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1 00:00:01,200 00:00:04,233
2 00:00:06,100 --> 00:00:07,866 It creeps! 00:00:06,100 --> 00:00:07,866 It creeps!
3 00:00:07,900 00:00:11,000 It crawls! It crawls!
4 00:00:11,033 00:00:12,333 It's this big, blobby yellow thing. It's this big, blobby yellow thing.
5 00:00:13,866 00:00:16,900 It's slime mold! It's slime mold!
6 00:00:16,933 00:00:18,533
7 00:00:18,566 --> 00:00:23,200 A slithering shape-shifter like no other on this planet. 00:00:18,566 --> 00:00:23,200 A slithering shape-shifter like no other on this planet.
8 00:00:23,233 00:00:24,900 It reminded us It reminded us
9 00:00:24,933 00:00:27,700 of this alien organism from a '50s movie of this alien organism from a '50s movie
10 00:00:27,733 00:00:29,400 that ate people. that ate people.
11 00:00:29,433 00:00:30,900 "The Blob"! "The Blob"!
12 00:00:30,933 00:00:35,366 This one-celled wonder has no brain. This one-celled wonder has no brain.
13 00:00:35,400 00:00:37,766 No brain, no organs, no neurons. No brain, no organs, no neurons.
14 00:00:37,800 00:00:39,100 Yet it's able to do some of the behaviors Yet it's able to do some of the behaviors
15 00:00:39,133 00:00:42,000 we normally associate with animals with brains. we normally associate with animals with brains.
16 00:00:42,033 00:00:44,166 How does it solve a maze? How does it solve a maze?
17 00:00:44,200 00:00:45,166 It is amazing. It is amazing.
18 00:00:45,200 00:00:47,500 Escape captivity? Escape captivity?
19 00:00:47,533 00:00:50,266 Compete for resources? Compete for resources?
20 00:00:50,300 00:00:53,866 Build efficient networks? Build efficient networks?
21 00:00:53,900 00:00:56,900 You start to think, does this organism You start to think, does this organism
22 00:00:56,933 00:00:58,366 possess intelligence? possess intelligence?
23 00:00:58,400 00:01:01,100 All of these are fundamental components All of these are fundamental components
24 00:01:01,133 00:01:02,200 to being smart. to being smart.
25 00:01:02,233 00:01:03,933 No brain? No brain?
26 00:01:03,966 00:01:05,033 No problem. No problem.
27 00:01:05,066 00:01:06,766 Clearly now, we see Clearly now, we see
28 00:01:06,800 00:01:09,100 that this can be done by one cell. that this can be done by one cell.
29 00:01:09,133 00:01:11,500 Can this ancient organism shed new light Can this ancient organism shed new light
30 00:01:11,533 00:01:14,433 on the evolutionary origins of intelligence? on the evolutionary origins of intelligence?
31 00:01:14,466 00:01:17,900 We can think of them as how intelligence started We can think of them as how intelligence started
32 00:01:17,933 00:01:19,066 way back. way back.
33 00:01:19,100 00:01:22,633 "The Secret Mind of Slime," "The Secret Mind of Slime,"
34 00:01:22,666 00:01:25,033 next, on "NOVA." next, on "NOVA."
35 00:01:25,066 00:01:28,133
36 00:01:44,933 --> 00:01:45,466 Major funding for "NOVA" is provided by the following: 00:01:44,933 --> 00:01:45,466 Major funding for "NOVA" is provided by the following:
37 00:01:45,500 00:01:49,033
38 00:01:49,066 --> 00:01:52,700 Lurking in the forest's shadowy undergrowth 00:01:49,066 --> 00:01:52,700 Lurking in the forest's shadowy undergrowth
39 00:01:52,733 00:01:55,466 lies an unlikely predator. lies an unlikely predator.
40 00:01:55,500 00:02:00,600 It creeps along, stalking its prey. It creeps along, stalking its prey.
41 00:02:00,633 00:02:04,533 Yet it is not an animal. Yet it is not an animal.
42 00:02:04,566 00:02:09,366 It has a fondness for dark, humid places, It has a fondness for dark, humid places,
43 00:02:09,400 00:02:11,200 yet it is not a fungus yet it is not a fungus
44 00:02:11,233 00:02:14,866 nor a plant. nor a plant.
45 00:02:14,900 00:02:18,933 It's a single-celled organism, It's a single-celled organism,
46 00:02:18,966 00:02:20,966 but not a bacterium. but not a bacterium.
47 00:02:21,000 00:02:22,933
48 00:02:22,966 --> 00:02:27,566 It's known as slime mold. 00:02:22,966 --> 00:02:27,566 It's known as slime mold.
49 00:02:27,600 00:02:31,000 It has no eyes, no mouth, no stomach, It has no eyes, no mouth, no stomach,
50 00:02:31,033 00:02:32,700 no legs. no legs.
51 00:02:32,733 00:02:35,433 Yet it can "see," "smell," Yet it can "see," "smell,"
52 00:02:35,466 00:02:37,133 and move around and move around
53 00:02:37,166 00:02:40,433 through its pulsating network of veins, through its pulsating network of veins,
54 00:02:40,466 00:02:43,233 gorging itself on bacteria, gorging itself on bacteria,
55 00:02:43,266 00:02:44,933 fungi, fungi,
56 00:02:44,966 00:02:46,666 yeasts, yeasts,
57 00:02:46,700 00:02:51,800 and growing exponentially. and growing exponentially.
58 00:02:51,833 00:02:55,800 This strange yet humble creature holds secrets that have This strange yet humble creature holds secrets that have
59 00:02:55,833 00:02:59,833 biologists, neuroscientists, and mathematicians biologists, neuroscientists, and mathematicians
60 00:02:59,866 00:03:02,200 scratching their heads. scratching their heads.
61 00:03:02,233 00:03:06,566 Because this organism, without a brain or a nervous system, Because this organism, without a brain or a nervous system,
62 00:03:06,600 00:03:09,666 seems capable of making choices, seems capable of making choices,
63 00:03:09,700 00:03:12,200 solving complex problems, solving complex problems,
64 00:03:12,233 00:03:15,966 and devising strategies. and devising strategies.
65 00:03:16,000 00:03:19,866 And it is forcing scientists to rethink intelligence And it is forcing scientists to rethink intelligence
66 00:03:19,900 00:03:26,666 as something that does not imply a need for a brain. as something that does not imply a need for a brain.
67 00:03:28,366 00:03:34,433
68 00:03:34,466 --> 00:03:38,433 Tanya Latty is a researcher at the University of Sydney 00:03:34,466 --> 00:03:38,433 Tanya Latty is a researcher at the University of Sydney
69 00:03:38,466 00:03:40,833 who studies slime mold. who studies slime mold.
70 00:03:40,866 00:03:43,266 You can find slime mold all over the place. You can find slime mold all over the place.
71 00:03:43,300 00:03:45,400 They're in leaf litter, they're in the soil, They're in leaf litter, they're in the soil,
72 00:03:45,433 00:03:47,366 they're on bits of wood. they're on bits of wood.
73 00:03:47,400 00:03:51,566 They're small structures that almost look like mushrooms. They're small structures that almost look like mushrooms.
74 00:03:51,600 00:03:56,300 Not only is Tanya an expert on slime mold, Not only is Tanya an expert on slime mold,
75 00:03:56,333 00:03:59,033 she's one of its biggest fans. she's one of its biggest fans.
76 00:03:59,066 00:04:00,766 How could you not love them? How could you not love them?
77 00:04:00,800 00:04:03,400 It's this big, blobby, yellow thing, you know, It's this big, blobby, yellow thing, you know,
78 00:04:03,433 00:04:05,000 it's just fundamentally cool. it's just fundamentally cool.
79 00:04:05,033 00:04:06,433 I stand by that! I stand by that!
80 00:04:06,466 00:04:09,133 "Slime Mold Identification and Appreciation." "Slime Mold Identification and Appreciation."
81 00:04:09,166 00:04:11,266 There it is. There it is.
82 00:04:11,300 00:04:12,833 She even follows them on Facebook. She even follows them on Facebook.
83 00:04:12,866 00:04:14,066 The spores are gorgeous. The spores are gorgeous.
84 00:04:14,100 00:04:15,800 They're, they're beautiful. They're, they're beautiful.
85 00:04:15,833 00:04:18,766
86 00:04:18,800 --> 00:04:21,366 The slime molds might be one of the most abundant things 00:04:18,800 --> 00:04:21,366 The slime molds might be one of the most abundant things
87 00:04:21,400 00:04:23,300 in the soil. in the soil.
88 00:04:23,333 00:04:26,900 There are spores everywhere. There are spores everywhere.
89 00:04:26,933 00:04:28,933
90 00:04:28,966 --> 00:04:30,066 Biologists have puzzled 00:04:28,966 --> 00:04:30,066 Biologists have puzzled
91 00:04:30,100 00:04:32,733 over where exactly this creature fits over where exactly this creature fits
92 00:04:32,766 00:04:35,200 into the great tree of life. into the great tree of life.
93 00:04:35,233 00:04:37,900 Slime molds branched off from that tree Slime molds branched off from that tree
94 00:04:37,933 00:04:42,200 before the plants, the fungi, and the animals. before the plants, the fungi, and the animals.
95 00:04:42,233 00:04:45,300 They're single-celled organisms, but the type of cell they have They're single-celled organisms, but the type of cell they have
96 00:04:45,333 00:04:48,166 is quite different from bacteria. is quite different from bacteria.
97 00:04:48,200 00:04:51,933 There's at least 900 different species of slime mold There's at least 900 different species of slime mold
98 00:04:51,966 00:04:53,266 that we know about, that we know about,
99 00:04:53,300 00:04:55,266 and that number is probably a massive underestimate. and that number is probably a massive underestimate.
100 00:04:55,300 00:04:57,633
101 00:04:57,666 --> 00:04:59,566 The slime mold most people think about 00:04:57,666 --> 00:04:59,566 The slime mold most people think about
102 00:04:59,600 00:05:01,466 is Physarum polycephalum. is Physarum polycephalum.
103 00:05:01,500 00:05:04,166 It's bright yellow, it grows really fast, It's bright yellow, it grows really fast,
104 00:05:04,200 00:05:06,200 and it's become kind of our lab rat and it's become kind of our lab rat
105 00:05:06,233 00:05:07,333 most scientists are studying, most scientists are studying,
106 00:05:07,366 00:05:09,333 probably because it's the easiest one probably because it's the easiest one
107 00:05:09,366 00:05:11,333 to grow in the lab. to grow in the lab.
108 00:05:11,366 00:05:13,466
109 00:05:13,500 --> 00:05:17,866 Some of them have great names, like the Dog's Vomit. 00:05:13,500 --> 00:05:17,866 Some of them have great names, like the Dog's Vomit.
110 00:05:17,900 00:05:22,900 They also come in reds and grays and browns and white. They also come in reds and grays and browns and white.
111 00:05:25,833 00:05:30,066 Tanya was a latecomer to slime mold research. Tanya was a latecomer to slime mold research.
112 00:05:30,100 00:05:35,166 She began her career studying the behavior of insects. She began her career studying the behavior of insects.
113 00:05:35,200 00:05:36,466 I'm an entomologist by training. I'm an entomologist by training.
114 00:05:36,500 00:05:38,133 I work with ants, I work with ants,
115 00:05:38,166 00:05:42,166 bees, and other invertebrates. bees, and other invertebrates.
116 00:05:42,200 00:05:44,533
117 00:05:44,566 --> 00:05:46,133 But ten years ago, 00:05:44,566 --> 00:05:46,133 But ten years ago,
118 00:05:46,166 00:05:49,533 while researching bees at Hokkaido University, while researching bees at Hokkaido University,
119 00:05:49,566 00:05:54,233 she had a chance encounter with slime mold she had a chance encounter with slime mold
120 00:05:54,266 00:05:57,900 through one of the most respected experts in the field: through one of the most respected experts in the field:
121 00:05:57,933 00:06:01,366   Professor Toshiyuki Nakagaki.   Professor Toshiyuki Nakagaki.
122 00:06:03,166 00:06:08,300 Slime mold is a serious subject of study in Japan, Slime mold is a serious subject of study in Japan,
123 00:06:08,333 00:06:13,266 one going back generations. one going back generations.
