Darwin regarded the pace of evolution as a gradual process of orderly steps. It proceeded at a constant rate. He adhered to Linnaeus’ motto : "Nature does not make leaps." This conception was reflected elsewhere in the scientific world, most notably with Darwin’s disciple, Charles Lyell, the apostle of gradualism in the field of geology. Darwin was so committed to gradualism, that he built his whole theory on it. "The geological record is extremely imperfect," stated Darwin, "and this fact will to a large extent explain why we do not find interminable varieties, connecting together all the extinct and existing forms of life by the finest graduated steps. He who rejects these views on the nature of the geological record, will rightly reject my whole theory." This Darwinism gradualism was rooted in the philosophical views of Victorian society. From this ‘evolution’ all the leaps, abrupt changes and revolutionary transformations are eliminated. This anti-dialectical outlook has held sway over the sciences to this present day. "A deeply rooted bias of Western thought predisposes us to look for continuity and gradual change," says Gould.
However, these views have given rise to a heated controversy. The present fossil record is full of gaps. It reveals long term trends, but they are also very jerky. Darwin believed that these jerks were due to the gaps in the record. Once the missing pieces were discovered, it would reveal a gradual smooth evolution of the natural world. Or would it ? Against the gradualist approach, palaeontologists Niles Eldredge and Stephen Jay Gould have put forward a theory of evolution called punctuated equilibria, suggesting that the fossil record is not as incomplete as had been thought. The gaps could reflect what really occurred. That evolution proceeds with leaps and jumps, punctuated with long periods of steady, gradual development.
"The history of life is not a continuum of development, but a record punctuated by brief, sometimes geologically instantaneous, episodes of mass extinction and subsequent diversification," says Gould. Rather than a gradual transition, "modern multicellular animals make their first uncontested appearance in the fossil record some 570 million years ago—and with a bang, not a protracted crescendo. This ‘Cambrian explosion’ marks the advent (at least into direct evidence) of virtually all major groups of modern animals—and all within the minuscule span, geologically speaking, of a few million years."
Gould also points to the feature that the boundaries of geological time coincide with turning points in the evolution of life. This conception of evolution comes very close to the Marxist view. Evolution is not some smooth, gradual movement from lower to higher. Evolution takes place through accumulated changes which burst through in a qualitative change, through revolutions and transformations. Almost a century ago, the Marxist George Plekhanov polemicised against the gradual conception of evolution :
"German idealist philosophy," he noted, "decisively revolted against such a misshapen conception of evolution. Hegel bitingly ridiculed it, and demonstrated irrefutably that both in nature and in human society leaps constituted just as essential a stage of evolution as gradual quantitative changes. ‘Changes in being,’ he says, ‘consists not only in the fact that one quantity passes into another quantity, but also that quality passes into quality, and vice versa. Each transition of the latter kind represents an interruption in gradualness, and gives the phenomenon a new aspect, qualitatively distinct from the previous one.’"
"Evolution" and "revolution" are two sides of the same process. In rejecting gradualism, Gould and Eldredge have sought an alternative explanation of evolution, and have been influenced by dialectical materialism. Gould’s paper on "Punctuated Equilibria" draws parallels with the materialist conception of history. Natural selection theory is a good explanation of how species get better at doing what they do, but provides an unsatisfactory explanation for the formation of new species. The fossil record shows six major mass extinctions took place at the beginning and end of the Cambrian period (600 million and 500 million years ago respectively), and the ends of the Devonian (345 million years ago), the Permian (225 million), the Triassic (180 million) and the Cretaceous (63 million). A qualitatively new approach is needed to explain this phenomenon.
Darwin regarded the pace of evolution as a gradual process of orderly steps. It proceeded at a constant rate. He adhered to Linnaeus’ motto : "Nature does not make leaps." This conception was reflected elsewhere in the scientific world, most notably with Darwin’s disciple, Charles Lyell, the apostle of gradualism in the field of geology. Darwin was so committed to gradualism, that he built his whole theory on it. "The geological record is extremely imperfect," stated Darwin, "and this fact will to a large extent explain why we do not find interminable varieties, connecting together all the extinct and existing forms of life by the finest graduated steps. He who rejects these views on the nature of the geological record, will rightly reject my whole theory." This Darwinism gradualism was rooted in the philosophical views of Victorian society. From this ‘evolution’ all the leaps, abrupt changes and revolutionary transformations are eliminated. This anti-dialectical outlook has held sway over the sciences to this present day. "A deeply rooted bias of Western thought predisposes us to look for continuity and gradual change," says Gould.
However, these views have given rise to a heated controversy. The present fossil record is full of gaps. It reveals long term trends, but they are also very jerky. Darwin believed that these jerks were due to the gaps in the record. Once the missing pieces were discovered, it would reveal a gradual smooth evolution of the natural world. Or would it ? Against the gradualist approach, palaeontologists Niles Eldredge and Stephen Jay Gould have put forward a theory of evolution called punctuated equilibria, suggesting that the fossil record is not as incomplete as had been thought. The gaps could reflect what really occurred. That evolution proceeds with leaps and jumps, punctuated with long periods of steady, gradual development.
"The history of life is not a continuum of development, but a record punctuated by brief, sometimes geologically instantaneous, episodes of mass extinction and subsequent diversification," says Gould. Rather than a gradual transition, "modern multicellular animals make their first uncontested appearance in the fossil record some 570 million years ago—and with a bang, not a protracted crescendo. This ‘Cambrian explosion’ marks the advent (at least into direct evidence) of virtually all major groups of modern animals—and all within the minuscule span, geologically speaking, of a few million years."
Gould also points to the feature that the boundaries of geological time coincide with turning points in the evolution of life. This conception of evolution comes very close to the Marxist view. Evolution is not some smooth, gradual movement from lower to higher. Evolution takes place through accumulated changes which burst through in a qualitative change, through revolutions and transformations. Almost a century ago, the Marxist George Plekhanov polemicised against the gradual conception of evolution :
"German idealist philosophy," he noted, "decisively revolted against such a misshapen conception of evolution. Hegel bitingly ridiculed it, and demonstrated irrefutably that both in nature and in human society leaps constituted just as essential a stage of evolution as gradual quantitative changes. ‘Changes in being,’ he says, ‘consists not only in the fact that one quantity passes into another quantity, but also that quality passes into quality, and vice versa. Each transition of the latter kind represents an interruption in gradualness, and gives the phenomenon a new aspect, qualitatively distinct from the previous one.’"
"Evolution" and "revolution" are two sides of the same process. In rejecting gradualism, Gould and Eldredge have sought an alternative explanation of evolution, and have been influenced by dialectical materialism. Gould’s paper on "Punctuated Equilibria" draws parallels with the materialist conception of history. Natural selection theory is a good explanation of how species get better at doing what they do, but provides an unsatisfactory explanation for the formation of new species. The fossil record shows six major mass extinctions took place at the beginning and end of the Cambrian period (600 million and 500 million years ago respectively), and the ends of the Devonian (345 million years ago), the Permian (225 million), the Triassic (180 million) and the Cretaceous (63 million). A qualitatively new approach is needed to explain this phenomenon.