TEDGlobal 2007
Spencer Wells: A family tree for humanity
史賓賽‧韋爾斯: 建立全體人類的族譜
Filmed:
Readability: 4.5
824,434 views
所有的人類皆共享一些DNA，這些DNA從我們共同的非洲祖先代代相傳至今。遺傳學家Spencer Well述說他所主持的「基因地圖計畫」如何用這些共有的DNA來探索我們人類 — 所有不同種族及國籍 — 是怎麼相互連結在一起。
Spencer Wells - Genographer
Spencer Wells studies human diversity -- the process by which humanity, which springs from a single common source, has become so astonishingly diverse and widespread. Full bio
Spencer Wells studies human diversity -- the process by which humanity, which springs from a single common source, has become so astonishingly diverse and widespread. Full bio
Double-click the English transcript below to play the video.
00:18
Jambo, bonjour, zdravstvujtye, dayo: these are a few of the languages
0
0
9000
(你好) 這幾種語言
00:27
that I've spoken little bits of over the course of the last six weeks,
1
9000
4000
我在過去六周裡或多或少有機會用到
00:31
as I've been to 17 countries I think I'm up to, on this crazy tour I've been doing,
2
13000
5000
我正在進行一個瘋狂的旅程，總共需要跑遍17國
00:36
checking out various aspects of the project that we're doing.
3
18000
3000
去檢視我們正在進行的一項研究計畫的各方面進度
00:39
And I'm going to tell you a little bit about later on.
4
21000
2000
我之後會向各位介紹這個計畫的內容
00:41
And visiting some pretty incredible places,
5
23000
3000
因為這個計劃，我拜訪許多絕妙的地方
00:44
places like Mongolia, Cambodia, New Guinea, South Africa, Tanzania twice --
6
26000
6000
像是蒙古、柬埔寨、新幾內亞、南非，還來了坦尚尼亞兩次
00:50
I was here a month ago.
7
32000
2000
而且上個月才剛來過
00:52
And the opportunity to make a whirlwind tour of the world like that
8
34000
5000
能有機會經驗這種旋風式的環遊世界之旅
00:57
is utterly amazing, for lots of reasons.
9
39000
3000
是件無與倫比的事，原因很多
01:00
You see some incredible stuff.
10
42000
2000
首先是可以大開眼界
01:02
And you get to make these spot comparisons
11
44000
2000
同時還能在全球各地
01:04
between people all around the globe.
12
46000
2000
比較各式各樣的人種
01:06
And the thing that you really take away from that,
13
48000
2000
最重要的是，你能夠領悟到
01:08
the kind of surface thing that you take away from it,
14
50000
3000
一件深刻的事實
01:11
is not that we're all one, although I'm going to tell you about that,
15
53000
4000
那並非「全球人類本一家」，雖然之後我會討論這個議題
01:15
but rather how different we are.
16
57000
2000
而是相反的—我們彼此之間有多麼不一樣
01:17
There is so much diversity around the globe.
17
59000
3000
放眼全球人種的高度多樣性
01:20
6,000 different languages spoken by six and a half billion people,
18
62000
3000
六十五億人口，不同膚色、容貌及體型
01:23
all different colors, shapes, sizes.
19
65000
3000
並講著六千多種語言
01:26
You walk down the street in any big city, you travel like that,
20
68000
3000
當你經驗類似旅行，漫步在各國大城市的街頭時
01:29
and you are amazed at the diversity in the human species.
21
71000
4000
全球人種的高度多樣性絕對會令你讚嘆
01:33
How do we explain that diversity?
22
75000
3000
我們該如何去解釋這樣的多樣性?
01:36
Well, that's what I'm going to talk about today,
23
78000
2000
這正是我今天的主題
01:38
is how we're using the tools of genetics,
24
80000
2000
我將解釋我們如何運用遺傳學的研究方法
01:40
population genetics in particular, to tell us how we generated this diversity,
25
82000
6000
特別是族群遺傳學，解釋人種多樣性的來源
01:46
and how long it took.
26
88000
2000
以及經過多少時間才產生
01:48
Now, the problem of human diversity,
27
90000
2000
現在，有關人種多樣性的問題
01:50
like all big scientific questions --
28
92000
2000
像其他所有重要的科學問題一樣
01:52
how do you explain something like that --
29
94000
2000
無法三言兩語就解釋完
01:54
can be broken down into sub-questions.
30
96000
2000
所以我將這個問題分成幾個子項目，
01:56
And you can ferret away at those little sub-questions.
31
98000
3000
再去逐一解釋
01:59
First one is really a question of origins.
32
101000
2000
首先是人類的起源
02:01
Do we all share a common origin, in fact?
33
103000
2000
我們是不是全都來自於同一個祖先呢？
02:03
And given that we do -- and that's the assumption
34
105000
3000
假設我們贊同這個觀點
02:06
everybody, I think, in this room would make -- when was that?
35
108000
3000
在場的每一位應該會想問：「那是從什麼時候開始？」
02:09
When did we originate as a species?
36
111000
2000
我們是在什麼時間點，形成同一個物種？
02:11
How long have we been divergent from each other?
37
113000
2000
之後又經過多久，才分化成現在的高多樣性
02:13
And the second question is related, but slightly different.
38
115000
4000
第二個問題與之前相關，但有些不同
02:17
If we do spring from a common source,
39
119000
2000
如果人類的確有共同祖先
02:19
how did we come to occupy every corner of the globe,
40
121000
2000
我們又是如何散布到世界上每個角落?
02:21
and in the process generate all of this diversity,
41
123000
2000
並且一步步發展成不同人種
02:23
the different ways of life, the different appearances,
42
125000
3000
不同的社會型態、不同的外表
02:26
the different languages around the world?
43
128000
2000
及不同語言的呢?
02:28
Well, the question of origins, as with so many other questions in biology,
44
130000
3000
人類起源的問題，如同其他生物學問題
02:31
seems to have been answered by Darwin over a century ago.
45
133000
2000
看起來似乎在超過一百年以前，已經被達爾文解開了
02:33
In "The Descent of Man," he wrote,
46
135000
2000
他在著作「人類的起源」中寫道：
02:35
"In each great region of the world, the living mammals
47
137000
2000
在世界每個區域，現存的哺乳動物
02:37
are closely related to the extinct species of the same region.
