Organic Evolution in Deep Time: Charles Darwin and the Fossil Record

Abstract

Abstract The heart and soul of geology are to be found in rock relationships and earth history. The fossil record was central and critical to geology emerging as geohistory, the first historical science, from the speculative geotheories of the 18th Century. The key figure was Cuvier. In the process of shaping geohistory, Cuvier and palaeontology produced the second historical science, namely biohistory, including faunal and floral succession in deep time; and biohistory and geohistory have been intertwined for two centuries. Lamarck kept alive the venerable theory of organic change, but evolution as heuristic scientific theory was stumbling. Even so, the fossil-based geological time scale was constructed in the six decades between Cuvier nailing bioextinction and Darwin nailing biospeciation. by about 1830, French molluscan palaeontology was building Tertiary stratigraphic succession, correlation and age determination in the palaeontological synthesis, i.e., biostratigraphy. Palaeontology revealed ancient and exotic life in a deep-time panorama of succession punctuated by extinctions and demanding explanation, but it contributed little to theory of evolutionary processes. Darwin’s world was Lyell’s gradualist world and his appreciation of environmental change as an evolutionary forcing factor lessened as competition came to dominate his thinking. Darwin’s Darwinism comprised five theories. Two were historical theories (the world and its biospecies change in deep time; and common descent in branching evolution produces the tree of life) and both were widely accepted by the generation after Darwin. The other three were causal or nomothetic theories (respectively speciation; gradual change not saltational; and variational change by natural and sexual selection) and they were accepted only in the 20th Century. For its importance to our culture, Darwin’s historicist worldview, in the face of entrenched, ahistorical opinion as to what science really is, outweighs disputes about the importance of selection. As stratigraphy and palaeontology went global and highly successful on most criteria, their evolutionary direction went ‘anti-Darwinian’ in the later 19th Century, towards such theories as orthogenesis, saltationism and a resurgent ‘Neo-Lamarckism’, mostly in Hyatt, Cope and Osborn in North America. This cluster of trends culminated a second time in the 1930s–1940s, in the macromutational typostrophism of the German synthesis, dominated by Schindewolf. Meanwhile there was a thin red line of Darwinian palaeontology down those decades from the 1860s to the 1920s. When population genetics emerged from decades of its own anti-Darwinism the Modern Synthesis was forged between natural history, genetics and palaeontology, the latter especially embodied by Simpson’s macroevolution. Darwin’s three causal theories came into their own in the 1930s–1950s in completing the Darwinian Revolution—or, as I prefer, installing the Darwinian Restoration. However, the Restoration was dominated by variational evolution, whilst practitioners of embryology and morphology, in the transformational mode of evolution, felt excluded. The roots of modern palaeobiology are firmly in the Darwinian Restoration and Simpsonian palaeontology and macroevolution. Modern palaeobiology (i) is thoroughly Darwinian in its historicism and variational evolution but (ii) is beyond Darwin in becoming pervasively hierarchical whilst (iii) reconciling with elements of the German Synthesis through collaboration with developmental genetics in evo-devo. Also (iv) we have gone beyond Darwin (and Simpson) primarily in the rise of micropalaeontology with its untold millions of specimens and in enormous progress in chronologically resolving and reconstructing bioevents and environmental shifts in the geological past. And (v) the tree of life is underlain by an anastomosing web of life. Deep-time palaeobiology becomes more autonomous as major soluble problems arise from the fossil record, utterly beyond the reach of shallow-time neontology. Securely embedded in thriving research programmes recovering the recorded history of life on earth, Darwinism lives!