万物简史 第640期:神秘的两足动物(18)

（单词翻译）

All this is problematic enough when you are the intellectual master of the planet,but when you are a small, vulnerable australopithecine, with a brain about thesize of an orange, the risk must have been enormous. Absolute brain size doesnot tell you everything-or possibly sometimes even much. Elephants and whalesboth have brains larger than ours, but you wouldn't have much troubleoutwitting them in contract negotiations¹. It is relative size that matters, apoint that is often overlooked. As Gould notes, A. africanus had a brain ofonly 450 cubic centimeters, smaller than that of a gorilla². But a typical africanus male weighed less than a hundred pounds, and a female much lessstill, whereas gorillas³ can easily top out at 600 pounds (Gould pp. 181-83).

即使在今天，当你已经成为这个星球的智力发达的主人时，这一切依然是个大问题。而对于矮小而又容易受到伤害的南方古猿来说，婴儿降生时的脑大约有一只柑橘那么大（注：诚然，脑的绝对大小并不能说明一切——有时甚至不能说明很多。大象和鲸的脑都比我们大，但是和它们相比你显然聪明许多。脑的大小只是一个相对重要的数据，一个常常可以忽略不计的数据。正如古尔德所指出的那样，南猿非洲种的脑只有450立方厘米，比大猩猩的要小。而一个典型的南猿非洲种体重小于45千克，女性则更轻，而大猩猩的体重则大都重达150多千克。），危险性肯定很大。

Sowhy did Lucy and her kind come down from the trees and out of the forests?Probably they had no choice. The slow rise of the Isthmus⁴ of Panama had cut theflow of waters from the Pacific into the Atlantic, diverting warming currentsaway from the Arctic and leading to the onset⁵ of an exceedingly sharp ice agein northern latitudes⁶. In Africa, this would have produced seasonal⁷ drying andcooling, gradually turning jungle into savanna⁸. "It was not so much thatLucy and her like left the forests," John Gribbin has written, "butthat the forests left them."

因此，露西和她的同类从树上来到地上，而后又走出非洲丛林，这是为什么？他们很可能别无选择。巴拿马地峡的慢慢上升阻断了太平洋的海水流进大西洋，改变了流向北极的暖流的方向，使得北纬地区出现了异常寒冷的冰川期。在非洲，季节性干燥和寒冷气候的出现逐渐使得森林变成了草原。“与其说露西和她的同类离开了森林，”约翰·格里宾写道，“不如说是森林离开了他们。”