124 00:06:13,300 00:06:14,733 The Emperor Hirohito himself The Emperor Hirohito himself
125 00:06:14,766 00:06:16,466 was a learned biologist was a learned biologist
126 00:06:16,500 00:06:21,500 who established a taxonomy of slime mold, who established a taxonomy of slime mold,
127 00:06:21,533 00:06:25,200 and even discovered a new species of the organism. and even discovered a new species of the organism.
128 00:06:25,233 00:06:29,700 In my research, I focus on this single, simple cell In my research, I focus on this single, simple cell
129 00:06:29,733 00:06:34,833 through the disciplines of physics and math. through the disciplines of physics and math.
130 00:06:34,866 00:06:36,366 I was able to see how he was doing things I was able to see how he was doing things
131 00:06:36,400 00:06:39,766 and learn a little bit about the slime mold. and learn a little bit about the slime mold.
132 00:06:39,800 00:06:41,800 Toshiyuki had been studying Toshiyuki had been studying
133 00:06:41,833 00:06:43,700 how this curious organism would react how this curious organism would react
134 00:06:43,733 00:06:49,466 when faced with a challenge traditionally posed to animals. when faced with a challenge traditionally posed to animals.
135 00:06:50,933 00:06:53,400 He did some of the first really awesome experiments He did some of the first really awesome experiments
136 00:06:53,433 00:06:55,733 on slime molds solving mazes. on slime molds solving mazes.
137 00:06:57,233 00:07:00,466 Could a slime mold find food Could a slime mold find food
138 00:07:00,500 00:07:04,366 placed at the far end of a labyrinth? placed at the far end of a labyrinth?
139 00:07:04,400 00:07:08,800
140 00:07:08,833 --> 00:07:11,933 I had never even heard of slime mold before I took this job. 00:07:08,833 --> 00:07:11,933 I had never even heard of slime mold before I took this job.
141 00:07:14,000 00:07:17,933 So here you have this organism that has no brain, no organs, So here you have this organism that has no brain, no organs,
142 00:07:17,966 00:07:20,300 no neurons of any kind. no neurons of any kind.
143 00:07:20,333 00:07:23,133 Yet it's able to do some of the behaviors Yet it's able to do some of the behaviors
144 00:07:23,166 00:07:26,766 we normally associate with animals with brains. we normally associate with animals with brains.
145 00:07:28,533 00:07:32,100
146 00:07:40,000 --> 00:07:42,966 It is mysterious. 00:07:40,000 --> 00:07:42,966 It is mysterious.
147 00:07:43,000 00:07:45,000 Astounding. Astounding.
148 00:07:45,033 00:07:48,333 Solving a maze is amazing. Solving a maze is amazing.
149 00:07:48,366 00:07:52,266
150 00:07:52,300 --> 00:07:54,566 How can a single-celled organism 00:07:52,300 --> 00:07:54,566 How can a single-celled organism
151 00:07:54,600 00:07:56,766 have such a capacity? have such a capacity?
152 00:07:59,033 00:08:03,466 Toshiyuki has devoted his career to studying this question. Toshiyuki has devoted his career to studying this question.
153 00:08:03,500 00:08:04,933 I mean, when you think about it, I mean, when you think about it,
154 00:08:04,966 00:08:08,466 99% of the living things on our planet are brainless. 99% of the living things on our planet are brainless.
155 00:08:08,500 00:08:11,466 But they need to find food, But they need to find food,
156 00:08:11,500 00:08:14,500 they need to find partners to reproduce often. they need to find partners to reproduce often.
157 00:08:14,533 00:08:17,433 They may need to hide from predators. They may need to hide from predators.
158 00:08:17,466 00:08:20,100 How do you do all of that when you don't have a brain? How do you do all of that when you don't have a brain?
159 00:08:20,133 00:08:24,300
160 00:08:24,333 --> 00:08:26,500 When I came back to Australia, I thought 00:08:24,333 --> 00:08:26,500 When I came back to Australia, I thought
161 00:08:26,533 00:08:31,400 it would be awesome to have one of these as a lab pet. it would be awesome to have one of these as a lab pet.
162 00:08:31,433 00:08:32,700 And it lived in my desk for a few weeks. And it lived in my desk for a few weeks.
163 00:08:32,733 00:08:37,766
164 00:08:37,800 --> 00:08:40,100 I started to notice that it was doing things 00:08:37,800 --> 00:08:40,100 I started to notice that it was doing things
165 00:08:40,133 00:08:42,700 a lot like my ants were doing. a lot like my ants were doing.
166 00:08:42,733 00:08:44,933
167 00:08:44,966 --> 00:08:48,833 So she introduced Physarum to one of her colleagues, 00:08:44,966 --> 00:08:48,833 So she introduced Physarum to one of her colleagues,
168 00:08:48,866 00:08:51,600 Audrey Dussutour. Audrey Dussutour.
169 00:08:51,633 00:08:52,700 I was a post-doc in Australia I was a post-doc in Australia
170 00:08:52,733 00:08:55,033 studying nutrition in ants. studying nutrition in ants.
171 00:08:56,166 00:08:59,833 It looked like an old omelet. It looked like an old omelet.
172 00:08:59,866 00:09:05,500 The next day, it had escaped from the box we had put him in. The next day, it had escaped from the box we had put him in.
173 00:09:05,533 00:09:08,000 It reminded us It reminded us
174 00:09:08,033 00:09:11,533 of this alien organism from a '50s movie of this alien organism from a '50s movie
175 00:09:11,566 00:09:13,933 that ate people... that ate people...
176 00:09:17,133 00:09:19,100 And grew and grew as it ate. And grew and grew as it ate.
177 00:09:19,133 00:09:20,933 It's unstoppable, it just kind of keeps coming. It's unstoppable, it just kind of keeps coming.
178 00:09:20,966 00:09:24,600 And then the world could fall before the blood-curdling threat And then the world could fall before the blood-curdling threat
179 00:09:24,633 00:09:26,233 of "The Blob"! of "The Blob"!
180 00:09:28,466 00:09:31,200 Physarum doesn't eat people. Physarum doesn't eat people.
181 00:09:31,233 00:09:34,066 It eats oatmeal, but it's really a glutton. It eats oatmeal, but it's really a glutton.
182 00:09:34,100 00:09:36,800 It doubles in size every day. It doubles in size every day.
183 00:09:36,833 00:09:39,266 I nicknamed it "Blob." I nicknamed it "Blob."
184 00:09:39,300 00:09:44,066 Physarum began consuming their time and attention. Physarum began consuming their time and attention.
185 00:09:44,100 00:09:46,500 And soon, Tanya and Audrey And soon, Tanya and Audrey
186 00:09:46,533 00:09:48,600 shifted the focus of their research shifted the focus of their research
187 00:09:48,633 00:09:51,233 to this remarkable creature, to this remarkable creature,
188 00:09:51,266 00:09:55,766 so radically different than any other they'd studied, so radically different than any other they'd studied,
189 00:09:55,800 00:10:00,200 with abilities beyond what could be expected with abilities beyond what could be expected
190 00:10:00,233 00:10:02,166 from a single cell, from a single cell,
191 00:10:02,200 00:10:07,033 beginning with an unmistakable knack beginning with an unmistakable knack
192 00:10:07,066 00:10:09,733 for finding food. for finding food.
193 00:10:09,766 00:10:12,833 Slime molds have receptors all over the cell body. Slime molds have receptors all over the cell body.
194 00:10:12,866 00:10:14,366 And that allows them to detect And that allows them to detect
195 00:10:14,400 00:10:16,633 different chemicals in the environment. different chemicals in the environment.
196 00:10:16,666 00:10:18,933 It's very similar to our sense of smell. It's very similar to our sense of smell.
197 00:10:18,966 00:10:21,033 We have receptors in our noses, We have receptors in our noses,
198 00:10:21,066 00:10:23,400 and we're actually detecting chemicals and we're actually detecting chemicals
199 00:10:23,433 00:10:25,533 coming off of our food in the air. coming off of our food in the air.
200 00:10:25,566 00:10:27,266 Slime molds are doing the same thing, Slime molds are doing the same thing,
201 00:10:27,300 00:10:30,933 but they're doing it through the soil or through a liquid medium. but they're doing it through the soil or through a liquid medium.
202 00:10:30,966 00:10:33,633 Like the surface of a petri dish. Like the surface of a petri dish.
203 00:10:33,666 00:10:35,133 They're able to sense the chemical cue They're able to sense the chemical cue
204 00:10:35,166 00:10:38,533 and that's what draws them towards the food. and that's what draws them towards the food.
205 00:10:38,566 00:10:41,466 Slime mold's receptors sense a wide range Slime mold's receptors sense a wide range
206 00:10:41,500 00:10:45,033 of these cues in their environment. of these cues in their environment.
207 00:10:45,066 00:10:49,600 It can detect moisture and perceive the pH. It can detect moisture and perceive the pH.
208 00:10:49,633 00:10:53,866 It can perceive light because it has photoreceptors. It can perceive light because it has photoreceptors.
209 00:10:53,900 00:10:56,533 So even though it is a single cell, it is, all at once, So even though it is a single cell, it is, all at once,
210 00:10:56,566 00:11:00,566 an eye, nose, ear, and so on. an eye, nose, ear, and so on.
211 00:11:00,600 00:11:05,166 But it was how Physarum used these senses But it was how Physarum used these senses
212 00:11:05,200 00:11:07,400 that captured their attention: that captured their attention:
213 00:11:07,433 00:11:11,200 an awareness of its environment; an awareness of its environment;
214 00:11:11,233 00:11:13,133 an ability to navigate; an ability to navigate;
215 00:11:13,166 00:11:19,533 and how it moved with seeming purpose. and how it moved with seeming purpose.
216 00:11:19,566 00:11:21,300 Here's an organism that knows how to react Here's an organism that knows how to react
217 00:11:21,333 00:11:25,233 and adapt to its environment, consistently and efficiently. and adapt to its environment, consistently and efficiently.
218 00:11:25,266 00:11:28,933 They knew that Physarum's receptors They knew that Physarum's receptors
219 00:11:28,966 00:11:31,400 allowed it to react to different stimuli. allowed it to react to different stimuli.
220 00:11:31,433 00:11:34,833 It will move towards a substance, like sugar, It will move towards a substance, like sugar,
221 00:11:34,866 00:11:39,533 but it will also move away from certain substances, like salt. but it will also move away from certain substances, like salt.
222 00:11:39,566 00:11:44,366 But was Physarum simply reacting to these stimuli? But was Physarum simply reacting to these stimuli?
223 00:11:44,400 00:11:50,400 Or was it using these receptors to do something more complex? Or was it using these receptors to do something more complex?
224 00:11:50,433 00:11:52,133 Was it taking in this information Was it taking in this information
225 00:11:52,166 00:11:54,133 about its environment about its environment
226 00:11:54,166 00:11:56,966 and making choices? and making choices?
227 00:11:58,666 00:12:01,500 So for their first experiment, So for their first experiment,
228 00:12:01,533 00:12:02,600 they would present Physarum they would present Physarum
229 00:12:02,633 00:12:06,066 with one of the most basic choices with one of the most basic choices
230 00:12:06,100 00:12:08,533 facing any living organism-- facing any living organism--
231 00:12:08,566 00:12:10,100 what to eat. what to eat.
232 00:12:10,133 00:12:14,233 We can offer it a choice between different food sources. We can offer it a choice between different food sources.
233 00:12:14,266 00:12:16,466 The purpose of this experiment The purpose of this experiment
234 00:12:16,500 00:12:19,066 was to see how Physarum regulates its nutritional needs. was to see how Physarum regulates its nutritional needs.
235 00:12:19,100 00:12:23,100 But before they could even begin, But before they could even begin,
236 00:12:23,133 00:12:24,333 they'd have to determine they'd have to determine
237 00:12:24,366 00:12:28,233 what exactly Physarum's nutritional needs were. what exactly Physarum's nutritional needs were.
238 00:12:28,266 00:12:32,366 In nature, Physarum feeds on a diverse diet In nature, Physarum feeds on a diverse diet
239 00:12:32,400 00:12:36,066 of micro-organisms from the forest floor. of micro-organisms from the forest floor.
240 00:12:37,566 00:12:39,900 But in laboratories around the world, But in laboratories around the world,
241 00:12:39,933 00:12:44,133 they're fed a single food-- oats. they're fed a single food-- oats.
