The smelly mystery of the human pheromone | Tristram Wyatt

321,461 views ・ 2014-05-15

TED


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

00:12
"Pheromone" is a very powerful word.
0
12880
3438
00:16
It conjures up sex, abandon, loss of control,
1
16318
4144
00:20
and you can see, it's very important as a word.
2
20462
3692
00:24
But it's only 50 years old. It was invented in 1959.
3
24154
5283
00:29
Now, if you put that word into the web,
4
29437
2549
00:31
as you may have done,
5
31986
1510
00:33
you'll come up with millions of hits,
6
33496
2392
00:35
and almost all of those sites are trying to sell you
7
35888
2645
00:38
something to make you irresistible
8
38533
2259
00:40
for 10 dollars or more.
9
40792
3073
00:43
Now, this is a very attractive idea,
10
43865
2223
00:46
and the molecules they mention
11
46088
2442
00:48
sound really science-y.
12
48530
1914
00:50
They've got lots of syllables.
13
50444
1584
00:52
It's things like androstenol, androstenone
14
52028
2873
00:54
or androstadienone.
15
54901
2441
00:57
It gets better and better,
16
57342
1642
00:58
and when you combine that with white lab coats,
17
58984
2790
01:01
you must imagine that there is
18
61774
1412
01:03
fantastic science behind this.
19
63186
2514
01:05
But sadly, these are fraudulent claims
20
65700
5122
01:10
supported by dodgy science.
21
70822
3339
01:14
The problem is that, although there are many
22
74161
2618
01:16
good scientists working on what they think
23
76779
2545
01:19
are human pheromones,
24
79324
1870
01:21
and they're publishing in respectable journals,
25
81194
2605
01:23
at the basis of this,
26
83799
1581
01:25
despite very sophisticated experiments,
27
85380
3336
01:28
there really is no good science behind it,
28
88716
2553
01:31
because it's based on a problem,
29
91269
3292
01:34
which is nobody has systematically gone through
30
94561
3450
01:38
all the odors that humans produce --
31
98011
2101
01:40
and there are thousands of molecules that we give off.
32
100112
2778
01:42
We're mammals. We produce a lot of smell.
33
102890
3110
01:46
Nobody has gone through systematically
34
106000
2144
01:48
to work out which molecules really are pheromones.
35
108144
2767
01:50
They've just plucked a few,
36
110911
1630
01:52
and all these experiments are based on those,
37
112541
1889
01:54
but there's no good evidence at all.
38
114430
3010
01:57
Now, that's not to say
39
117440
2178
01:59
that smell is not important to people.
40
119618
2162
02:01
It is, and some people are real enthusiasts,
41
121780
3502
02:05
and one of these was Napoleon.
42
125282
3497
02:08
And famously, you may remember
43
128779
1792
02:10
that out on the campaign trail for war,
44
130571
3097
02:13
he wrote to his lover, Empress Josephine,
45
133668
2807
02:16
saying, "Don't wash. I'm coming home."
46
136475
3234
02:19
(Laughter)
47
139709
602
02:20
So he didn't want to lose any of her richness
48
140311
2921
02:23
in the days before he'd get home,
49
143232
2349
02:25
and it is still, you'll find websites
50
145581
2377
02:27
that offer this as a major quirk.
51
147958
3902
02:31
At the same time, though,
52
151860
1164
02:33
we spend about as much money
53
153024
2453
02:35
taking the smells off us
54
155477
1771
02:37
as putting them back on in perfumes,
55
157248
2721
02:39
and perfumes are a multi-billion-dollar business.
56
159969
4191
02:44
So what I want to do in the rest of this talk
57
164160
2403
02:46
is tell you about what pheromones really are,
58
166563
5278
02:51
tell you why I think we would expect
59
171841
2998
02:54
humans to have pheromones,
60
174839
2748
02:57
tell you about some of the confusions in pheromones,
61
177587
4493
03:02
and then finally, I want to end with
62
182080
2792
03:04
a promising avenue which shows us
63
184872
1970
03:06
the way we ought to be going.
64
186842
4148
03:10
So the ancient Greeks knew
65
190990
4181
03:15
that dogs sent invisible signals between each other.
