Deborah Gordon: What ants teach us about the brain, cancer and the Internet

78,465 views ・ 2014-05-13

TED


Please double-click on the English subtitles below to play the video.

00:13
I study ants
0
13099
1619
00:14
in the desert, in the tropical forest
1
14718
3297
00:18
and in my kitchen,
2
18015
1528
00:19
and in the hills around Silicon Valley where I live.
3
19543
4020
00:23
I've recently realized that ants
4
23563
1676
00:25
are using interactions differently
5
25239
2278
00:27
in different environments,
6
27517
1828
00:29
and that got me thinking that we could learn from this
7
29345
2000
00:31
about other systems,
8
31345
1555
00:32
like brains and data networks that we engineer,
9
32900
5588
00:38
and even cancer.
10
38488
2846
00:41
So what all these systems have in common
11
41334
1752
00:43
is that there's no central control.
12
43086
2857
00:45
An ant colony consists of sterile female workers --
13
45943
3820
00:49
those are the ants you see walking around —
14
49763
2386
00:52
and then one or more reproductive females
15
52149
2156
00:54
who just lay the eggs.
16
54305
2103
00:56
They don't give any instructions.
17
56408
2009
00:58
Even though they're called queens,
18
58417
1984
01:00
they don't tell anybody what to do.
19
60401
2165
01:02
So in an ant colony, there's no one in charge,
20
62566
3276
01:05
and all systems like this without central control
21
65842
2778
01:08
are regulated using very simple interactions.
22
68620
3919
01:12
Ants interact using smell.
23
72549
2727
01:15
They smell with their antennae,
24
75276
2187
01:17
and they interact with their antennae,
25
77463
2761
01:20
so when one ant touches another with its antennae,
26
80224
3009
01:23
it can tell, for example, if the other ant
27
83233
1607
01:24
is a nestmate
28
84840
1634
01:26
and what task that other ant has been doing.
29
86474
4236
01:30
So here you see a lot of ants moving around
30
90710
3200
01:33
and interacting in a lab arena
31
93910
1933
01:35
that's connected by tubes to two other arenas.
32
95843
3438
01:39
So when one ant meets another,
33
99281
2504
01:41
it doesn't matter which ant it meets,
34
101785
2089
01:43
and they're actually not transmitting
35
103874
1885
01:45
any kind of complicated signal or message.
36
105759
3465
01:49
All that matters to the ant is the rate
37
109224
2111
01:51
at which it meets other ants.
38
111335
2821
01:54
And all of these interactions, taken together,
39
114156
2757
01:56
produce a network.
40
116913
2505
01:59
So this is the network of the ants
41
119418
2210
02:01
that you just saw moving around in the arena,
42
121628
2644
02:04
and it's this constantly shifting network
43
124272
3287
02:07
that produces the behavior of the colony,
44
127559
2520
02:10
like whether all the ants are hiding inside the nest,
45
130079
2881
02:12
or how many are going out to forage.
46
132960
2694
02:15
A brain actually works in the same way,
47
135654
1759
02:17
but what's great about ants is
48
137413
1500
02:18
that you can see the whole network as it happens.
49
138913
4867
02:23
There are more than 12,000 species of ants,
50
143780
3100
02:26
in every conceivable environment,
51
146880
2125
02:29
and they're using interactions differently
52
149005
2649
02:31
to meet different environmental challenges.
53
151654
2768
02:34
So one important environmental challenge
54
154422
2305
02:36
that every system has to deal with
55
156727
1870
02:38
is operating costs, just what it takes
56
158597
2083
02:40
to run the system.
57
160680
2265
02:42
And another environmental challenge is resources,
58
162945
2548
02:45
finding them and collecting them.
59
165493
2336
02:47
In the desert, operating costs are high
60
167829
2783
02:50
because water is scarce,
61
170612
1773
02:52
and the seed-eating ants that I study in the desert
62
172385
2499
02:54
have to spend water to get water.
63
174884
2900
02:57
So an ant outside foraging,
64
177784
2139
02:59
searching for seeds in the hot sun,
65
179923
2037
03:01
just loses water into the air.
66
181960
2007
03:03
But the colony gets its water
67
183967
1664
03:05
by metabolizing the fats out of the seeds
68
185631
1766
03:07
that they eat.
