经济学人下载:人类本质 什么是人类

Science and technology
科学技术

The nature of humanity
人类本质

What's a man?
什么是人类

Studies of brain genetics are starting to reveal what makes humans human
大脑遗传研究，为你解开人之所以为人的奥秘

THE problem with understanding human uniqueness is precisely that it is unique.
研究人类独特性的难题在于这个独特性本身就很独特。

Though the proper study of mankind may be man, that study will yield little if there is no reference point to compare man with.
虽然人类研究的主体对象是人，但是如果没有比照对象的参与，研究很难有所突破。

That, at least, is the philosophy of Svante Paabo of the Max Planck Institute for Evolutionary Anthropology, in Leipzig.
至少，来自莱比锡马克斯普朗克进化人类研究所的斯万特帕珀是这样认为的。

Dr Paabo, whose work on fossil DNA was the inspiration for Jurassic Park,
帕珀博士主要研究化石的DNA，正是受到《侏罗纪公园》启发，

has since become interested in human evolution.
他对人类进化史产生了浓厚的兴趣。

To this end, he and his colleagues have sequenced the DNA of both Neanderthal man and an Asian species of prehistoric human,
为了一探究竟，他和同事将穴居人和史前亚洲人种,

the Denisovians, which Dr Paabo's own work identified.
帕珀博士将其定义为丹尼索维亚人的DNA按序排列。

Now he has turned his attentions to modern Homo sapiens.
现在他又将注意力转移到了现代智人身上。

In collaboration with a team from the Chinese Academy of Sciences,
帕珀博士和同事菲利普卡托维奇与中国科学院的科学家们相互合作，

Dr Paabo and his colleague Philipp Khaitovich have compared genetic activity over the course of a lifetime in the brains of humans, chimpanzees and rhesus monkeys.
将人类，猩猩，以及恒河猴有生之年的大脑遗传活动进行了比对。

They have then matched what they found with what is known of Neanderthals,
随后，他们将研究成果同穴居人研究成果相配对，

and think they have thus discovered at least part of the genetic difference between Homo sapiens and the others that creates human uniqueness.
并发现了智人和其他物种的差异，至少是部分差异。正是这些差异造就了人类独一无二的特性。

Dr Paabo and his colleagues focused their examination,
帕珀博士和同事十分重视实验，

just published in Genome Research, on two parts of the brain.
他们只在《基因研究》杂志上刊登了大脑两个区域的研究成果。

One was the dorsolateral prefrontal cortex,
区域一是大脑背外侧前额皮层，

which is the seat of abstract reasoning and social behaviour,things that humans are particularly good at.
主管抽象思考和社交行为一类人类尤为擅长的活动。

The other was the lateral cerebellar cortex, which is more to do with manual abilities.
区域二是同动手能力联系密切的外侧小脑皮层。

They extracted cells, post mortem, from people, chimps and monkeys of many ages, and looked at which genes had been active in these cells when the owners were alive.
他们从不同年龄层的人类，黑猩猩以及猴子尸体上提取相关细胞，然后观察哪些基因在宿主存活时表现活跃。

The vortex of the cortex
皮层漩涡

They did this by examining the RNA in the cells.
他们通过检验细胞中的RNA来进行观察。

RNA molecules are single-stranded copies of the double-helical DNA genes in the cell nucleus.
RNA分子是细胞核内的双螺旋DNA基因的单链拷贝。

Their job is to carry instructions from the genes to a cell's protein-making machinery.
RNA的工作是把基因的指令带到细胞的蛋白质形成机构内。

Most primate genes have now been identified,
现在大部分灵长类动物的基因都已被识别出来，

so it is possible to make chips covered with complementary strands to the RNA messengers,
所以人类可以制作一张芯片，在上面布满结构互补的单链RNA，

to which these messengers will uniquely stick, and which thus act as probes for particular messenger molecules.
因为信使RNA会与其紧密结合，所以可以专门用该芯片来搜寻携带遗传信息的分子。

Using such chips, Dr Khaitovich and Dr Paabo were able to find out when, during the course of life, particular genes were active,
卡托维奇博士和帕珀博士计算出了不同年龄段的不同个体的大脑的特定区域内每个基因细胞里的RNA数量，

by working out how much RNA from each gene cells from particular parts of the brains of individuals of different ages contained.
并利用该芯片，找出了一生中表现活跃的几个特定基因。

Their results fell into six categories.
以下是他们的六大发现。

First, they found some genes whose expression patterns over a lifetime were uniquely human and others that were uniquely chimpanzee.
发现一，有的基因的表达方式为人类特有，有的为猩猩特有，

Second, they discovered that there were more uniquely human expression patterns than uniquely chimp ones.
发现二，人类特有的基因表达要多于猩猩。

Third, unique human expression patterns were more common in the prefrontal cortex than in the cerebellum.
发现三，人类特有的基因表达多出现与前额叶皮层，而不是小脑。

Fourth, though these uniquely expressed genes were most active in the young of all species,
发现四，尽管这些物种特有的表达基因最活跃的时期都在青年期，

their period of activity was several years longer in humans than in the others.
但是人类基因的活跃期较长，能持续数年。

Fifth, the activities of a lot of the uniquely active genes seemed to be correlated:
发现五，许多活跃基因所进行的活动是相互联系的:

the researchers identified seven groups of genes which each seemed to be working as a module.
研究者发现了七组基因，似乎每一组都是独立的单元。

And sixth, these modular genes seem to be involved in the crucial job of linking nerve cells together through junctions called synapses.
发现六：这些单位基因组似乎在担子不轻，它们要经过各个枢纽将神经细胞连接到一起，这些枢纽名叫突触。

To summarise, human beings have suites of genes that probably cause their brains to be plastic,
总之，人类特有的一套套基因让大脑具备了可塑性，

and thus receptive to change far longer than is true for chimps or monkeys.
而且应变能力的维持时间要远远长于猩猩和猴子的大脑。

Moreover, Dr Khaitovich was able to work out how the expression of these modules of genes was co-ordinated,
另外，卡托维奇博士通过观察控制基因单位的开关，

by looking at the switches, known as transcription factors, that turn them on and off.
也就是众所周知的转录因子，已经能够解答各个基因单位的表达是如何协调的问题。

Indeed, by comparing modern genomes with their discoveries about Neanderthals Dr Paabo's group has found that the regulatory process for one of the modules came into existence after the modern human and Neanderthal lines separated from one another, about 300,000 years ago.
的确，通过比对现代人基因组和穴居人研究成果，帕珀博士一行人已经发现了某组基因的调节过程，早在30万年前，当现代人类从穴居人家系中分离出来时，该组基因就已存在。

Unfortunately, it is not possible to look at the expression pattern of genes in Neanderthals, and it probably never will be.
然而不幸的是，现在已经无法观察穴居人的基因表达方式，而且可能再也看不到了。

But it might be possible, as knowledge advances, to reconstruct part of it from a better understanding of that extinct species's DNA.
但是随着知识的积累，科学倒是家可以凭借对已消亡的物种的DNA更深入的了解，将穴居人的部分基因重现出来。

Pleistocene Park, anybody?
拍一部《更新世公园》，怎么样？