66
195171
4054
03:19
A female dog in heat
67
199225
2374
03:21
sent an invisible signal to male dogs
68
201599
1916
03:23
for miles around,
69
203515
1455
03:24
and it wasn't a sound, it was a smell.
70
204970
2105
03:27
You could take the smell from the female dog,
71
207075
2181
03:29
and the dogs would chase the cloth.
72
209256
2463
03:31
But the problem for everybody
73
211719
1608
03:33
who could see this effect
74
213327
2113
03:35
was that you couldn't identify the molecules.
75
215440
1622
03:37
You couldn't demonstrate it was chemical.
76
217062
2453
03:39
The reason for that, of course,
77
219515
1315
03:40
is that each of these animals
78
220830
1415
03:42
produces tiny quantities,
79
222245
1606
03:43
and in the case of the dog,
80
223851
1659
03:45
males dogs can smell it, but we can't smell it.
81
225510
2902
03:48
And it was only in 1959 that a German team,
82
228412
4358
03:52
after spending 20 years in search of these molecules,
83
232770
3352
03:56
discovered, identified, the first pheromone,
84
236122
3781
03:59
and this was the sex pheromone of a silk moth.
85
239903
3278
04:03
Now, this was an inspired choice by Adolf Butenandt and his team,
86
243181
3674
04:06
because he needed half a million moths
87
246855
2126
04:08
to get enough material to do the chemical analysis.
88
248981
3027
04:12
But he created the model
89
252008
2089
04:14
for how you should go about pheromone analysis.
90
254097
2364
04:16
He basically went through systematically,
91
256461
2681
04:19
showing that only the molecule in question
92
259142
2945
04:22
was the one that stimulated the males,
93
262087
1866
04:23
not all the others.
94
263953
2053
04:26
He analyzed it very carefully.
95
266006
2158
04:28
He synthesized the molecule,
96
268164
1817
04:29
and then tried the synthesized molecule on the males
97
269981
3308
04:33
and got them to respond and showed it was,
98
273289
2861
04:36
indeed, that molecule.
99
276150
1760
04:37
That's closing the circle.
100
277910
2150
04:40
That's the thing which has never been done with humans:
101
280060
2705
04:42
nothing systematic, no real demonstration.
102
282765
3610
04:46
With that new concept,
103
286375
1734
04:48
we needed a new word,
104
288109
1709
04:49
and that was the word "pheromone,"
105
289818
2835
04:52
and it's basically transferred excitement,
106
292653
3601
04:56
transferred between individuals,
107
296254
2269
04:58
and since 1959, pheromones have been found
108
298523
2826
05:01
right the way across the animal kingdom,
109
301349
1875
05:03
in male animals, in female animals.
110
303224
2202
05:05
It works just as well underwater
111
305426
1545
05:06
for goldfish and lobsters.
112
306971
2022
05:08
And almost every mammal you can think of
113
308993
1747
05:10
has had a pheromone identified,
114
310740
1823
05:12
and of course, an enormous number of insects.
115
312563
3830
05:16
So we know that pheromones exist
116
316393
1969
05:18
right the way across the animal kingdom.
117
318362
3061
05:21
What about humans?
118
321423
1773
05:23
Well, the first thing, of course,
119
323196
1248
05:24
is that we're mammals,
120
324444
1657
05:26
and mammals are smelly.
121
326101
1559
05:27
As any dog owner can tell you,
122
327660
1876
05:29
we smell, they smell.
123
329536
1981
05:31
But the real reason we might think
124
331517
1981
05:33
that humans have pheromones
125
333498
1825
05:35
is the change that occurs as we grow up.
126
335323
3218
05:38
The smell of a room of teenagers
127
338541
2451
05:40
is quite different
128
340992
1489
05:42
from the smell of a room of small children.
129
342481
2820
05:45
What's changed? And of course, it's puberty.
130
345301
2872
05:48
Along with the pubic hair
131
348173
1459
05:49
and the hair in the armpits,
132
349632
1693
05:51
new glands start to secrete in those places,
133
351325
3742
05:55
and that's what's making the change in smell.
134
355067
2615
05:57
If we were any other kind of mammal,
135
357682
2148
05:59
or any other kind of animal,
136
359830
1189
06:01
we would say,
137
361019
1137
06:02
"That must be something to do with pheromones,"
138
362156
1872
06:04
and we'd start looking properly.