242 00:12:44,166 00:12:47,700 Slime molds inexplicably love rolled oats. Slime molds inexplicably love rolled oats.
243 00:12:47,733 00:12:49,300 And that's good for them, but for this experiment, And that's good for them, but for this experiment,
244 00:12:49,333 00:12:51,066 we had to design different diets. we had to design different diets.
245 00:12:54,466 00:12:57,366 So we had to invent special recipes for Blob. So we had to invent special recipes for Blob.
246 00:12:59,266 00:13:00,800 Making their Australian laboratory Making their Australian laboratory
247 00:13:00,833 00:13:03,833 seem more like a British bake-off. seem more like a British bake-off.
248 00:13:06,933 00:13:08,600 We had to do a lot of different mixing and cooking We had to do a lot of different mixing and cooking
249 00:13:08,633 00:13:09,866 to figure out to figure out
250 00:13:09,900 00:13:11,866 the ratio of proteins to carbohydrates the ratio of proteins to carbohydrates
251 00:13:11,900 00:13:13,066 that the slime mold did the best on. that the slime mold did the best on.
252 00:13:13,100 00:13:15,133 So, the ones that maximize their growth. So, the ones that maximize their growth.
253 00:13:16,866 00:13:19,766 We created these sort of crèmes brûlées. We created these sort of crèmes brûlées.
254 00:13:19,800 00:13:24,833 We called them custards. We called them custards.
255 00:13:24,866 00:13:27,133 35 different recipes. 35 different recipes.
256 00:13:27,166 00:13:30,700 Each had a particular ratio of protein to sugar. Each had a particular ratio of protein to sugar.
257 00:13:30,733 00:13:35,766 To determine which of these recipes was best, To determine which of these recipes was best,
258 00:13:35,800 00:13:38,700 the judge in this test kitchen the judge in this test kitchen
259 00:13:38,733 00:13:40,766 was Physarum. was Physarum.
260 00:13:42,800 00:13:47,200 They placed Physarum on each of these 35 mixtures of protein They placed Physarum on each of these 35 mixtures of protein
261 00:13:47,233 00:13:50,866 and carbohydrates-- basically, sugar-- and carbohydrates-- basically, sugar--
262 00:13:50,900 00:13:54,433 and found that Physarum needed both to survive. and found that Physarum needed both to survive.
263 00:13:54,466 00:14:00,466 But too much protein, and Physarum would split apart. But too much protein, and Physarum would split apart.
264 00:14:00,500 00:14:03,800 Too much sugar proved fatal. Too much sugar proved fatal.
265 00:14:03,833 00:14:05,633 With just the right balance, With just the right balance,
266 00:14:05,666 00:14:09,133 Physarum grew and remained healthiest. Physarum grew and remained healthiest.
267 00:14:09,166 00:14:13,900 Audrey and Tanya had found Physarum's optimal diet. Audrey and Tanya had found Physarum's optimal diet.
268 00:14:15,666 00:14:19,066 Now they were ready to test if Physarum could find it Now they were ready to test if Physarum could find it
269 00:14:19,100 00:14:22,733 when presented with multiple options. when presented with multiple options.
270 00:14:22,766 00:14:24,966 We offered Physarum a buffet. We offered Physarum a buffet.
271 00:14:25,000 00:14:27,233 In this buffet, In this buffet,
272 00:14:27,266 00:14:30,100 Physarum had a variety of custards to choose from, Physarum had a variety of custards to choose from,
273 00:14:30,133 00:14:33,133 each with a different ratio of protein to sugar. each with a different ratio of protein to sugar.
274 00:14:33,166 00:14:36,733 Could Physarum find one with the proper balance Could Physarum find one with the proper balance
275 00:14:36,766 00:14:40,733 among these seven different ratios of nutrients? among these seven different ratios of nutrients?
276 00:14:40,766 00:14:46,266 There was one slight problem. There was one slight problem.
277 00:14:46,300 00:14:50,966 Physarum is slow, it is extremely slow. Physarum is slow, it is extremely slow.
278 00:14:53,300 00:14:55,433 Way slower than a slug. Way slower than a slug.
279 00:14:55,466 00:15:01,433 Not even half the speed of the minute hand on this watch. Not even half the speed of the minute hand on this watch.
280 00:15:01,466 00:15:07,300 Physarum... is... slow. Physarum... is... slow.
281 00:15:07,333 00:15:12,000 At least 24 hours for a single experiment. At least 24 hours for a single experiment.
282 00:15:15,566 00:15:20,366 So to observe and record their slime mold experiments, So to observe and record their slime mold experiments,
283 00:15:20,400 00:15:24,033 Tanya and Audrey relied on time-lapse photography. Tanya and Audrey relied on time-lapse photography.
284 00:15:24,066 00:15:28,700 In images taken over periods of hours and even days, In images taken over periods of hours and even days,
285 00:15:28,733 00:15:31,100 Physarum comes to life, Physarum comes to life,
286 00:15:31,133 00:15:34,400 unfurling its tendril-like extensions unfurling its tendril-like extensions
287 00:15:34,433 00:15:37,100 called pseudopods. called pseudopods.
288 00:15:38,900 00:15:42,366 It's detected that food cue, and it's extended a pseudopod out. It's detected that food cue, and it's extended a pseudopod out.
289 00:15:44,400 00:15:46,366 I get the impression they don't super-like I get the impression they don't super-like
290 00:15:46,400 00:15:48,066 that blue food source. that blue food source.
291 00:15:48,100 00:15:51,133 In fact, it contains levels of sugar In fact, it contains levels of sugar
292 00:15:51,166 00:15:53,166 that would be lethal to Physarum. that would be lethal to Physarum.
293 00:15:53,200 00:15:56,766 And so, it heads elsewhere. And so, it heads elsewhere.
294 00:15:56,800 00:15:58,166 You can see it's sort of dividing You can see it's sort of dividing
295 00:15:58,200 00:15:59,500 into a bunch of pseudopods... into a bunch of pseudopods...
296 00:16:03,533 00:16:06,166 It's contacted that one in the middle. It's contacted that one in the middle.
297 00:16:06,200 00:16:08,700 I'm not sure if it's actually chosen that one. I'm not sure if it's actually chosen that one.
298 00:16:08,733 00:16:12,000 It's the best ratio it's sensed so far. It's the best ratio it's sensed so far.
299 00:16:12,033 00:16:16,300 It begins eating, and continues searching. It begins eating, and continues searching.
300 00:16:16,333 00:16:17,800 Slime mold can, and so it does. Slime mold can, and so it does.
301 00:16:17,833 00:16:20,166 It'll first engulf the food It'll first engulf the food
302 00:16:20,200 00:16:22,900 and then send out pseudopods to start looking, and then send out pseudopods to start looking,
303 00:16:22,933 00:16:25,266 because you never know what's around the corner. because you never know what's around the corner.
304 00:16:25,300 00:16:29,233 The slime mold soon abandons that source. The slime mold soon abandons that source.
305 00:16:29,266 00:16:30,633 It's sort of shifted. It's sort of shifted.
306 00:16:30,666 00:16:34,300 The slime mold clearly likes the left side better. The slime mold clearly likes the left side better.
307 00:16:34,333 00:16:38,033 On this side is the best nutritional balance. On this side is the best nutritional balance.
308 00:16:38,066 00:16:40,600 Given seven options, Given seven options,
309 00:16:40,633 00:16:47,466 Physarum found the optimal ratio of protein to sugar. Physarum found the optimal ratio of protein to sugar.
310 00:16:47,500 00:16:51,266 Blob headed towards the custard that would maximize growth. Blob headed towards the custard that would maximize growth.
311 00:16:51,300 00:16:53,700 It will always try to optimize It will always try to optimize
312 00:16:53,733 00:16:56,633 both protein and sugar. both protein and sugar.
313 00:16:58,666 00:17:01,366 But had Physarum made a decision? But had Physarum made a decision?
314 00:17:01,400 00:17:04,066 Was this truly a choice? Was this truly a choice?
315 00:17:04,100 00:17:05,600 We have to be very careful We have to be very careful
316 00:17:05,633 00:17:07,266 using words like "choice" or "decide." using words like "choice" or "decide."
317 00:17:07,300 00:17:09,200 We're not saying that they have feelings We're not saying that they have feelings
318 00:17:09,233 00:17:12,633 or that they're thinking or doing those decisions or that they're thinking or doing those decisions
319 00:17:12,666 00:17:14,133 the same way that we do. the same way that we do.
320 00:17:14,166 00:17:16,133 What we are saying is that slime molds are able to make choices What we are saying is that slime molds are able to make choices
321 00:17:16,166 00:17:17,900 because, if you give them an option because, if you give them an option
322 00:17:17,933 00:17:19,366 between two or more items, between two or more items,
323 00:17:19,400 00:17:22,800 they will consistently make certain choices over others. they will consistently make certain choices over others.
324 00:17:22,833 00:17:27,433 Choice or not, they had conclusively shown Choice or not, they had conclusively shown
325 00:17:27,466 00:17:30,533 that Physarum had effectively taken in information that Physarum had effectively taken in information
326 00:17:30,566 00:17:32,266 about its environment about its environment
327 00:17:32,300 00:17:35,366 and turned that into action-- and turned that into action--
328 00:17:35,400 00:17:41,066 action that in itself is mystifying. action that in itself is mystifying.
329 00:17:41,100 00:17:46,166 It begs the question, "How does a cell move It begs the question, "How does a cell move
330 00:17:46,200 00:17:48,100 "if it has no appendages, "if it has no appendages,
331 00:17:48,133 00:17:49,900 no legs?" no legs?"
332 00:17:49,933 00:17:51,766 It's a system quite unique in nature. It's a system quite unique in nature.
333 00:17:51,800 00:17:54,033 If you look at it closely, you'll see If you look at it closely, you'll see
334 00:17:54,066 00:17:58,233 that it is crisscrossed with a network of veins. that it is crisscrossed with a network of veins.
335 00:17:58,266 00:18:00,533 The veins of slime molds are constantly pulsing, The veins of slime molds are constantly pulsing,
336 00:18:00,566 00:18:02,433 and that drives it forwards. and that drives it forwards.
337 00:18:11,366 00:18:12,633 In Bremen, Germany, In Bremen, Germany,
338 00:18:12,666 00:18:15,633 Hans-Guünther Doöbereiner and his team Hans-Guünther Doöbereiner and his team
339 00:18:15,666 00:18:20,533 study the mechanics of Physarum's movement. study the mechanics of Physarum's movement.
340 00:18:20,566 00:18:24,100 There is a stream of what we call protoplasm. There is a stream of what we call protoplasm.
341 00:18:24,133 00:18:29,433 You can see here that there's a flow within these veins. You can see here that there's a flow within these veins.
342 00:18:29,466 00:18:32,566 That flow is produced by proteins That flow is produced by proteins
343 00:18:32,600 00:18:34,500 that wrap around the veins that wrap around the veins
344 00:18:34,533 00:18:37,433 and rhythmically squeeze and relax, and rhythmically squeeze and relax,
345 00:18:37,466 00:18:40,766 propelling the protoplasm within. propelling the protoplasm within.
346 00:18:40,800 00:18:43,433 And that liquid is driven through the veins And that liquid is driven through the veins
347 00:18:43,466 00:18:47,333 to the growth front of Physarum. to the growth front of Physarum.
348 00:18:47,366 00:18:50,900 The growth front is Physarum's forward-moving branches, The growth front is Physarum's forward-moving branches,
349 00:18:50,933 00:18:53,666 fed by these veins. fed by these veins.
350 00:18:53,700 00:18:57,666 But how does Physarum coordinate this movement But how does Physarum coordinate this movement
351 00:18:57,700 00:19:02,833 in order to navigate towards its next meal? in order to navigate towards its next meal?
352 00:19:02,866 00:19:04,133 In our bodies, we have a brain that tells In our bodies, we have a brain that tells
353 00:19:04,166 00:19:05,433 the rest of our body what to do. the rest of our body what to do.
354 00:19:05,466 00:19:07,300 That's not the case in the slime mold at all. That's not the case in the slime mold at all.
355 00:19:07,333 00:19:08,466 It's totally decentralized. It's totally decentralized.
356 00:19:08,500 00:19:10,633 And so every bit of slime mold And so every bit of slime mold
357 00:19:10,666 00:19:13,300 is essentially deciding for itself. is essentially deciding for itself.
