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We tend to think of biological sex as having one of two distinct genetic codes:
我们倾向于认为生物的性别 与1/2个基因编码有关：
If your sex chromosomes – that is, the 23rd pair in your cells – are X and Y,
也就是性染色体-即你细胞中的第23对染色体 是X和Y 那么你就是男性
then you're male, if you have X and X, you're female.
倘若你是X和X 那么你就是女性
But, like so many things in biology, and the world, it's not that simple.
但是 跟生物领域的许多东西 以及这个世界一样 这没有那么简单
Humans and other animals that have sex characteristics – that is, things like sex hormones, gonads, and genitals –
人类和动物都有性特征 比如性激素 性腺 生殖器
that don't fit the male/female binary are considered intersex.
但如果不符合雌雄两种性别 则被视作中性生物
These conditions can also be called differences of sex development, or DSDs.
这种情况也被称作 性发展差异 即DSDs
And there are a lot of various DSDs out there, which can affect physical appearance,
这种DSDs有各种表现形式 比如可以影响生理外形
or even the behavior of an entire group of animals.
甚至影响整个动物种群的行为
In humans, intersex conditions are mostly caused by genetics, like variations in chromosomes or in a single gene.
对人类而言 中性人大部分由基因造成 比如染色体 或是单个基因的变异
Some kinds of intersex conditions are known as chromosomal DSDs,
一些中间性的成因是染色体的性发展差异 表现在人类身上就是
and in humans they're linked to an unusual combination of X and Y sex chromosomes.
X与Y性染色体的不正常组合
If an XY individual has an extra X chromosome, for example, so they're XXY, or even XXXY–
举个例子 如果一个XY个体多了一条X染色体 那么他就成了XXY甚至是XXXY
the result is a condition known as Klinefelter syndrome.
这种结果造成的情况就是Klinefelter综合征（先天性曲细精管发育不全综合征）
That extra X chromosome can affect how the person's testes work, including how much testosterone they secrete.
这条多余的X染色体能够影响一个人的睾丸工作 包括他们释放多少睾丸酮
Lower levels of testosterone can affect how secondary sex characteristics develop, like body hair, or breast tissue.
低水平的睾丸酮会影响第二性征的发育 比如体毛和乳腺组织
And some people with Klinefelter syndrome might also be unusually tall,
一些有Klinefelter综合征的人通常比较高 大概是因为
possibly because of a height-related gene on the X chromosome.
X染色体上的身高决定基因
By contrast, there's also Turner syndrome, in which a person has just one X chromosome, and no Y.
相反 也会有人患特纳综合症 即只有一条X染色体而没有 Y染色体
In this case, a person might start developing female sex characteristics, like someone with two X chromosomes.
这种情况下 这个人就会发育女性的性特征 跟正常的有两条X染色体的女性一样
But without a second copy of the X chromosome genes, their ovaries might not develop completely,
但是因为少了第二条X染色体 她们的卵巢不会发育完全
which could result in the inability to secrete sex hormones and develop secondary sex characteristics.
可能导致不能释放性激素和第二性征不能发育
Some people with Turner syndrome might also be shorter, because they're missing a copy of that height gene.
一些有特纳综合症的人可能会比较矮 因为他们缺失了 复制出的决定身高基因的那一部分
And others might experience more serious health problems like heart defects, diabetes, and low levels of thyroid hormone.
并且有的人会患上更多更严重的病比如心脏缺损 糖尿病 和甲状腺素水平低下
But sex characteristics aren't just dependent on whether you're XX, XY or neither.
但是性征不全是决定于你是否是XX型 XY性或者二者皆不是
There are also hormonal DSDs, which interfere with how sex hormones are made and used, usually because of individual genes.
由于单个基因的影响 激素也会产生性别发展差异 而这会影响性激素的 产生量和作用量
Alterations in these genes can affect how your body processes androgens,
这些基因上发生的改变可能会影响你身体的雄激素
the hormones that generally help develop male sex characteristics, or estrogens and progesterone,
这种激素 通常是帮助雄性性征发育的 也会影响雌激素和孕激素
which help with female characteristics.
而这个是对女性性征发育有帮助的
Mutations in the androgen receptor gene, for example, mean that no matter how many androgens
举个例子 若雄激素受体基因产生突变 意味着无论多少雄激素
are floating around in your bloodstream, your cells can't respond to them.
游荡在你的血液之中 你的细胞都不会对它们产生任何反应
In XY individuals, this can lead to the development of some female secondary sex characteristics–
而这对于基因型为XY的个体来说 就会导致一些女性第二性征的发育
a condition called androgen insensitivity syndrome.
