In Pursuit of the Gene: From Darwin to DNA

When William Bateson introduced the word "genetics" in 1905, he meant it to name a new branch of inquiry. Bateson well knew that scientifically minded people had long been researching inheritance. But the recent recovery of the ideas of Darwin's contemporary Gregor Mendel had, in Bateson's view, changed everything. By the crossbreeding of pea varieties and the tracking of specific traits through several generations, Mendel had exposed patterns whose explanation lay, he proposed, in the combining and recombining of stable underlying factors. Mendel's achievement was the model for genetics. Within the next decade the new "Mendelians" would start calling the factors "genes".

This shift happens about two thirds of the way through the science writer James Schwartz's In Pursuit of the Gene. Before there was talk of genes, there was talk of "pangenes" and, earlier still, "gemmules". Making use of correspondence from the period, Schwartz industriously retraces the debate linking Darwin's own theory of inheritance, published in 1868, to Bateson's triumph over critics of the new Mendelian approach. A lengthy summary of the parallel changes in cell biology climaxes in the conjecture that Mendelian factors were parts of chromosomes - a conjecture that grew increasingly plausible to many as, from about 1912, T. H. Morgan and his students at Columbia began to map genes on to the chromosomes of fruit flies.

Surprisingly, Schwartz narrows focus for the rest of the book to just one of Morgan's students, Hermann Muller. Certainly the brilliant, awkward Muller can bear the attention. Again and again, he applied himself to cracking the hard cases, the apparent exceptions to the Mendelian-chromosomal rules. His solutions invariably took genetic theory and practice to new levels of complexity and subtlety.

There were also pioneering X-ray studies of mutation, for which Muller won the Nobel Prize in 1946, and reconsiderations of everything from evolutionary theory to the molecular structure of the gene. His teaching on the latter topic went deep with one of his graduate students, James Watson, co-discoverer in 1953 of the double helical structure of DNA, which Muller and others had suspected was the genetic molecule.

Schwartz devotes some of his most absorbing, albeit demanding, pages to explaining the accomplishments that so impressed Muller's peers. Along the way Schwartz weaves in elements of Muller's extraordinary private life and genetics' extraordinary public life in the interwar years, drawing on documents made available only recently. Immersed in the left-wing causes of the day, including Communism, eugenics and open marriage, Muller was nevertheless undone by his wife's affair with a younger man in his lab, and in 1932 attempted suicide. His survival re-energised him, and he was soon off to the Soviet Union, where he had previously helped start fruit-fly genetics and where he now attempted, unsuccessfully, to make the case for a national eugenics programme to Stalin himself. Schwartz writes movingly about Muller's ineffective attempts to save Soviet genetics from its then-rising nemesis, T. D. Lysenko.

In good and less good ways, In Pursuit of the Gene amounts to an old-fashioned historical introduction to the concepts and methods that stabilised into textbook genetics in the pre-molecular era. It will tell you more than other popular histories about what Muller and his like believed about heredity and how to study it. But the narrative is triumphalist, tending to mislead about ideas and individuals that the genetic heroes disparaged. The ultimate effect is to sell this material short. You would hardly guess it from Schwartz, but some of Mendelism's critics had a point. At a time when genomics is prompting rethinking across the board, we might even have something to learn from them.