TED2008
Peter Ward: A theory of Earth's mass extinctions
Filmed:
Readability: 3.9
1,130,090 views
Asteroid strikes get all the coverage, but "Medea Hypothesis" author Peter Ward argues that most of Earth's mass extinctions were caused by lowly bacteria. The culprit, a poison called hydrogen sulfide, may have an interesting application in medicine.
Peter Ward - Paleontologist
Peter D. Ward studies life on Earth -- where it came from, how it might end, and how utterly rare it might be. Full bio
Peter D. Ward studies life on Earth -- where it came from, how it might end, and how utterly rare it might be. Full bio
Double-click the English transcript below to play the video.
00:18
So, I want to start out with
0
0
2000
00:20
this beautiful picture from my childhood.
1
2000
2000
00:22
I love the science fiction movies.
2
4000
2000
00:24
Here it is: "This Island Earth."
3
6000
2000
00:26
And leave it to Hollywood to get it just right.
4
8000
2000
00:28
Two-and-a-half years in the making.
5
10000
2000
00:30
(Laughter)
6
12000
3000
00:33
I mean, even the creationists give us 6,000,
7
15000
3000
00:36
but Hollywood goes to the chase.
8
18000
2000
00:38
And in this movie, we see what we think is out there:
9
20000
4000
00:42
flying saucers and aliens.
10
24000
3000
00:45
Every world has an alien, and every alien world has a flying saucer,
11
27000
3000
00:48
and they move about with great speed. Aliens.
12
30000
4000
00:53
Well, Don Brownlee, my friend, and I finally got to the point
13
35000
3000
00:56
where we got tired of turning on the TV
14
38000
3000
00:59
and seeing the spaceships and seeing the aliens every night,
15
41000
3000
01:02
and tried to write a counter-argument to it,
16
44000
3000
01:05
and put out what does it really take for an Earth to be habitable,
17
47000
4000
01:09
for a planet to be an Earth, to have a place
18
51000
2000
01:11
where you could probably get not just life, but complexity,
19
53000
3000
01:14
which requires a huge amount of evolution,
20
56000
2000
01:16
and therefore constancy of conditions.
21
58000
3000
01:19
So, in 2000 we wrote "Rare Earth." In 2003, we then asked,
22
61000
3000
01:22
let's not think about where Earths are in space, but how long has Earth been Earth?
23
64000
5000
01:27
If you go back two billion years,
24
69000
2000
01:29
you're not on an Earth-like planet any more.
25
71000
2000
01:31
What we call an Earth-like planet is actually a very short interval of time.
26
73000
4000
01:35
Well, "Rare Earth" actually
27
77000
2000
01:37
taught me an awful lot about meeting the public.
28
79000
3000
01:40
Right after, I got an invitation to go to a science fiction convention,
29
82000
3000
01:43
and with all great earnestness walked in.
30
85000
3000
01:46
David Brin was going to debate me on this,
31
88000
2000
01:48
and as I walked in, the crowd of a hundred started booing lustily.
32
90000
4000
01:52
I had a girl who came up who said, "My dad says you're the devil."
33
94000
3000
01:55
You cannot take people's aliens away from them
34
97000
4000
01:59
and expect to be anybody's friends.
35
101000
4000
02:03
Well, the second part of that, soon after --
36
105000
2000
02:05
and I was talking to Paul Allen; I saw him in the audience,
37
107000
3000
02:08
and I handed him a copy of "Rare Earth."
38
110000
2000
02:10
And Jill Tarter was there, and she turned to me,
39
112000
4000
02:14
and she looked at me just like that girl in "The Exorcist."
40
116000
3000
02:17
It was, "It burns! It burns!"
41
119000
2000
02:19
Because SETI doesn't want to hear this.
42
121000
2000
02:21
SETI wants there to be stuff out there.
43
123000
3000
02:24
I really applaud the SETI efforts, but we have not heard anything yet.