139
364028
2656
06:06
But there are some problems, and this is why,
140
366684
1976
06:08
I think, people have not looked for
141
368660
3069
06:11
pheromones so effectively in humans.
142
371729
2917
06:14
There are, indeed, problems.
143
374646
1571
06:16
And the first of these
144
376217
2184
06:18
is perhaps surprising.
145
378401
1517
06:19
It's all about culture.
146
379918
1834
06:21
Now moths don't learn a lot
147
381752
2147
06:23
about what is good to smell, but humans do,
148
383899
3617
06:27
and up to the age of about four,
149
387516
1846
06:29
any smell, no matter how rancid,
150
389362
2719
06:32
is simply interesting.
151
392081
1799
06:33
And I understand that the major role of parents
152
393880
2052
06:35
is to stop kids putting their fingers in poo,
153
395932
3681
06:39
because it's always something nice to smell.
154
399613
2798
06:42
But gradually we learn what's not good,
155
402411
2691
06:45
and one of the things we learn
156
405102
1490
06:46
at the same time as what is not good
157
406592
2135
06:48
is what is good.
158
408727
1758
06:50
Now, the cheese behind me
159
410485
2262
06:52
is a British, if not an English, delicacy.
160
412747
3951
06:56
It's ripe blue Stilton.
161
416698
3437
07:00
Liking it is incomprehensible to people from other countries.
162
420135
4362
07:04
Every culture has its own special food
163
424497
3285
07:07
and national delicacy.
164
427782
2096
07:09
If you were to come from Iceland,
165
429878
2052
07:11
your national dish
166
431930
1324
07:13
is deep rotted shark.
167
433254
2976
07:16
Now, all of these things are acquired tastes,
168
436230
2130
07:18
but they form almost a badge of identity.
169
438360
3160
07:21
You're part of the in-group.
170
441520
4820
07:26
The second thing is the sense of smell.
171
446340
3582
07:29
Each of us has a unique odor world,
172
449922
3469
07:33
in the sense that what we smell,
173
453391
2539
07:35
we each smell a completely different world.
174
455930
2859
07:38
Now, smell was the hardest
175
458789
1709
07:40
of the senses to crack,
176
460498
1861
07:42
and the Nobel Prize awarded to
177
462359
1715
07:44
Richard Axel and Linda Buck
178
464074
1633
07:45
was only awarded in 2004
179
465707
2433
07:48
for their discovery of how smell works.
180
468140
2790
07:50
It's really hard,
181
470930
1377
07:52
but in essence, nerves from the brain
182
472307
2591
07:54
go up into the nose
183
474898
2213
07:57
and on these nerves exposed in the nose
184
477111
2381
07:59
to the outside air are receptors,
185
479492
3054
08:02
and odor molecules coming in on a sniff
186
482546
3149
08:05
interact with these receptors,
187
485695
2150
08:07
and if they bond, they send the nerve a signal
188
487845
4259
08:12
which goes back into the brain.
189
492104
2308
08:14
We don't just have one kind of receptor.
190
494412
2062
08:16
If you're a human, you have about 400
191
496474
1876
08:18
different kinds of receptors,
192
498350
2065
08:20
and the brain knows what you're smelling
193
500415
2967
08:23
because of the combination of receptors
194
503382
1811
08:25
and nerve cells that they trigger,
195
505193
2513
08:27
sending messages up to the brain
196
507706
1558
08:29
in a combinatorial fashion.
197
509264
2906
08:32
But it's a bit more complicated,
198
512170
990
08:33
because each of those 400
199
513160
2135
08:35
comes in various variants,
200
515295
2151
08:37
and depending which variant you have,
201
517446
2071
08:39
you might smell coriander, or cilantro, that herb,
202
519517
4182
08:43
either as something delicious and savory
203
523699
2618
08:46
or something like soap.
204
526317
2174
08:48
So we each have an individual world of smell,
205
528491
2686
08:51
and that complicates anything
206
531177
1641
08:52
when we're studying smell.
207
532818
2296
08:55
Well, we really ought to talk about armpits,
208
535114
2692
08:57
and I have to say that I do have particularly good ones.
