experience \Nthe conscious part of pain.
Dialogue: 0,0:03:24.52,0:03:27.48,Default,,0000,0000,0000,,Other invertebrate animals \Nare more complicated, though,
Dialogue: 0,0:03:27.48,0:03:28.80,Default,,0000,0000,0000,,like the octopus,
Dialogue: 0,0:03:28.80,0:03:30.30,Default,,0000,0000,0000,,which has a sophisticated brain
Dialogue: 0,0:03:30.30,0:03:34.24,Default,,0000,0000,0000,,and is thought to be one of the most \Nintelligent invertebrate animals.
Dialogue: 0,0:03:34.24,0:03:39.69,Default,,0000,0000,0000,,Yet, in many countries, people continue\Nthe practice of eating live octopus.
Dialogue: 0,0:03:39.69,0:03:43.90,Default,,0000,0000,0000,,We also boil live crawfish, shrimp, \Nand crabs
Dialogue: 0,0:03:43.90,0:03:47.12,Default,,0000,0000,0000,,even though we don't really know\Nhow they're effected either.
Dialogue: 0,0:03:47.12,0:03:48.100,Default,,0000,0000,0000,,This poses an ethical problem
Dialogue: 0,0:03:48.100,0:03:52.90,Default,,0000,0000,0000,,because we may be causing these animals\Nunnecessary suffering.
Dialogue: 0,0:03:52.90,0:03:57.04,Default,,0000,0000,0000,,Scientific experimentation,\Nthough controversial, gives us some clues.
Dialogue: 0,0:03:57.04,0:04:01.38,Default,,0000,0000,0000,,Tests on hermit crabs show that they'll\Nleave an undesirable shell
Dialogue: 0,0:04:01.38,0:04:03.50,Default,,0000,0000,0000,,if they're zapped with electricity
Dialogue: 0,0:04:03.50,0:04:05.81,Default,,0000,0000,0000,,but stay if it's a good shell.
Dialogue: 0,0:04:05.81,0:04:09.26,Default,,0000,0000,0000,,And octopi that may originally curl up\Nan injured arm to protect it
Dialogue: 0,0:04:09.26,0:04:12.31,Default,,0000,0000,0000,,will risk using it to catch prey.
Dialogue: 0,0:04:12.31,0:04:16.83,Default,,0000,0000,0000,,That suggests that these animals make\Nvalue judgements around sensory input
Dialogue: 0,0:04:16.83,0:04:20.30,Default,,0000,0000,0000,,instead of just reacting \Nreflexively to harm.
Dialogue: 0,0:04:20.30,0:04:23.90,Default,,0000,0000,0000,,Meanwhile, crabs have been known\Nto repeatedly rub a spot on their bodies
Dialogue: 0,0:04:23.90,0:04:26.69,Default,,0000,0000,0000,,where they've received an electric shock.
Dialogue: 0,0:04:26.69,0:04:28.57,Default,,0000,0000,0000,,And even seas lugs flinch
Dialogue: 0,0:04:28.57,0:04:31.90,Default,,0000,0000,0000,,when they know they're about \Nto receive a noxious stimulus.
Dialogue: 0,0:04:31.90,0:04:35.98,Default,,0000,0000,0000,,That means they have some memory\Nof physical sensations.
Dialogue: 0,0:04:35.98,0:04:38.37,Default,,0000,0000,0000,,We still have a lot to learn about\Nanimal pain.
Dialogue: 0,0:04:38.37,0:04:40.39,Default,,0000,0000,0000,,As our knowledge grows,
Dialogue: 0,0:04:40.39,0:04:45.13,Default,,0000,0000,0000,,it may one day allow us to live in a world\Nwhere we don't cause pain needlessly.