44
126000
3000
02:27
And I really do think we have to start thinking
45
129000
2000
02:29
about what's a good planet and what isn't.
46
131000
3000
02:32
Now, I throw this slide up because it indicates to me that,
47
134000
3000
02:35
even if SETI does hear something, can we figure out what they said?
48
137000
4000
02:39
Because this was a slide that was passed
49
141000
2000
02:41
between the two major intelligences on Earth -- a Mac to a PC --
50
143000
4000
02:45
and it can't even get the letters right --
51
147000
3000
02:48
(Laughter)
52
150000
2000
02:50
-- so how are we going to talk to the aliens?
53
152000
2000
02:52
And if they're 50 light years away, and we call them up,
54
154000
3000
02:55
and you blah, blah, blah, blah, blah,
55
157000
2000
02:57
and then 50 years later it comes back and they say, Please repeat?
56
159000
3000
03:00
I mean, there we are.
57
162000
2000
03:02
Our planet is a good planet because it can keep water.
58
164000
3000
03:05
Mars is a bad planet, but it's still good enough for us to go there
59
167000
4000
03:09
and to live on its surface if we're protected.
60
171000
2000
03:11
But Venus is a very bad -- the worst -- planet.
61
173000
3000
03:14
Even though it's Earth-like, and even though early in its history
62
176000
3000
03:17
it may very well have harbored Earth-like life,
63
179000
3000
03:20
it soon succumbed to runaway greenhouse --
64
182000
3000
03:23
that's an 800 degrees [Fahrenheit] surface --
65
185000
2000
03:25
because of rampant carbon dioxide.
66
187000
3000
03:28
Well, we know from astrobiology that we can really now predict
67
190000
3000
03:31
what's going to happen to our particular planet.
68
193000
3000
03:34
We are right now in the beautiful Oreo
69
196000
3000
03:37
of existence -- of at least life on Planet Earth --
70
199000
3000
03:40
following the first horrible microbial age.
71
202000
3000
03:43
In the Cambrian explosion, life emerged from the swamps,
72
205000
3000
03:46
complexity arose,
73
208000
2000
03:48
and from what we can tell, we're halfway through.
74
210000
3000
03:51
We have as much time for animals to exist on this planet
75
213000
3000
03:54
as they have been here now,
76
216000
2000
03:56
till we hit the second microbial age.
77
218000
2000
03:58
And that will happen, paradoxically --
78
220000
2000
04:00
everything you hear about global warming --
79
222000
2000
04:02
when we hit CO2 down to 10 parts per million,
80
224000
3000
04:05
we are no longer going to have to have plants
81
227000
2000
04:07
that are allowed to have any photosynthesis, and there go animals.
82
229000
4000
04:11
So, after that we probably have seven billion years.
83
233000
2000
04:13
The Sun increases in its intensity, in its brightness,
84
235000
3000
04:16
and finally, at about 12 billion years after it first started,
85
238000
5000
04:21
the Earth is consumed by a large Sun,
86
243000
3000
04:24
and this is what's left.
87
246000
3000
04:27
So, a planet like us is going to have an age and an old age,
88
249000
4000
04:31
and we are in its golden summer age right now.
89
253000
4000
04:35
But there's two fates to everything, isn't there?
90
257000
2000
04:37
Now, a lot of you are going to die of old age,
91
259000
3000
04:40
but some of you, horribly enough, are going to die in an accident.
92
262000
3000
04:43
And that's the fate of a planet, too.
93
265000
2000
04:45
Earth, if we're lucky enough -- if it doesn't get hit by a Hale-Bopp,
94
267000
4000
04:49
or gets blasted by some supernova nearby
95
271000
4000
04:53
in the next seven billion years -- we'll find under your feet.
96
275000
3000
04:56
But what about accidental death?
97
278000
2000
04:58
Well, paleontologists for the last 200 years
98
280000
2000
05:00
have been charting death. It's strange --
99
282000
2000
05:02
extinction as a concept wasn't even thought about
100
284000
3000
05:05
until Baron Cuvier in France found this first mastodon.