69
187397
1934
03:09
So in this environment, interactions are used
70
189331
3159
03:12
to activate foraging.
71
192490
1549
03:14
An outgoing forager doesn't go out unless
72
194039
2264
03:16
it gets enough interactions with returning foragers,
73
196303
2573
03:18
and what you see are the returning foragers
74
198876
1990
03:20
going into the tunnel, into the nest,
75
200866
1824
03:22
and meeting outgoing foragers on their way out.
76
202690
2636
03:25
This makes sense for the ant colony,
77
205326
1623
03:26
because the more food there is out there,
78
206949
2323
03:29
the more quickly the foragers find it,
79
209272
1851
03:31
the faster they come back,
80
211123
1236
03:32
and the more foragers they send out.
81
212359
2801
03:35
The system works to stay stopped,
82
215160
2507
03:37
unless something positive happens.
83
217667
2015
03:39
So interactions function to activate foragers.
84
219682
3881
03:43
And we've been studying the evolution of this system.
85
223563
2907
03:46
First of all, there's variation.
86
226470
1091
03:47
It turns out that colonies are different.
87
227561
2479
03:50
On dry days, some colonies forage less,
88
230040
2696
03:52
so colonies are different in how
89
232736
1505
03:54
they manage this trade-off
90
234241
1354
03:55
between spending water to search for seeds
91
235595
3168
03:58
and getting water back in the form of seeds.
92
238763
3320
04:02
And we're trying to understand why
93
242083
1719
04:03
some colonies forage less than others
94
243802
2140
04:05
by thinking about ants as neurons,
95
245942
2325
04:08
using models from neuroscience.
96
248267
2338
04:10
So just as a neuron adds up its stimulation
97
250605
2674
04:13
from other neurons to decide whether to fire,
98
253279
2006
04:15
an ant adds up its stimulation from other ants
99
255285
2885
04:18
to decide whether to forage.
100
258170
2023
04:20
And what we're looking for is whether there might be
101
260193
1637
04:21
small differences among colonies
102
261830
1992
04:23
in how many interactions each ant needs
103
263822
3314
04:27
before it's willing to go out and forage,
104
267136
1926
04:29
because a colony like that would forage less.
105
269062
3767
04:32
And this raises an analogous question about brains.
106
272829
3139
04:35
We talk about the brain,
107
275968
1412
04:37
but of course every brain is slightly different,
108
277380
2890
04:40
and maybe there are some individuals
109
280270
1379
04:41
or some conditions
110
281649
1319
04:42
in which the electrical properties of neurons are such
111
282968
3222
04:46
that they require more stimulus to fire,
112
286190
3870
04:50
and that would lead to differences in brain function.
113
290060
3726
04:53
So in order to ask evolutionary questions,
114
293786
2334
04:56
we need to know about reproductive success.
115
296120
2679
04:58
This is a map of the study site
116
298799
2325
05:01
where I have been tracking this population
117
301124
2553
05:03
of harvester ant colonies for 28 years,
118
303677
3293
05:06
which is about as long as a colony lives.
119
306970
2262
05:09
Each symbol is a colony,
120
309232
2099
05:11
and the size of the symbol is how many offspring it had,
121
311331
3266
05:14
because we were able to use genetic variation
122
314597
1913
05:16
to match up parent and offspring colonies,
123
316510
2711
05:19
that is, to figure out which colonies
124
319221
3297
05:22
were founded by a daughter queen
125
322518
1925
05:24
produced by which parent colony.
126
324443
2068
05:26
And this was amazing for me, after all these years,
127
326511
2002
05:28
to find out, for example, that colony 154,
128
328513
3128
05:31
whom I've known well for many years,
129
331641
2176
05:33
is a great-grandmother.
130
333817
1819
05:35
Here's her daughter colony,
131
335636
1740
05:37
here's her granddaughter colony,
132
337376
2684
05:40
and these are her great-granddaughter colonies.
133
340060
2392
05:42
And by doing this, I was able to learn
134
342452
2025
05:44
that offspring colonies resemble parent colonies
135
344477
3283
05:47
in their decisions about which days are so hot
136
347760
2217
05:49
that they don't forage,
137
349977
1778
05:51
and the offspring of parent colonies
138
351755
1464
05:53
live so far from each other that the ants never meet,
139
353219
2906
05:56
so the ants of the offspring colony
140
356125
2289
05:58
can't be learning this from the parent colony.
