Predicting evolutionary trajectories of computational and biological populations
I call this experiment 'replaying life's tape.' You press the rewind button and, making sure you thoroughly erase everything that actually happened, go back to any time and place in the past... Then let the tape run again and see if the repetition looks at all like the original.
The bad news is that we cannot possibly perform this experiment.
S.J. Gould (1989), Wonderful Life: the Burgess Shale and the Nature of History.
How repeatable is evolution? There are at least seven ways to evolve an eye. By contrast, there appear to be fewer ways for humans to evolve lactose tolerance or for stickleback fish to adapt to evade predators in Canadian lakes. When birds make it to remote islands, they often lose the ability to fly