A recent open access article at Science Advances caught our attention: “Mapping life’s disparity and evolutionary constraints in a geometric complexity space.” From page 13 (emphasis added):
As argued by [Stephen Jay] Gould, evolution is generally understood as a process operating at the intersection of innumerable random biological and environmental factors, making it highly sensitive to historical contingencies and largely unpredictable in the long run (117). Within this conceptual scheme, living forms arise and evolve in multiple and erratic directions from an initially simple and irreducible configuration typical of the earliest life forms (e.g., rounded bacterial shape). Thereby, the observed growth of complexity could just result from chance such that the expansion of life into the most remote, complex, and heteromorphic areas of geometric complexity space could just be a matter of time and opportunities (118, 119), rather than the outcome of specific constraints or biases. While the role of contingency cannot be dismissed, multiple examples of anatomical convergence among independent lineages yet indicate that deep physical, chemical, and biological constraints have imposed directional patterns on morphological evolution (5, 7, 8). Here, our results appear to support the prevalence of such underlying necessity at the whole biosphere scale.
Appeals to contingency (i.e., in-principle unrepeatable singularities) disable theory testing. If anything can happen…don’t bother to test, because you can’t. Just believe.
Rules enable testing.