人类大脑越来越小 智商也越来越低?

　　It's not something we'd like to admit, but it seems the human race may actually be becoming increasingly dumb. Man's brain has been gradually shrinking over the last 20,000 years, according to a new report. This decrease in size follows two million years during which the human cranium steadily grew in size, and it's happened all over the world, to both sexes and every race。

　　也许我们真的不愿意承认，但是，近日一项新发现在这个“科学大爆炸”的时代提出犹如一声惊雷，让“自以为很聪明”的人类“扪心自问”：我们真的 “越来越笨”了吗？。据悉，实验将远古时代的人脑与现代对比，惊人发现，虽然在200万年来，人类的“头颅”是在缓慢变大的，但是“人脑”在近2万年来却 “越变越小”，这个残酷的事实不仅仅发生在人类身上，科学家证实脑容量缩小的现象在地球上生活的任何种族的人类群体都有体现。

　　'Over the past 20,000 years, the average volume of the human male brain has decreased from 1,500 cubic centimetres to 1,350 cubic centimetres, losing a chunk the size of a tennis ball,' Kathleen McAuliffe writes in Discover magazine. 'The female brain has shrunk by about the same proportion.'

　　根据研究发现，在过去2万年来，人类的大脑容量逐渐缩小，平均来说，男性脑容量从1500立方厘米降至1350厘米，也就是相当于一个 “网球”大小的脑容量就这么凭空消失了。此外，女性的脑容量缩小的程度与男性“旗鼓相当”，难道脑容量缩小，智力会下降吗？两者有无直接的关系呢？

　　Some paleontologists agree with this diagnosis, that our brains may have become smaller in size, but increasingly efficient. But others believe that man has indeed become steadily more stupid as he has evolved. Several theories have been advanced to explain the mystery of the shrinking brain. One is that big heads were necessary to survive Upper Paleolithic life, which involved cold, outdoor activities. A second theory is that skulls developed to cope with a chewy diet of rabbits, reindeer, foxes and horses。

　　一些古生物学者对此持保留态度，他们认为脑容量虽然减少，但是人脑的工作效率仍旧处于逐步增高的状态。但是，无论种族、性别，人类脑容量缩小还是一个不争的事实。部分古生物学者还是这样分析脑容量缩小的原因的，他们认为在旧石器时代中，古代人类可能需要在复杂的环境下生存，比如大量咬嚼大块食物(野兔、狐狸、马匹等)、从而直接锻炼了脸部、甚至脑部的发达，另外，脑容量越大、适应野外寒冷环境的能力更强。如今，人类的食物愈发简单化，不需要很发达的咬嚼能力，所以脑容量的减少的原因还是有迹可循的。

　　As our food has become easier to eat, so our heads have stopped growing, according to supporters of this theory. Other experts say that with high infant mortality, only the toughest survived - and the toughest tended to have big heads. Therefore a gradually decreasing infant mortality rate has led to a proportionate decrease in the size of our brains。

　　此外，还有一个理论认为，过去婴儿的死亡率很高，但是依照“适者生存”的道理，头脑大的婴儿生命力更强，不会被淘汰，能够存活下来。而如今的科技发达，即使脑容量小的婴儿也能存活。