Hendrik Poinar: Bring back the woolly mammoth!

243,131 views ・ 2013-05-30

TED


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

00:00
Translator: Joseph Geni Reviewer: Morton Bast
0
0
7000
00:12
When I was a young boy,
1
12868
1786
00:14
I used to gaze through the microscope of my father
2
14654
2608
00:17
at the insects in amber that he kept in the house.
3
17262
3358
00:20
And they were remarkably well preserved,
4
20620
2557
00:23
morphologically just phenomenal.
5
23177
2245
00:25
And we used to imagine that someday,
6
25422
2194
00:27
they would actually come to life
7
27616
1609
00:29
and they would crawl out of the resin,
8
29225
1997
00:31
and, if they could, they would fly away.
9
31222
2744
00:33
If you had asked me 10 years ago whether or not
10
33966
2376
00:36
we would ever be able to sequence the genome of extinct animals,
11
36342
3198
00:39
I would have told you, it's unlikely.
12
39540
2475
00:42
If you had asked whether or not we would actually be able
13
42015
1895
00:43
to revive an extinct species,
14
43910
2152
00:46
I would have said, pipe dream.
15
46062
1659
00:47
But I'm actually standing here today, amazingly,
16
47721
2525
00:50
to tell you that not only is the sequencing
17
50246
2007
00:52
of extinct genomes a possibility, actually a modern-day reality,
18
52253
4190
00:56
but the revival of an extinct species is actually within reach,
19
56443
4293
01:00
maybe not from the insects in amber --
20
60736
1839
01:02
in fact, this mosquito was actually used
21
62575
1960
01:04
for the inspiration for "Jurassic Park" —
22
64535
2352
01:06
but from woolly mammoths, the well preserved remains
23
66887
2560
01:09
of woolly mammoths in the permafrost.
24
69447
2207
01:11
Woollies are a particularly interesting,
25
71654
2073
01:13
quintessential image of the Ice Age.
26
73727
2546
01:16
They were large. They were hairy.
27
76273
1825
01:18
They had large tusks, and we seem to have
28
78098
1984
01:20
a very deep connection with them, like we do with elephants.
29
80082
2900
01:22
Maybe it's because elephants share
30
82982
2515
01:25
many things in common with us.
31
85497
1822
01:27
They bury their dead. They educate the next of kin.
32
87319
2728
01:30
They have social knits that are very close.
33
90047
3020
01:33
Or maybe it's actually because we're bound by deep time,
34
93067
2870
01:35
because elephants, like us, share their origins in Africa
35
95937
3338
01:39
some seven million years ago,
36
99275
2123
01:41
and as habitats changed and environments changed,
37
101398
2794
01:44
we actually, like the elephants, migrated out
38
104192
3610
01:47
into Europe and Asia.
39
107802
2220
01:50
So the first large mammoth that appears on the scene
40
110022
2703
01:52
is meridionalis, which was standing four meters tall
41
112725
3406
01:56
weighing about 10 tons, and was a woodland-adapted species
42
116131
3832
01:59
and spread from Western Europe clear across Central Asia,
43
119963
2962
02:02
across the Bering land bridge
44
122925
2250
02:05
and into parts of North America.
45
125175
2310
02:07
And then, again, as climate changed as it always does,
46
127485
2688
02:10
and new habitats opened up,
47
130173
1510
02:11
we had the arrival of a steppe-adapted species
48
131683
2476
02:14
called trogontherii in Central Asia
49
134159
2248
02:16
pushing meridionalis out into Western Europe.
50
136407
2750
02:19
And the open grassland savannas of North America
51
139157
2395
02:21
opened up, leading to the Columbian mammoth,
52
141552
2160
02:23
a large, hairless species in North America.
