Genetic Prehistory in Selective Breeding: A Prelude to Mendel

  • Roger J. Wood & Vítĕzslav Orel
Oxford University Press: 2001. 342 pp. £49.50, $85

Successful improvement of crops and livestock was carried out long before Mendel elucidated the principles of inheritance, and the effectiveness of artificial selection was a major contributor to Darwin's theory of evolution by natural selection. Quite simply, as offspring resemble their parents, selective breeding usually provides results. Indeed, simple selection of the best performers is still the main component of most animal breeding programmes for major traits such as growth rate. But we can now use Mendel's laws to explain why it works and is an efficient practice.

In Genetic Prehistory in Selective Breeding, Roger Wood, of the University of Manchester, and Vítězslav Orel, emeritus head of the Mendelianum in Brno, aim to set the scene for Mendel's work, particularly in the context of ideas and practice in animal breeding in central Europe. The superior fine wool of the Spanish merino sheep was recognized in the textile industry; but, in an old version of the nature–nurture debate, an important question was the extent to which its quality would be retained in different environments and in successive crosses to local breeds. Among those interested was C. F. Napp, who was abbot of the monastery at Brno when Mendel entered it in 1843 and throughout the time of the latter's famous work. Napp participated in the discussions of the local sheep-breeders' society, was interested in the scientific basis of improvement and was presumably a stimulus to Mendel.

In the later part of the eighteenth century, Robert Bakewell in England had demonstrated the effectiveness of selection — aided by inbreeding — to fix qualities, with great success and to widespread acclaim. His influence was substantial and many interested breeders, including some from central Europe, visited him. Bakewell, however, had improved meat production in sheep and so it was not certain that his methods were relevant to improving wool quality and yield. Wood and Orel's chapters on Bakewell's ideas and work are, in themselves, a fascinating story, although better known than that of the work of breeders in mainland Europe.

While the problems of sheep, and specifically wool, improvement were presumably a stimulus to Mendel, both his and his abbot's interests were wider. Napp, for example, was also president of the area's Pomological and Oenological Society. Perhaps more significantly for the advancement of science, Mendel conducted his crossing experiments on traits with discrete classes — the tall and dwarf peas had a non-overlapping distribution. He would almost certainly have got nowhere studying a trait such as wool diameter, which has a continuous distribution and no clearly segregating classes in a cross.

Although I do not find Wood and Orel's implicit thesis of the important influence of sheep-breeding on Mendel's work wholly convincing, it is nevertheless both an interesting and a stimulating study. They have undertaken an impressive amount of research in the archives on sheep-breeding in Europe in the eighteenth and nineteenth centuries, and presented their findings and conclusions clearly and logically. I learnt a lot from the book.