358 00:19:13,333 00:19:16,966 What "every bit" would be in a single-celled organism What "every bit" would be in a single-celled organism
359 00:19:17,000 00:19:22,566 is confusing, even for the people that study Physarum. is confusing, even for the people that study Physarum.
360 00:19:22,600 00:19:25,600 So to better understand what the "parts" are So to better understand what the "parts" are
361 00:19:25,633 00:19:29,066 that make up this single cell, that make up this single cell,
362 00:19:29,100 00:19:32,500 Hans-Guünther's team shredded Physarum Hans-Guünther's team shredded Physarum
363 00:19:32,533 00:19:36,466 into thousands of tiny fragments. into thousands of tiny fragments.
364 00:19:38,666 00:19:42,700 The veins, the pseudopods-- The veins, the pseudopods--
365 00:19:42,733 00:19:45,666 all of the familiar structures-- are gone. all of the familiar structures-- are gone.
366 00:19:45,700 00:19:51,300 What remains are random bits of protoplasm, What remains are random bits of protoplasm,
367 00:19:51,333 00:19:55,366 the goo that Physarum is made of. the goo that Physarum is made of.
368 00:19:55,400 00:19:57,800 For Physarum, For Physarum,
369 00:19:57,833 00:20:02,300 this is a minor setback. this is a minor setback.
370 00:20:02,333 00:20:04,866 Viewed under a microscope, Viewed under a microscope,
371 00:20:04,900 00:20:09,833 these bits are already pulsing. these bits are already pulsing.
372 00:20:11,366 00:20:17,833 And as they watch, Physarum begins forming back together. And as they watch, Physarum begins forming back together.
373 00:20:17,866 00:20:21,566 These separate, small objects join up These separate, small objects join up
374 00:20:21,600 00:20:24,800 to form an interconnected network. to form an interconnected network.
375 00:20:24,833 00:20:27,666 You can see more and more of them coming together. You can see more and more of them coming together.
376 00:20:27,700 00:20:30,933 Physarum is reassembling itself Physarum is reassembling itself
377 00:20:30,966 00:20:33,333 into its familiar network of veins, into its familiar network of veins,
378 00:20:33,366 00:20:38,766 fanning out in every direction. fanning out in every direction.
379 00:20:38,800 00:20:43,066 Hans-Guünther has found that Physarum's parts Hans-Guünther has found that Physarum's parts
380 00:20:43,100 00:20:46,333 are interchangeable. are interchangeable.
381 00:20:49,400 00:20:51,300 A dog is always a dog. A dog is always a dog.
382 00:20:51,333 00:20:53,633 A bacterium is always a bacterium. A bacterium is always a bacterium.
383 00:20:53,666 00:20:56,800 But Physarum is more like... But Physarum is more like...
384 00:20:56,833 00:21:01,500 A Transformer. A Transformer.
385 00:21:01,533 00:21:04,100 It's a natural, biological Transformer. It's a natural, biological Transformer.
386 00:21:07,366 00:21:10,200 Any part of the slime mold can pretty much recreate Any part of the slime mold can pretty much recreate
387 00:21:10,233 00:21:12,366 any other part of the slime mold. any other part of the slime mold.
388 00:21:12,400 00:21:13,566 And that's because, if you think of a slime mold And that's because, if you think of a slime mold
389 00:21:13,600 00:21:15,066 as being almost like a soup, as being almost like a soup,
390 00:21:15,100 00:21:17,533 there is all these different components of the cell there is all these different components of the cell
391 00:21:17,566 00:21:18,833 that do different jobs. that do different jobs.
392 00:21:18,866 00:21:22,066 They can organize and pack tightly to form a vein. They can organize and pack tightly to form a vein.
393 00:21:22,100 00:21:23,466 They can be less packed together They can be less packed together
394 00:21:23,500 00:21:27,233 to form this free-flowing cytoplasm. to form this free-flowing cytoplasm.
395 00:21:27,266 00:21:29,566 It will just reorganize itself and become a slime mold again It will just reorganize itself and become a slime mold again
396 00:21:29,600 00:21:30,700 with all the normal slime mold bits. with all the normal slime mold bits.
397 00:21:30,733 00:21:32,600 So it can totally reorganize itself. So it can totally reorganize itself.
398 00:21:32,633 00:21:36,233 These individually pulsing bits These individually pulsing bits
399 00:21:36,266 00:21:37,600  are the key to its movement.  are the key to its movement.
400 00:21:37,633 00:21:41,166 If certain areas begin beating faster than others, If certain areas begin beating faster than others,
401 00:21:41,200 00:21:45,200 Physarum will move in that direction. Physarum will move in that direction.
402 00:21:45,233 00:21:47,733 Cytoplasm will flow in the area where there's the most pulsing. Cytoplasm will flow in the area where there's the most pulsing.
403 00:21:47,766 00:21:51,333 And one thing that controls these pulses And one thing that controls these pulses
404 00:21:51,366 00:21:53,533 is Physarum's receptors. is Physarum's receptors.
405 00:21:53,566 00:21:56,166 Once that receptor detects the food, that triggers Once that receptor detects the food, that triggers
406 00:21:56,200 00:21:58,900 that part of the slime mold that's closest to the food that part of the slime mold that's closest to the food
407 00:21:58,933 00:22:00,033 to start pulsing faster. to start pulsing faster.
408 00:22:00,066 00:22:01,033 And so the slime mold starts to flow And so the slime mold starts to flow
409 00:22:01,066 00:22:03,200 in the direction of the food. in the direction of the food.
410 00:22:13,833 00:22:15,133 Hans-Guünther has been mapping Hans-Guünther has been mapping
411 00:22:15,166 00:22:18,800 Physarum's patterns of structure and movement, Physarum's patterns of structure and movement,
412 00:22:18,833 00:22:21,666 and says that, in many ways, and says that, in many ways,
413 00:22:21,700 00:22:23,933 it resembles the flow of traffic it resembles the flow of traffic
414 00:22:23,966 00:22:26,433 on human transportation networks. on human transportation networks.
415 00:22:30,866 00:22:35,000 In Japan, members of Toshiyuki's team have been studying this. In Japan, members of Toshiyuki's team have been studying this.
416 00:22:35,033 00:22:37,800 Physarum is particularly interesting Physarum is particularly interesting
417 00:22:37,833 00:22:41,433 because it is, basically, an adaptive transportation network. because it is, basically, an adaptive transportation network.
418 00:22:50,100 00:22:51,900 In this experiment, In this experiment,
419 00:22:51,933 00:22:54,233 Physarum is meticulously placed Physarum is meticulously placed
420 00:22:54,266 00:22:56,800 over the entire surface of the labyrinth. over the entire surface of the labyrinth.
421 00:23:00,500 00:23:03,100 At the entrance and exit are oat flakes, At the entrance and exit are oat flakes,
422 00:23:03,133 00:23:05,666 to see how Physarum will handle the presence to see how Physarum will handle the presence
423 00:23:05,700 00:23:08,433 of two food sources. of two food sources.
424 00:23:12,433 00:23:17,266 One by one, it eliminates unproductive pathways One by one, it eliminates unproductive pathways
425 00:23:17,300 00:23:20,600 until there's just one vein left, until there's just one vein left,
426 00:23:20,633 00:23:25,833 linking the two food sources by the shortest path. linking the two food sources by the shortest path.
427 00:23:25,866 00:23:29,066 By reconfiguring itself in this way, By reconfiguring itself in this way,
428 00:23:29,100 00:23:33,500 Physarum has optimized its intake of nutrients. Physarum has optimized its intake of nutrients.
429 00:23:37,000 00:23:40,233 But two points are easy. But two points are easy.
430 00:23:45,866 00:23:48,966 Toshiyuki began to test Physarum's ability Toshiyuki began to test Physarum's ability
431 00:23:49,000 00:23:54,366 to optimize its form over many more points, to optimize its form over many more points,
432 00:23:54,400 00:23:58,300 eventually increasing the number to 37. eventually increasing the number to 37.
433 00:23:58,333 00:24:03,766 The number of possible ways to connect 37 points The number of possible ways to connect 37 points
434 00:24:03,800 00:24:06,333 is somewhere in the neighborhood of an eight is somewhere in the neighborhood of an eight
435 00:24:06,366 00:24:10,800 followed by 54 zeros. followed by 54 zeros.
436 00:24:10,833 00:24:13,700 Can Physarum find the optimal way? Can Physarum find the optimal way?
437 00:24:13,733 00:24:16,900 And to make it interesting, And to make it interesting,
438 00:24:16,933 00:24:21,366 Toshiyuki and his team gave Physarum a real-world problem, Toshiyuki and his team gave Physarum a real-world problem,
439 00:24:21,400 00:24:25,733 one that human engineers had already solved: one that human engineers had already solved:
440 00:24:25,766 00:24:28,966 find the most efficient transportation network find the most efficient transportation network
441 00:24:29,000 00:24:31,066 in the greater Tokyo area. in the greater Tokyo area.
442 00:24:31,100 00:24:36,166 Using oat flakes to represent principal towns and cities, Using oat flakes to represent principal towns and cities,
443 00:24:36,200 00:24:39,600 Physarum is placed where Tokyo would be. Physarum is placed where Tokyo would be.
444 00:24:40,966 00:24:46,433 Can Physarum create an efficient network? Can Physarum create an efficient network?
445 00:24:50,833 00:24:54,933 Physarum explores its environment Physarum explores its environment
446 00:24:54,966 00:24:57,866 and, as it discovers the oat flakes, and, as it discovers the oat flakes,
447 00:24:57,900 00:25:01,466 reconfigures its network of veins, reconfigures its network of veins,
448 00:25:01,500 00:25:05,933 reinforcing the links between the food sources reinforcing the links between the food sources
449 00:25:05,966 00:25:09,800 and making the others disappear. and making the others disappear.
450 00:25:09,833 00:25:11,900 What we're getting is something that looks an awful lot What we're getting is something that looks an awful lot
451 00:25:11,933 00:25:14,700 like the actual Tokyo metro system, like the actual Tokyo metro system,
452 00:25:14,733 00:25:18,333 far more like it than we would expect by chance. far more like it than we would expect by chance.
453 00:25:18,366 00:25:23,466 Physarum has created an optimal network. Physarum has created an optimal network.
454 00:25:27,500 00:25:31,600 Something it's done successfully for millions of years, Something it's done successfully for millions of years,
455 00:25:31,633 00:25:34,700 long before humans came along. long before humans came along.
456 00:25:45,633 00:25:47,500 We noticed almost always, We noticed almost always,
457 00:25:47,533 00:25:49,000 when they were searching a plate, when they were searching a plate,
458 00:25:49,033 00:25:51,166 they would never go back over where they had been before, they would never go back over where they had been before,
459 00:25:51,200 00:25:53,733 and that was unusual. and that was unusual.
460 00:25:53,766 00:25:57,666 Unusual because that would seem to imply that Physarum Unusual because that would seem to imply that Physarum
461 00:25:57,700 00:26:00,466 would have to remember. would have to remember.
462 00:26:00,500 00:26:03,300 We assumed that it didn't have any classic memory, We assumed that it didn't have any classic memory,
463 00:26:03,333 00:26:05,166 that it wasn't remembering where it had been, that it wasn't remembering where it had been,
464 00:26:05,200 00:26:07,200 which left the question, "Well, then, how is it doing it?" which left the question, "Well, then, how is it doing it?"
465 00:26:11,566 00:26:14,266 The answer came from Physarum itself. The answer came from Physarum itself.
466 00:26:14,300 00:26:20,633 It had been leaving a trail of clues written in slime. It had been leaving a trail of clues written in slime.
467 00:26:20,666 00:26:23,166 This grey stuff, that's the slime trail, This grey stuff, that's the slime trail,
468 00:26:23,200 00:26:27,033 which is kind of like the slime trails that we see behind slugs. which is kind of like the slime trails that we see behind slugs.
469 00:26:28,933 00:26:32,266 So you have to ask, "Does Blob use its trail So you have to ask, "Does Blob use its trail
470 00:26:32,300 00:26:34,133 to memorize its environment?" to memorize its environment?"
471 00:26:36,300 00:26:38,433 Ants emit trails of pheromones Ants emit trails of pheromones
472 00:26:38,466 00:26:41,633 to mark their paths to where they've found food. to mark their paths to where they've found food.
