We were meant to be...

摘要

Rerun the tape of life, as the late Stephen Jay Gould repeatedly observed, and the evolutionary outcome will be completely different. This time aardvarks, snapdragons and humans. Next time or elsewhere, who knows? The prevailing view of evolution is that life has no direction - no goals, no predictable outcomes. Hedged in by circumstances and coincidence, the course of life lurches from one point to another. It is pure chance that 3 billion years of evolution on Earth have produced a peculiarly clever ape. We may find distant echoes of our aptitude for tool making and language and our relentless curiosity in other animals, but intelligence like ours is very special. Right? Wrong! The history of life on Earth appears impossibly complex and unpredictable, but take a closer look and you'll find a deep structure. Physics and chemistry dictate that many things simply are not possible, and these constraints extend to biology. The solution to a particular biological problem can often only be handled in one of a few ways, which is why when you examine the tapestry of evolution you see the same patterns emerging over and over again. Gould's idea of rerunning the tape of life is not hypothetical, it's happening all around us. And the result is well known to biologists - evolutionary convergence.