“Things fall apart; the centre cannot hold”

-W.B. Yeats, The Second Coming (1919)

In his 1997 book “Full House,” the late paleontologist Stephen Jay Gould discussed the idea of progress in evolution. He noted that Darwin went back and forth over the idea, at times arguing that natural selection had the power to refine organisms and “tend to progress toward perfection” and at other times writing that “after long reflection, I cannot avoid the conviction that no innate tendency to progressive development exists” (p. 137 and 141).

Gould himself acknowledged that it certainly seems like life has progressed over the billions of years it has existed on earth:

“And yet, undeniably (even for such curmudgeons as me), a basic fact of the history of life – the basic fact, one might well say – seems to cry out for progress as the central trend and defining feature of life’s history. The first fossil evidence of life, from rocks some 3.5 billion years in age, consists only of bacteria, the simplest forms that could be preserved in the geological record. Now we have oak trees, praying mantises, hippopotamuses, and people. How could anyone deny that such a history displays progress above anything else?” (p. 145)

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