48
139000
3000
都與當地已絕種的物種有緊密的關係
02:40
It's therefore probable that Africa was formerly inhabited by extinct apes
49
142000
3000
所以已絕跡的類人猿，之前可能住在非洲
02:43
closely allied to the gorilla and chimpanzee,
50
145000
3000
他們與大猩猩與黑猩猩應是近親
02:46
and as these two species are now man's nearest allies,
51
148000
3000
這兩個物種是最接近我們現代人類的「親戚」
02:49
it's somewhat more probable that our early progenitors
52
151000
2000
因此，人類最原始的祖先
02:51
lived on the African continent than elsewhere."
53
153000
2000
有可能來自非洲大陸，而非其他地區
02:53
So we're done, we can go home -- finished the origin question.
54
155000
4000
這樣就解決人類源起的問題啦! 我們可以解散了，不是嗎？
02:57
Well, not quite. Because Darwin was talking about our distant ancestry,
55
159000
4000
等等，還沒結束！達爾文解釋的是人類的遠祖
03:01
our common ancestry with apes.
56
163000
2000
我們與類人猿共同的祖先
03:03
And it is quite clear that apes originated on the African continent.
57
165000
4000
很明顯的，類人猿起源於非洲大陸
03:07
Around 23 million years ago, they appear in the fossil record.
58
169000
3000
從化石推斷，大約是從兩千三百萬年前開始出現
03:10
Africa was actually disconnected from the other landmasses at that time,
59
172000
3000
當時，非洲大陸已經與其它大陸隔絕
03:13
due to the vagaries of plate tectonics, floating around the Indian Ocean.
60
175000
4000
由於板塊持續運動，非洲大陸在印度洋上漂浮
03:17
Bumped into Eurasia around 16 million years ago,
61
179000
2000
並在一千六百萬年前與歐亞板塊碰撞
03:19
and then we had the first African exodus, as we call it.
62
181000
3000
因此產生了所謂的第一次「非洲物種遷移」
03:22
The apes that left at that time ended up in Southeast Asia,
63
184000
2000
遷徙的類人猿最後在東南亞落腳
03:24
became the gibbons and the orangutans.
64
186000
2000
演化為長臂猿和猩猩
03:26
And the ones that stayed on in Africa
65
188000
2000
那些留在非洲的
03:28
evolved into the gorillas, the chimpanzees and us.
66
190000
2000
演化為大猩猩、黑猩猩，還有我們人類
03:30
So, yes, if you're talking about our common ancestry with apes,
67
192000
3000
所以沒錯，如果指的是人類與猿類的共同祖先
03:33
it's very clear, by looking at the fossil record, we started off here.
68
195000
4000
化石紀錄的確證明我們起源於非洲大陸
03:37
But that's not really the question I'm asking.
69
199000
2000
但這不是我真正的問題
03:39
I'm asking about our human ancestry,
70
201000
2000
我問的是「人類」本身的祖先
03:41
things that we would recognize as being like us
71
203000
3000
就是那些會被認為長得像我們的東西
03:44
if they were sitting here in the room.
72
206000
2000
就像假設他們就坐在這個空間裡
03:46
If they were peering over your shoulder,
73
208000
2000
假如他們正從你的背後看著你
03:48
you wouldn't leap back, like that. What about our human ancestry?
74
210000
3000
你也不會嚇一大跳。那麼，人類的祖先從哪裡來?
03:51
Because if we go far enough back,
75
213000
2000
如果我們回溯到遠古時期
03:53
we share a common ancestry with every living thing on Earth.
76
215000
3000
我們與地球上所有的生物都擁有共同祖先
03:56
DNA ties us all together, so we share ancestry with barracuda
77
218000
3000
依據DNA排列，我們甚至跟梭魚、
03:59
and bacteria and mushrooms, if you go far enough back -- over a billion years.
78
221000
5000
細菌、蘑菇的祖先都一樣—如果回溯到數十億年前
04:04
What we're asking about though is human ancestry.
79
226000
2000
但是我問的是人類本身的祖先
04:06
How do we study that?
80
228000
2000
怎麼研究這個問題呢？
04:08
Well, historically, it has been studied using the science of paleoanthropology.
81
230000
4000
遠古人類學家其實已經研究這個問題很多年了
04:12
Digging things up out of the ground,
82
234000
2000
挖掘古生物遺跡
04:14
and largely on the basis of morphology --
83
236000
2000
大致上依據型態去分類
04:16
the way things are shaped, often skull shape -- saying,
84
238000
3000
按照各種骨頭的形狀去分類—多數是頭骨
04:19
"This looks a little bit more like us than that, so this must be my ancestor.
85
241000
4000
舉例來說，這個比那個看起來更像我們一點
04:23
This must be who I'm directly descended from."
86
245000
3000
所以想必這個就是我們的祖先
04:26
The field of paleoanthropology, I'll argue,
87
248000
3000
我必須說，古生物學在這一點上
04:29
gives us lots of fascinating possibilities about our ancestry,
88
251000
3000
提供我們許多有趣的可能答案
04:32
but it doesn't give us the probabilities that we really want as scientists.
89
254000
3000
但是沒有提供每一項可能答案的機率，這是科學家真正需要的
04:35
What do I mean by that?
90
257000
2000
怎麼說呢?
04:37
You're looking at a great example here.
91
259000
2000
這邊就有一個很好的例子
04:39
These are three extinct species of hominids,
92
261000
2000
這三種絕種的原始人
04:41
potential human ancestors.
93
263000
2000
每一種都可能是人類的祖先
04:43
All dug up just west of here in Olduvai Gorge, by the Leakey family.
94
265000
3000
三種都是李奇家族在奧度瓦伊谷以西挖掘出來的
04:46
And they're all dating to roughly the same time.
95
268000
2000
他們生活的時期也都差不多
04:48
From left to right, we've got Homo erectus, Homo habilis,
96
270000
2000
從左到右分別是直立人 、巧人
04:50
and Australopithecus -- now called Paranthropus boisei,
97
272000
3000
以及南方古猿，現在稱為鮑氏傍人的更新紀靈長類
04:53
the robust australopithecine. Three extinct species, same place, same time.
98
275000
5000
三個絕跡的物種，出現在同一個時間、同一個地點
04:58
That means that not all three could be my direct ancestor.
99
280000
3000
這意味著不可能三種都是我們的祖先
05:01
Which one of these guys am I actually related to?
100
283000
3000
那我們到底是從哪一種演化來的呢?
05:04
Possibilities about our ancestry, but not the probabilities that we're really looking for.