101
287000
3000
05:08
He couldn't match it up to any bones on the planet,
102
290000
2000
05:10
and he said, Aha! It's extinct.
103
292000
2000
05:12
And very soon after, the fossil record started yielding
104
294000
3000
05:15
a very good idea of how many plants and animals there have been
105
297000
3000
05:18
since complex life really began to leave
106
300000
2000
05:20
a very interesting fossil record.
107
302000
3000
05:23
In that complex record of fossils,
108
305000
3000
05:26
there were times when lots of stuff
109
308000
2000
05:28
seemed to be dying out very quickly,
110
310000
2000
05:30
and the father/mother geologists
111
312000
2000
05:32
called these "mass extinctions."
112
314000
2000
05:34
All along it was thought to be either an act of God
113
316000
2000
05:36
or perhaps long, slow climate change,
114
318000
2000
05:38
and that really changed in 1980,
115
320000
2000
05:40
in this rocky outcrop near Gubbio,
116
322000
3000
05:43
where Walter Alvarez, trying to figure out
117
325000
3000
05:46
what was the time difference between these white rocks,
118
328000
3000
05:49
which held creatures of the Cretaceous period,
119
331000
2000
05:51
and the pink rocks above, which held Tertiary fossils.
120
333000
2000
05:53
How long did it take to go from one system to the next?
121
335000
4000
05:57
And what they found was something unexpected.
122
339000
2000
05:59
They found in this gap, in between, a very thin clay layer,
123
341000
3000
06:02
and that clay layer -- this very thin red layer here --
124
344000
3000
06:05
is filled with iridium.
125
347000
2000
06:07
And not just iridium; it's filled with glassy spherules,
126
349000
3000
06:10
and it's filled with quartz grains
127
352000
2000
06:12
that have been subjected to enormous pressure: shock quartz.
128
354000
4000
06:16
Now, in this slide the white is chalk,
129
358000
2000
06:18
and this chalk was deposited in a warm ocean.
130
360000
3000
06:21
The chalk itself's composed by plankton
131
363000
2000
06:23
which has fallen down from the sea surface onto the sea floor,
132
365000
4000
06:27
so that 90 percent of the sediment here is skeleton of living stuff,
133
369000
3000
06:30
and then you have that millimeter-thick red layer,
134
372000
2000
06:32
and then you have black rock.
135
374000
2000
06:34
And the black rock is the sediment on the sea bottom
136
376000
3000
06:37
in the absence of plankton.
137
379000
2000
06:39
And that's what happens in an asteroid catastrophe,
138
381000
4000
06:43
because that's what this was, of course. This is the famous K-T.
139
385000
3000
06:46
A 10-kilometer body hit the planet.
140
388000
2000
06:48
The effects of it spread this very thin impact layer all over the planet,
141
390000
4000
06:52
and we had very quickly the death of the dinosaurs,
142
394000
3000
06:55
the death of these beautiful ammonites,
143
397000
2000
06:57
Leconteiceras here, and Celaeceras over here,
144
399000
2000
06:59
and so much else.
145
401000
2000
07:01
I mean, it must be true,
146
403000
2000
07:03
because we've had two Hollywood blockbusters since that time,
147
405000
3000
07:06
and this paradigm, from 1980 to about 2000,
148
408000
3000
07:09
totally changed how we geologists thought about catastrophes.
149
411000
5000
07:14
Prior to that, uniformitarianism was the dominant paradigm:
150
416000
3000
07:17
the fact that if anything happens on the planet in the past,
151
419000
3000
07:20
there are present-day processes that will explain it.
152
422000
4000
07:24
But we haven't witnessed a big asteroid impact,
153
426000
3000
07:27
so this is a type of neo-catastrophism,
154
429000
2000
07:29
and it took about 20 years for the scientific establishment
155
431000
3000
07:32
to finally come to grips: yes, we were hit;
156
434000
2000
07:34
and yes, the effects of that hit caused a major mass extinction.
