GOULD X BUSH OF BIOLF

So we learn that not only is our sun a minor star in a not very interesting galaxy nowhere near the center of anything, but that our species, of which we are so justly proud, is far from the center of the biological universe, though a considerable danger to the survival of much of that universe— bacteria, however, being relatively safe from our depredations. Gould has long argued that the primary trend of biological evolution is toward diversity, variety, rather than toward greater complexity, which is only a marginal and minor development taking life as a whole. Indeed, there has also been massive evolution toward decreased complexity, as among the vast number of parasite species that normally are less complex than their ancestors after they have offl oaded functions onto their hosts. Gould often turns Darwin’s image of the tree of life into the bush of life, as a bush shows less directionality in its widely branching stems. I am ready to agree with Gould in giving us another shock to our natural anthropocentrism, but I don’t believe, and neither does Gould, that our sheer existence and our complexity are not worthy of the most careful study. However far out in right fi eld (Gould was a great fan of baseball) we as a species might be, we are the only species that we are and we must surely try to understand ourselves. But, as I noted in the Preface, a vote of thanks to the bacteria is surely in order: “Th e Age of Bacteria transformed the earth from a cratered moonlike terrain of volcanic glassy rocks into the fertile planet in which we make our home.” And lest we underestimate these tiny organisms, invisible to the naked eye, we must remember what extraordinary capacities they have.