101
286000
5000
這些「可能」是我們的祖先，但沒有告訴我們這個「可能」的機率
05:10
Well, a different approach has been to look at morphology in humans
102
292000
4000
另一個角度，是從體型來判斷
05:14
using the only data that people really had at hand until quite recently --
103
296000
3000
使用人們到目前為止僅有的資料
05:17
again, largely skull shape.
104
299000
2000
同樣的，大部分是靠頭骨形狀
05:19
The first person to do this systematically was Linnaeus,
105
301000
4000
第一個將這種方式系統化的科學家是林奈
05:23
Carl von Linne, a Swedish botanist,
106
305000
2000
卡爾·林奈, 瑞典植物學家
05:25
who in the eighteenth century took it upon himself
107
307000
2000
在十八世紀，獨自完成這項工作
05:27
to categorize every living organism on the planet.
108
309000
2000
把地球上所有生物做好分類
05:29
You think you've got a tough job?
109
311000
2000
還會抱怨你的工作很難嗎?
05:31
And he did a pretty good job.
110
313000
2000
他做得相當不錯
05:33
He categorized about 12,000 species in "Systema Naturae."
111
315000
4000
將一萬兩千個物種分類，記載在「自然系統」一書中
05:37
He actually coined the term Homo sapiens -- it means wise man in Latin.
112
319000
3000
他還創造了智人一詞--在拉丁文中是指有智慧的人
05:40
But looking around the world at the diversity of humans, he said,
113
322000
4000
環顧這世上五花八門的人種，他說：
05:44
"Well, you know, we seem to come in discreet sub-species or categories."
114
326000
4000
我們只是具有微妙差異的亞種，或不同的智人而已
05:48
And he talked about Africans and Americans and Asians and Europeans,
115
330000
4000
然後他開始區分出非洲人、美洲人、亞洲人、和歐洲人
05:52
and a blatantly racist category he termed "Monstrosus,"
116
334000
3000
也公然地以種族歧視的觀點，區分出一種「怪獸」
05:55
which basically included all the people he didn't like,
117
337000
3000
基本上囊括所有他不喜歡的人種
05:58
including imaginary folk like elves.
118
340000
3000
還包括妖精等想像人物
06:02
It's easy to dismiss this as the perhaps well-intentioned
119
344000
5000
我們很容易就可以把他的行為，當成是十八世紀中古科學家
06:07
but ultimately benighted musings of an eighteenth century scientist
120
349000
3000
立意良善卻愚昧的「前達爾文」研究
06:10
working in the pre-Darwinian era.
121
352000
2000
並且嗤之以鼻
06:12
Except, if you had taken physical anthropology
122
354000
2000
但是，如果你曾經修過人類學的課程
06:14
as recently as 20 or 30 years ago, in many cases you would have learned
123
356000
4000
在二、三十年前，
06:18
basically that same classification of humanity.
124
360000
2000
這還是正統的人類分類學呢！
06:20
Human races that according to physical anthropologists of 30, 40 years ago --
125
362000
5000
根據三、四時年前人類學家的說法--
06:25
Carlton Coon is the best example --
126
367000
2000
卡爾頓 庫恩為此學說的代表性典範--
06:27
had been diverging from each other -- this was in the post-Darwinian era --
127
369000
4000
人類族群分支，出現在超過百萬年前，直立人的出現以後
06:31
for over a million years, since the time of Homo erectus.
128
373000
3000
--這可是後達爾文時代的學說了
06:34
But based on what data?
129
376000
2000
可是這樣的觀點的根據又是什麼?
06:36
Very little. Very little. Morphology and a lot of guesswork.
130
378000
4000
很少，幾乎沒有。單是靠形態學加上各種猜想而已
06:40
Well, what I'm going to talk about today,
131
382000
2000
我今天要講的就是
06:42
what I'm going to talk about now is a new approach to this problem.
132
384000
3000
一個新的方法，來解答這個問題
06:45
Instead of going out and guessing about our ancestry,
133
387000
3000
這個新方法不是挖掘骨骸，
06:48
digging things up out of the ground, possible ancestors,
134
390000
2000
到處碰碰運氣
06:50
and saying it on the basis of morphology --
135
392000
2000
單憑化石外型，猜想我們的祖先到底是誰
06:52
which we still don't completely understand,
136
394000
2000
甚至在我們尚未完全了解如何運用化石外型合理推論
06:54
we don't know the genetic causes underlying this morphological variation --
137
396000
4000
因為我們還不確定遺傳與外型的關聯性
06:58
what we need to do is turn the problem on its head.
138
400000
2000
我們必須做的是，把問題倒過來看
07:00
Because what we're really asking is a genealogical problem,
139
402000
4000
畢竟想探討的是個族譜議題
07:04
or a genealogical question.
140
406000
2000
或是尋找人類族譜的答案
07:06
What we're trying to do is construct a family tree for everybody alive today.
141
408000
5000
因此，我們試圖建立起一個能連結所有人類的族譜
07:11
And as any genealogist will tell you --
142
413000
2000
就像每個族譜學者會告訴你的--
07:13
anybody have a member of the family, or maybe you
143
415000
2000
每個人都有家族成員，或者你可能
07:15
have tried to construct a family tree, trace back in time?
144
417000
3000
也曾試著建構自己的族譜，追溯祖先的歷史？
07:18
You start in the present, with relationships you're certain about.
145
420000
2000
你會從那些你確定的家族關係著手
07:20
You and your siblings, you have a parent in common.
146
422000
2000
例如：你和兄弟姊妹有著共同的父母
07:22
You and your cousins share a grandparent in common.
147
424000
2000
你和堂表親有著共同的祖父母
07:24
You gradually trace further and further back into the past,
148
426000
3000
漸漸地，你可以回溯到更遙遠的過去
07:27
adding these ever more distant relationships.
149
429000
2000
加入更多遠親關係
07:29
But eventually, no matter how good you are at digging up the church records,
150
431000
4000
到最後，無論你多麼擅長挖掘教會檔案
07:33
and all that stuff, you hit what the genealogists call a brick wall.
151
435000
4000
或是其他家族資料，你終會遇到一個狀況—族譜學家口中的「碰壁」
07:37
A point beyond which you don't know anything else about your ancestors,
152
439000
3000
也就是，到了這一步，你再也找不出更多祖先的訊息
07:40
and you enter this dark and mysterious realm we call history
153
442000
4000
然後陷入一個神祕的世界—我們所謂的「歷史」
07:44
that we have to feel our way through with whispered guidance.
154
446000
3000
接著，只能仰賴微小的線索，繼續前進
07:47
Who were these people who came before?