141
358414
2244
06:00
And so our next step is to look
142
360658
1381
06:02
for the genetic variation underlying this resemblance.
143
362039
5276
06:07
So then I was able to ask, okay, who's doing better?
144
367315
4125
06:11
Over the time of the study,
145
371440
1460
06:12
and especially in the past 10 years,
146
372900
1465
06:14
there's been a very severe and deepening drought
147
374365
3308
06:17
in the Southwestern U.S.,
148
377673
2127
06:19
and it turns out that the colonies that conserve water,
149
379800
3053
06:22
that stay in when it's really hot outside,
150
382853
4429
06:27
and thus sacrifice getting as much food as possible,
151
387282
2632
06:29
are the ones more likely to have offspring colonies.
152
389914
2945
06:32
So all this time, I thought that colony 154
153
392859
2269
06:35
was a loser, because on really dry days,
154
395128
2670
06:37
there'd be just this trickle of foraging,
155
397798
1868
06:39
while the other colonies were out
156
399666
1591
06:41
foraging, getting lots of food,
157
401257
2117
06:43
but in fact, colony 154 is a huge success.
158
403374
3020
06:46
She's a matriarch.
159
406394
1332
06:47
She's one of the rare great-grandmothers on the site.
160
407726
3052
06:50
To my knowledge, this is the first time
161
410778
2785
06:53
that we've been able to track
162
413563
1639
06:55
the ongoing evolution of collective behavior
163
415202
3001
06:58
in a natural population of animals
164
418203
2117
07:00
and find out what's actually working best.
165
420320
4657
07:04
Now, the Internet uses an algorithm
166
424977
2421
07:07
to regulate the flow of data
167
427398
2853
07:10
that's very similar to the one
168
430251
2227
07:12
that the harvester ants are using to regulate
169
432478
2376
07:14
the flow of foragers.
170
434854
1541
07:16
And guess what we call this analogy?
171
436395
3366
07:19
The anternet is coming.
172
439761
1518
07:21
(Applause)
173
441279
1721
07:23
So data doesn't leave the source computer
174
443000
3454
07:26
unless it gets a signal that there's enough bandwidth
175
446454
2861
07:29
for it to travel on.
176
449315
2729
07:32
In the early days of the Internet,
177
452044
1441
07:33
when operating costs were really high
178
453485
2274
07:35
and it was really important not to lose any data,
179
455759
3227
07:38
then the system was set up for interactions
180
458986
2157
07:41
to activate the flow of data.
181
461143
3062
07:44
It's interesting that the ants are using an algorithm
182
464205
2385
07:46
that's so similar to the one that we recently invented,
183
466590
3896
07:50
but this is only one of a handful of ant algorithms
184
470486
2953
07:53
that we know about,
185
473439
1419
07:54
and ants have had 130 million years
186
474858
3193
07:58
to evolve a lot of good ones,
187
478051
2026
08:00
and I think it's very likely
188
480077
1506
08:01
that some of the other 12,000 species
189
481583
2557
08:04
are going to have interesting algorithms
190
484140
2697
08:06
for data networks
191
486837
1024
08:07
that we haven't even thought of yet.
192
487861
2697
08:10
So what happens when operating costs are low?
193
490558
3085
08:13
Operating costs are low in the tropics,
194
493643
1787
08:15
because it's very humid, and it's easy for the ants
195
495430
2096
08:17
to be outside walking around.
196
497526
2824
08:20
But the ants are so abundant
197
500350
1653
08:22
and diverse in the tropics
198
502003
1818
08:23
that there's a lot of competition.
199
503821
2598
08:26
Whatever resource one species is using,
200
506419
1952
08:28
another species is likely to be using that
201
508371
3172
08:31
at the same time.
202
511543
2379
08:33
So in this environment, interactions are used
203
513922
2608
08:36
in the opposite way.
204
516530
1945
08:38
The system keeps going
205
518475
1395
08:39
unless something negative happens,
206
519870
1554
08:41
and one species that I study makes circuits
207
521424
2167
08:43
in the trees of foraging ants
208
523591
2159
08:45
going from the nest to a food source and back,
209
525750
2981
08:48
just round and round,
210
528731
1329
08:50
unless something negative happens,
211
530060
1442
08:51
like an interaction
212
531502
1609
08:53
with ants of another species.