157
436000
4000
07:39
Well, there are five major mass extinctions
158
441000
2000
07:41
over the last 500 million years, called the Big Five.
159
443000
3000
07:44
They range from 450 million years ago
160
446000
3000
07:47
to the last, the K-T, number four,
161
449000
2000
07:49
but the biggest of all was the P, or the Permian extinction,
162
451000
4000
07:53
sometimes called the mother of all mass extinctions.
163
455000
2000
07:55
And every one of these has been subsequently blamed
164
457000
3000
07:58
on large-body impact.
165
460000
2000
08:00
But is this true?
166
462000
2000
08:03
The most recent, the Permian, was thought to have been an impact
167
465000
3000
08:06
because of this beautiful structure on the right.
168
468000
2000
08:08
This is a Buckminsterfullerene, a carbon-60.
169
470000
3000
08:11
Because it looks like those terrible geodesic domes
170
473000
3000
08:14
of my late beloved '60s,
171
476000
2000
08:16
they're called "buckyballs."
172
478000
2000
08:18
This evidence was used to suggest
173
480000
2000
08:20
that at the end of the Permian, 250 million years ago, a comet hit us.
174
482000
4000
08:24
And when the comet hits, the pressure produces the buckyballs,
175
486000
3000
08:27
and it captures bits of the comet.
176
489000
2000
08:29
Helium-3: very rare on the surface of the Earth, very common in space.
177
491000
4000
08:34
But is this true?
178
496000
2000
08:36
In 1990, working on the K-T extinction for 10 years,
179
498000
4000
08:40
I moved to South Africa to begin work twice a year
180
502000
3000
08:43
in the great Karoo desert.
181
505000
2000
08:45
I was so lucky to watch the change of that South Africa
182
507000
3000
08:48
into the new South Africa as I went year by year.
183
510000
3000
08:51
And I worked on this Permian extinction,
184
513000
2000
08:53
camping by this Boer graveyard for months at a time.
185
515000
3000
08:56
And the fossils are extraordinary.
186
518000
3000
08:59
You know, you're gazing upon your very distant ancestors.
187
521000
2000
09:01
These are mammal-like reptiles.
188
523000
2000
09:03
They are culturally invisible. We do not make movies about these.
189
525000
3000
09:06
This is a Gorgonopsian, or a Gorgon.
190
528000
2000
09:08
That's an 18-inch long skull of an animal
191
530000
4000
09:12
that was probably seven or eight feet, sprawled like a lizard,
192
534000
4000
09:16
probably had a head like a lion.
193
538000
2000
09:18
This is the top carnivore, the T-Rex of its time.
194
540000
2000
09:20
But there's lots of stuff.
195
542000
2000
09:22
This is my poor son, Patrick.
196
544000
2000
09:24
(Laughter)
197
546000
1000
09:25
This is called paleontological child abuse.
198
547000
3000
09:28
Hold still, you're the scale.
199
550000
2000
09:30
(Laughter)
200
552000
5000
09:36
There was big stuff back then.
201
558000
3000
09:39
Fifty-five species of mammal-like reptiles.
202
561000
3000
09:42
The age of mammals had well and truly started
203
564000
3000
09:45
250 million years ago ...
204
567000
2000
09:47
... and then a catastrophe happened.
205
569000
3000
09:50
And what happens next is the age of dinosaurs.
206
572000
2000
09:52
It was all a mistake; it should have never happened. But it did.
207
574000
4000
09:56
Now, luckily,
208
578000
2000
09:58
this Thrinaxodon, the size of a robin egg here:
209
580000
3000
10:01
this is a skull I've discovered just before taking this picture --
210
583000
3000
10:04
there's a pen for scale; it's really tiny --
211
586000
2000
10:06
this is in the Lower Triassic, after the mass extinction has finished.