473 00:26:41,666 00:26:45,166 Then other members of the colony use that trail Then other members of the colony use that trail
474 00:26:45,200 00:26:47,000 as an "external memory" as an "external memory"
475 00:26:47,033 00:26:51,233 to navigate to the food and back. to navigate to the food and back.
476 00:26:51,266 00:26:52,933 Because we worked with ants, we were kind of familiar Because we worked with ants, we were kind of familiar
477 00:26:52,966 00:26:55,300 with this idea of having an external form of memory; with this idea of having an external form of memory;
478 00:26:55,333 00:26:59,133 it's not encoded in a brain, it's marked on the environment. it's not encoded in a brain, it's marked on the environment.
479 00:26:59,166 00:27:05,333 In Physarum's case, its trail is a signal to keep away. In Physarum's case, its trail is a signal to keep away.
480 00:27:05,366 00:27:08,466 That slime is, in fact, a repellent. That slime is, in fact, a repellent.
481 00:27:08,500 00:27:11,100 Slime mold never wants to go back to where it has left Slime mold never wants to go back to where it has left
482 00:27:11,133 00:27:12,766 its own slime. its own slime.
483 00:27:14,433 00:27:18,933 So we set up an experiment to see if this slime was being used So we set up an experiment to see if this slime was being used
484 00:27:18,966 00:27:21,300  as a kind of external memory:  as a kind of external memory:
485 00:27:21,333 00:27:24,433 the U-Shaped Trap. the U-Shaped Trap.
486 00:27:26,300 00:27:29,033 The U-Shaped Trap was an experimental challenge The U-Shaped Trap was an experimental challenge
487 00:27:29,066 00:27:32,966 used in early machine-learning research used in early machine-learning research
488 00:27:33,000 00:27:35,500 to test things like a robot's navigational memory. to test things like a robot's navigational memory.
489 00:27:35,533 00:27:39,500 A robot is given a goal, which it can sense, A robot is given a goal, which it can sense,
490 00:27:39,533 00:27:43,200 and a U-shaped barrier, which it can't. and a U-shaped barrier, which it can't.
491 00:27:43,233 00:27:46,166 I mean, if you don't have a system of memory I mean, if you don't have a system of memory
492 00:27:46,200 00:27:47,300 or some other mechanism, or some other mechanism,
493 00:27:47,333 00:27:49,133 you just keep running into the wall. you just keep running into the wall.
494 00:27:49,166 00:27:52,866 And that's not a good thing. And that's not a good thing.
495 00:27:52,900 00:27:55,733 Robots without a system of memory would often Robots without a system of memory would often
496 00:27:55,766 00:27:58,633 remain trapped in this loop. remain trapped in this loop.
497 00:27:58,666 00:28:01,733 In this experiment, In this experiment,
498 00:28:01,766 00:28:04,466 Physarum's goal was food. Physarum's goal was food.
499 00:28:07,133 00:28:09,800 Blob can spot the food source at a distance Blob can spot the food source at a distance
500 00:28:09,833 00:28:13,000 because it is diffusing into the environment. because it is diffusing into the environment.
501 00:28:13,033 00:28:15,400 If the slime mold If the slime mold
502 00:28:15,433 00:28:18,600 just follows that smell cue, it's gonna hit a wall. just follows that smell cue, it's gonna hit a wall.
503 00:28:18,633 00:28:20,833 And without some sort of memory or some other system, And without some sort of memory or some other system,
504 00:28:20,866 00:28:22,300 we expect it we expect it
505 00:28:22,333 00:28:23,966 to just keep smashing itself against that wall, to just keep smashing itself against that wall,
506 00:28:24,000 00:28:26,733 and it won't escape. and it won't escape.
507 00:28:26,766 00:28:29,366 So what will Blob do? So what will Blob do?
508 00:28:29,400 00:28:31,533 So the slime mold would go down, hit the wall, So the slime mold would go down, hit the wall,
509 00:28:31,566 00:28:32,700 but when it goes to do it the second time, but when it goes to do it the second time,
510 00:28:32,733 00:28:34,066 it detects that it's already been there it detects that it's already been there
511 00:28:34,100 00:28:36,366 and sort of takes a step back, and sort of takes a step back,
512 00:28:36,400 00:28:37,966 and you can almost see it tracing the wall, and you can almost see it tracing the wall,
513 00:28:38,000 00:28:41,100 and then coming up the side and zipping down and then coming up the side and zipping down
514 00:28:41,133 00:28:44,400 and finding the food source really quickly. and finding the food source really quickly.
515 00:28:48,200 00:28:50,333 So once we'd shown that Blob was able to do that, So once we'd shown that Blob was able to do that,
516 00:28:50,366 00:28:53,166 we performed the experiment a second time, we performed the experiment a second time,
517 00:28:53,200 00:28:55,666 but this time, but this time,
518 00:28:55,700 00:28:59,333 we covered the environment with slime. we covered the environment with slime.
519 00:28:59,366 00:29:03,900 We made Blob think it had already explored the area. We made Blob think it had already explored the area.
520 00:29:03,933 00:29:06,100 The slime mold can still detect there was a food cue The slime mold can still detect there was a food cue
521 00:29:06,133 00:29:08,066 and it still moved towards it, and it still moved towards it,
522 00:29:08,100 00:29:09,733 but it was unable to tell the difference but it was unable to tell the difference
523 00:29:09,766 00:29:13,166 between where it had been and where it hadn't been yet. between where it had been and where it hadn't been yet.
524 00:29:13,200 00:29:15,500 And so because of that when it got to the bottom of the U, And so because of that when it got to the bottom of the U,
525 00:29:15,533 00:29:18,533 it just gets stuck and can't quite figure out how to get out. it just gets stuck and can't quite figure out how to get out.
526 00:29:18,566 00:29:24,066 It was no longer able to find the food source. It was no longer able to find the food source.
527 00:29:24,100 00:29:27,466 And so Tanya and Audrey concluded And so Tanya and Audrey concluded
528 00:29:27,500 00:29:29,966 that Physarum's trail does, in fact, that Physarum's trail does, in fact,
529 00:29:30,000 00:29:33,766 serve as an external memory. serve as an external memory.
530 00:29:39,733 00:29:41,966 For slime mold researchers, For slime mold researchers,
531 00:29:42,000 00:29:44,433 the mounting evidence of these behaviors the mounting evidence of these behaviors
532 00:29:44,466 00:29:45,833 led them to pose a question led them to pose a question
533 00:29:45,866 00:29:50,600 that makes many scientists nervous. that makes many scientists nervous.
534 00:29:50,633 00:29:53,266 When you see what Physarum polycephalum can do-- When you see what Physarum polycephalum can do--
535 00:29:53,300 00:29:56,533 it can get through a labyrinth, create optimized networks, it can get through a labyrinth, create optimized networks,
536 00:29:56,566 00:29:59,233 escape from a trap, balance its own diet-- escape from a trap, balance its own diet--
537 00:29:59,266 00:30:04,066 "Does this organism possess intelligence?" "Does this organism possess intelligence?"
538 00:30:04,100 00:30:05,633 So that word is tricky. So that word is tricky.
539 00:30:05,666 00:30:08,033 Defining intelligence is not an easy thing, Defining intelligence is not an easy thing,
540 00:30:08,066 00:30:10,500 and certainly many people have different definitions for it. and certainly many people have different definitions for it.
541 00:30:10,533 00:30:13,466 The question of intelligence The question of intelligence
542 00:30:13,500 00:30:16,300 depends a lot on how we define intelligence. depends a lot on how we define intelligence.
543 00:30:16,333 00:30:19,166 Due to the fact that it is so tightly linked Due to the fact that it is so tightly linked
544 00:30:19,200 00:30:20,333 to the human beings, to the human beings,
545 00:30:20,366 00:30:21,666 it is very difficult now it is very difficult now
546 00:30:21,700 00:30:24,066 to speak about intelligence in other organisms. to speak about intelligence in other organisms.
547 00:30:24,100 00:30:29,900 A commonly accepted idea is that the only living organisms A commonly accepted idea is that the only living organisms
548 00:30:29,933 00:30:31,566 who display intelligence who display intelligence
549 00:30:31,600 00:30:33,600 are those with a nervous system and brain. are those with a nervous system and brain.
550 00:30:33,633 00:30:38,000 I say with certainty that I believe this idea is wrong. I say with certainty that I believe this idea is wrong.
551 00:30:38,033 00:30:42,633 In my opinion, I call this intelligent behavior. In my opinion, I call this intelligent behavior.
552 00:30:42,666 00:30:46,966 For centuries, most scientists believed For centuries, most scientists believed
553 00:30:47,000 00:30:48,333 the trait of intelligence-- the trait of intelligence--
554 00:30:48,366 00:30:50,966 the ability to reason and think-- the ability to reason and think--
555 00:30:51,000 00:30:53,800 was unique to Homo sapiens. was unique to Homo sapiens.
556 00:30:55,933 00:30:59,633 It wasn't until the mid-20th century that researchers started It wasn't until the mid-20th century that researchers started
557 00:30:59,666 00:31:03,200 to document cognitive abilities in our primate cousins, to document cognitive abilities in our primate cousins,
558 00:31:03,233 00:31:06,933 as well as other animals, farther and farther from us as well as other animals, farther and farther from us
559 00:31:06,966 00:31:09,366 on the evolutionary tree. on the evolutionary tree.
560 00:31:09,400 00:31:15,866 Chimpanzees and even crows making and using tools. Chimpanzees and even crows making and using tools.
561 00:31:15,900 00:31:20,533 Whales and dolphins using sound to communicate complex ideas. Whales and dolphins using sound to communicate complex ideas.
562 00:31:20,566 00:31:26,600 Birds demonstrating memories of places, things, and past events. Birds demonstrating memories of places, things, and past events.
563 00:31:26,633 00:31:31,300 Sea lions that can grasp logic. Sea lions that can grasp logic.
564 00:31:31,333 00:31:35,533 And evidence that many animals can actually count. And evidence that many animals can actually count.
565 00:31:37,533 00:31:40,333 Audrey and Tanya now found themselves Audrey and Tanya now found themselves
566 00:31:40,366 00:31:42,466 among the small but growing ranks of researchers among the small but growing ranks of researchers
567 00:31:42,500 00:31:44,833 pushing the boundaries of intelligence pushing the boundaries of intelligence
568 00:31:44,866 00:31:47,200 beyond the animal kingdom altogether, beyond the animal kingdom altogether,
569 00:31:47,233 00:31:50,600 searching for signs of intelligence in organisms searching for signs of intelligence in organisms
570 00:31:50,633 00:31:54,233 with no brains at all. with no brains at all.
571 00:31:54,266 00:31:58,566 The first conclusive evidence was soon found in plants. The first conclusive evidence was soon found in plants.
572 00:32:02,033 00:32:05,700 In Florence, Italy, the idea of plant intelligence In Florence, Italy, the idea of plant intelligence
573 00:32:05,733 00:32:09,300 has become the focus of some serious scientific study has become the focus of some serious scientific study
574 00:32:09,333 00:32:11,766 thanks to these two biologists, thanks to these two biologists,
575 00:32:11,800 00:32:13,800 Stefano Mancuso Stefano Mancuso
576 00:32:13,833 00:32:16,100 and Frantisek Baluska, and Frantisek Baluska,
577 00:32:16,133 00:32:21,133 who founded the Society for Plant Signaling and Behavior. who founded the Society for Plant Signaling and Behavior.
578 00:32:21,166 00:32:25,700 The notion of intelligence in plants is not new. The notion of intelligence in plants is not new.
579 00:32:25,733 00:32:30,600 Charles Darwin himself faced ridicule by his peers Charles Darwin himself faced ridicule by his peers
580 00:32:30,633 00:32:33,366 when, after extensive experimentation, when, after extensive experimentation,
581 00:32:33,400 00:32:37,800 he proposed that plants possessed a cognitive organ he proposed that plants possessed a cognitive organ
582 00:32:37,833 00:32:42,833 and that it resided in their root tips. and that it resided in their root tips.
583 00:32:42,866 00:32:46,466 Darwin says that in the tip of the root, Darwin says that in the tip of the root,
584 00:32:46,500 00:32:49,766 there's the precise equivalent of a small brain, there's the precise equivalent of a small brain,
585 00:32:49,800 00:32:53,766 like the brain of an insect, that guides the plant. like the brain of an insect, that guides the plant.
