THE MEANING OF EVOLUTION Robert J Richards Publisher: University of Chicago Press, Chicago Price: Not stated
DID CHARLES Darwin see evolution as "progressive", as being singlemindedly directed toward producing ever more advanced forms of life? Most contemporary scholars say no. But in this daring challenge to prevailing views, Robert J Richards of the University of Chicago argues that current perspectives on Darwin and his theory are both ideologically prejudiced and scientifically unsound.
The book is not just a treatise on evolution or on Darwin; it is also an instructive manual on the successful historian's craft and methodology. Richards reaches with ease a goal many authors aspire to but few achieve: he not only informs but shows why being informed is essential to an understanding of contemporary issues and contemporary reality. The lucidity of Richards' language, despite the heavy subject he deals with, makes it impossible to put the book down before finishing it.
The volume is a provocative reinterpretation of Darwin; it digs directly into the origins of evolutionary theory. Richards holds that Darwin did concern himself with the idea of progress. In constructing his theory, he drew on the traditional embryological meanings of the term "evolution" and "descent with modification". Richards argues that contemporary researchers reject this interpretation because they impose on Darwin some deeply-entrenched assumptions underlying current evolutionary thought.
In the 17th and 18th centuries, evolution referred to the embryological theory of "preformation" -- the idea that the embryo exists as a miniature adult of its own species that simply grows, or evolves, during gestation.
However, by the early 19th century, the idea of preformation had become the concept of "evolutionary recapitulation" -- which says that during its development, an embryo passes through a series of stages of its ancestral species. This "species descent with modification" was an idea of evolution that philosophers and biologists of the 19th century struggled with while examining its impact on their views of the natural world.
Most historians today interpret these two theories of evolution to be quite distinct in substance, argues Richards. He says, "I now believe these terms are historically joined through a process not unlike evolution itself: The older embryological idea gradually became transformed over two centuries into the more familiar one referring to species change, yet while retaining vestiges of its past."
The missing linkage between these two theories of evolution had so far been thought to have achieved real significance only at the end of the 19th century, when it was "crudely used by that archprogressionist and bete noir of all good Darwinians, Ernst Haeckel".
Haeckel's theory revolved around the doctrine that the embryo retraced the same morphological steps that the species went through in its evolutionary development; in other words, that ontogeny (the origin and development of the individual) had "recapitulated" phylogeny (the evolutionary development of a group of organisms).
For Darwin, Richards shows, embryological recapitulation provided a graphic model of how species evolve. If an embryo could be seen as successively taking the structures and forms of its ancestral species, then the evolution of life itself could be seen as a succession of species, each subtly transformed from its ancestor.
Before Darwin, natural historians had systematised relations among animals. They traced out how apparently disparate groups united into common types and even thought of the relations they discussed in genealogical terms -- as though one animal group had given birth to another. Darwin interpreted these connections as "dynamic" and "real genealogical" relations of descent.
Richards argues that the current tendency to see evolution as a process that is not progressive, and one which does not explain phenomena by the purpose they serve, does a serious disservice to Darwin. It imposes perspectives on him that deny the progressive heart of his embryological models and his evolutionary theory.
Today, freely flowing variational possibilities are regarded as the essence of evolution. In effect, recapitulation is considered restrictive. Recapitulation, however, has always been linked to progress; in fact, many of today's historians hold that progressive evolutionary processes can only be the assured by fixed goals to be achieved.
It is unseemly, then, argues Richards, to force Darwin to endorse Haeckel's chief biological principle -- ontogeny recapitulating phylogeny. He stresses that an ideology that influences an interpretation of the past need not necessarily be unsavoury.
The contemporary scientific assumptions that some present day historians discover in Darwin's thought have helped in the development of a neo-Darwinian theory. This new-fangled one dismisses the three older ideas of evolution modelled on individual evolution: specifically, embryogenesis (the formation of an embryo), recapitulating phylogeny and progressive evolution. The ethical and social components of this ideology are not only acceptable but indeed admirable.
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