212
588000
4000
10:10
You can see the eye socket and you can see the little teeth in the front.
213
592000
3000
10:13
If that does not survive, I'm not the thing giving this talk.
214
595000
5000
10:18
Something else is, because if that doesn't survive, we are not here;
215
600000
4000
10:22
there are no mammals. It's that close; one species ekes through.
216
604000
4000
10:26
Well, can we say anything about the pattern of who survives and who doesn't?
217
608000
3000
10:29
Here's sort of the end of that 10 years of work.
218
611000
2000
10:31
The ranges of stuff -- the red line is the mass extinction.
219
613000
3000
10:34
But we've got survivors and things that get through,
220
616000
2000
10:36
and it turns out the things that get through preferentially are cold bloods.
221
618000
4000
10:40
Warm-blooded animals take a huge hit at this time.
222
622000
4000
10:45
The survivors that do get through
223
627000
2000
10:47
produce this world of crocodile-like creatures.
224
629000
3000
10:50
There's no dinosaurs yet; just this slow, saurian, scaly, nasty,
225
632000
4000
10:54
swampy place with a couple of tiny mammals hiding in the fringes.
226
636000
5000
10:59
And there they would hide for 160 million years,
227
641000
3000
11:02
until liberated by that K-T asteroid.
228
644000
3000
11:05
So, if not impact, what?
229
647000
2000
11:07
And the what, I think, is that we returned, over and over again,
230
649000
4000
11:11
to the Pre-Cambrian world, that first microbial age,
231
653000
3000
11:14
and the microbes are still out there.
232
656000
2000
11:16
They hate we animals.
233
658000
2000
11:18
They really want their world back.
234
660000
2000
11:20
And they've tried over and over and over again.
235
662000
4000
11:24
This suggests to me that life causing these mass extinctions
236
666000
3000
11:27
because it did is inherently anti-Gaian.
237
669000
3000
11:30
This whole Gaia idea, that life makes the world better for itself --
238
672000
5000
11:35
anybody been on a freeway on a Friday afternoon in Los Angeles
239
677000
4000
11:39
believing in the Gaia theory? No.
240
681000
2000
11:41
So, I really suspect there's an alternative,
241
683000
3000
11:44
and that life does actually try to do itself in --
242
686000
2000
11:46
not consciously, but just because it does.
243
688000
2000
11:48
And here's the weapon, it seems, that it did so over the last 500 million years.
244
690000
4000
11:52
There are microbes which, through their metabolism,
245
694000
3000
11:55
produce hydrogen sulfide,
246
697000
2000
11:57
and they do so in large amounts.
247
699000
3000
12:00
Hydrogen sulfide is very fatal to we humans.
248
702000
3000
12:03
As small as 200 parts per million will kill you.
249
705000
4000
12:09
You only have to go to the Black Sea and a few other places -- some lakes --
250
711000
4000
12:13
and get down, and you'll find that the water itself turns purple.
251
715000
4000
12:17
It turns purple from the presence of numerous microbes
252
719000
3000
12:20
which have to have sunlight and have to have hydrogen sulfide,
253
722000
3000
12:23
and we can detect their presence today -- we can see them --
254
725000
4000
12:27
but we can also detect their presence in the past.
255
729000
2000
12:29
And the last three years have seen
256
731000
2000
12:31
an enormous breakthrough in a brand-new field.
257
733000
3000
12:34
I am almost extinct --
258
736000
2000
12:36
I'm a paleontologist who collects fossils.
259
738000
2000
12:38
But the new wave of paleontologists -- my graduate students --
260
740000
3000
12:41
collect biomarkers.
261
743000
2000
12:43
They take the sediment itself, they extract the oil from it,
262
745000
4000
12:47
and from that they can produce compounds
263
749000
2000
12:49
which turn out to be very specific to particular microbial groups.