53
143712
2540
02:26
And it was really only about 500,000 years later
54
146252
2911
02:29
that we had the arrival of the woolly,
55
149163
2705
02:31
the one that we all know and love so much,
56
151868
2028
02:33
spreading from an East Beringian point of origin
57
153896
3310
02:37
across Central Asia, again pushing the trogontherii
58
157206
2886
02:40
out through Central Europe,
59
160092
1651
02:41
and over hundreds of thousands of years
60
161743
2066
02:43
migrating back and forth across the Bering land bridge
61
163809
3084
02:46
during times of glacial peaks
62
166893
2027
02:48
and coming into direct contact
63
168920
1796
02:50
with the Columbian relatives living in the south,
64
170716
2804
02:53
and there they survive over hundreds of thousands of years
65
173520
3288
02:56
during traumatic climatic shifts.
66
176808
2177
02:58
So there's a highly plastic animal dealing with great transitions
67
178985
4216
03:03
in temperature and environment, and doing very, very well.
68
183201
2848
03:06
And there they survive on the mainland until about 10,000 years ago,
69
186049
3991
03:10
and actually, surprisingly, on the small islands off of Siberia
70
190040
3153
03:13
and Alaska until about 3,000 years ago.
71
193193
2474
03:15
So Egyptians are building pyramids
72
195667
1689
03:17
and woollies are still living on islands.
73
197356
2766
03:20
And then they disappear.
74
200122
1549
03:21
Like 99 percent of all the animals that have once lived,
75
201671
2254
03:23
they go extinct, likely due to a warming climate
76
203925
3263
03:27
and fast-encroaching dense forests
77
207204
2082
03:29
that are migrating north,
78
209286
1501
03:30
and also, as the late, great Paul Martin once put it,
79
210787
2973
03:33
probably Pleistocene overkill,
80
213760
1751
03:35
so the large game hunters that took them down.
81
215511
2573
03:38
Fortunately, we find millions of their remains
82
218084
2262
03:40
strewn across the permafrost buried deep
83
220346
2677
03:43
in Siberia and Alaska, and we can actually go up there
84
223023
3125
03:46
and actually take them out.
85
226148
1910
03:48
And the preservation is, again,
86
228058
1524
03:49
like those insects in [amber], phenomenal.
87
229582
2570
03:52
So you have teeth, bones with blood
88
232152
3520
03:55
which look like blood, you have hair,
89
235672
2040
03:57
and you have intact carcasses or heads
90
237712
1527
03:59
which still have brains in them.
91
239239
2943
04:02
So the preservation and the survival of DNA
92
242182
2371
04:04
depends on many factors, and I have to admit,
93
244553
2072
04:06
most of which we still don't quite understand,
94
246625
2328
04:08
but depending upon when an organism dies
95
248953
2072
04:11
and how quickly he's buried, the depth of that burial,
96
251025
4489
04:15
the constancy of the temperature of that burial environment,
97
255514
3302
04:18
will ultimately dictate how long DNA will survive
98
258816
2568
04:21
over geologically meaningful time frames.
99
261384
2861
04:24
And it's probably surprising to many of you
100
264245
1644
04:25
sitting in this room that it's not the time that matters,
101
265889
3140
04:29
it's not the length of preservation,
102
269029
1627
04:30
it's the consistency of the temperature of that preservation that matters most.
103
270656
3982
04:34
So if we were to go deep now within the bones
104
274638
2819
04:37
and the teeth that actually survived the fossilization process,
105
277457
2975
04:40
the DNA which was once intact, tightly wrapped
106
280432
3392
04:43
around histone proteins, is now under attack
107
283824
2368
04:46
by the bacteria that lived symbiotically with the mammoth
108
286192
2966
04:49
for years during its lifetime.
109
289158
1810
04:50
So those bacteria, along with the environmental bacteria,
110
290968
3201
04:54
free water and oxygen, actually break apart the DNA
111
294169
3703
04:57
into smaller and smaller and smaller DNA fragments,
112
297872
2545
05:00
until all you have are fragments that range
113
300417
2321
05:02
from 10 base pairs to, in the best case scenarios,
114
302738
2681
05:05
a few hundred base pairs in length.
115
305419
2373
05:07
So most fossils out there in the fossil record
116
307792
2311
05:10
are actually completely devoid of all organic signatures.
117
310103
2713
05:12
But a few of them actually have DNA fragments
118
312816
2433
05:15
that survive for thousands,
119
315249
1874
05:17
even a few millions of years in time.