155
449000
2000
我們的祖先是誰？他們先來後到的順序呢？
07:49
We have no written record. Well, actually, we do.
156
451000
3000
我們沒有文字記錄。嗯，事實上，我們是有...
07:52
Written in our DNA, in our genetic code --
157
454000
3000
這些文字寫在我們的DNA上，藏在我們的遺傳密碼之中
07:55
we have a historical document that takes us back in time
158
457000
2000
像整套的歷史捲軸，帶領我們回到過去
07:57
to the very earliest days of our species. And that's what we study.
159
459000
4000
直到人類的起源；這就是我們的研究
08:01
Now, a quick primer on DNA.
160
463000
2000
先來簡單介紹一下DNA
08:03
I suspect that not everybody in the audience is a geneticist.
161
465000
3000
我猜應該不是每個聽眾都是遺傳學家
08:06
It is a very long, linear molecule, a coded version
162
468000
4000
DNA是個很長的鏈型分子，一本密碼書
08:10
of how to make another copy of you. It's your blueprint.
163
472000
3000
教你如何複製自己，也就是建構你的藍圖
08:13
It's composed of four subunits: A, C, G and T, we call them.
164
475000
3000
由四種成分組成，我們稱之為A、C、G、T
08:16
And it's the sequence of those subunits that defines that blueprint.
165
478000
4000
這些成分的排列順序決定了整個藍圖
08:20
How long is it? Well, it's billions of these subunits in length.
166
482000
3000
ＤＮＡ有多長?大概有數十億個上述成分
08:23
A haploid genome -- we actually have two copies of all of our chromosomes --
167
485000
3000
所有的基因都是一式兩份，染色體也是
08:26
a haploid genome is around 3.2 billion nucleotides in length.
168
488000
4000
每份約有32億個核苷酸
08:30
And the whole thing, if you add it all together,
169
492000
2000
所以把兩份染色體加起來
08:32
is over six billion nucleotides long.
170
494000
2000
就有超過六十億個核苷酸
08:34
If you take all the DNA out of one cell in your body,
171
496000
3000
如果你從一個細胞內，拿出所有的DNA
08:37
and stretch it end to end, it's around two meters long.
172
499000
4000
拉長後，大概足足有兩公尺
08:41
If you take all the DNA out of every cell in your body,
173
503000
2000
如果你拿出體內所有的DNＡ
08:43
and you stretch it end to end, it would reach from here to the moon and back,
174
505000
4000
足以從地球連接到月亮，然後再回到地球
08:47
thousands of times. It's a lot of information.
175
509000
3000
往返幾千次，所以ＤＮＡ之中能夠包含大量訊息
08:50
And so when you're copying this DNA molecule to pass it on, it's a pretty tough job.
176
512000
6000
也因此，複製這些DNA，將訊息傳遞給後代，勢必是個艱鉅的任務
08:56
Imagine the longest book you can think of, "War and Peace."
177
518000
4000
試想一本你能想到最厚重的書,比如戰爭與和平
09:00
Now multiply it by 100.
178
522000
2000
乘上一百倍
09:02
And imagine copying that by hand.
179
524000
2000
然後你必須手抄複製這些內容
09:04
And you're working away until late at night,
180
526000
2000
徹夜不眠
09:06
and you're very, very careful, and you're drinking coffee
181
528000
2000
你小心翼翼地抄寫，喝著咖啡提神
09:08
and you're paying attention, but, occasionally,
182
530000
2000
你集中全副精神,但有的時候
09:10
when you're copying this by hand,
183
532000
2000
當你完全以手抄複製
09:12
you're going to make a little typo, a spelling mistake --
184
534000
2000
難免會抄錯--例如拼音錯誤
09:14
substitute an I for an E, or a C for a T.
185
536000
4000
誤將I寫成E、C寫成T
09:18
Same thing happens to our DNA as it's being passed on through the generations.
186
540000
4000
相同情形也會發生在當DNA被一代一代傳下來的時候
09:22
It doesn't happen very often. We have a proofreading mechanism built in.
187
544000
3000
這並不常發生，因為我們體內有自動校對機制
09:25
But when it does happen, and these changes get transmitted down
188
547000
2000
但是一旦發生，這些手誤將傳遞下去
09:27
through the generations, they become markers of descent.
189
549000
3000
一代接著一代，成為子子孫孫身上的標記
09:30
If you share a marker with someone,
190
552000
2000
因此如果你跟某人的標記相同
09:32
it means you share an ancestor at some point in the past,
191
554000
3000
那正說明你們可能血脈相連
09:35
the person who first had that change in their DNA.
192
557000
2000
能夠追溯到第一個抄錯的祖先
09:37
And it's by looking at the pattern of genetic variation,
193
559000
3000
透過檢視遺傳變異的型態
09:40
the pattern of these markers in people all over the world,
194
562000
3000
現今全球人類共有的型態
09:43
and assessing the relative ages when they occurred throughout our history,
195
565000
4000
分析這些標記從何時出現
09:47
that we've been able to construct a family tree for everybody alive today.
196
569000
3000
是現今最新建立人類族譜的方式
09:50
These are two pieces of DNA that we use quite widely in our work.
197
572000
3000
這邊有兩個我們研究中常用的ＤＮＡ片段
09:53
Mitochondrial DNA, tracing a purely maternal line of descent.
198
575000
3000
一個是粒線體ＤＮＡ，總是來自母系
09:56
You get your mtDNA from your mother, and your mother's mother,
199
578000
3000
你的粒線體ＤＮＡ從母親那裏得到，你母親的粒線體DNA從你外祖母那裏得到
09:59
all the way back to the very first woman.
200
581000
2000
一路追下去，可以找到人類的第一個女性
10:01
The Y chromosome, the piece of DNA that makes men men,
201
583000
3000
還有另一個片段是Ｙ染色體，即雄性染色體
10:04
traces a purely paternal line of descent.
202
586000
3000
總是來自父系
10:07
Everybody in this room, everybody in the world,
203
589000
4000
這演講廳裡所有的人，以及全世界所有的人
10:11
falls into a lineage somewhere on these trees.
204
593000
4000
都能在這個族譜找到一個位置
10:15
Now, even though these are simplified versions of the real trees,
205
597000
3000
即使我用的是簡化版本的族譜
10:18
they're still kind of complicated, so let's simplify them.
206
600000
2000
還是相當複雜，所以我簡化一點來說明
10:20
Turn them on their sides, combine them so that they look like a tree
207
602000
2000
將投影片轉個方向，看起來像棵樹
10:22
with the root at the bottom and the branches going up.
