地球的力量

Then later came the evolution of Homo erectus,
接着进化成直立人
who was the first to make sophisticated stone tools.
直立猿人是我们首先造出精密石器的祖先
But what caused these rapid changes has always been a bit of a mystery.
石器的出现是伟大的巨变至今仍有一些迷题尚未解开

It now seems that they tie in with the two greatest advances of the ice sheets.
现在的研究显示他们与北冰原的两个最剧烈的变化有联系
Each time the ice advanced,
一旦冰层面积扩展
more of the Sun's energy was reflected from the planet.
更多的太阳能被反射进空间
This contributed to more extreme climatic conditions around the world.
导致世界许多区域出现极端气候
In East Africa, home to our ancestors,
在非洲东部，我们祖先的家乡
the climate became unstable and unpredictable.
气候变得混乱和不可预知
In this fast-changing world, those who adapted best thrived.
在这种变化无常的世界里，谁能够快速适应谁才能存活
Both big brains and new weapons gave our ancestors an edge.
大容量的头脑以及先进的工具使我们的祖先拥有了优势
Eventually, out of the climatic turmoil modern humans began to emerge.
最终，当气候稳定，现代人类出现了
If it wasn't for the recent ice age
如果不是冰河时代
helping to drive climate change in East Africa,
改变了非洲东部的气候
we might not be here at all.
我们将不会出现在这里
So what does the future hold for the planet's ice,
那么冰层未来是怎样的？
now that the Earth's climate is warming?
地球又是否正在变暖？
A good place to find out is Greenland.
格陵兰是个寻找这个答案的好地方

重点讲解

1、evolution
进化
the evolution of plants and animals.
动植物的进化
the theory of evolution by natural selection.
自然选择的进化论
演变;演化;演进;发展
a crucial period in the evolution of modern physics.
现代物理学演化过程中的重要时期
an accurate account of his country's evolution.
对他的国家演进的准确描述
2、contribute
(为…)做贡献
The three sons also contribute to the family business.
这3个儿子也为家族事业做出了贡献。
I believe that each of us can contribute to the future of the world.
我相信我们每一个人都能够对世界的未来有所贡献。
捐献;捐助;援助
The US is contributing $4 billion in loans, credits and grants.
美国将提供40亿美元的信贷和赠款。
They say they would like to contribute more to charity, but money is tight this year.
他们说他们很想捐献更多的钱支持慈善事业，但是今年的钱非常紧张。
促成;促使；是导致…的原因之一
The report says design faults in both the vessels contributed to the tragedy.
报告说两艘船存在的设计缺陷也促成了这场悲剧的发生。
Stress, both human and mechanical, may also be a contributing factor.
来自人的和机械方面的压力可能也是一个因素。