这里是今日热点节目。
Three million years may seem like a long time. But when you consider that planet Earth is more than 4.5 billion years old, it is a pretty short period of time.
300万年可能看上去是很长一段时间，但是考虑到地球的年龄超过了45亿年，这就是非常短的一段时间了。
And it is over that shorter time period that the whales in our oceans today got to be so large.
而就是在这么短一段时间里，我们现在海洋中的鲸鱼变成了如此之大。
The blue whale is the largest animal that has ever lived. They weigh more than even the biggest dinosaurs. They can grow to 30 meters long and weigh up to 130,000 kilograms.
蓝鲸是有史以来最大的动物，它们甚至比最大的恐龙还要重。蓝鲸可以长到30米长，重达130吨。
Blue whales are part of the baleen whale family. Baleen is a kind of food-filtering structure in the mouths of the whales. The whales developed this system about 30 million years ago.
蓝鲸属于须鲸类。鲸须是鲸鱼口腔中的一种食物过滤结构。鲸鱼在3千万年前发育出了这种系统。
Other whales in the baleen family include fin whales, bowhead whales, and right whales. Today, these whales can weigh well over 70,000 kilograms.
其它须鲸类鲸鱼还包括长须鲸、弓头鲸和露脊鲸。今天，这些鲸鱼的体重可以远远超过70吨。
But for millions of years, they were not nearly that large, scientists say.
但是科学家表示，数百万年来，鲸鱼并没有这么大。
"All of a sudden – ‘boom' – we see them get very big, like blue whales," scientist Nick Pyenson told the New York Times. He and other researchers recently published an article on whale size in the British research journal Proceedings of the Royal Society B.
科学家尼克·派森（Nick Pyenson）对纽约时报表示，“突然间我们就看到它们就变得非常大了，就像蓝鲸一样。”派森和其它研究人员最近在《英国皇家学会会刊B辑》上发表了一篇关于鲸鱼大小的文章。
"It's like going from whales the size of minivans to longer than two school buses," Pyenson added.
派森补充说，“鲸鱼就像是从一辆小货车变成比两辆校车还要长。”
The researchers -- Pyenson, Jeremy Goldbogen and Graham Slater -- believe that a change in the Earth's climate caused whales to get so large only about 3 million years ago.
派森、杰里米·葛保根（ Goldbogen）和格雷厄姆·斯莱特（Graham Slater）这些研究人员认为，大约300万年前，地球气候变化导致鲸鱼变得如此之大。
This change led to food becoming more easily available.
这种变化导致鲸鱼更容易获得食物。
An oncoming ice age made the ocean water cold. High winds mixed the water in the ocean faster than before. Rain and snow made more nutrients run off from the land into the water. The nutrients resulted in algae. That attracted small fish and shrimp called krill.
随即而来的冰河时代（指第四纪冰期）使得海水变得冰冷。狂风使得海水融合得比以前更快。雨雪使得更多的营养物质从陆地流入水中。这种养分产生了藻类，吸引了小鱼和磷虾。
The mixture of nutrients resulted in more food for large whales to eat.
养分的混合物导致鲸鱼有更多食物可食用。
Whales that were able to quickly eat a lot of food survived. And they got larger. Whales that had teeth instead of baleen, however, did not survive.
能够快速食用大量食物的鲸鱼存活了下来，它们变得越来越大。然而有牙齿但没有鲸须的鲸鱼没能幸存下来。
The largest baleen whales then produced other large whales.
这种最大的须鲸然后产生了其它大型鲸鱼。
Over the next three or four million years, the baleen whales grew 10 times bigger than they had been, the researchers say.
研究人员表示，在接下来的三到四百万年中，须鲸比它们之前变大了十倍。
It is possible that the largest whales are gone, the researchers said. But, as they told the BBC, blue whales could grow even bigger -- or they could slowly die – depending on Earth's changing climate.
研究人员表示，这种最大的鲸鱼有可能会消失。但是，就像他们告诉英国广播公司的，蓝鲸可能会变得更大，或是慢慢地消亡，这都取决于地球的气候变化。
And that's What's Trending Today.
以上就是本期今日热点的全部内容。
I'm Dan Friedell.
我是丹·费里德尔。(51VOA.COM对本文翻译保留全部权利，未经授权请勿转载，违者必究！)