264
751000
4000
12:53
It's because lipids are so tough, they can get preserved in sediment
265
755000
4000
12:57
and last the hundreds of millions of years necessary,
266
759000
3000
13:00
and be extracted and tell us who was there.
267
762000
2000
13:02
And we know who was there. At the end of the Permian,
268
764000
3000
13:05
at many of these mass extinction boundaries,
269
767000
2000
13:07
this is what we find: isorenieratene. It's very specific.
270
769000
4000
13:11
It can only occur if the surface of the ocean has no oxygen,
271
773000
4000
13:15
and is totally saturated with hydrogen sulfide --
272
777000
3000
13:18
enough, for instance, to come out of solution.
273
780000
3000
13:21
This led Lee Kump, and others from Penn State and my group,
274
783000
4000
13:25
to propose what I call the Kump Hypothesis:
275
787000
3000
13:28
many of the mass extinctions were caused by lowering oxygen,
276
790000
3000
13:31
by high CO2. And the worst effect of global warming, it turns out:
277
793000
4000
13:35
hydrogen sulfide being produced out of the oceans.
278
797000
3000
13:38
Well, what's the source of this?
279
800000
2000
13:40
In this particular case, the source over and over has been flood basalts.
280
802000
4000
13:44
This is a view of the Earth now, if we extract a lot of it.
281
806000
3000
13:47
And each of these looks like a hydrogen bomb;
282
809000
2000
13:49
actually, the effects are even worse.
283
811000
2000
13:51
This is when deep-Earth material comes to the surface,
284
813000
3000
13:54
spreads out over the surface of the planet.
285
816000
2000
13:56
Well, it's not the lava that kills anything,
286
818000
3000
13:59
it's the carbon dioxide that comes out with it.
287
821000
2000
14:01
This isn't Volvos; this is volcanoes.
288
823000
3000
14:04
But carbon dioxide is carbon dioxide.
289
826000
2000
14:07
So, these are new data Rob Berner and I -- from Yale -- put together,
290
829000
3000
14:10
and what we try to do now is
291
832000
2000
14:12
track the amount of carbon dioxide in the entire rock record --
292
834000
3000
14:15
and we can do this from a variety of means --
293
837000
3000
14:18
and put all the red lines here,
294
840000
2000
14:20
when these -- what I call greenhouse mass extinctions -- took place.
295
842000
3000
14:23
And there's two things that are really evident here to me,
296
845000
2000
14:25
is that these extinctions take place when CO2 is going up.
297
847000
3000
14:28
But the second thing that's not shown on here:
298
850000
3000
14:31
the Earth has never had any ice on it
299
853000
3000
14:34
when we've had 1,000 parts per million CO2.
300
856000
4000
14:38
We are at 380 and climbing.
301
860000
2000
14:40
We should be up to a thousand in three centuries at the most,
302
862000
3000
14:43
but my friend David Battisti in Seattle says he thinks a 100 years.
303
865000
4000
14:47
So, there goes the ice caps,
304
869000
2000
14:49
and there comes 240 feet of sea level rise.
305
871000
4000
14:53
I live in a view house now;
306
875000
2000
14:55
I'm going to have waterfront.
307
877000
2000
14:57
All right, what's the consequence? The oceans probably turn purple.
308
879000
4000
15:01
And we think this is the reason that complexity took so long
309
883000
3000
15:04
to take place on planet Earth.
310
886000
2000
15:06
We had these hydrogen sulfide oceans for a very great long period.
311
888000
3000
15:09
They stop complex life from existing.
312
891000
4000
15:13
We know hydrogen sulfide is erupting presently a few places on the planet.
313
895000
5000
15:18
And I throw this slide in -- this is me, actually, two months ago --
314
900000
4000
15:22
and I throw this slide in because here is my favorite animal, chambered nautilus.
315
904000
4000
15:26
It's been on this planet since the animals first started -- 500 million years.