586 00:32:53,800 00:32:56,933 We started to argue that this theory We started to argue that this theory
587 00:32:56,966 00:32:58,700 is really not crazy theory. is really not crazy theory.
588 00:32:58,733 00:33:02,333 They came to this conclusion after conducting They came to this conclusion after conducting
589 00:33:02,366 00:33:04,966 their own root-tip experiments. their own root-tip experiments.
590 00:33:06,633 00:33:08,500 It was thought that a root arrived It was thought that a root arrived
591 00:33:08,533 00:33:09,800 at an obstacle at an obstacle
592 00:33:09,833 00:33:13,733 and did something like that to find a way out. and did something like that to find a way out.
593 00:33:13,766 00:33:16,800 Instead, what I saw was different. Instead, what I saw was different.
594 00:33:16,833 00:33:20,633 The roots turned well before reaching the obstacle. The roots turned well before reaching the obstacle.
595 00:33:20,666 00:33:24,300 They were able to sense what was around them They were able to sense what was around them
596 00:33:24,333 00:33:28,066 and calculate the shortest path in response. and calculate the shortest path in response.
597 00:33:28,100 00:33:31,466 Stefano thought that this kind of "sensing" behavior Stefano thought that this kind of "sensing" behavior
598 00:33:31,500 00:33:34,666 would require coordination of the cells in the root tip. would require coordination of the cells in the root tip.
599 00:33:36,700 00:33:38,500 He discovered that a specific region He discovered that a specific region
600 00:33:38,533 00:33:39,966 was sending out electrical signals was sending out electrical signals
601 00:33:40,000 00:33:42,600 to the surrounding area. to the surrounding area.
602 00:33:42,633 00:33:47,133 Could this be the "brain" that Darwin hypothesized? Could this be the "brain" that Darwin hypothesized?
603 00:33:48,733 00:33:52,500 When this section was cut off, When this section was cut off,
604 00:33:52,533 00:33:55,233 the root could still grow, the root could still grow,
605 00:33:55,266 00:33:58,600 but it lost the ability to sense its environment but it lost the ability to sense its environment
606 00:33:58,633 00:34:01,000 and adapt accordingly. and adapt accordingly.
607 00:34:01,033 00:34:05,466 From this, Stefano concluded that Darwin was correct: From this, Stefano concluded that Darwin was correct:
608 00:34:05,500 00:34:06,566 plant roots did appear plant roots did appear
609 00:34:06,600 00:34:10,700 to contain a kind of sensory organ. to contain a kind of sensory organ.
610 00:34:12,166 00:34:15,066 Plants are like upside-down humans: Plants are like upside-down humans:
611 00:34:15,100 00:34:16,700 they have their heads underground, they have their heads underground,
612 00:34:16,733 00:34:20,533 and the part we can see is the reproductive part. and the part we can see is the reproductive part.
613 00:34:20,566 00:34:21,866 And that's how we should look at plants, And that's how we should look at plants,
614 00:34:21,900 00:34:24,866 something like this pot. something like this pot.
615 00:34:31,200 00:34:33,700 Since plants now did seem to have some form Since plants now did seem to have some form
616 00:34:33,733 00:34:34,966 of sensory ability, of sensory ability,
617 00:34:35,000 00:34:37,700 Stefano and Frantisek began searching Stefano and Frantisek began searching
618 00:34:37,733 00:34:39,000 for more complex behavior for more complex behavior
619 00:34:39,033 00:34:42,800 which might conclusively demonstrate intelligence: which might conclusively demonstrate intelligence:
620 00:34:42,833 00:34:45,900 memory and learning. memory and learning.
621 00:34:45,933 00:34:50,200 One of the most basic types of learning in brained creatures One of the most basic types of learning in brained creatures
622 00:34:50,233 00:34:52,166 can be seen in these pigeons, can be seen in these pigeons,
623 00:34:52,200 00:34:55,333 who've learned not to fear humans. who've learned not to fear humans.
624 00:34:55,366 00:34:57,933 They even tune them out. They even tune them out.
625 00:34:57,966 00:35:00,866 Habituation, as it's called, Habituation, as it's called,
626 00:35:00,900 00:35:05,000 enables organisms to focus on the important information, enables organisms to focus on the important information,
627 00:35:05,033 00:35:09,166 while filtering out the noise in the world around them. while filtering out the noise in the world around them.
628 00:35:10,833 00:35:13,366 To test for this type of learning in plants, To test for this type of learning in plants,
629 00:35:13,400 00:35:15,000 Stefano and his colleagues Stefano and his colleagues
630 00:35:15,033 00:35:19,333 turned to this intriguing specimen, Mimosa pudica, turned to this intriguing specimen, Mimosa pudica,
631 00:35:19,366 00:35:25,233 which reacts to disturbances by folding its leaves. which reacts to disturbances by folding its leaves.
632 00:35:25,266 00:35:27,466 If this reaction is purely mechanical, If this reaction is purely mechanical,
633 00:35:27,500 00:35:31,466 they should respond this way every time they're disturbed, they should respond this way every time they're disturbed,
634 00:35:31,500 00:35:36,166 even after numerous disturbances that don't prove to be harmful. even after numerous disturbances that don't prove to be harmful.
635 00:35:36,200 00:35:39,200 So they repeatedly dropped plants So they repeatedly dropped plants
636 00:35:39,233 00:35:41,366 from a height of six inches-- from a height of six inches--
637 00:35:41,400 00:35:44,366 not particularly harmful for pudica. not particularly harmful for pudica.
638 00:35:44,400 00:35:47,333 And after only five or six drops, And after only five or six drops,
639 00:35:47,366 00:35:51,733 the plants stopped reacting. the plants stopped reacting.
640 00:35:51,766 00:35:53,400 And yet, when they were disturbed in other ways, And yet, when they were disturbed in other ways,
641 00:35:53,433 00:35:57,566 they still responded by folding their leaves. they still responded by folding their leaves.
642 00:35:59,300 00:36:01,700 We showed that Mimosa pudica was able to memorize We showed that Mimosa pudica was able to memorize
643 00:36:01,733 00:36:02,966 different stimuli different stimuli
644 00:36:03,000 00:36:05,433 and to differentiate and to differentiate
645 00:36:05,466 00:36:09,000 between a dangerous stimulus and one that wasn't dangerous, between a dangerous stimulus and one that wasn't dangerous,
646 00:36:09,033 00:36:11,300 and then respond accordingly. and then respond accordingly.
647 00:36:11,333 00:36:15,166 This was, indeed, quite a sensation. This was, indeed, quite a sensation.
648 00:36:15,200 00:36:19,166 Stefano and his colleagues had documented intriguing evidence Stefano and his colleagues had documented intriguing evidence
649 00:36:19,200 00:36:20,333 of memory and learning of memory and learning
650 00:36:20,366 00:36:22,966 in a brainless organism. in a brainless organism.
651 00:36:30,033 00:36:35,900 For Audrey, this raised a tantalizing question. For Audrey, this raised a tantalizing question.
652 00:36:35,933 00:36:37,300 So with Physarum we asked, So with Physarum we asked,
653 00:36:37,333 00:36:39,600 "Are we going to find this kind of ability "Are we going to find this kind of ability
654 00:36:39,633 00:36:42,800 that can be found in plants?" that can be found in plants?"
655 00:36:42,833 00:36:45,200 She and Tanya had proven that Physarum used She and Tanya had proven that Physarum used
656 00:36:45,233 00:36:47,366 a kind of external memory. a kind of external memory.
657 00:36:47,400 00:36:49,900 But was it possible that Physarum But was it possible that Physarum
658 00:36:49,933 00:36:54,600 possessed some true internal memory? possessed some true internal memory?
659 00:36:54,633 00:36:57,266 Is slime mold capable of remembering? Is slime mold capable of remembering?
660 00:36:57,300 00:37:00,033 Is it capable of learning? Is it capable of learning?
661 00:37:00,066 00:37:02,266 That question is the Holy Grail. That question is the Holy Grail.
662 00:37:04,066 00:37:06,633 Proving that Physarum had these capabilities could show Proving that Physarum had these capabilities could show
663 00:37:06,666 00:37:10,633 that a single-celled creature was capable of intelligence, that a single-celled creature was capable of intelligence,
664 00:37:10,666 00:37:15,233 and might very well force scientists to reconsider and might very well force scientists to reconsider
665 00:37:15,266 00:37:19,133 the idea of intelligence itself. the idea of intelligence itself.
666 00:37:19,166 00:37:23,233 So we set up an experiment to see if Blob learned things-- So we set up an experiment to see if Blob learned things--
667 00:37:23,266 00:37:25,600  a habituation experiment.  a habituation experiment.
668 00:37:27,533 00:37:29,766 The objective was to try and habituate Physarum The objective was to try and habituate Physarum
669 00:37:29,800 00:37:33,500 to a substance it was repulsed by. to a substance it was repulsed by.
670 00:37:33,533 00:37:35,700 In this case, salt. In this case, salt.
671 00:37:35,733 00:37:39,266
672 00:37:39,300 --> 00:37:42,733 Between this Physarum and a tasty snack 00:37:39,300 --> 00:37:42,733 Between this Physarum and a tasty snack
673 00:37:42,766 00:37:47,633 is a bridge a few centimeters long. is a bridge a few centimeters long.
674 00:37:47,666 00:37:53,400 Normally, Physarum makes the crossing in about an hour. Normally, Physarum makes the crossing in about an hour.
675 00:37:53,433 00:37:55,333
676 00:37:55,366 --> 00:37:57,533 For her experiment, 00:37:55,366 --> 00:37:57,533 For her experiment,
677 00:37:57,566 00:37:59,933 Audrey coated the bridge in salt. Audrey coated the bridge in salt.
678 00:37:59,966 00:38:05,766 Not enough to harm Physarum, but enough to leave a bad taste. Not enough to harm Physarum, but enough to leave a bad taste.
679 00:38:05,800 00:38:08,633
680 00:38:08,666 --> 00:38:13,666 It took Blob ten hours to cross the bridge. 00:38:08,666 --> 00:38:13,666 It took Blob ten hours to cross the bridge.
681 00:38:13,700 00:38:15,533 The next day, we'd do it again. The next day, we'd do it again.
682 00:38:15,566 00:38:17,766
683 00:38:17,800 --> 00:38:20,100 By day two, that same Physarum 00:38:17,800 --> 00:38:20,100 By day two, that same Physarum
684 00:38:20,133 00:38:23,200 was moving faster over the salt bridge. was moving faster over the salt bridge.
685 00:38:23,233 00:38:27,800 This time, it takes eight hours to cross the bridge. This time, it takes eight hours to cross the bridge.
686 00:38:27,833 00:38:30,866 Audrey repeated this for five days, and each day, Audrey repeated this for five days, and each day,
687 00:38:30,900 00:38:37,100 Physarum moved more quickly across the salt bridge. Physarum moved more quickly across the salt bridge.
688 00:38:37,133 00:38:40,233 By the fifth day, Blob takes no more time By the fifth day, Blob takes no more time
689 00:38:40,266 00:38:44,133 than our "control" Blob that crossed the bridge with no salt. than our "control" Blob that crossed the bridge with no salt.
690 00:38:44,166 00:38:50,133 So Physarum ends up getting used to a substance it doesn't like. So Physarum ends up getting used to a substance it doesn't like.
691 00:38:50,166 00:38:53,633 It seemed that Physarum learned to tolerate, It seemed that Physarum learned to tolerate,
692 00:38:53,666 00:38:56,133 or habituate to the salt. or habituate to the salt.
693 00:38:56,166 00:38:59,400
694 00:38:59,433 --> 00:39:04,100 Had Physarum actually learned that the salt wasn't harmful? 00:38:59,433 --> 00:39:04,100 Had Physarum actually learned that the salt wasn't harmful?
695 00:39:04,133 00:39:09,866 If this were true, it would mean that somewhere, inside Physarum, If this were true, it would mean that somewhere, inside Physarum,
696 00:39:09,900 00:39:14,800 there was a form of memory. there was a form of memory.