120
317123
3749
05:20
And using state-of-the-art clean room technology,
121
320872
2188
05:23
we've devised ways that we can actually pull these DNAs
122
323060
2664
05:25
away from all the rest of the gunk in there,
123
325724
2504
05:28
and it's not surprising to any of you sitting in the room
124
328228
2199
05:30
that if I take a mammoth bone or a tooth
125
330427
2121
05:32
and I extract its DNA that I'll get mammoth DNA,
126
332548
2999
05:35
but I'll also get all the bacteria that once lived with the mammoth,
127
335547
3811
05:39
and, more complicated, I'll get all the DNA
128
339358
2247
05:41
that survived in that environment with it,
129
341605
2184
05:43
so the bacteria, the fungi, and so on and so forth.
130
343789
3174
05:46
Not surprising then again that a mammoth
131
346963
2405
05:49
preserved in the permafrost will have something
132
349368
1672
05:51
on the order of 50 percent of its DNA being mammoth,
133
351040
2868
05:53
whereas something like the Columbian mammoth,
134
353908
2023
05:55
living in a temperature and buried in a temperate environment
135
355931
2617
05:58
over its laying-in will only have 3 to 10 percent endogenous.
136
358548
3817
06:02
But we've come up with very clever ways
137
362365
2443
06:04
that we can actually discriminate, capture and discriminate,
138
364808
3106
06:07
the mammoth from the non-mammoth DNA,
139
367914
1975
06:09
and with the advances in high-throughput sequencing,
140
369889
2550
06:12
we can actually pull out and bioinformatically
141
372439
2837
06:15
re-jig all these small mammoth fragments
142
375276
2969
06:18
and place them onto a backbone
143
378245
2297
06:20
of an Asian or African elephant chromosome.
144
380542
2559
06:23
And so by doing that, we can actually get all the little points
145
383101
2576
06:25
that discriminate between a mammoth and an Asian elephant,
146
385677
2825
06:28
and what do we know, then, about a mammoth?
147
388502
3039
06:31
Well, the mammoth genome is almost at full completion,
148
391541
3153
06:34
and we know that it's actually really big. It's mammoth.
149
394694
3541
06:38
So a hominid genome is about three billion base pairs,
150
398235
3185
06:41
but an elephant and mammoth genome
151
401420
1577
06:42
is about two billion base pairs larger, and most of that
152
402997
2656
06:45
is composed of small, repetitive DNAs
153
405653
2624
06:48
that make it very difficult to actually re-jig the entire structure of the genome.
154
408277
4633
06:52
So having this information allows us to answer
155
412910
2361
06:55
one of the interesting relationship questions
156
415271
2135
06:57
between mammoths and their living relatives,
157
417406
2172
06:59
the African and the Asian elephant,
158
419578
2044
07:01
all of which shared an ancestor seven million years ago,
159
421622
3167
07:04
but the genome of the mammoth shows it to share
160
424789
2089
07:06
a most recent common ancestor with Asian elephants
161
426878
2780
07:09
about six million years ago,
162
429658
1416
07:11
so slightly closer to the Asian elephant.
163
431074
2473
07:13
With advances in ancient DNA technology,
164
433547
2724
07:16
we can actually now start to begin to sequence
165
436271
1953
07:18
the genomes of those other extinct mammoth forms that I mentioned,
166
438224
3311
07:21
and I just wanted to talk about two of them,
167
441535
1887
07:23
the woolly and the Columbian mammoth,
168
443422
2054
07:25
both of which were living very close to each other
169
445476
2418
07:27
during glacial peaks,
170
447894
2625
07:30
so when the glaciers were massive in North America,
171
450519
2163
07:32
the woollies were pushed into these subglacial ecotones,
172
452682
2595
07:35
and came into contact with the relatives living to the south,
173
455277
3211
07:38
and there they shared refugia,
174
458488
2012
07:40
and a little bit more than the refugia, it turns out.
175
460500
2384
07:42
It looks like they were interbreeding.
