lection is a theory of "trial and error exter- 

 nalism" — organisms propose via their 

 storehouse of variation, and environments 

 dispose of nearly all — not an efficient and 

 human "goal-directed intemalism" (which 

 would be fast and lovely, but nature does 

 not know the way). Darwin certainly 

 grasped this central irony of our being 

 when he wrote to his best friend Joseph 

 Hooker in 1 856: "What a book a devil's 

 G chaplain might write on the clumsy, 

 O wasteful, blundering, low, and horribly 

 • i-H cruel works of naUire." 

 "*^ The Peculiar Pathway: We look at the 

 ^ paleontological pattern of life's unfolding, 

 -^ and we try to extract a story that suits our 

 ^ prejudices. We speak of an "age of inver- 

 >^ tebrates" followed by an "age of fishes, 

 pL^ reptiles, and mammals," all capped by an 

 "age of man." We draw our sequences of 

 pictures and arrange our chapters in text- 

 books, so that trilobites come first and 

 people last. But invertebrates have always 

 dominated the world of multicellulai" ani- 

 mal life in numbers of species and 

 prospects for long-term success, while 

 Homo sapiens is one tiny twig on life's ex- 

 uberantly branching bush. (I do not deny 

 the unparalleled impact of our species 

 upon the planet, but magnitude of result 

 bears no relationship whatever to pre- 

 dictability of origin.) 



This is not the "age of man"; it is not 

 even the "age of insects" — a proper desig- 

 nation if we wish to honor multicellular 

 animal life. As it was in the beginning, is 

 now, and ever shall be until the sun ex- 

 plodes, this is the "age of bacteria." Bacte- 

 ria began the story 3.5 billion years ago, as 

 life arose near the lower limits of its 



preservable complexity. The bacterial 

 mode has never altered; the most common 

 and successful forms of life have been 

 constant. Bacteria span a broader range of 

 biochemistries and live in a wider range of 

 environments; they cannot be nuked into 

 oblivion; they overwhelm all else in fre- 

 quency and variety; the number of E. coli 

 cells in the gut of any human exceeds the 

 count of all humans that have Uved since 

 our African dawn. 



No trend of complexity or progress ex- 

 ists in the usual sense; the history of life 

 features no upward thrust as a central ten- 

 dency of evolution; the bacterial mode has 

 persisted for more than three billion years. 

 At most, every once in a while, a lineage 

 or two tumbles into a domain of enhanced 

 complexity, for this is the only open direc- 

 tion available (the numerous forms that 

 evolve greater simplicity fall into a do- 

 main of overlap with creatures already ex- 

 isting). We focus upon this tiny tail in the 

 distribution of complexity only because 

 we reside there ourselves. 



Moreover, the pattern of occupation for 

 this small tail of complexity departs maxi- 

 mally from any notion of a predictably 

 steady unfolding. With the exception of 

 simple algae (a pathway unrelated to the 

 genealogical story of animals), life re- 

 mained unicellular for five-sixths of his- 

 tory. All but one phylum arose in a single 

 geological whoosh, within some five mil- 

 lion years or so, at the dawn of Cambrian 

 times, 530 million years ago (the "lowly" 

 Bryozoa, not our exalted chordate selves, 

 form the single exception of slightly later 

 origin). 



In a basic anatomical sense, the history 



of life since then has been a tale of many 

 variations on a few underlying themes. (I 

 do not deny the unusual interest of some of 

 these variations, including human con- 

 sciousness.) The earth doesn't even permit 

 exclusive evolution by the already messy 

 and contingent rules of competitive nat- 

 ural selection. Mass extinctions punctuate 

 the history of life, imposing regimes of 

 death for reasons unrelated to Darwinian 

 struggles of normal times. If a large ex- 

 traterrestrial body had not struck the earth 

 65.3 million years ago, dinosaurs would 

 probably still be dominating mammals, 

 and no conscious being would have the 

 privilege of pondering a world queerer 

 than we can suppose. 



How can Darwinism be exalting, and 

 "this view of life" grand, if all our com- 

 forts be thus stripped away in favor of 

 such messiness, contingency, and caprice 

 in the details that matter (like the probabil- 

 ity of our own evolution), with generalities 

 confined to broad domains that offer so lit- 

 tle solace (mass extinction as a recurring 

 phenomenon; natural selection as a gov- 

 erning principle; invariance of the bacter- 

 ial mode as a result). First, do not doubt 

 the salutary effects of such a cold bath. We 

 never should have sought either solace or 

 moral instruction in Nature, who was not 

 made for us, or even with us in mind, and 

 who existed by her own rules for billions 

 of years before we arrived. Better to learn 

 a stem truth about marvelous multifarious- 

 ness (and cosmic indifference to us) than 

 to persist in a myth of warm cuddliness or 

 intrinsic harmony that might channel 

 proper attention from our own bodies and 

 minds (true humanism) as the source of 

 ethics and value. 



Second, a world queerer than we can 

 suppose must be, to anyone with a mod- 

 icum of curiosity, so much more interest- 

 ing a place than a planet crafted to feed our 

 bovine complacency. Darwin's revolution 

 remains incomplete, in Freud's crucial 

 sense, until we face the cosmic insignifi- 

 cance that our own evolution truly im- 

 plies — thus liberating us to grasp the 

 deeply human meaning of our lives and 

 most curious brainpower. We shall soon 

 celebrate the two-thousandth birthday of a 

 most interesting man who not only told us 

 that the truth would make us free but who 

 also spoke for all kinds of enlightenment 

 in saying: "I am not come to destroy, but to 

 fulfill." 



Stephen Jay Gould teaches biology, geol- 

 ogy, and the history of science at Harvard 

 University. 



8 N.ATURAL History 6/94 