697 00:39:14,833 00:39:16,300 Of course, some were skeptical, Of course, some were skeptical,
698 00:39:16,333 00:39:18,000 because we were up against the dogma because we were up against the dogma
699 00:39:18,033 00:39:19,733 that learning was strictly reserved that learning was strictly reserved
700 00:39:19,766 00:39:21,233 for organisms with a brain. for organisms with a brain.
701 00:39:21,266 00:39:27,266 So Audrey wasn't leaving things to chance. So Audrey wasn't leaving things to chance.
702 00:39:27,300 00:39:29,966 If you want to prove If you want to prove
703 00:39:30,000 00:39:31,433 that a single-celled creature can learn, that a single-celled creature can learn,
704 00:39:31,466 00:39:32,833 you've got to be sure you've got to be sure
705 00:39:32,866 00:39:34,933 you can convince your colleagues. you can convince your colleagues.
706 00:39:34,966 00:39:36,833 On each of these tiny salt bridges, On each of these tiny salt bridges,
707 00:39:36,866 00:39:40,233 they repeated the experiment, again and again. they repeated the experiment, again and again.
708 00:39:40,266 00:39:42,700 4,000 times 4,000 times
709 00:39:42,733 00:39:46,233 on 4,000 different Blobs. on 4,000 different Blobs.
710 00:39:46,266 00:39:50,766
711 00:39:50,800 --> 00:39:53,400 The results were consistent. 00:39:50,800 --> 00:39:53,400 The results were consistent.
712 00:39:53,433 00:39:55,533 Physarum had altered its behavior Physarum had altered its behavior
713 00:39:55,566 00:39:57,133 through its past experiences, through its past experiences,
714 00:39:57,166 00:40:02,933 a fundamental definition of learning. a fundamental definition of learning.
715 00:40:02,966 00:40:05,566 Audrey had demonstrated learning and memory Audrey had demonstrated learning and memory
716 00:40:05,600 00:40:08,133 in a single-celled organism. in a single-celled organism.
717 00:40:08,166 00:40:10,900 A creature this simple A creature this simple
718 00:40:10,933 00:40:15,833 demonstrated the ability to learn. demonstrated the ability to learn.
719 00:40:15,866 00:40:17,766 But how do they do it? But how do they do it?
720 00:40:25,333 00:40:28,300 Audrey showed very nicely in her work Audrey showed very nicely in her work
721 00:40:28,333 00:40:32,266 that Physarum clearly has memory and learned from its experience that Physarum clearly has memory and learned from its experience
722 00:40:32,300 00:40:34,600 to adaptively make decisions about where it's going to go to adaptively make decisions about where it's going to go
723 00:40:34,633 00:40:36,500 and how it's going to explore its environment. and how it's going to explore its environment.
724 00:40:36,533 00:40:39,566 All of these are fundamental components to being smart. All of these are fundamental components to being smart.
725 00:40:39,600 00:40:43,600 Director of the Allen Discovery Center Michael Levin Director of the Allen Discovery Center Michael Levin
726 00:40:43,633 00:40:46,233 listens in on the electrical signals listens in on the electrical signals
727 00:40:46,266 00:40:48,200 exchanged between cells. exchanged between cells.
728 00:40:48,233 00:40:52,933 My lab focuses on bioelectricity. My lab focuses on bioelectricity.
729 00:40:52,966 00:40:54,833 All cells are electrically active, All cells are electrically active,
730 00:40:54,866 00:40:58,633 and these electrical signals enable cells and these electrical signals enable cells
731 00:40:58,666 00:41:01,633 to join into networks that store memories to join into networks that store memories
732 00:41:01,666 00:41:03,400 and process information and make decisions. and process information and make decisions.
733 00:41:03,433 00:41:07,433 It was previously thought that these cognitive abilities It was previously thought that these cognitive abilities
734 00:41:07,466 00:41:10,700 came from the conversations between many cells. came from the conversations between many cells.
735 00:41:10,733 00:41:15,366 But Physarum had just proven that wrong. But Physarum had just proven that wrong.
736 00:41:15,400 00:41:17,466 Physarum is one single cell. Physarum is one single cell.
737 00:41:17,500 00:41:19,733 And so this takes us away from questions And so this takes us away from questions
738 00:41:19,766 00:41:22,333 of cell-to-cell communication, of cell-to-cell communication,
739 00:41:22,366 00:41:24,233 all these thingsthat multicellular organisms do all these thingsthat multicellular organisms do
740 00:41:24,266 00:41:27,833 that we think of as really important for cognition, that we think of as really important for cognition,
741 00:41:27,866 00:41:29,533 but clearly now, we see but clearly now, we see
742 00:41:29,566 00:41:31,466 that this can be done by one cell. that this can be done by one cell.
743 00:41:31,500 00:41:34,500 Michael learned a lot about cellular communication Michael learned a lot about cellular communication
744 00:41:34,533 00:41:37,366 from his work with a curious multi-celled creature from his work with a curious multi-celled creature
745 00:41:37,400 00:41:39,333 called a planarian. called a planarian.
746 00:41:46,433 00:41:49,533 A small aquatic worm with the unusual ability A small aquatic worm with the unusual ability
747 00:41:49,566 00:41:56,166 to regrow missing or damaged parts of its body. to regrow missing or damaged parts of its body.
748 00:41:56,200 00:41:58,166 They regenerate every part of the body. They regenerate every part of the body.
749 00:41:58,200 00:42:00,900 So if cut into pieces, every piece of a planarian So if cut into pieces, every piece of a planarian
750 00:42:00,933 00:42:04,433 knows exactly what a standard planarian body should look like. knows exactly what a standard planarian body should look like.
751 00:42:04,466 00:42:07,933    
752 00:42:07,966 00:42:09,500 When a planarian is cut in half, When a planarian is cut in half,
753 00:42:09,533 00:42:14,333 its cells regenerate to rebuild a head at one end, its cells regenerate to rebuild a head at one end,
754 00:42:14,366 00:42:16,900 and a tail at the other. and a tail at the other.
755 00:42:16,933 00:42:18,766 Everything that's missing in the correct location, Everything that's missing in the correct location,
756 00:42:18,800 00:42:22,266 and it stops when it's done. and it stops when it's done.
757 00:42:22,300 00:42:24,633 But how? But how?
758 00:42:24,666 00:42:28,800 Michael and his team began to tinker with planarian cells Michael and his team began to tinker with planarian cells
759 00:42:28,833 00:42:30,766 to see if they could affect how these worms to see if they could affect how these worms
760 00:42:30,800 00:42:35,133 controlled their regeneration. controlled their regeneration.
761 00:42:35,166 00:42:36,466 We've discovered We've discovered
762 00:42:36,500 00:42:38,600 that part of this control is an electric circuit that part of this control is an electric circuit
763 00:42:38,633 00:42:41,433 that allows these cells to store this kind of information. that allows these cells to store this kind of information.
764 00:42:44,433 00:42:47,533 And what we found is that if we temporarily-- And what we found is that if we temporarily--
765 00:42:47,566 00:42:48,900 just for 48 hours-- just for 48 hours--
766 00:42:48,933 00:42:52,100 alter this electric circuit, and, in essence, alter this electric circuit, and, in essence,
767 00:42:52,133 00:42:55,466 rewrite the finely encoded pattern memory rewrite the finely encoded pattern memory
768 00:42:55,500 00:42:56,500 of these tissues... of these tissues...
769 00:42:59,766 00:43:02,000 When they regenerate, they can regenerate When they regenerate, they can regenerate
770 00:43:02,033 00:43:05,233 as two-headed animals. as two-headed animals.
771 00:43:05,266 00:43:07,666 Michael and his team did this without any kind Michael and his team did this without any kind
772 00:43:07,700 00:43:09,866 of gene editing. of gene editing.
773 00:43:09,900 00:43:12,833 It was done purely through the manipulation of the signals It was done purely through the manipulation of the signals
774 00:43:12,866 00:43:15,200 between its cells. between its cells.
775 00:43:15,233 00:43:17,366 And so this tells you And so this tells you
776 00:43:17,400 00:43:18,900 that the information that is needed that the information that is needed
777 00:43:18,933 00:43:21,133 to specify what kind of body you are going to make to specify what kind of body you are going to make
778 00:43:21,166 00:43:25,400 is not entirely specified in the genome. is not entirely specified in the genome.
779 00:43:25,433 00:43:30,233 Michael says that cells function like electronic processors. Michael says that cells function like electronic processors.
780 00:43:30,266 00:43:32,533 Bioelectricity is the software that is run on these cells, Bioelectricity is the software that is run on these cells,
781 00:43:32,566 00:43:37,533 and it can be rewritten. and it can be rewritten.
782 00:43:39,833 00:43:42,866 Michael wondered if Physarum was using bioelectricity Michael wondered if Physarum was using bioelectricity
783 00:43:42,900 00:43:44,966 as its system of memory. as its system of memory.
784 00:43:47,100 00:43:49,000 What does it mean for a chunk of cytoplasm What does it mean for a chunk of cytoplasm
785 00:43:49,033 00:43:51,400 that you can pick up and hold in your hand and analyze that you can pick up and hold in your hand and analyze
786 00:43:51,433 00:43:52,633 molecularly, electrically, and so on molecularly, electrically, and so on
787 00:43:52,666 00:43:56,133 to really store an experience or a memory to really store an experience or a memory
788 00:43:56,166 00:43:58,933 or an inference from past experiences? or an inference from past experiences?
789 00:43:58,966 00:44:02,000 So they tested Physarum's veins So they tested Physarum's veins
790 00:44:02,033 00:44:04,900 for signs of bioelectrical signals, for signs of bioelectrical signals,
791 00:44:04,933 00:44:09,466 and found that it produced electrical waves and found that it produced electrical waves
792 00:44:09,500 00:44:14,466 that matched the flow of its protoplasm within. that matched the flow of its protoplasm within.
793 00:44:16,033 00:44:18,900 What we're doing is attempting to read the mind What we're doing is attempting to read the mind
794 00:44:18,933 00:44:20,833 of the Physarum. of the Physarum.
795 00:44:20,866 00:44:24,466 As it turns out, reading Physarum's mind As it turns out, reading Physarum's mind
796 00:44:24,500 00:44:27,300 is all about body language. is all about body language.
797 00:44:27,333 00:44:29,300 One of the important things about Physarum, One of the important things about Physarum,
798 00:44:29,333 00:44:34,533 its body structure and its behavior are simultaneous. its body structure and its behavior are simultaneous.
799 00:44:34,566 00:44:37,466 In other words, the behavior of the slime mold is executed In other words, the behavior of the slime mold is executed
800 00:44:37,500 00:44:40,500 by altering its body structure. by altering its body structure.
801 00:44:40,533 00:44:43,733 Meaning, if Physarum was communicating internally Meaning, if Physarum was communicating internally
802 00:44:43,766 00:44:47,333 using bioelectric signals, using bioelectric signals,
803 00:44:47,366 00:44:51,966 those signals would change along with Physarum's shape. those signals would change along with Physarum's shape.
804 00:44:53,500 00:44:57,533 Michael's colleague Andrew Adamatzky Michael's colleague Andrew Adamatzky
805 00:44:57,566 00:44:59,066 attempted to communicate with Physarum attempted to communicate with Physarum
806 00:44:59,100 00:45:02,200 by sending it electrical signals. by sending it electrical signals.
807 00:45:02,233 00:45:05,500 He found that different signals would cause Physarum He found that different signals would cause Physarum
808 00:45:05,533 00:45:08,333 to grow in different ways. to grow in different ways.
809 00:45:08,366 00:45:11,133 Some signals sent between two points Some signals sent between two points
810 00:45:11,166 00:45:13,233 made Physarum reconfigure its body made Physarum reconfigure its body
811 00:45:13,266 00:45:16,333 as it would between two oat flakes. as it would between two oat flakes.
812 00:45:16,366 00:45:19,466 Other signals repelled Physarum, Other signals repelled Physarum,
813 00:45:19,500 00:45:23,866 causing it to shift its body away from the source, causing it to shift its body away from the source,
814 00:45:23,900 00:45:26,866 much in the way it does with salt. much in the way it does with salt.