这种病叫做雄激素不敏感综合征
On the other hand, XX individuals might experience a condition called congenital adrenal hyperplasia.
另一方面 XX个体可能患上先天性肾上腺皮质增生症
This is when the body doesn't produce enough of an enzyme known as 21-hydroxylase,
这种病是当身体产生的21—羟化酶不够时
which results in the over production of androgens, and therefore the development of male secondary sex traits.
就会造成雄性激素的过度生成 因此就会加剧雄性第二性征的 发育
But of course, intersex conditions aren't only found in humans.
当然 中性不只是存在人类之中
Plenty of other animals can reproduce sexually, but have more than just males and females.
许多其他动物也是有性繁殖 但不仅仅局限于雄性和雌性
Some animals don't actually have two separate sexes, and are hermaphroditic –
有些动物并没有明显区分开的两性特征 它们多是雌雄同体
like snails, slugs, and worms – which have both male and female reproductive organs.
比如蜗牛 蛞蝓 蠕虫—这些动物同时具有雄性和雌性的生殖器官
Other animals just have one set of reproductive organs … but they can change.
还有些动物只有一种生殖器官 但是它们可以改变
Clownfish, for example, live in social groups that consist of one breeding pair with a female and male,
例如小丑鱼 是群居动物 它们群体只有一对繁殖体 一只雌性鱼和 一只雄性鱼
plus a group of other not-completely-developed males.
再加上一群其他的不完全发育的雄性
If the female dies, or is taken away for some reason,
如果雌性育种鱼死掉了或者是被抓走了
the breeding male's hormone production changes so it loses its male reproductive organs and develops female ones.
雄性育种鱼的荷尔蒙产生就会改变 然后它的雄性生殖器官会消失 并发育出雌性的生殖器官
This male-to-female change is called protandry,
这种由雄性到雌性的转变被称作雄性先熟
and is basically a way to make sure there's always a mating pair without as much competition.
主要是确保 种群内部有且只有一对交配个体
Knowing this makes Finding Nemo seem … a little inaccurate.
知道了这些就会让《海底总动员》这部电影看起来 嗯…有一点点不准确
Because his dad would actually become his new mom.
因为它的爸爸会理所应当的成为它的新妈妈
Other species of fish can change from female to male – called protogyny –
还有些鱼类可以从雌性变到雄 叫做雌性先熟
or change sex bidirectionally, depending on the pressure to breed.
还有的会 双向性反转 这取决于种群内部的育种压力
Scientists have also discovered that a lot of animals that we think have distinct male and female sexes,
科学家同样也发现许多 我们认为可以明确区分雌雄的动物
also experience intersex conditions.
同样存在中间性问题
Researchers have found variations in the reproductive anatomy in species like black bears,
研究者在一些物种的性器官解剖中 比如黑熊
spotted hyenas, and leopard geckos, which suggests that they have chromosomal or hormonal DSDs too.
斑鬣狗 和豹纹壁虎等 发现他们同样有染色体或激素的 性发展差异
And this is just some of the stuff that we've noticed.
这仅仅是我们注意到了的几个物种
Who knows how many other sex variations might be out there in the animal kingdom?
谁知道在这偌大的动物王国中有多少性别变异存在呢？
Thanks for watching this episode of SciShow, which was brought to you by our patrons on Patreon.
感谢收看这一期的科学秀 感谢我们的赞助商为大家带来这期节目 感谢Patreon公司
If haven't heard about this, we're doing something little different with Patreon for the last four month of this year.
不知你是否知道 在今年的最后四个月 我们正与Patreon公司 做着不同以往的一些研究
We are gonna take all that money the people give us last four month,
我们将利用这四个月时间众筹的资金
and we are gonna put it into a brand new channel, and we haven't decided what the channel is gonna be yet.
投入到一个全新的领域 虽然我们还没有决定是哪个领域
It's either gonna be SciShow life, Scishow Psychology, or SciShow Health.
要么是科学秀生活 科学秀心理 或是科学秀健康
And who's gonna choose which for one of those things that's gonna be is our Patreon patrons.
总之最后帮我们敲定选择的是我们的Patreon 金主
So if you would like to have a voice in that decision,
如果你想要声援这个决定
and also if you would like to give us money so that we can continue doing cool stuff,
如果你想要出一点余力 让我们继续做这件酷毙了的事情
I'm so thankful that we can, you can go to patreon.com/scishow.
那么我不胜感激 详情请参见 patreon.com/sicshow
