Origins of other life, and more on negative capability

From the NYT book review of "What Darwin Got Wrong," which was linked in the Dyson interview that was linked in my prior post:

How does one detect life on Mars?  One suggestion was to send up a sort of microscope, collect some dust from the Martian surface, and see if anything wiggled.  If it wiggles it is alive.  This seemed too unsophisticated for the space scientists. 

Instead they sent up a sort of vacuum cleaner filled with a nutrient solution containing a radioactively labeled simple sugar.  If the dust sucked up from the surface contained living cells, they would start to grow and divide, metabolize the sugar, and release radioactive carbon dioxide, which would be detected by a counter.  The Mars lander never detected any life activity although it was determined to be in perfect working order.  But that does not mean that there is no life on Mars.  It means that there is no life in Martian dust that grows on the sort of sugar provided.  This device certainly would not have detected a science-fiction Martian.  What the space scientists had done was to provide an ecological niche for a specific kind of life that they knew from earth, a niche that does not match a vast variety of earthly organisms.  If you do not specify the kind of organism you are looking for you cannot specify its ecological niche.  Perhaps the space program should look again for wiggly things.

This quotation is a casual aside in the review, but I liked it even more than the main body.  It's so difficult for us to think about the development of life in any way but our own, as if the development of DNA itself were not something of a long shot, and something we have no reason at all to suppose might develop spontaneously in parallel on another planet.

On the subject of the book itself, the reviewer notes the extraordinary hostility that has greeted its authors, who are viewed suspiciously as catering to religious extremists.  In fact, they mostly are complaining of a tendency to take literally Darwin's "metaphor" of natural selection and talk as if nature willed a new creature into being.  As evolutionary biologists often note with exasperation, evolution has no foresight.  The reviewer suggests that instead of “natural selection” we should talk about differential rates of survival and reproduction.  That's not very pithy, though, does it?  At least "natural selection" deftly gets across the idea that a few successful individuals are plucked out of the group in the sense of thriving where others fail, such that their descendants come to dominate the population.  The whole idea of calling it "natural" selection surely was to contrast this unintentional mechanical process with deliberate design of the sort that produced poodles from wolves.  But it's true that a lot of anthropomorphic nonsense is talked by supposedly secular biologists who would faint dead away if that tendency were equated with the worldview of the intelligent-design community.  As the reviewer observes:

The other source of anxiety and anger is that the argument made by Fodor and Piattelli-Palmarini strikes at the way in which evolutionary biologists provide adaptive natural historical explanations for a vast array of phenomena, as well as the use by a wider scholarly community of the metaphor of natural selection to provide theories of history, social structure, human psychological phenomena, and culture. If you make a living by inventing scenarios of how natural selection produced, say, xenophobia and racism or the love of music, you will not take kindly to the book. 

Even biologists who have made fundamental contributions to our understanding of what the actual genetic changes are in the evolution of species cannot resist the temptation to defend evolution against its know-nothing enemies by appealing to the fact that biologists are always able to provide plausible scenarios for evolution by natural selection. But plausibility is not science.  True and sufficient explanations of particular examples of evolution are extremely hard to arrive at because we do not have world enough and time.  The cytogeneticist Jakov Krivshenko used to dismiss merely plausible explanations, in a strong Russian accent that lent it greater derisive force, as “idel specoolations.”

Even at the expense of having to say “I don’t know how it evolved” most of the time, biologists should not engage in idle speculations.