209
537806
3396
09:01
Now, I'm not going to share them with you,
210
541202
2002
09:03
but this is the place that most people
211
543204
1979
09:05
have looked for pheromones.
212
545183
1737
09:06
There is one good reason,
213
546920
1503
09:08
which is, the great apes have armpits
214
548423
3404
09:11
as their unique characteristic.
215
551827
2328
09:14
The other primates have scent glands
216
554155
2401
09:16
in other parts of the body.
217
556556
1830
09:18
The great apes have these armpits
218
558386
2354
09:20
full of secretory glands
219
560740
2217
09:22
producing smells all the time,
220
562957
2341
09:25
enormous numbers of molecules.
221
565298
3700
09:28
When they're secreted from the glands,
222
568998
1703
09:30
the molecules are odorless.
223
570701
2004
09:32
They have no smell at all,
224
572705
2075
09:34
and it's only the wonderful bacteria
225
574780
1969
09:36
growing on the rainforest of hair
226
576749
2213
09:38
that actually produces the smells
227
578962
1456
09:40
that we know and love.
228
580418
2021
09:42
And so incidentally, if you want to reduce
229
582439
1900
09:44
the amount of smell,
230
584339
1430
09:45
clear-cutting your armpits
231
585769
1920
09:47
is a very effective way of reducing
232
587689
2256
09:49
the habitat for bacteria,
233
589945
1514
09:51
and you'll find they remain less smelly
234
591459
2337
09:53
for much longer.
235
593796
2094
09:55
But although we've focused on armpits,
236
595890
2546
09:58
I think it's partly because they're the least
237
598436
1367
09:59
embarrassing place to go and ask people for samples.
238
599803
3967
10:03
There is actually another reason why we might not
239
603770
2612
10:06
be looking for a universal sex pheromone there,
240
606382
2776
10:09
and that's because 20 percent of the world's population
241
609158
3839
10:12
doesn't have smelly armpits like me.
242
612997
3445
10:16
And these are people from China, Japan,
243
616442
3916
10:20
Korea, and other parts of northeast Asia.
244
620358
2595
10:22
They simply don't secrete those odorless precursors
245
622953
3524
10:26
that the bacteria love to use to produce the smells
246
626477
4253
10:30
that in an ethnocentric way we always thought of
247
630730
2349
10:33
as characteristic of armpits.
248
633079
2105
10:35
So it doesn't apply to 20 percent of the world.
249
635184
4507
10:39
So what should we be doing
250
639691
3002
10:42
in our search for human pheromones?
251
642693
3053
10:45
I'm fairly convinced that we do have them.
252
645746
2452
10:48
We're mammals, like everybody else
253
648198
1953
10:50
who's a mammal, and we probably do have them.
254
650151
3979
10:54
But what I think we should do
255
654130
1583
10:55
is go right back to the beginning,
256
655713
1939
10:57
and basically look all over the body.
257
657652
2339
10:59
No matter how embarrassing,
258
659991
1691
11:01
we need to search and go for the first time
259
661682
3378
11:05
where no one else has dared tread.
260
665060
2460
11:07
It's going to be difficult,
261
667520
1148
11:08
it's going to be embarrassing, but we need to look.
262
668668
2575
11:11
We also need to go back to the ideas
263
671243
2947
11:14
that Butenandt used when he was studying the silk moth.
264
674190
3267
11:17
We need to go back and look systematically
265
677457
3468
11:20
at all the molecules that are being produced,
266
680925
2138
11:23
and work out which ones are really involved.
267
683063
2433
11:25
It isn't good enough simply to pluck a couple
268
685496
2106
11:27
and say, "They'll do."
269
687602
1944
11:29
We have to actually demonstrate
270
689546
1399
11:30
that they really have the effects we claim.
271
690945
2810
11:33
There is one team that I'm actually very impressed by.
272
693755
3234
11:36
They're in France, and their previous success
273
696989
3176
11:40
was identifying the rabbit mammary pheromone.
274
700165
4377
11:44
They've turned their attention now
275
704542
2569
11:47
to human babies and mothers.
276
707111
3185
11:50
So this is a baby having a drink of milk
277
710296
3071
11:53
from its mother's breast.
