i*****s
发帖数: 4596 | 1 http://www.nytimes.com/2013/02/15/science/studying-recent-human
East Asian Physical Traits Linked to 35,000-Year-Old Mutation
By NICHOLAS WADE
Published: February 14, 2013
Gaining a deep insight into human evolution, researchers have identified a
mutation in a critical human gene as the source of several distinctive
traits that make East Asians different from other races.
The traits — thicker hair shafts, more sweat glands, characteristically
identified teeth and smaller breasts — are the result of a gene mutation
that occurred about 35,000 years ago, the researchers have concluded.
The discovery explains a crucial juncture in the evolution of East Asians.
But the method can also be applied to some 400 other sites on the human
genome. The DNA changes at these sites, researchers believe, mark the
turning points in recent human evolution as the populations on each
continent diverged from one another.
The first of those sites to be studied contains the gene known as EDAR.
Africans and Europeans carry the standard version of the gene, but in most
East Asians, one of the DNA units has mutated.
Seeking to understand if the gene was the cause of thicker hair in East
Asians with the variant gene, a team of researchers led by Yana G. Kamberov
and Pardis C. Sabeti at the Broad Institute in Cambridge, Mass., decided to
test the gene in mice, where its effects could be more easily explored.
Mice already have EDAR, an ancient mammalian gene that plays a leading role
in the embryo in shaping hair, skin and teeth. The Broad team engineered a
strain of mice whose EDAR gene had the same DNA change as the East Asian
version of EDAR.
When the mice grew up, the researchers found they did indeed have thicker
hair shafts, confirming that the changed gene was the cause of East Asians’
thicker hair. But the gene had several other effects, they report in
Thursday’s issue of the journal Cell.
One was that the mice, to the researchers’ surprise, had extra sweat glands
. A Chinese member of the team, Sijia Wang, then tested people in China and
discovered that they, too, had more numerous sweat glands, evidently another
effect of the gene.
Another surprise was that the engineered mice had less breast tissue,
meaning that EDAR could be the reason that East Asian women have generally
smaller breasts.
East Asians have distinctively shaped teeth for which their version of EDAR
is probably responsible. But the mice were less helpful on this point; their
teeth are so different from humans’ that the researchers could not see any
specific change.
The finding that the gene has so many effects raises the question of which
one was the dominant trigger for natural selection.
Dr. Sabeti said the extra sweat glands could have been the feature favored
by natural selection, with all the other effects being dragged along in its
train.
“We’re the only mammals to have changed their entire hair pattern. So the
changes in teeth, hair and breasts — it’s very possible they are the
passengers and thermoregulation is the key,” she said, referring to the
role of sweat glands in cooling the body.
East Asians are sometimes assumed to have evolved in a cold environment
because of their narrow nostrils, which conserve heat, and the extra eyelid
fat that insulates the eye. But the Broad team calculates that the EDAR
variant arose about 35,000 years ago in central China and that the region
was then quite warm and humid. Extra sweat glands would have been
advantageous to the hunter-gatherers who lived at that time.
But Joshua Akey, a geneticist at the University of Washington in Seattle,
said he thought the more likely cause of the gene’s spread among East
Asians was sexual selection. Thick hair and small breasts are visible sexual
signals which, if preferred by men, could quickly become more common as the
carriers had more children. The genes underlying conspicuous traits, like
blue eyes and blond hair in Europeans, have very strong signals of selection
, Dr. Akey said, and the sexually visible effects of EDAR are likely to have
been stronger drivers of natural selection than sweat glands.
Yet a third view is held by Dr. Kamberov, who believes that each of the
effects of the EDAR variant may have been favored by natural selection at a
different time. A series of selections on different traits thus made the
variant version so common among East Asians. About 93 percent of Han Chinese
carry the variant, as do about 70 percent of people in Japan and Thailand,
and 60 to 90 percent of American Indians, a population descended from East
Asians.