316
908000
4000
15:30
This is a tracking experiment, and any of you scuba divers,
317
912000
3000
15:33
if you want to get involved in one of the coolest projects ever,
318
915000
3000
15:36
this is off the Great Barrier Reef.
319
918000
2000
15:38
And as we speak now,
320
920000
1000
15:39
these nautilus are tracking out their behaviors to us.
321
921000
3000
15:42
But the thing about this is that every once in a while
322
924000
4000
15:46
we divers can run into trouble,
323
928000
2000
15:48
so I'm going to do a little thought experiment here.
324
930000
2000
15:50
This is a Great White Shark that ate some of my traps.
325
932000
3000
15:53
We pulled it up; up it comes. So, it's out there with me at night.
326
935000
3000
15:56
So, I'm swimming along, and it takes off my leg.
327
938000
3000
15:59
I'm 80 miles from shore, what's going to happen to me?
328
941000
3000
16:02
Well now, I die.
329
944000
2000
16:04
Five years from now, this is what I hope happens to me:
330
946000
2000
16:06
I'm taken back to the boat, I'm given a gas mask:
331
948000
3000
16:09
80 parts per million hydrogen sulfide.
332
951000
3000
16:12
I'm then thrown in an ice pond, I'm cooled 15 degrees lower
333
954000
4000
16:16
and I could be taken to a critical care hospital.
334
958000
4000
16:20
And the reason I could do that is because we mammals
335
962000
2000
16:22
have gone through a series of these hydrogen sulfide events,
336
964000
3000
16:25
and our bodies have adapted.
337
967000
2000
16:27
And we can now use this as what I think will be a major medical breakthrough.
338
969000
4000
16:31
This is Mark Roth. He was funded by DARPA.
339
973000
2000
16:33
Tried to figure out how to save Americans after battlefield injuries.
340
975000
4000
16:37
He bleeds out pigs.
341
979000
2000
16:39
He puts in 80 parts per million hydrogen sulfide --
342
981000
3000
16:42
the same stuff that survived these past mass extinctions --
343
984000
3000
16:45
and he turns a mammal into a reptile.
344
987000
2000
16:47
"I believe we are seeing in this response the result of mammals and reptiles
345
989000
4000
16:51
having undergone a series of exposures to H2S."
346
993000
3000
16:54
I got this email from him two years ago;
347
996000
2000
16:56
he said, "I think I've got an answer to some of your questions."
348
998000
3000
16:59
So, he now has taken mice down
349
1001000
2000
17:01
for as many as four hours, sometimes six hours,
350
1003000
4000
17:05
and these are brand-new data he sent me on the way over here.
351
1007000
2000
17:07
On the top, now, that is a temperature record of a mouse who has gone through --
352
1009000
5000
17:12
the dotted line, the temperatures.
353
1014000
2000
17:14
So, the temperature starts at 25 centigrade,
354
1016000
2000
17:16
and down it goes, down it goes.
355
1018000
1000
17:17
Six hours later, up goes the temperature.
356
1019000
2000
17:19
Now, the same mouse is given 80 parts per million hydrogen sulfide
357
1021000
5000
17:24
in this solid graph,
358
1026000
2000
17:26
and look what happens to its temperature.
359
1028000
2000
17:28
Its temperature drops.
360
1030000
2000
17:30
It goes down to 15 degrees centigrade from 35,
361
1032000
4000
17:34
and comes out of this perfectly fine.
362
1036000
3000
17:37
Here is a way we can get people to critical care.
363
1039000
3000
17:40
Here's how we can bring people cold enough to last till we get critical care.
364
1042000
5000
17:46
Now, you're all thinking, yeah, what about the brain tissue?
365
1048000
4000
17:50
And so this is one of the great challenges that is going to happen.
366
1052000
3000
17:53
You're in an accident. You've got two choices:
367
1055000
2000
17:55
you're going to die, or you're going to take the hydrogen sulfide
368
1057000
3000
17:58
and, say, 75 percent of you is saved, mentally.
