Deep Thoughts: we don't develop inexorably, we happen randomly

Natural History and the Nature of History -- by Richard York and Brett Clark

Over 500 million years ago, Pikaia, a two-inch-long worm-like creature, swam in the Cambrian seas. It was not particularly common, nor in anyway would it have appeared remarkable to a hypothetical naturalist surveying the fauna of the time. Pikaia is the first known chordate, the phylum to which Homo sapiens and all other vertebrates belong. As the late Stephen Jay Gould, paleontologist, evolutionary theorist, and dialectical biologist, posited in one of his most renowned books, Wonderful Life (1989), an exceptional level of human arrogance is necessary to argue that Pikaia was superior to its many contemporaries who either went extinct or, through the vagaries of history, dwindled to obscurity.

Yet, despite the absurdity of it, bourgeois thought is so deeply committed to portraying history as a march of progress leading inexorably to the present that many natural historians have long argued that evolution on earth unfolded in a predictable, progressive manner, with the emergence of humanity, or at least a conscious intelligent being, as its inevitable outcome. This view fits well with the perspective of the dominant classes of various historical ages, who typically believe the particular hierarchical social order that supports them is both natural and inevitable, the point toward which history had been striving.

As Marxist scholars have long recognized, ruling-class ideology gets smuggled into the damnedest places, including interpretations of the natural world. This elite construction of nature, which often involves demarcating so-called inherent hierarchies, is often used to justify inequalities in the social world. It would be wise to call into question such depictions of the social and natural world and to seek an understanding of natural history free of this ideology.

Running counter to much of prevailing thought, one of Gould’s central themes is that of historical contingency—events often occurring effectively by chance and that are not predictable before hand (although they may be rendered sensible in hindsight) may change the course of history, foreclosing some options and opening others. The trilobites so common before their disappearance in the granddaddy of all mass extinctions—that which ended the Permian period 250 million years ago—did not vanish due to inherent inferiority. After all, they had thrived for three hundred million years, longer than mammals have been around and over one thousand times longer than Homo sapiens has trod upon the earth.

Rather, they likely blinked out due to bad luck in an unpredictable, and still unexplained, global shake up that took with it over 90 percent of all species then extant. It is hard to imagine that the descendants of Pikaia made it through this bottleneck due to anything but good fortune. Furthermore, had a comet not collided with the earth 65 million years ago, at the close of the Cretaceous period, the dinosaurs almost surely would have persisted in their dominance over the inconsequential rat-like ancestors of mammals, and their lineage would have taken a different path.

Due to the dominance of contingency in natural and social history, the world of the present is only one of the many worlds that are possible; it does not represent a foreordained order. Or to use Gould’s powerful metaphor, if we were to “replay the tape of life,” a different history would unfold, almost surely without the appearance of humans or any creature especially similar to us; a history that would appear just as sensible and even as “inevitable” as the history that actually occurred.

Due to the dominance of contingency in natural and social history, the world of the present is only one of the many worlds that are possible; it does not represent a foreordained order. Or to use Gould’s powerful metaphor, if we were to “replay the tape of life,” a different history would unfold, almost surely without the appearance of humans or any creature especially similar to us; a history that would appear just as sensible and even as “inevitable” as the history that actually occurred.