The Broad team is studying EDAR as part of a larger plan to identify all the
genetic variants responsible for recent human evolution. Many researchers,
including Dr. Sabeti, have devised ways of scanning the human genome to
detect the fingerprints of natural selection. But these scans have typically
identified large chunks of the genome that contain many genes. There is
often no way to tell which gene was the target of natural selection.
A team led by Dr. Sabeti and Sharon R. Grossman of the Broad Institute has
now refined the usual scanning methods and identified 412 sites on the
genome that have been under selection. Each site is small enough that it
contains at most a single gene.
Each race has a different set of selected regions, reflecting the fact that
the human population had dispersed from its African homeland and faced
different challenges that led to genetic adaptation on each continent. About
140 of the sites affected by natural selection are in Europeans, 140 in
East Asians and 132 in Africans, the authors report in another article
published Thursday in Cell.
Inserting some of the other selected genes into mice might help explain why
they were favored, and point to critical turning points in recent human
evolution, Dr. Sabeti said.
In the case of EDAR, putting the gene into mice has only magnified the
mystery of why it was selected. But the researchers are not discouraged. “A
reflection of good science is that a step forward opens up a lot more
questions,” Dr. Akey said.
A version of this article appeared in print on February 15, 2013, on page
A18 of the New York edition with the headline: East Asian Physical Traits
Linked to 35,000-Year-Old Mutation. |
c****i
发帖数: 688 | 2 国内女性据说乳罩增大了一号。
【在 i*****s 的大作中提到】
: http://www.nytimes.com/2013/02/15/science/studying-recent-human
:
: East Asian Physical Traits Linked to 35,000-Year-Old Mutation
: By NICHOLAS WADE
: Published: February 14, 2013
: Gaining a deep insight into human evolution, researchers have identified a
: mutation in a critical human gene as the source of several distinctive
: traits that make East Asians different from other races.
: The traits — thicker hair shafts, more sweat glands, characteristically
: identified teeth and smaller breasts — are the result of a gene mutation
|
c******a
发帖数: 4400 | 3 这个基因突变，难道要一大堆人一起突变？如果只有几个人基因突变，怎么可能保持的
下来？ |
i*****s
发帖数: 4596 | 4 有选择优势呗。
【在 c******a 的大作中提到】
: 这个基因突变，难道要一大堆人一起突变？如果只有几个人基因突变，怎么可能保持的
: 下来？
|
c****i
发帖数: 688 | 5 你要看人口基数啊，就是这几只突变的人活下来了，以后就是他们的基因了。
其实乳房那么大，本来没什么用。
【在 c******a 的大作中提到】
: 这个基因突变，难道要一大堆人一起突变？如果只有几个人基因突变，怎么可能保持的
: 下来？
|
y*h
发帖数: 25423 | 6
买乳罩增大了一号跟乳是否增大了一号没有必然联系。
【在 c****i 的大作中提到】
: 国内女性据说乳罩增大了一号。
|
c****i
发帖数: 688 | 7 应该有联系，看看小留和猥琐女的对比就有分晓。
【在 y*h 的大作中提到】
:
: 买乳罩增大了一号跟乳是否增大了一号没有必然联系。
|
h******8
发帖数: 3778 | |
h******1
发帖数: 16295 | |
c****i
发帖数: 688 | 10 同样的女人，一个太大，一个太小，你选哪个。
【在 h******1 的大作中提到】
: 太大太小都不好看.
