An academic writing in Nature had noted how a paleontologist, asked by a colleague whether he thought an old skull was varnished or not,
一位学者在《自然》杂志撰文说，有一位古生物学家的同事问那位古生物学家一个古人颅骨是否上了漆，他用舌头舔了舔骸骨的顶部，
had licked its top and announced that it was.
然后说是上了漆的。
"In the process," noted the Nature article, "large amounts of modern human DNA would have been transferred to the skull," rendering it useless for future study.
“在此过程中，” 《自然》杂志的文章写道，“有大量的现代人DNA会转到这个颅骨上。”这使得骸骨无法再用来进行研究。
I asked Harding about this. "Oh, it would almost certainly have been contaminated already," she said.
我就这件事咨询哈丁。“哎呀，几乎可以肯定它已经被污染了。”她说，
Just handling a bone will contaminate it. Breathing on it will contaminate it.
只要摸一下骨头，它就会被污染。向它哈一口气，它也会被污染。
Most of the water in our labs will contaminate it.
我的实验室里的水也会污染它。
We are all swimming in foreign DNA.
我们周围都是陌生的DNA。
In order to get a reliably clean specimen you have to excavate it in sterile conditions and do the tests on it at the site.
要想得到一个可靠的清洁的标本，你必须在消过毒的条件下将它们挖掘出来，并且在当场就做实验。
It is the trickiest thing in the world not to contaminate a specimen.
要想不污染标本，世上没有比这更困难的事了。
So should such claims be treated dubiously? I asked. Harding nodded solemnly. "Very," she said.
那么，所有的这类结论都应该受到质疑吗？我问。哈丁严肃地点点头。“当然。”她说。
If you wish to understand at once why we know as little as we do about human origins, I have the place for you.
如果你想立即知道我们为什么对人类起源了解得这样少，我可以带你去一个地方。
It is to be found a little beyond the edge of the blue Ngong Hills in Kenya, to the south and west of Nairobi.
这个地方位于肯尼亚昂加山的边缘，内罗毕西南部。

Drive out of the city on the main highway to Uganda, and there comes a moment of startling glory when the ground falls away
要是你往东驶出内罗毕市，沿通向乌干达的快速干道前行，爬上一个高坡就看到一个无比壮丽的景象，
and you are presented with a hang glider's view of boundless, pale green African plain.
只见面前是望不到边的淡绿色的非洲平原。
This is the Great Rift Valley, which arcs across three thousand miles of east Africa, marking the tectonic rupture that is setting Africa adrift from Asia.
这就是绵延东非达4800公里的东非大裂谷。非洲就从这条板块裂缝漂离亚洲。
Here, perhaps forty miles out of Nairobi, along the baking valley floor, is an ancient site called Olorgesailie,
这里距内罗毕约65公里，靠近谷底干枯的地带是一个被称为奥洛戛萨里的古老地方，
which once stood beside a large and pleasant lake.
这里一度濒临一个巨大的湖泊。