Review by Richard England of Forsdyke's book The Origin of Species, Revisited (2001)

The 'Origin of Species' Revisited: A Victorian Who Anticipated Modern Developments in Darwin's Theory

Reviewed in University of Toronto Quarterly 72 Number 1, Winter 2002/3 by Richard England

Revisiting the Origin of Species, Donald Forsdyke attempts to answer biological questions that have lingered since the nineteenth century, and to restore the memory of a forgotten Victorian evolutionist, George Romanes. Forsdyke, a lab scientist, explains how DNA's having different levels of information leads to hybrid sterility and the creation of reproductively isolated subgroups in natural populations - or incipient species. His hunt for Victorian precursors turns up Romanes's very similar theory of 'physiological selection,' which was rejected in its day. The result is an intriguing hybrid in its own right. It blends recent science and Victorian history, scientific text with popular book, and Whig history of science with a hint of the sociology of knowledge. While it is more successful in some of these crosses than others, overall it proves an original, if somewhat challenging, work.

Forsdyke's central claim is that DNA speaks with an accent. Human speech conveys at least two levels of information, the meaning of the words and the accent of the speaker. While it is commonly known that DNA codes for proteins, there is a secondary level of information, the ratio of the DNA base pairs cytosine and guanine to adenine and thymine (C+G %) in a genome. Because there is redundancy in the way that DNA codes for amino acids, C+G % can vary between groups without affecting the proteins they produce, so groups with quite different overall levels of cytosine and guanine in their genome might well be physically identical. However, differences in C+G % can affect the biochemistry of DNA recombination - in other words, it can make varieties with different levels of C+G % mutually infertile.

This is the real origin of species, according to Forsdyke. Darwinian natural selection can cause species to adapt to changed circumstances, but it cannot make them diverge, or speciate. However, random drift in C+G % can create mutually infertile subgroups within a population, which natural selection can then act on to create new species. If natural selection is not the direct cause of speciation, we should expect to find many closely related species which differ in unimportant particulars, such as colouration.

This fact has long been noted, and provided Romanes with support for his theory of physiological selection, which he proposed in 1886. His main opponent was Alfred Wallace, the co-discoverer of natural selection, who insisted that all characteristics were useful, even the apparently trifling characters which separated species. Romanes, Darwin's scientific confidant, criticized this as an over-reliance on natural selection, and suggested that species came into being because of variations in their reproductive systems which created isolated populations. Only then could natural selection act on them to create species. This theory of physiological selection mirrors Forsdyke's late-twentieth-century view, although Romanes, of course, could not explain the reproductive variations which lead to hybrid sterility.

Forsdyke, a self-described Whig historian, suggests that Romanes' 'right answer' was dismissed by critics because it seemed too much like divine creation. However, he does not explain the connection well, and such criticism seems unlikely in the case of Romanes, who had a strong reputation for opposing those who tried to fit God into the details of evolutionary theory. Forsdyke seems nearer the mark when he appears to appreciate the sociology of knowledge, comparing past and present 'dynamics of peer resistance to novel ideas.' Then, as now, Darwinism was criticized, and there was the same pressure for evolutionary theorists to present a unified front to their critics.

Ultimately Forsdyke's revival of Romanes will depend on the success of his own updated version of physiological selection. If it is accepted as an important contribution to evolutionary theory, then historians may well give Romanes the same kind of attention that has been lavished on other rediscovered scientists, like Gregor Mendel. If, however, the implications of C+G % are discounted as a speculation, Forsdyke himself may share the obscure fate of his historical hero. Whether or not the theory advanced here is adopted by evolutionary biologists, the book shows the potential of modern biochemistry and bioinformatics to revolutionize both our understanding of biological questions and the history of biology.