208
604000
3000
底下是樹根、上面是樹枝
10:25
What's the take-home message?
209
607000
2000
其中說明了什麼？
10:27
Well, the thing that jumps out at you first
210
609000
2000
你最先注意到的
10:29
is that the deepest lineages in our family trees
211
611000
3000
應該是最底層的家族關係
10:32
are found within Africa, among Africans.
212
614000
5000
來自非洲
10:37
That means that Africans have been accumulating
213
619000
3000
這代表非洲人身上
10:40
this mutational diversity for longer.
214
622000
3000
攜帶突變多樣性的時間最長
10:43
And what that means is that we originated in Africa. It's written in our DNA.
215
625000
4000
因此說明了人類起源於非洲，而且這個訊息寫在我們的ＤＮＡ上
10:47
Every piece of DNA we look at has greater diversity within Africa than outside of Africa.
216
629000
5000
每個ＤＮＡ片段，在非洲都可以找到更高的多樣性
10:52
And at some point in the past, a sub-group of Africans
217
634000
3000
過去的某個時間，一部分的非洲人
10:55
left the African continent to go out and populate the rest of the world.
218
637000
4000
離開非洲大陸，遷移到其他地區定居
10:59
Now, how recently do we share this ancestry?
219
641000
2000
問題是，這件事是在何時發生的?
11:01
Was it millions of years ago, which we might suspect
220
643000
4000
幾百萬年前嗎?
11:05
by looking at all this incredible variation around the world?
221
647000
3000
如同我們從全世界如此多樣的人種來推測的一般?
11:08
No, the DNA tells a story that's very clear.
222
650000
3000
答案是否，DNA的歷史書中明文記載
11:11
Within the last 200,000 years, we all share an ancestor, a single person --
223
653000
5000
過去二十萬年中，我們仍擁有共同祖先，同一個人
11:16
Mitochondrial Eve, you might have heard about her -- in Africa,
224
658000
4000
粒線體夏娃，你或許聽過— 也出現在非洲
11:20
an African woman who gave rise to all the mitochondrial diversity in the world today.
225
662000
3000
這位非洲女性，是現代各式各樣粒線體的起源
11:23
But what's even more amazing
226
665000
2000
但是更驚人的是
11:25
is that if you look at the Y-chromosome side,
227
667000
2000
如果檢視Ｙ染色體
11:27
the male side of the story, the Y-chromosome Adam
228
669000
4000
父系起源— Ｙ染色體亞當
11:31
only lived around 60,000 years ago.
229
673000
2000
距離我們只有六萬年之久
11:33
That's only about 2,000 human generations,
230
675000
3000
不過兩千的世代而已
11:36
the blink of an eye in an evolutionary sense.
231
678000
3000
對演化史而言，一眨眼的時間
11:40
That tells us we were all still living in Africa at that time.
232
682000
3000
這說明了，六萬年前，人類仍然生活在非洲
11:43
This was an African man who gave rise
233
685000
2000
一位非洲男性
11:45
to all the Y chromosome diversity around the world.
234
687000
2000
把Ｙ染色體傳遞給全世界
11:47
It's only within the last 60,000 years
235
689000
2000
在僅僅過去六萬年的時間裡
11:49
that we have started to generate this incredible diversity we see around the world.
236
691000
4000
人種開始產生了難以置信的多樣性
11:53
Such an amazing story.
237
695000
2000
多令人震驚的故事
11:55
We're all effectively part of an extended African family.
238
697000
3000
我們每個人都是非洲大家族的成員之一
11:59
Now, that seems so recent. Why didn't we start to leave earlier?
239
701000
3000
那麼，問題來了：為什麼人類不是在更早之前離開非洲？
12:02
Why didn't Homo erectus evolve into separate species,
240
704000
4000
直立人為什麼沒有演化成其他物種？
12:06
or sub-species rather, human races around the world?
241
708000
2000
或是其他亞種呢？為什麼直立人沒有成為現代人種？
12:08
Why was it that we seem to have come out of Africa so recently?
242
710000
4000
為什麼我們這麼晚才從非洲遷移出來？
12:12
Well, that's a big question. These "why" questions,
243
714000
2000
這是個大哉問，因為問的是為什麼
12:14
particularly in genetics and the study of history in general, are always the big ones,
244
716000
5000
無論對遺傳學家或歷史學家，都是大問題
12:19
the ones that are tough to answer.
245
721000
2000
問題難度較高
12:21
And so when all else fails, talk about the weather.
246
723000
3000
所以，當其他途徑都不通的時候，讓我們談一下全球氣候變遷的議題
12:24
What was going on to the world's weather around 60,000 years ago?
247
726000
3000
六萬年前，全球氣候出了什麼狀況？
12:27
Well, we were going into the worst part of the last ice age.
248
729000
3000
那時剛好是最近一個冰河時期最嚴重的時候
12:30
The last ice age started roughly 120,000 years ago.
249
732000
3000
最近一個冰河時期始於十二萬年以前
12:33
It went up and down, and it really started to accelerate around 70,000 years ago.
250
735000
4000
氣候開始不穩定，來到約七萬年前時，更加惡化
12:37
Lots of evidence from sediment cores
251
739000
2000
從沉積物、
12:39
and the pollen types, oxygen isotopes and so on.
252
741000
3000
花粉類型、氧同位素等等的證據中都如此顯示
12:42
We hit the last glacial maximum around 16,000 years ago,
253
744000
3000
一萬六千年前，冰河時期進入高峰
12:45
but basically, from 70,000 years on, things were getting really tough,
254
747000
4000
然後在七萬年前左右，氣候條件變得極為嚴苛
12:49
getting very cold. The Northern Hemisphere had massive growing ice sheets.
255
751000
5000
溫度極低，整個北半球壟罩在冰層中
12:54
New York City, Chicago, Seattle, all under a sheet of ice.
256
756000
4000
紐約、芝加哥、西雅圖
12:58
Most of Britain, all of Scandinavia, covered by ice several kilometers thick.
257
760000
5000
英國的絕大部分、整個斯堪地那維亞半島，全都被冰層覆蓋
13:03
Now, Africa is the most tropical continent on the planet --
258
765000
3000
非洲--地球上最熱的大陸
13:06
about 85 percent of it lies between Cancer and Capricorn --
259
768000
4000
百分之八十五的位置介於巨蟹座即摩羯座之間
13:10
and there aren't a lot of glaciers here,
260
772000
2000
卻沒有什麼冰層存在
13:12
except on the high mountains here in East Africa.
