Water under a troubled bridge

The Yangtze River dolphin, or baiji, is functionally extinct. And the Yangtze River porpoise, or jiangzhu, seems set to meet the same fate. For all we know, the law of the survival of the fittest is at work here.

But is it? Doesn't evolution usually take thousands, if not hundreds of thousands, of years to have its effects? The Yangtze River, according to many experts, is 45 million years old. The baiji evolved about 20 millions years later. It took another 5 million years for it to swim from the Pacific Ocean into the Yangtze and make its permanent home there. Yet it has only taken a few decades for it to become functionally extinct.

Many would argue that almost the same fate befell the dodos and yet the world hasn't been any poorer for it.