|
|
|
y*h
发帖数: 25423 | |
y*h
发帖数: 25423 | |
y*h
发帖数: 25423 | |
y*h
发帖数: 25423 | |
y*h
发帖数: 25423 | |
y*h
发帖数: 25423 | |
y*h
发帖数: 25423 | |
y*h
发帖数: 25423 | |
c******a
发帖数: 4400 | 19 难道一大堆爆乳女中，一个小平胸有选择优势？
【在 i*****s 的大作中提到】
: 有选择优势呗。
|
i*****s
发帖数: 4596 | 20 胸大无脑，没听说过？
【在 c******a 的大作中提到】
: 难道一大堆爆乳女中，一个小平胸有选择优势？
|
|
|
w*********g
发帖数: 10097 | 21 这个发现是不是可以推测这么几点：
1.单独一个copy的mutation就有phenotype说明是显性的，那么东亚女中不多见的大胸
女就应该是双隐，所以如果胸小的女生想改善基因让女儿胸大，那找老公的时候注意一
下婆婆是不是大胸就有更大的机率女儿胸大了？
2.胸小的东亚女是不是代表相对更纯的基因？而巨乳的东亚女则很可能是祖上混入了高
加索人种的血统，从而带入了更多的野生行copy? |
s*******e
发帖数: 1389 | 22 看了眼Fig,
1,南美人，尤其墨西哥人，带有370A的比例和中国人几乎一样高。但是就我所知，墨墨
们的胸部是我见过最大的。
2，不知道他们怎么选的老鼠，370A的老鼠明显比370V的瘦。尼玛瘦老鼠的胸部小有啥
好奇怪的。
3，老鼠毛的差异比人种间毛发的差异小得多。他们无法用图片显示，用了个极tricky
的统计显示突变的老鼠中宽毛的比例多了一点点。
编吧，继续编。反正这种东西人民群众喜闻乐见。
【在 i*****s 的大作中提到】
: http://www.nytimes.com/2013/02/15/science/studying-recent-human
:
: East Asian Physical Traits Linked to 35,000-Year-Old Mutation
: By NICHOLAS WADE
: Published: February 14, 2013
: Gaining a deep insight into human evolution, researchers have identified a
: mutation in a critical human gene as the source of several distinctive
: traits that make East Asians different from other races.
: The traits — thicker hair shafts, more sweat glands, characteristically
: identified teeth and smaller breasts — are the result of a gene mutation
|
i*****s
发帖数: 4596 | 23
tricky
【在 s*******e 的大作中提到】
: 看了眼Fig,
: 1,南美人，尤其墨西哥人，带有370A的比例和中国人几乎一样高。但是就我所知，墨墨
: 们的胸部是我见过最大的。
: 2，不知道他们怎么选的老鼠，370A的老鼠明显比370V的瘦。尼玛瘦老鼠的胸部小有啥
: 好奇怪的。
: 3，老鼠毛的差异比人种间毛发的差异小得多。他们无法用图片显示，用了个极tricky
: 的统计显示突变的老鼠中宽毛的比例多了一点点。
: 编吧，继续编。反正这种东西人民群众喜闻乐见。
|
m**t
发帖数: 40 | 24 南美和墨西哥应该是指native americans而不是混了欧洲，非洲血的
tricky
【在 s*******e 的大作中提到】
: 看了眼Fig,
: 1,南美人，尤其墨西哥人，带有370A的比例和中国人几乎一样高。但是就我所知，墨墨
: 们的胸部是我见过最大的。
: 2，不知道他们怎么选的老鼠，370A的老鼠明显比370V的瘦。尼玛瘦老鼠的胸部小有啥
: 好奇怪的。
: 3，老鼠毛的差异比人种间毛发的差异小得多。他们无法用图片显示，用了个极tricky
: 的统计显示突变的老鼠中宽毛的比例多了一点点。
: 编吧，继续编。反正这种东西人民群众喜闻乐见。
|
i*****s
发帖数: 4596 | 25 中国确实北方女胸更大，黑龙江除外。
【在 w*********g 的大作中提到】
: 这个发现是不是可以推测这么几点：
: 1.单独一个copy的mutation就有phenotype说明是显性的，那么东亚女中不多见的大胸
: 女就应该是双隐，所以如果胸小的女生想改善基因让女儿胸大，那找老公的时候注意一
: 下婆婆是不是大胸就有更大的机率女儿胸大了？
: 2.胸小的东亚女是不是代表相对更纯的基因？而巨乳的东亚女则很可能是祖上混入了高
: 加索人种的血统，从而带入了更多的野生行copy?