213
533111
2739
08:55
So here's an example of ant security.
214
535850
2937
08:58
In the middle, there's an ant
215
538787
1858
09:00
plugging the nest entrance with its head
216
540645
2463
09:03
in response to interactions with another species.
217
543108
2993
09:06
Those are the little ones running around
218
546101
1659
09:07
with their abdomens up in the air.
219
547760
2751
09:10
But as soon as the threat is passed,
220
550511
2046
09:12
the entrance is open again,
221
552557
2755
09:15
and maybe there are situations
222
555312
1790
09:17
in computer security
223
557102
1089
09:18
where operating costs are low enough
224
558191
2206
09:20
that we could just block access temporarily
225
560397
3375
09:23
in response to an immediate threat,
226
563772
2193
09:25
and then open it again,
227
565965
2026
09:27
instead of trying to build
228
567991
1269
09:29
a permanent firewall or fortress.
229
569260
3980
09:33
So another environmental challenge
230
573240
1940
09:35
that all systems have to deal with
231
575180
1695
09:36
is resources, finding and collecting them.
232
576875
5452
09:42
And to do this, ants solve the problem
233
582327
1673
09:44
of collective search,
234
584000
1258
09:45
and this is a problem that's of great interest
235
585258
1576
09:46
right now in robotics,
236
586834
1484
09:48
because we've understood that,
237
588318
1732
09:50
rather than sending a single,
238
590050
1614
09:51
sophisticated, expensive robot out
239
591664
3495
09:55
to explore another planet
240
595159
1417
09:56
or to search a burning building,
241
596576
2567
09:59
that instead, it may be more effective
242
599143
2600
10:01
to get a group of cheaper robots
243
601743
4377
10:06
exchanging only minimal information,
244
606120
2545
10:08
and that's the way that ants do it.
245
608665
2799
10:11
So the invasive Argentine ant
246
611464
1765
10:13
makes expandable search networks.
247
613229
2330
10:15
They're good at dealing with the main problem
248
615559
2273
10:17
of collective search,
249
617832
1331
10:19
which is the trade-off between
250
619163
2566
10:21
searching very thoroughly
251
621729
1336
10:23
and covering a lot of ground.
252
623065
1997
10:25
And what they do is,
253
625062
895
10:25
when there are many ants in a small space,
254
625957
2387
10:28
then each one can search very thoroughly
255
628344
2213
10:30
because there will be another ant nearby
256
630557
1624
10:32
searching over there,
257
632181
1357
10:33
but when there are a few ants
258
633538
1647
10:35
in a large space,
259
635185
2055
10:37
then they need to stretch out their paths
260
637240
2414
10:39
to cover more ground.
261
639654
1803
10:41
I think they use interactions to assess density,
262
641457
2954
10:44
so when they're really crowded,
263
644411
1229
10:45
they meet more often,
264
645640
1102
10:46
and they search more thoroughly.
265
646742
2465
10:49
Different ant species must use different algorithms,
266
649207
3400
10:52
because they've evolved to deal with
267
652607
2522
10:55
different resources,
268
655129
1671
10:56
and it could be really useful to know about this,
269
656800
2559
10:59
and so we recently asked ants
270
659359
1642
11:01
to solve the collective search problem
271
661001
2450
11:03
in the extreme environment
272
663451
1368
11:04
of microgravity
273
664819
1558
11:06
in the International Space Station.
274
666377
1976
11:08
When I first saw this picture, I thought,
275
668353
1545
11:09
Oh no, they've mounted the habitat vertically,
276
669898
2857
11:12
but then I realized that, of course, it doesn't matter.
277
672755
2618
11:15
So the idea here is that the ants
278
675373
2637
11:18
are working so hard to hang on
279
678010
1970
11:19
to the wall or the floor or whatever you call it
280
679980
3057
11:23
that they're less likely to interact,
281
683037
3009
11:26
and so the relationship between
282
686046
1244
11:27
how crowded they are and how often they meet
283
687290
2120
11:29
would be messed up.
284
689410
1725
11:31
We're still analyzing the data.
