Harry Whittington, Cambridge Professor, Wollaston medalist (2001) and until his death at age 94, the world’s leading authority on trilobites, led a brilliant and influential scientific team that brought the Burgess Shale fossils (Middle Cambrian, British Columbia, Canada) to scientific prominence and international attention. Whittington and his students, including luminaries such as Derek Briggs and Simon Conway Morris, pioneered advances in our understanding of the taphonomy, systematics and evolutionary significance of these now famous Cambrian fossils.
Leading his team via several methodological guideposts, Whittington showed the path that led the group to an unprecedented series of major discoveries. Whittington’s first guidepost is his own detailed, painstaking descriptive work. His discussion (p. 84, Treatise on Invertebrate Paleontology, Part O revised, Trilobita) of supposed colour markings in trilobites is a case in point. Here the focus is on parsing the geochemistry behind the enigmatic shell patterns. A race to interpret the paleoecological significance of the supposed colour markings (important as this may be for future investigation) is notably absent from the discussion.
Whittington’s second guidepost reads: “Follow the evidence wherever it leads.” In a magic moment in the history of science, laughter from the professional audience greeted Whittington’s 1972 restoration of the google-eyed, proboscis bearing Opabinia. The levity left Whittington somewhat perplexed, but this episode of amusement at the staid gathering in fact marked the beginning of a new phase in paleontology. Whittington had brought his audience face to face with the strangeness of the Cambrian diversification. Our current understanding of the diversity of form among Cambrian animals is a direct result of Whittington’s research programme.
In his letter to Stephen Jay Gould (1 March 1988) regarding the Burgess monographs, Whittington reminisced that “perhaps these necessarily dry papers conveyed a little of the excitement of discovery—it certainly was an intriguing investigation which had its moments of great joy when a new and unexpected structure was revealed by preparation.” In an epic clash of intellect that followed (culminating in a live debate at Yale University), Gould and Conway Morris crossed swords over interpretation of the Burgess Shale fossils. Gould argued in
Wonderful Life that the kaleidoscopic disparity of the Burgess oddities would have rendered it impossible in principle to select a winner in the struggle for survival. Gould concluded that chance is all, contingency rules history, and that, ultimately, it is up to us alone to impart meaning to the whole.
Conway Morris, in pointed contradiction to Gould’s scheme, documented (
Crucible of Creation, Life’s Solution) the theme of repeating pattern in the kaleidoscopic vista. For Conway Morris, the ubiquity of convergent evolution in the history of life speaks of regularity, even predictability to the overall pattern. It now seems clear, however, that neither Gould’s random contingency nor Conway Morris’s purposeful inevitability, both of which take the Burgess Shale as their starting point, adequately address the confounding suddenness of the Cambrian event.
At the end of his insightful book
The Burgess Shale (1985), Whittington emphasized the abruptness of the Cambrian event, and in the last line he noted that “we are far from explaining the evolutionary pathways that coincided there, or those that lead from it.” This remains true today. Whittington stressed, as Stefan Bengtson said in his review of the book, the fact that the “shale holds many embarrassingly modern looking organisms”. This modern aspect was subsequently underscored by discovery of the Cambrian fish Myllokunmingia from Chengjiang, China. And in a remarkable reinterpretation appearing in May 2010, Martin Smith and Jean Bernard Caron reconstruct the Burgess Shale problematicum Nectocaris as a squid like, soft bodied cephalopod.
Even if we accept Ediacaran fossils such as Spriggina and Kimberella as Proterozoic ancestors of trilobites and mollusks, respectively, the speed and phylogenetic magnitude of the Cambrian diversification strains the credibility of arguments that attribute the event to slow accumulation of microevolutionary change. The discoveries of Nectocaris (cephalopod) and Myllokunmingia (fish) in Early Cambrian strata render the evolutionary conundrum considerably more acute. Simon Conway Morris speculates that we may be entering some sort of post Darwinian world. Any kind of post Darwinian world that we might imagine must provide an adequate explanation for the Cambrian event.
Perhaps Whittington’s greatest scientific legacy is that he leaves us with tools and guideposts that will direct us to solutions, if any may be found, to the Cambrian problem. We must follow the evidence where it leads. Harry Whittington leaves us an inspirational record as paleontologist and world class mentor who led by example and coordinated an astonishing burst of new discovery.
Mark McMenamin