Presented at NASA's First Astrobiology Science Conference, 3-5 Apr 2000, Ames Research Center CA
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Is Sustained Macroevolutionary Progress Possible? What'sNEW
Microevolutionary change has been demonstrated with closed-system biological experiments (Papadopoulos) and in computer models (Ray). Sustained macroevolutionary progress (SMP) that can lead from prokaryotes to people has not. In 1988, Ernst Mayr wrote, "Unfortunately, the genetics of microevolutionary processes has been unable to provide a full explanation of macroevolution." Today, a score of sequenced genomes later, W. Ford Doolittle observes, "Many eukaryotic genes ...seem to have come from nowhere."
Two recent insights point to a new possible explanation for the apparent SMP on Earth. The first insight is that microorganisms from space may have seeded life on Earth; the second is that horizontal gene transfer plays a major role in evolution. The new possible explanation is "strong panspermia," according to which microorganisms from space provide the new genes necessary for SMP on Earth. Thus, if the planet is an open biological system, perhaps what we call macroevolutionary progress is actually the incremental development of pre-existing, highly evolved cosmic life.
Strong panspermia accords well with several phenomena that have troubled standard Darwinism, including life's rapid start on Earth, punctuated equilibrium, convergent evolution, the ubiquity of certain master control genes, and the fact that many genes appear older, by sequence analysis, than they should be according to the fossil record.
But when pursued to its logical conclusion, the theory conflicts with most versions of the Big Bang and with customary Western thought, which hold that life cannot simply descend from prior life, highly evolved or not, ad infinitum. However, until SMP is demonstrated, this objection is overburdened.
If SMP is possible, closed-system experiments should be able to demonstrate it. Success in biological experiments would be decisive, but computer models should be able to get results faster. A positive result would give the existing paradigm much-needed confirmation. Of course, before results could be interpreted, a way to measure and verify SMP would have to be established — a worthy task in itself.
But if SMP is not possible, we would not have to abandon science altogether, as participants on both sides in the "darwinism versus creationism" debate suggest. Instead, in a role reversal, cosmology would have to accommodate a fundamental biological principle.
The issue is important. Let's conduct experiments to learn if SMP is possible.
ReferencesDoolittle, W. Ford. Sci Am 2000 Feb; 282(2): 90.
Mayr, Ernst. Toward a new philosophy of biology. Cambridge: Harvard University Press, 1988. p 405.
Papadopoulos, D. et al. PNAS USA 1999; 96: 3807.
Ray, Thomas, "Artificial Life," 15 July 1996: http://www.hip.atr.co.jp/~ray/pubs/fatm/fatm.html