278
713367
2643
11:56
Her nipple is completely hidden
279
716010
2183
11:58
by the baby's head,
280
718193
1246
11:59
but what you'll notice is a white droplet
281
719439
3751
12:03
with an arrow pointing to it,
282
723190
1781
12:04
and that's the secretion from the areolar glands.
283
724971
3199
12:08
Now, we all have them, men and women,
284
728170
2990
12:11
and these are the little bumps around the nipple,
285
731160
2818
12:13
and if you're a lactating woman,
286
733978
1959
12:15
these start to secrete.
287
735937
2337
12:18
It's a very interesting secretion.
288
738274
2589
12:20
What Benoist Schaal and his team developed
289
740863
3003
12:23
was a simple test to investigate
290
743866
2407
12:26
what the effect of this secretion might be,
291
746273
2806
12:29
in effect, a simple bioassay.
292
749079
2976
12:32
So this is a sleeping baby,
293
752055
2675
12:34
and under its nose, we've put a clean glass rod.
294
754730
4989
12:39
The baby remains sleeping,
295
759719
2111
12:41
showing no interest at all.
296
761830
2341
12:44
But if we go to any mother
297
764171
2074
12:46
who is secreting from the areolar glands,
298
766245
2429
12:48
so it's not about recognition,
299
768674
1577
12:50
it can be from any mother,
300
770251
2228
12:52
if we take the secretion
301
772479
1352
12:53
and now put it under the baby's nose,
302
773831
2904
12:56
we get a very different reaction.
303
776735
2091
12:58
It's a connoisseur's reaction of delight,
304
778826
2984
13:01
and it opens its mouth
305
781810
2060
13:03
and sticks out its tongue
306
783870
1653
13:05
and starts to suck.
307
785523
2087
13:07
Now, since this is from any mother,
308
787610
2340
13:09
it could really be a pheromone.
309
789950
1792
13:11
It's not about individual recognition.
310
791742
1779
13:13
Any mother will do.
311
793521
1876
13:15
Now, why is this important,
312
795397
1463
13:16
apart from being simply very interesting?
313
796860
2458
13:19
It's because women vary
314
799318
1807
13:21
in the number of areolar glands that they have,
315
801125
2773
13:23
and there is a correlation between the ease
316
803898
2196
13:26
with which babies start to suckle
317
806094
2542
13:28
and the number of areolar glands she has.
318
808636
1862
13:30
It appears that the more secretions she's got,
319
810498
2798
13:33
the more likely the baby is to suckle quickly.
320
813296
3662
13:36
If you're a mammal,
321
816958
1460
13:38
the most dangerous time in life
322
818418
2543
13:40
is the first few hours after birth.
323
820961
2309
13:43
You have to get that first drink of milk,
324
823270
3760
13:47
and if you don't get it, you won't survive.
325
827030
3491
13:50
You'll be dead.
326
830521
1464
13:51
Since many babies actually find it difficult
327
831985
2638
13:54
to take that first meal,
328
834623
1649
13:56
because they're not getting the right stimulus,
329
836272
1977
13:58
if we could identify what that molecule was,
330
838249
3210
14:01
and the French team are being very cautious,
331
841459
1987
14:03
but if we could identify the molecule,
332
843446
2115
14:05
synthesize it, it would then mean
333
845561
2794
14:08
premature babies would be more likely to suckle,
334
848355
1906
14:10
and every baby would have a better chance
335
850261
2928
14:13
of survival.
336
853189
1321
14:14
So what I want to argue is this is one example
337
854510
2540
14:17
of where a systematic, really scientific approach
338
857050
3596
14:20
can actually bring you a real understanding
339
860646
2722
14:23
of pheromones.
340
863368
1108
14:24
There could be all sorts of medical interventions.
341
864476
2614
14:27
There could be all sorts of things
342
867090
1254
14:28
that humans are doing with pheromones
343
868344
1700
14:30
that we simply don't know at the moment.
344
870044
2048
14:32
What we need to remember is pheromones
345
872092
1886
14:33
are not just about sex.
346
873978
1378
14:35
They're about all sorts of things to do
347
875356
1716
14:37
with a mammal's life.
348
877072
1723
14:38
So do go forward and do search for more.
349
878795
2689
14:41
There's lots to find.
350
881484
1040
14:42
Thank you very much.
351
882524
1866
14:44
(Applause)
352
884390
4488
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