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Paper: A Plurality of Worlds, a Plurality of Bodyplans?
Volume: 213, Bioastronomy '99: A New Era in Bioastronomy
Page: 411
Authors: Conway Morris, Simon
Abstract: The term ``Earth-like'' begs many questions. So far as our neighbouring planets are concerned things have become badly unstuck. Further afield, so to speak, optimism returns so that few doubt that somewhere ``out there'' life survives, and perhaps flourishes. As there is no definitive evidence either way, we are free to conjecture. Is the rest of the Galaxy sterile, or should we be elevating Life to a cosmic principle? Let us adopt a view of cautious, perhaps English, pessimism. Yes, extraterrestrial life exists, but it is highly sporadic. Planet X has been discovered, and we are about to set foot on its surface. What will we see? In part that will depend on whether we are using an electron microscope or a pair of binoculars. In the excitement of arrival organisms probably will look rather strange. On closer inspection we may find that there is little new under the Sun. Why should this be so? In brief, because this planet shows that despite the richness of life, the dance repeatedly returns to common themes. In other words convergence is the rule, not the exception. Whether organisms show optimization is more contentious, but palaeontologists are able to point to some fossil examples that frankly are shockingly badly designed. Can we imagine a type of organism that ``ought'' to exist, or at least is biologically conceivable. In characteristically ponderous fashion Richard Fortey invokes huge ``airships'', straining the stratosphere for plankton. There are, however, some problems with such a concept. As and when we descend to this new planet avoiding these aerial behemoths will probably be the least of our problems. But once safely on the surface we probably won't know whether to laugh or cry.
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