369
1060000
3000
18:01
What are you going to do?
370
1063000
2000
18:03
Do we all have to have a little button saying, Let me die?
371
1065000
3000
18:06
This is coming towards us,
372
1068000
2000
18:08
and I think this is going to be a revolution.
373
1070000
2000
18:10
We're going to save lives, but there's going to be a cost to it.
374
1072000
3000
18:13
The new view of mass extinctions is, yes, we were hit,
375
1075000
2000
18:15
and, yes, we have to think about the long term,
376
1077000
2000
18:17
because we will get hit again.
377
1079000
2000
18:19
But there's a far worse danger confronting us.
378
1081000
2000
18:21
We can easily go back to the hydrogen sulfide world.
379
1083000
3000
18:24
Give us a few millennia --
380
1086000
2000
18:26
and we humans should last those few millennia --
381
1088000
2000
18:28
will it happen again? If we continue, it'll happen again.
382
1090000
4000
18:32
How many of us flew here?
383
1094000
2000
18:34
How many of us have gone through
384
1096000
2000
18:36
our entire Kyoto quota
385
1098000
3000
18:39
just for flying this year?
386
1101000
2000
18:41
How many of you have exceeded it? Yeah, I've certainly exceeded it.
387
1103000
3000
18:44
We have a huge problem facing us as a species.
388
1106000
3000
18:47
We have to beat this.
389
1109000
2000
18:49
I want to be able to go back to this reef. Thank you.
390
1111000
4000
18:53
(Applause)
391
1115000
6000
18:59
Chris Anderson: I've just got one question for you, Peter.
392
1121000
2000
19:01
Am I understanding you right, that what you're saying here
393
1123000
2000
19:03
is that we have in our own bodies
394
1125000
2000
19:05
a biochemical response to hydrogen sulfide
395
1127000
4000
19:09
that in your mind proves that there have been past mass extinctions
396
1131000
3000
19:12
due to climate change?
397
1134000
2000
19:14
Peter Ward: Yeah, every single cell in us
398
1136000
2000
19:16
can produce minute quantities of hydrogen sulfide in great crises.
399
1138000
3000
19:20
This is what Roth has found out.
400
1142000
1000
19:21
So, what we're looking at now: does it leave a signal?
401
1143000
2000
19:23
Does it leave a signal in bone or in plant?
402
1145000
2000
19:25
And we go back to the fossil record and we could try to detect
403
1147000
3000
19:28
how many of these have happened in the past.
404
1150000
2000
19:30
CA: It's simultaneously
405
1152000
2000
19:32
an incredible medical technique, but also a terrifying ...
406
1154000
3000
19:35
PW: Blessing and curse.
407
1157000
3000
ABOUT THE SPEAKER
Peter Ward - PaleontologistPeter D. Ward studies life on Earth -- where it came from, how it might end, and how utterly rare it might be.
Why you should listen
Paleontologist and astrobiologist Peter D. Ward studies the Cretaceous-Tertiary extinction event (the one that killed the dinosaurs) and other mass extinctions. He is a leader in the intriguing new field of astrobiology, the study of the origin, distribution and evolution of life in the universe.
In his book Rare Earth he theorizes that complex life itself is so rare, it's quite possible that Earth is the only planet that has any. But, he theorizes, simple life may exist elsewhere -- and possibly be more common than we think.
His upcoming book, The Medea Hypothesis, makes a bold argument that even here on Earth, life has come close to being wiped out several times. Contrary to the "Gaia hypothesis" of a self-balancing, self-perpetuating circle of life, Ward's Medea hypothesis details the scary number of times that life has come close to flatlining, whether due to comet strikes or an overabundance of bacteria.
In March 2009, Ward's 8-hour television series, Animal Armageddon, premieres on Animal Planet Network.
In April 2013, Ward published a surprisingly moving essay about his life's obsession: the chambered nautilus >>
Peter Ward | Speaker | TED.com