285
691135
1395
11:32
I don't have the results yet.
286
692530
1964
11:34
But it would be interesting to know
287
694494
1694
11:36
how other species solve this problem
288
696188
2459
11:38
in different environments on Earth,
289
698647
2564
11:41
and so we're setting up a program
290
701211
1266
11:42
to encourage kids around the world
291
702477
2160
11:44
to try this experiment with different species.
292
704637
2536
11:47
It's very simple.
293
707173
1767
11:48
It can be done with cheap materials.
294
708940
2090
11:51
And that way, we could make a global map
295
711030
2833
11:53
of ant collective search algorithms.
296
713863
3347
11:57
And I think it's pretty likely that the invasive species,
297
717210
2483
11:59
the ones that come into our buildings,
298
719693
2149
12:01
are going to be really good at this,
299
721842
1742
12:03
because they're in your kitchen
300
723584
1848
12:05
because they're really good at finding food and water.
301
725432
3907
12:09
So the most familiar resource for ants
302
729339
3265
12:12
is a picnic,
303
732604
1315
12:13
and this is a clustered resource.
304
733919
2145
12:16
When there's one piece of fruit,
305
736064
999
12:17
there's likely to be another piece of fruit nearby,
306
737063
2515
12:19
and the ants that specialize on clustered resources
307
739578
3432
12:23
use interactions for recruitment.
308
743010
1942
12:24
So when one ant meets another,
309
744952
1277
12:26
or when it meets a chemical deposited
310
746229
1625
12:27
on the ground by another,
311
747854
1736
12:29
then it changes direction to follow
312
749590
1833
12:31
in the direction of the interaction,
313
751423
1573
12:32
and that's how you get the trail of ants
314
752996
1977
12:34
sharing your picnic.
315
754973
1413
12:36
Now this is a place where I think we might be able
316
756386
1695
12:38
to learn something from ants about cancer.
317
758081
3741
12:41
I mean, first, it's obvious that we could do a lot
318
761822
1981
12:43
to prevent cancer
319
763803
1610
12:45
by not allowing people to spread around
320
765413
2577
12:47
or sell the toxins that promote
321
767990
1944
12:49
the evolution of cancer in our bodies,
322
769934
2780
12:52
but I don't think the ants can help us much with this
323
772714
2346
12:55
because ants never poison their own colonies.
324
775060
3358
12:58
But we might be able to learn something from ants
325
778418
1332
12:59
about treating cancer.
326
779750
1763
13:01
There are many different kinds of cancer.
327
781513
2225
13:03
Each one originates in a particular part of the body,
328
783738
2978
13:06
and then some kinds of cancer will spread
329
786716
2966
13:09
or metastasize to particular other tissues
330
789682
2830
13:12
where they must be getting resources that they need.
331
792512
2880
13:15
So if you think from the perspective
332
795392
1808
13:17
of early metastatic cancer cells
333
797200
1950
13:19
as they're out searching around
334
799150
1623
13:20
for the resources that they need,
335
800773
2317
13:23
if those resources are clustered,
336
803090
1983
13:25
they're likely to use interactions for recruitment,
337
805073
3013
13:28
and if we can figure out how cancer cells are recruiting,
338
808086
3093
13:31
then maybe we could set traps
339
811179
2347
13:33
to catch them before they become established.
340
813526
4049
13:37
So ants are using interactions in different ways
341
817575
3235
13:40
in a huge variety of environments,
342
820810
2602
13:43
and we could learn from this
343
823412
1821
13:45
about other systems that operate
344
825233
1777
13:47
without central control.
345
827010
2337
13:49
Using only simple interactions,
346
829347
1979
13:51
ant colonies have been performing
347
831326
1795
13:53
amazing feats for more than 130 million years.
348
833121
3633
13:56
We have a lot to learn from them.
349
836754
2140
13:58
Thank you.
350
838894
2738
14:01
(Applause)
351
841632
2733
About this website

This site will introduce you to YouTube videos that are useful for learning English. You will see English lessons taught by top-notch teachers from around the world. Double-click on the English subtitles displayed on each video page to play the video from there. The subtitles scroll in sync with the video playback. If you have any comments or requests, please contact us using this contact form.

https://forms.gle/WvT1wiN1qDtmnspy7