815 00:45:28,233 00:45:30,833 Andrew and Michael believe that this shows Physarum Andrew and Michael believe that this shows Physarum
816 00:45:30,866 00:45:34,033 is using bioelectricity to process information is using bioelectricity to process information
817 00:45:34,066 00:45:36,866 as it adapts to the world around it, as it adapts to the world around it,
818 00:45:36,900 00:45:41,300 and that Physarum's simple design was a step along the way and that Physarum's simple design was a step along the way
819 00:45:41,333 00:45:44,266 towards the evolution of multicellular organisms towards the evolution of multicellular organisms
820 00:45:44,300 00:45:48,133 with specialized cells like neurons with specialized cells like neurons
821 00:45:48,166 00:45:51,666 and more complex brain circuitry. and more complex brain circuitry.
822 00:45:51,700 00:45:53,533 I think evolution discovered very early on I think evolution discovered very early on
823 00:45:53,566 00:45:56,466 that electricity and the circuits that you can make that electricity and the circuits that you can make
824 00:45:56,500 00:45:58,500 out of very simple electrical components out of very simple electrical components
825 00:45:58,533 00:46:01,966 are an extremely powerful and robust system are an extremely powerful and robust system
826 00:46:02,000 00:46:03,633 for processing information, for processing information,
827 00:46:03,666 00:46:05,300 making decisions, storing memories. making decisions, storing memories.
828 00:46:08,133 00:46:11,100 Things it now appears that Physarum was doing Things it now appears that Physarum was doing
829 00:46:11,133 00:46:17,200 long before the arrival of creatures with brains. long before the arrival of creatures with brains.
830 00:46:27,400 00:46:28,600 We started to wonder We started to wonder
831 00:46:28,633 00:46:31,700 whether a Blob that had learned something whether a Blob that had learned something
832 00:46:31,733 00:46:36,300 could transfer its learning to another Blob. could transfer its learning to another Blob.
833 00:46:36,333 00:46:42,433 could Physarum communicate a memory? could Physarum communicate a memory?
834 00:46:42,466 00:46:44,233 Because of what she had learned Because of what she had learned
835 00:46:44,266 00:46:45,833 about Physarum's shape-shifting nature, about Physarum's shape-shifting nature,
836 00:46:45,866 00:46:48,233 Audrey knew she could cut it into pieces Audrey knew she could cut it into pieces
837 00:46:48,266 00:46:52,466 and it would re-form. and it would re-form.
838 00:46:52,500 00:46:54,666 If you take a Blob and cut it in half, If you take a Blob and cut it in half,
839 00:46:54,700 00:46:57,333 you always end up with two separate Blobs. you always end up with two separate Blobs.
840 00:46:57,366 00:47:00,133 So how does that work? So how does that work?
841 00:47:00,166 00:47:04,033 It works because of Physarum's odd, soupy anatomy. It works because of Physarum's odd, soupy anatomy.
842 00:47:04,066 00:47:08,166 Most single-celled organisms have a single nucleus. Most single-celled organisms have a single nucleus.
843 00:47:08,200 00:47:09,800 When they grow by dividing, When they grow by dividing,
844 00:47:09,833 00:47:13,900 each new cell still has a single nucleus. each new cell still has a single nucleus.
845 00:47:13,933 00:47:15,866 If you were to cut that in half If you were to cut that in half
846 00:47:15,900 00:47:18,800 you'd have two halves of a dead cell. you'd have two halves of a dead cell.
847 00:47:18,833 00:47:23,600 But when Physarum grows, its nuclei divide, But when Physarum grows, its nuclei divide,
848 00:47:23,633 00:47:28,366 and yet they all remain within the same cell membrane. and yet they all remain within the same cell membrane.
849 00:47:28,400 00:47:31,733 And that's why, when you divide one Physarum in half, And that's why, when you divide one Physarum in half,
850 00:47:31,766 00:47:36,266 you will have two complete living Physarum. you will have two complete living Physarum.
851 00:47:36,300 00:47:37,500 And these Physarum And these Physarum
852 00:47:37,533 00:47:40,433 can also join together with any other Physarum can also join together with any other Physarum
853 00:47:40,466 00:47:42,100 that they encounter. that they encounter.
854 00:47:44,533 00:47:47,333 If you then take those two Blobs and put them side by side, If you then take those two Blobs and put them side by side,
855 00:47:47,366 00:47:48,366 they'll combine. they'll combine.
856 00:47:48,400 00:47:52,600 For Blobs, one plus one equals one. For Blobs, one plus one equals one.
857 00:47:52,633 00:47:56,433 The fusion occurs when the two membranes stick together. The fusion occurs when the two membranes stick together.
858 00:47:56,466 00:47:59,166 They open up, and then the networks of veins They open up, and then the networks of veins
859 00:47:59,200 00:48:02,900 connect to create a single, autonomous Blob. connect to create a single, autonomous Blob.
860 00:48:04,566 00:48:07,333 So Audrey brought together thousands of Physarum So Audrey brought together thousands of Physarum
861 00:48:07,366 00:48:09,100 that she had accustomed to salt that she had accustomed to salt
862 00:48:09,133 00:48:14,633 with others that weren't-- so-called naiïve ones. with others that weren't-- so-called naiïve ones.
863 00:48:17,500 00:48:19,933 If we allowed two Blobs to fuse together for three hours, If we allowed two Blobs to fuse together for three hours,
864 00:48:19,966 00:48:23,700 the information passed from one to the other. the information passed from one to the other.
865 00:48:23,733 00:48:27,600 The naiïve Blob now liked salt. The naiïve Blob now liked salt.
866 00:48:27,633 00:48:30,666 It looked as though the memory was passed It looked as though the memory was passed
867 00:48:30,700 00:48:34,600 through the system of veins. through the system of veins.
868 00:48:34,633 00:48:37,666 Slime mold demonstrated the ability to communicate Slime mold demonstrated the ability to communicate
869 00:48:37,700 00:48:40,833 the information it had learned. the information it had learned.
870 00:48:44,166 00:48:46,366 And over time, Audrey began to notice And over time, Audrey began to notice
871 00:48:46,400 00:48:48,800 that Physarum from different places that Physarum from different places
872 00:48:48,833 00:48:52,666 showed different behaviors. showed different behaviors.
873 00:48:52,700 00:48:56,433 To Audrey, this is slime mold personality. To Audrey, this is slime mold personality.
874 00:48:56,466 00:48:58,666 We realized that there were lots of differences We realized that there were lots of differences
875 00:48:58,700 00:49:00,000 between our Blobs. between our Blobs.
876 00:49:00,033 00:49:03,600 Depending on where they came from, Depending on where they came from,
877 00:49:03,633 00:49:07,466 her Physarum seemed to have distinct characteristics. her Physarum seemed to have distinct characteristics.
878 00:49:07,500 00:49:10,500 The Japanese Physarum is fast. The Japanese Physarum is fast.
879 00:49:10,533 00:49:14,833 The Australian careful and well-mannered. The Australian careful and well-mannered.
880 00:49:14,866 00:49:17,500 Its behavior is much more consistent Its behavior is much more consistent
881 00:49:17,533 00:49:18,900 from one day to another from one day to another
882 00:49:18,933 00:49:20,100 and it does not escape. and it does not escape.
883 00:49:20,133 00:49:24,566 The American is... problematic. The American is... problematic.
884 00:49:24,600 00:49:27,166 When the American Blob arrived, When the American Blob arrived,
885 00:49:27,200 00:49:29,600 we gave it organic oat flakes. we gave it organic oat flakes.
886 00:49:29,633 00:49:31,000 And it completely refused. And it completely refused.
887 00:49:31,033 00:49:33,266 It even got out of its box It even got out of its box
888 00:49:33,300 00:49:36,066 because it preferred the well-known American brand. because it preferred the well-known American brand.
889 00:49:39,033 00:49:43,000 She put them to the test in a 250-millimeter dash. She put them to the test in a 250-millimeter dash.
890 00:49:44,566 00:49:47,600 And out of the blocks, Japan is certainly showing speed, And out of the blocks, Japan is certainly showing speed,
891 00:49:47,633 00:49:50,600 with America close behind. with America close behind.
892 00:49:50,633 00:49:51,933 The Japanese Blob The Japanese Blob
893 00:49:51,966 00:49:54,900 is extremely fast, but often makes bad decisions. is extremely fast, but often makes bad decisions.
894 00:49:54,933 00:49:58,100 Australia has not yet started. Australia has not yet started.
895 00:49:58,133 00:49:59,266 The Australian Blob The Australian Blob
896 00:49:59,300 00:50:01,600 takes a little more time to make decisions. takes a little more time to make decisions.
897 00:50:01,633 00:50:05,900 Japan, now sending pseudopods in the wrong direction, Japan, now sending pseudopods in the wrong direction,
898 00:50:05,933 00:50:07,333 has lost its lead to the U.S. has lost its lead to the U.S.
899 00:50:07,366 00:50:10,433 But the U.S. appears to be slowing down, But the U.S. appears to be slowing down,
900 00:50:10,466 00:50:12,133 possibly attempting an escape. possibly attempting an escape.
901 00:50:12,166 00:50:16,000 And Japan takes back the lead. And Japan takes back the lead.
902 00:50:16,033 00:50:19,400 Australia still not sure whether to start. Australia still not sure whether to start.
903 00:50:19,433 00:50:22,300 America, now moving forward again... America, now moving forward again...
904 00:50:22,333 00:50:24,900 And the winner... And the winner...
905 00:50:24,933 00:50:28,266 Japan! Japan!
906 00:50:35,633 00:50:38,033 The discoveries of these pioneers The discoveries of these pioneers
907 00:50:38,066 00:50:40,466 studying cognition in brainless organisms studying cognition in brainless organisms
908 00:50:40,500 00:50:44,866 have scientists rethinking thinking. have scientists rethinking thinking.
909 00:50:44,900 00:50:48,966 Organisms like slime mold provide a window Organisms like slime mold provide a window
910 00:50:49,000 00:50:50,700 into evolution's early experiments into evolution's early experiments
911 00:50:50,733 00:50:53,666 in problem solving. in problem solving.
912 00:50:53,700 00:50:56,633 We're just starting to scratch the surface of understanding We're just starting to scratch the surface of understanding
913 00:50:56,666 00:50:58,966 the cognitive capabilities of these really the cognitive capabilities of these really
914 00:50:59,000 00:51:03,233 radically different biological architectures. radically different biological architectures.
915 00:51:03,266 00:51:08,133 We can think of them as how intelligence started way back. We can think of them as how intelligence started way back.
916 00:51:08,166 00:51:10,333 The early origins of decision making. The early origins of decision making.
917 00:51:10,366 00:51:14,000 We can also learn a little bit about some of the rules We can also learn a little bit about some of the rules
918 00:51:14,033 00:51:15,566 that underlie problem solving that underlie problem solving
919 00:51:15,600 00:51:17,566 across lots of different types of systems. across lots of different types of systems.
920 00:51:19,533 00:51:22,633 And more importantly, for us, at least, And more importantly, for us, at least,
921 00:51:22,666 00:51:25,566 early solutions to problem solving like these early solutions to problem solving like these
922 00:51:25,600 00:51:29,966 would lead to the specialization of cells. would lead to the specialization of cells.
923 00:51:30,000 00:51:32,366 They're an example of the most basic form They're an example of the most basic form
924 00:51:32,400 00:51:33,733 of multicellularity. of multicellularity.
925 00:51:33,766 00:51:36,833 They don't have organs or anything like that, They don't have organs or anything like that,
926 00:51:36,866 00:51:39,133 but they're the very beginning of what we would expect to see but they're the very beginning of what we would expect to see
927 00:51:39,166 00:51:41,333 in multicellular life. in multicellular life.
928 00:51:41,366 00:51:45,233 Neurons did not appear from scratch during evolution, Neurons did not appear from scratch during evolution,
929 00:51:45,266 00:51:47,400 but actually are the result but actually are the result
930 00:51:47,433 00:51:49,733 of the specialization of much more ancient cells. of the specialization of much more ancient cells.
931 00:51:49,766 00:51:52,900 All of the machinery thatwe find in neurons, in synapses, All of the machinery thatwe find in neurons, in synapses,
932 00:51:52,933 00:51:54,200 all of these things were present all of these things were present
933 00:51:54,233 00:51:57,166 even in our unicellular ancestor. even in our unicellular ancestor.
934 00:51:57,200 00:52:01,033 and eventually, to creatures like us. and eventually, to creatures like us.
934 00:51:57,200 00:52:01,033 and eventually, to creatures like us. and eventually, to creatures like us.