Lamarck Lives?

Bernard Shaw invented a new religion that he called "Creative Evolution," with a crucial emphasis on the word "Creative." He even wrote a Bible for it in the form of plays and essays, most explicitly in Back to Methuselah, subtitled A Metabiological Pentateuch. While very happy with the concept of evolution, Shaw disagreed with Darwin's supposed view that all evolution was the result of "natural selection," which Shaw deemed too utterly mechanistic, accidental, and fatalistic to account for the great variety and current level of evolution, preferring the supposed view of Darwin's predecessor Jean-Baptiste Lamarck that in addition to natural selection (a term perhaps not used in Lamarck's day but understood in other terms) some evolution was determined by the passing on of "acquired characteristics," reintroducing "free will" and "creativity" into the process of evolution. Shaw had in mind, of course, that with the arrival of Homo sapiens evolution had created a species that could consciously contribute to future evolution, and Shaw hoped the contribution would be in the form of a moral and political maturation acquired by some that could be passed on to contemporaries and then genetically to their children-to-be. Gene editing of the sort imagined today was not in the discussion then. Note that I've used the word "supposed" to indicate that Shaw's view of Darwin and Lamarck has been and is contested, true also of many others who had similar views.

Regardless, what has been said so far is excuse enough to provide a brief review of and to highly recommend David Quammen's The Tangled Tree, an entertaining narrative history of microbiology since Darwin that explains the twists and turns of both practice and theory as technological advances in microscopy have made lab experiments more definitive, it would seem, even if battles about the meaning of the evidence continue. Quammen keeps reminding us that that is how science is supposed to work. Nevertheless, that Quammen's book has received much high praise suggests that he is accurately reporting some considerable degree of consensus among microbiologists.

Quammen's book explains how evolution as currently documented contradicts the implication of Darwin's "Tree of Life" image that all evolution is vertical, with lower forms at the bottom and higher forms at the top. This "Tree" still has its adherents, especially in popular understanding, but the most remarkable discoveries of the past sixty years or so have shown increasing evidence that a substantial amount of evolution has been horizontal rather than vertical, with bacterial invasions even across all life forms, including by infective bacteria, with results that altered the direction of evolution with the combining of efforts and abilities and shapes and sizes and so on by warring organisms who sometimes war not to the death but to cooperative symbiosis. Some of this symbiosis and its future development suggests that "acquired characteristics" can be and have been passed on, and so Lamarck's name occasionally pops up in support of the idea. This passing on of "acquired characteristics," however, has so far been demonstrated only at very low levels, perhaps a billion years away from what Shaw hoped for. At any rate, this horizontal evolution mixes with vertical evolution to make for a very tangled tree, so much so that many microbiologists have given up the image of a tree entirely as some models of evolution now have little to no resemblance at all to a tree.

That's the essence of the book's narrative, but there is also much detail about the leading microbiologists, the work done in their labs, and the generally cooperative spirit among scientists. We owe them our gratitude.

My thanks to John Pfeiffer for persuading me to read The Tangled Tree.