Finally, but perhaps above all, human nature is a factor in all this. Scientists have a natural tendency to interpret finds in the way that most flatters their stature. It is a rare paleontologist indeed who announces that he has found a cache of bones but that they are nothing to get excited about. Or as John Reader understatedly observes in the book Missing Links, "It is remarkable how often the first interpretations of new evidence have confirmed the preconceptions of its discoverer."
最后，在这一切中也许是最重要的，是人性的因素。科学家总是很自然地倾向于将他们的发现以最有利于确立他们声誉的方式加以阐释。很少有哪位古生物学家在声称发现一批骨头时会说他的发现是没有什么了不起的。正如约翰·里德在他的《缺失的环节》一书中实事求是地所说的那样：“发现者在首次解释新证据的时候往往都会说这证实了自己事先的想法，这是很有意思的。”
All this leaves ample room for arguments, of course, and nobody likes to argue more than paleoanthropologists. "And of all the disciplines in science, paleoanthropology boasts perhaps the largest share of egos," say the authors of the recent Java Man —a book, it may be noted, that itself devotes long, wonderfully unselfconscious passages to attacks on the inadequacies of others, in particular the authors' former close colleague Donald Johanson. Here is a small sampling:
所有这些都肯定为日后的争论留出了很大的空间，也没有任何人比古人类学家更喜欢争论的了。“在所有科学家中，古人类学家也许是把自尊发挥到极致的一类人。“最近出版的《爪哇人》一书的作者们这样说道。该书一个值得一提的特点，就是用了大段篇幅，毫不掩饰她对别人，尤其是对他们以前的好友加同事唐纳德·约翰森的缺点进行了批评。下面就是其中的一小段：
In our years of collaboration at the institute he [Johanson] developed a well-deserved, if unfortunate, reputation for unpredictable and high-decibel personal verbal assaults, sometimes accompanied by the tossing around of books or whatever else came conveniently to hand.

我们在研究所共事的时候，他（约翰森）不幸染上了一种喜怒无常、大声呵斥人的习惯，有时还伴以随手扔书本或手边任何东西的剧烈动作。

So, bearing in mind that there is little you can say about human prehistory that won't be disputed by someone somewhere, other than that we most certainly had one, what we think we know about who we are and where we come from is roughly this:
因此，请牢牢记住，有关史前人类史，你很难说还有什么问题不会在某人某地引起争议。我们最有把握的只有这么一点，那就是我们认为我们知道我们是谁，我们从什么地方来，大情况如下：
For the first 99.99999 percent of our history as organisms, we were in the same ancestral line as chimpanzees. Virtually nothing is known about the prehistory of chimpanzees, but whatever they were, we were. Then about seven million years ago something major happened. A group of new beings emerged from the tropical forests of Africa and began to move about on the open savanna.
作为生物，我们在99.99999%的历史时期和非洲黑猩猩有着共同的家谱。有关史前的非洲黑猩猩，我们几乎一无所知，可是不管它们的情况是怎样的，都和我们的祖先别无二致。接着，大约700万年前，某种具有决定意义的事情发生了。一群新的动物走出非洲热带森林，开始在广阔的大草原上四处走动。