261
774000
2000
除了在東非少數的高山地區之外
13:14
So what was going on here? We weren't covered in ice in Africa.
262
776000
3000
那裏發生了什麼事呢？人類沒有被冰層覆蓋
13:17
Rather, Africa was drying out at that time.
263
779000
3000
非洲大陸變得相當乾燥
13:20
This is a paleo-climatological map
264
782000
2000
這是遠古氣候分布圖
13:22
of what Africa looked like between 60,000 and 70,000 years ago,
265
784000
3000
顯示非洲大陸約六萬到七萬年前的面貌
13:25
reconstructed from all these pieces of evidence that I mentioned before.
266
787000
4000
從我前面提過的各種證據拼湊出來的
13:29
The reason for that is that ice actually sucks moisture out of the atmosphere.
267
791000
4000
非洲乾燥的原因是，冰其實會由大氣中吸收水分
13:33
If you think about Antarctica, it's technically a desert, it gets so little precipitation.
268
795000
4000
想像一下南極，基本上是整片沙漠，降雨量幾乎是零
13:37
So the whole world was drying out.
269
799000
2000
所以當時全球面臨乾旱
13:39
The sea levels were dropping. And Africa was turning to desert.
270
801000
4000
海平面下降，非洲大陸一片荒漠
13:43
The Sahara was much bigger then than it is now.
271
805000
3000
撒哈拉沙漠的面積比今日大很多
13:46
And the human habitat was reduced to just a few small pockets,
272
808000
3000
與今日人類活動範圍相較
13:49
compared to what we have today.
273
811000
2000
當時人類的居住地只剩下四散的小區域
13:51
The evidence from genetic data
274
813000
2000
遺傳證據顯示
13:53
is that the human population around this time, roughly 70,000 years ago,
275
815000
3000
七萬年前左右，
13:56
crashed to fewer than 2,000 individuals.
276
818000
3000
全球人口銳減至二千人以下
13:59
We nearly went extinct. We were hanging on by our fingernails.
277
821000
4000
那時，我們瀕臨絕種，只差一步就完蛋了
14:03
And then something happened. A great illustration of it.
278
825000
3000
接著有個事件發生，請看圖示
14:06
Look at some stone tools.
279
828000
2000
看看這些石器
14:08
The ones on the left are from Africa, from around a million years ago.
280
830000
4000
左邊是非洲挖掘出來的，距今約一萬年前
14:12
The ones on the right were made by Neanderthals, our distant cousins,
281
834000
3000
右邊是尼安德塔人製作的，我們的遠房表親
14:15
not our direct ancestors, living in Europe,
282
837000
2000
不是我們的直系祖先，曾經住在歐洲
14:17
and they date from around 50,000 or 60,000 years ago.
283
839000
4000
約五萬到六萬年前絕跡
14:21
Now, at the risk of offending any paleoanthropologists
284
843000
3000
接下來我要說的，
14:24
or physical anthropologists in the audience,
285
846000
3000
可能會冒犯在場的遠古人類學家或人類學家
14:27
basically there's not a lot of change between these two stone tool groups.
286
849000
5000
這兩種石器，基本上沒有太多進化
14:32
The ones on the left are pretty similar to the ones on the right.
287
854000
3000
左邊看起來跟右邊的很像
14:35
We are in a period of long cultural stasis from a million years ago
288
857000
4000
一百萬年前，直到六、七十萬年前
14:39
until around 60,000 to 70,000 years ago.
289
861000
2000
人類文明的進展處於停滯階段
14:41
The tool styles don't change that much.
290
863000
2000
使用的工具型態沒有什麼改變
14:43
The evidence is that the human way of life
291
865000
2000
這個證據說明，人類生活方式
14:45
didn't change that much during that period.
292
867000
2000
在那個時期，變化不大
14:47
But then 50, 60, 70 thousand years ago, somewhere in that region,
293
869000
5000
但進入七萬、六萬、五萬年前，在非洲的某個地區
14:52
all hell breaks loose. Art makes its appearance.
294
874000
3000
出現大幅度的變化，藝術開始發跡
14:55
The stone tools become much more finely crafted.
295
877000
3000
石器雕刻變得更加精緻
14:58
The evidence is that humans begin to specialize in particular prey species,
296
880000
2000
這代表人類在那時
15:01
at particular times of the year.
297
883000
2000
開始在每年的特定時候去獵食特定物種
15:03
The population size started to expand.
298
885000
3000
人口數量開始擴增
15:06
Probably, according to what many linguists believe,
299
888000
2000
根據語言學家的推測
15:08
fully modern language, syntactic language -- subject, verb, object --
300
890000
4000
完整的現代語言（句型）--包含主詞、動詞、受詞
15:12
that we use to convey complex ideas, like I'm doing now, appeared around that time.
301
894000
4000
就像我現在用來傳遞複雜概念的語言，也隨之出現
15:16
We became much more social. The social networks expanded.
302
898000
4000
人類的社交性大增、社交關係更加複雜
15:20
This change in behavior allowed us to survive these worsening conditions in Africa,
303
902000
5000
而這些行為的演化，幫助我們熬過惡劣的氣候
15:25
and they allowed us to start to expand around the world.
304
907000
4000
並且開始遷徙到全世界
15:30
We've been talking at this conference about African success stories.
305
912000
3000
這個演講已經談到許多人類在非洲的成功故事
15:33
Well, you want the ultimate African success story?
306
915000
3000
想要聽一聽非洲成功故事的大結局嗎？
15:36
Look in the mirror. You're it. The reason you're alive today
307
918000
3000
照個鏡子，就是你。今天你之所以生存在此
15:39
is because of those changes in our brains that took place in Africa --
308
921000
4000
全來自於當時非洲大陸人腦的成功演化
15:43
probably somewhere in the region where we're sitting right now,
309
925000
3000
搞不好就是我們現在所在之處
15:46
around 60, 70 thousand years ago --
310
928000
3000
距今六、七萬年前
15:49
allowing us not only to survive in Africa, but to expand out of Africa.
311
931000
3000
這些演化不但幫助人類存活下來，還從非洲遷移至全球
15:52
An early coastal migration along the south coast of Asia,
312
934000
3000
沿著非洲南部的海岸線
15:55
leaving Africa around 60,000 years ago,
313
937000
2000
大約六萬年前離開非洲
15:57
reaching Australia very rapidly, by 50,000 years ago.
314
939000
4000
五萬年前定居有些人開始定居澳洲
16:01
A slightly later migration up into the Middle East.