|
w*********g
发帖数: 10097 | 26 能编到Cell也不容易啊
南美可能还是欧洲混血的结果吧
tricky
【在 s*******e 的大作中提到】
: 看了眼Fig,
: 1,南美人，尤其墨西哥人，带有370A的比例和中国人几乎一样高。但是就我所知，墨墨
: 们的胸部是我见过最大的。
: 2，不知道他们怎么选的老鼠，370A的老鼠明显比370V的瘦。尼玛瘦老鼠的胸部小有啥
: 好奇怪的。
: 3，老鼠毛的差异比人种间毛发的差异小得多。他们无法用图片显示，用了个极tricky
: 的统计显示突变的老鼠中宽毛的比例多了一点点。
: 编吧，继续编。反正这种东西人民群众喜闻乐见。
|
s*******e
发帖数: 1389 | 27 红色为370A
【在 i*****s 的大作中提到】
: 中国确实北方女胸更大，黑龙江除外。
|
l*****i
发帖数: 20533 | 28 其他倒没什么。只是，看了这文章才知道，原来印第安人是源自东亚已经是基因学定论
了。 |
i*****s
发帖数: 4596 | 29 你在美国见到的墨女并不具有代表性吧，何况是个人印象。google那个图里墨女胸也小啊
【在 s*******e 的大作中提到】
: 红色为370A
|
b***y
发帖数: 14281 | 30 早期原始社会说不定真的有优势。没看到非洲土人女人胸前两个袋子，又大又垂，看着
一点没有美感，反而让人感到恶心？这个时候，小一些，两个挺起的山峰会有吸引力的
多。古代社会女人不带胸罩也不懂得保持还要干重体力活，胸大而不垂的恐怕绝无仅有
。胸大为美可能只是现代人的感受，就象以瘦为美一样。
【在 c******a 的大作中提到】
: 难道一大堆爆乳女中，一个小平胸有选择优势？
|
|
|
s*******e
发帖数: 1389 | 31 哈哈，你说的对，是我个人印象。我在NYC，Harlem，这里的墨墨可能营养好，垃圾食
品吃的多吧。
小啊
【在 i*****s 的大作中提到】
: 你在美国见到的墨女并不具有代表性吧，何况是个人印象。google那个图里墨女胸也小啊
|
d*****4
发帖数: 6237 | 32 开什么玩笑
胸大而挺是现代人的审美还差不多
人类爱大胸是很天然的，刚生出来眼里只有大胸，属于原始记忆
何况大胸意味着奶水丰富，人类活动的所有原始动力都是种族繁衍，大胸自然就有选择
优势了
而且所谓亚洲女人胸小，主要还是因为瘦导致的吧，瘦才是畸形审美，中国原来是穷导
致瘦，现在是以瘦为美，平均罩杯怎么会大
【在 b***y 的大作中提到】
: 早期原始社会说不定真的有优势。没看到非洲土人女人胸前两个袋子，又大又垂，看着
: 一点没有美感，反而让人感到恶心？这个时候，小一些，两个挺起的山峰会有吸引力的
: 多。古代社会女人不带胸罩也不懂得保持还要干重体力活，胸大而不垂的恐怕绝无仅有
: 。胸大为美可能只是现代人的感受，就象以瘦为美一样。
|
b***y
发帖数: 14281 | 33 你怎么知道人类爱胸大是天然的？小孩爱吃奶还是天然的呢，成年以后就不喜欢了。古
代人胸大下垂，很难看。你自己去看看非洲土人的照片，美个屁啊。虽然繁殖是原始动
力，不见的审美一定和繁殖的需要相吻合。孔雀的尾巴就是例子。而且，胸大未必奶水
丰富，这个是已经证实的结论，胸的大小和奶水的多少其实没有关联。
【在 d*****4 的大作中提到】
: 开什么玩笑
: 胸大而挺是现代人的审美还差不多
: 人类爱大胸是很天然的，刚生出来眼里只有大胸，属于原始记忆
: 何况大胸意味着奶水丰富，人类活动的所有原始动力都是种族繁衍，大胸自然就有选择
: 优势了
: 而且所谓亚洲女人胸小，主要还是因为瘦导致的吧，瘦才是畸形审美，中国原来是穷导
: 致瘦，现在是以瘦为美，平均罩杯怎么会大
|
