Once again (never finished it in 2-3 tries)delving into Wonderful Life by Harvard paleontologist Stephen Jay Gould.

Much of it is technical detail, but the overall descriptions and astounding implications make my brain churn.

"Gould's thesis in Wonderful Life was that chance was one of the decisive factors in the evolution of life on earth. He based this argument on the wonderfully preserved fossil fauna of the Burgess Shale, animals from around 505 million years ago, just after the Cambrian explosion"