315
943000
2000
稍晚一點，一部分的人搬到中東
16:03
These would have been savannah hunters.
316
945000
2000
成為所謂的草原獵人
16:05
So those of you who are going on one of the post-conference tours,
317
947000
2000
如果有人參加本次演講之後的遊覽形成
16:07
you'll get to see what a real savannah is like.
318
949000
2000
將可見識到真正的草原獵人
16:09
And it's basically a meat locker.
319
951000
2000
簡單說，是一群不折不扣的肉食主義者
16:11
People who would have specialized in killing the animals,
320
953000
3000
他們進化為一群捕獵專家
16:14
hunting the animals on those meat locker savannahs, moving up,
321
956000
3000
獵捕動物後，向北遷移
16:17
following the grasslands into the Middle East around 45,000 years ago,
322
959000
4000
在四萬五千年前左右，沿著草原地區，遷移至中東地區
16:21
during one of the rare wet phases in the Sahara.
323
963000
2000
那時撒哈拉沙漠適逢一段難得的濕潤期
16:23
Migrating eastward, following the grasslands,
324
965000
3000
於是人類繼續沿著適合生存的草原
16:26
because that's what they were adapted to live on.
325
968000
2000
向東前進
16:28
And when they reached Central Asia,
326
970000
2000
來到中亞
16:30
they reached what was effectively a steppe super-highway,
327
972000
3000
他們沿著當時的「高速公路」
16:33
a grassland super-highway.
328
975000
2000
沿途都是草原構成的高速公路
16:35
The grasslands at that time -- this was during the last ice age --
329
977000
2000
當時仍處於冰河時期尾聲
16:37
stretched basically from Germany all the way over to Korea,
330
979000
3000
一路從德國延伸到韓國，盡是草原
16:40
and the entire continent was open to them.
331
982000
2000
整片大陸都供他們去探索
16:42
Entering Europe around 35,000 years ago,
332
984000
2000
三萬五千年前，人類棲地擴展至歐洲
16:44
and finally, a small group migrating up
333
986000
2000
最後，一小群人北上
16:46
through the worst weather imaginable, Siberia,
334
988000
4000
前進西伯利亞
16:50
inside the Arctic Circle, during the last ice age --
335
992000
2000
在冰河時期末，住進北極圈
16:52
temperature was at -70, -80, even -100, perhaps --
336
994000
4000
當時氣溫大約華氏零下七、八十度，甚至一百度
16:56
migrating into the Americas, ultimately reaching that final frontier.
337
998000
4000
最後終於來到美洲，就是人類遷徙路徑的終點
17:00
An amazing story, and it happened first in Africa.
338
1002000
4000
這個故事的動人之處是，一切源於非洲
17:04
The changes that allowed us to do that,
339
1006000
2000
且當時祖先的行為改變，使我們有機會
17:06
the evolution of this highly adaptable brain that we all carry around with us,
340
1008000
3000
演化出高度適應力的大腦，而現在每一個人都擁有它
17:09
allowing us to create novel cultures,
341
1011000
2000
進而創造出新的文明
17:11
allowing us to develop the diversity
342
1013000
3000
發展出高度多元性
17:14
that we see on a whirlwind trip like the one I've just been on.
343
1016000
3000
就像我在這趟旋風式旅途中看到的一樣
17:18
Now, that story I just told you is literally a whirlwind tour
344
1020000
4000
其實，我剛剛講的人類歷史，就是一段旋風式旅程
17:22
of how we populated the world, the great Paleolithic wanderings of our species.
345
1024000
5000
一個人類散布至全球各地的奇蹟、一個舊石器時代的奇蹟
17:27
And that's the story that I told a couple of years ago
346
1029000
2000
這也是我在幾年前
17:29
in my book, "The Journey of Man," and a film that we made with the same title.
347
1031000
4000
我的拙作「人類的旅程」一書中所講的故事
17:33
And as we were finishing up that film --
348
1035000
3000
之後我們與國家地理頻道合作，翻拍成同名影集
17:36
it was co-produced with National Geographic --
349
1038000
2000
當拍攝工作結束之際
17:38
I started talking to the folks at NG about this work.
350
1040000
3000
我跟合作夥伴聊起這項研究計畫的始末
17:41
And they got really excited about it. They liked the film, but they said,
351
1043000
4000
他們相當撼動，也非常喜歡拍攝成果，但是他們問：
17:45
"You know, we really see this as kind of
352
1047000
2000
你知道，我們真的覺得
17:47
the next wave in the study of human origins, where we all came from,
353
1049000
4000
利用ＤＮＡ研究人類起源
17:51
using the tools of DNA to map the migrations around the world.
354
1053000
5000
及祖先遷徙的路徑，將帶動一股學術界的新潮流
17:56
You know, the study of human origins is kind of in our DNA,
355
1058000
2000
既然人類起源都記錄在ＤＮＡ之中
17:58
and we want to take it to the next level.
356
1060000
2000
我們當然想更進一步了解
18:00
What do you want to do next?"
357
1062000
2000
所以，你計畫下一步研究什麼？
18:02
Which is a great question to be asked by National Geographic.
358
1064000
2000
國家地理頻道提出了個好問題
18:04
And I said, "Well, you know, what I've sketched out here is just that.
359
1066000
4000
我說：我畫得這個草圖其實還很粗糙
18:08
It is a very coarse sketch of how we migrated around the planet.
360
1070000
4000
只是大致說明人類遷移的路徑
18:12
And it's based on a few thousand people we've sampled from,
361
1074000
3000
而且是從數千人身上採樣的而已
18:15
you know, a handful of populations around the world.
362
1077000
2000
相較於全世界人口，畢竟占少數
18:17
Studied a few genetic markers, and there are lots of gaps on this map.
363
1079000
4000
我們也只針對少數遺傳標籤做了研究，遷移地圖並不完整
18:21
We've just connected the dots. What we need to do
364
1083000
2000
我們頂多是將片段的資料串連起來
18:23
is increase our sample size by an order of magnitude or more --
365
1085000
4000
接著，當然需要增加樣本數，至少十倍
18:27
hundreds of thousands of DNA samples from people all over the world."
366
1089000
4000
採集各地人類，成千上萬的ＤＮＡ樣本
18:31
And that was the genesis of the Genographic Project.
367
1093000
3000
這只是一個基因地理學計畫的起源
18:34
The project launched in April 2005.
368
1096000
3000
此計畫從2005年四月開始
18:37
It has three core components. Obviously, science is a big part of it.