176
462884
2500
07:45
And that this is not an uncommon feature
177
465384
1633
07:47
in Proboscideans, because it turns out
178
467017
1638
07:48
that large savanna male elephants will outcompete
179
468655
2913
07:51
the smaller forest elephants for their females.
180
471568
3368
07:54
So large, hairless Columbians
181
474936
2312
07:57
outcompeting the smaller male woollies.
182
477248
1803
07:59
It reminds me a bit of high school, unfortunately.
183
479051
2618
08:01
(Laughter)
184
481669
2339
08:04
So this is not trivial, given the idea that we want
185
484008
2694
08:06
to revive extinct species, because it turns out
186
486702
2205
08:08
that an African and an Asian elephant
187
488907
1820
08:10
can actually interbreed and have live young,
188
490727
2095
08:12
and this has actually occurred by accident in a zoo
189
492822
2141
08:14
in Chester, U.K., in 1978.
190
494963
3042
08:18
So that means that we can actually take Asian elephant chromosomes,
191
498005
3146
08:21
modify them into all those positions we've actually now
192
501151
2158
08:23
been able to discriminate with the mammoth genome,
193
503309
2384
08:25
we can put that into an enucleated cell,
194
505693
2781
08:28
differentiate that into a stem cell,
195
508474
2259
08:30
subsequently differentiate that maybe into a sperm,
196
510733
2320
08:33
artificially inseminate an Asian elephant egg,
197
513053
2624
08:35
and over a long and arduous procedure,
198
515677
3107
08:38
actually bring back something that looks like this.
199
518784
3509
08:42
Now, this wouldn't be an exact replica,
200
522293
1690
08:43
because the short DNA fragments that I told you about
201
523983
2482
08:46
will prevent us from building the exact structure,
202
526465
2481
08:48
but it would make something that looked and felt
203
528946
1536
08:50
very much like a woolly mammoth did.
204
530482
3107
08:53
Now, when I bring up this with my friends,
205
533589
2744
08:56
we often talk about, well, where would you put it?
206
536333
2608
08:58
Where are you going to house a mammoth?
207
538941
1688
09:00
There's no climates or habitats suitable.
208
540629
2040
09:02
Well, that's not actually the case.
209
542669
1340
09:04
It turns out that there are swaths of habitat
210
544009
2893
09:06
in the north of Siberia and Yukon
211
546902
2335
09:09
that actually could house a mammoth.
212
549237
1206
09:10
Remember, this was a highly plastic animal
213
550443
2245
09:12
that lived over tremendous climate variation.
214
552688
2661
09:15
So this landscape would be easily able to house it,
215
555349
2882
09:18
and I have to admit that there [is] a part of the child in me,
216
558231
3660
09:21
the boy in me, that would love to see
217
561891
1285
09:23
these majestic creatures walk across the permafrost
218
563176
2846
09:26
of the north once again, but I do have to admit
219
566022
2455
09:28
that part of the adult in me sometimes wonders
220
568477
2144
09:30
whether or not we should.
221
570621
2405
09:33
Thank you very much.
222
573026
1685
09:34
(Applause)
223
574711
5198
09:39
Ryan Phelan: Don't go away.
224
579909
1517
09:41
You've left us with a question.
225
581426
1732
09:43
I'm sure everyone is asking this. When you say, "Should we?"
226
583158
3524
09:46
it feels like you're reticent there,
227
586682
2609
09:49
and yet you've given us a vision of it being so possible.
228
589291
2978
09:52
What's your reticence?
229
592269
1326
09:53
Hendrik Poinar: I don't think it's reticence.
230
593595
1306
09:54
I think it's just that we have to think very deeply
231
594901
3798
09:58
about the implications, ramifications of our actions,
232
598699
2551
10:01
and so as long as we have good, deep discussion
233
601250
2200
10:03
like we're having now, I think
234
603450
2016
10:05
we can come to a very good solution as to why to do it.
235
605466
2706
10:08
But I just want to make sure that we spend time
236
608172
1637
10:09
thinking about why we're doing it first.
237
609809
1849
10:11
RP: Perfect. Perfect answer. Thank you very much, Hendrik.
238
611658
2781
10:14
HP: Thank you. (Applause)
239
614439
2464
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