369
1099000
4000
包含三項核心領域，科學當然是一個重要的部分
18:41
The field research that we're doing around the world with indigenous peoples.
370
1103000
3000
另一個是各地原住民的實地考察
18:44
People who have lived in the same location for a long period of time
371
1106000
3000
原住民指的是在同一地點，長時間生活的人種
18:47
retain a connection to the place where they live
372
1109000
2000
他們與居住地的關係緊密
18:49
that many of the rest of us have lost.
373
1111000
2000
這是現代大多數人所缺乏的
18:52
So my ancestors come from all over northern Europe.
374
1114000
2000
比如我的祖先來自歐洲各地
18:54
I live in the Eastern Seaboard of North America when I'm not traveling.
375
1116000
3000
當我不是在旅行時，我則居住在美國東岸
18:57
Where am I indigenous to? Nowhere really. My genes are all jumbled up.
376
1119000
3000
我的故鄉是哪裡呢？哪裡都不算，在遷移地圖上，我的基因位置到處都是
19:00
But there are people who retain that link to their ancestors
377
1122000
3000
但是有些原住民，與祖先的連結還在
19:03
that allows us to contextualize the DNA results.
378
1125000
3000
使我們能夠將ＤＮＡ的結果串連起來
19:06
That's the focus of the field research,
379
1128000
2000
這是實地考察的重點
19:08
the centers that we've set up all over the world --
380
1130000
2000
我們已在世界各地設點
19:10
10 of them, top population geneticists.
381
1132000
3000
其中十個點，有頂尖的族群遺傳學家駐守
19:13
But, in addition, we wanted to open up this study to anybody around the world.
382
1135000
3000
最後，我們希望對全球的人開放參與本計畫的機會
19:16
How often do you get to participate in a big scientific project?
383
1138000
4000
你有多少機會可以參與一項大型科學研究計畫？
19:20
The Human Genome Project, or a Mars Rover mission.
384
1142000
2000
如同「人類基因研究計畫」、「火星探索計畫」一般
19:22
In this case, you actually can.
385
1144000
2000
現在你有機會成為我們的一份子
19:24
You can go onto our website, Nationalgeographic.com/genographic.
386
1146000
4000
上我們的網站:Nationalgeographic.com/genographic
19:28
You can order a kit. You can test your own DNA.
387
1150000
3000
訂購一套工具組，檢測自己的DNA
19:31
And you can actually submit those results to the database,
388
1153000
3000
並將結果提交到我們的資料庫
19:34
and tell us a little about your genealogical background,
389
1156000
2000
輸入一些家族資料
19:36
have the data analyzed as part of the scientific effort.
390
1158000
4000
我們就會當作研究計畫的一部分，分析你所提供的數據
19:40
Now, this is all a nonprofit enterprise, and so the money that we raise,
391
1162000
4000
這完全是非營利的，因此我們募集到的所有經費
19:44
after we cover the cost of doing the testing and making the kit components,
392
1166000
3000
扣除研究成本及製作工具組的成本之後
19:47
gets plowed back into the project.
393
1169000
2000
就用之於本研究計畫
19:49
The majority going to something we call the Legacy Fund.
394
1171000
2000
其中多數會捐給人類遺產保存基金會
19:51
It's a charitable entity, basically a grant-giving entity
395
1173000
4000
這是個慈善性的基金會
19:55
that gives money back to indigenous groups around the world
396
1177000
2000
把錢捐獻給全球需要的原住民
19:57
for educational, cultural projects initiated by them.
397
1179000
4000
贊助他們自行發起的各項教育、文化發展活動
20:01
They apply to this fund in order to do various projects,
398
1183000
2000
他們向這個基金會申請經費，來執行各種計畫
20:03
and I'll show you a couple of examples.
399
1185000
2000
讓我提供一些實例
20:05
So how are we doing on the project? We've got about 25,000 samples
400
1187000
3000
我們計畫進行的如何呢? 目前已經得到的DNA樣本數共有兩萬五千個
20:08
collected from indigenous people around the world.
401
1190000
2000
來自世界各處的原住民
20:10
The most amazing thing has been the interest on the part of the public;
402
1192000
3000
而震撼人心的是，來自各界的關注
20:13
210,000 people have ordered these participation kits
403
1195000
3000
從兩年前計畫開始以來
20:16
since we launched two years ago,
404
1198000
2000
全球已經有二十一萬人訂購DNA測試組
20:18
which has raised around five million dollars,
405
1200000
3000
因此我們募集了五百萬美元
20:21
the majority of which, at least half, is going back into the Legacy Fund.
406
1203000
3000
至少一半以上的經費，也已經回饋給人類遺產保存基金會
20:24
We've just awarded the first Legacy Grants totaling around 500,000 dollars.
407
1206000
4000
我們才剛捐出一筆五十萬美元
20:28
Projects around the world -- documenting oral poetry in Sierra Leone,
408
1210000
3000
作為保存席拉里昂口傳詩歌
20:31
preserving traditional weaving patterns in Gaza,
409
1213000
3000
、保護加沙傳統編織
20:34
language revitalization in Tajikistan, etc., etc.
410
1216000
3000
或復興塔克亞語等相關文化保存活動之用
20:37
So the project is going very, very well,
411
1219000
3000
目前計畫進行得非常順利
20:40
and I urge you to check out the website and watch this space.
412
1222000
4000
我在這裡，鼓勵各位去瀏覽我們的網站，並持續關注這項研究
20:44
Thank you very much.
413
1226000
2000
非常感謝各位!
20:46
(Applause)
414
1228000
2000
(掌聲)
ABOUT THE SPEAKER
Spencer Wells - GenographerSpencer Wells studies human diversity -- the process by which humanity, which springs from a single common source, has become so astonishingly diverse and widespread.
Why you should listen
By analyzing DNA from people in all regions of the world, Spencer Wells has concluded that all humans alive today are descended
from a single man who lived in Africa around 60,000 to 90,000 years ago. Now, Wells is working on the follow-up question: How did this man, sometimes called "Ychromosomal Adam," become the multicultural, globe-spanning body of life known as humanity?
Wells was recently named project director of the National Geographic Society's multiyear Genographic Project, which uses DNA samples to trace human migration out of Africa. In his 2002 book The Journey of Man: A Genetic Odyssey, he shows how genetic data can trace human migrations over the past 50,000 years, as our ancestors wandered out of Africa to fill up the continents of the globe.
Spencer Wells | Speaker | TED.com