James Watt Mavor (1883-1963): A Forgotten Discoverer of Radiation Effects on Heredity

JAMES WATT MAVOR (1883-1963): A FORGOTTEN DISCOVERER OF RADIATION EFFECTS ON HEREDITY ERNEST B. HOOK* Discovery of the induction of transmissible genetic effects by ionizing radiation is usually attributed to H. J. Müller working in Drosophila, who reported his observations in 1927 [1], and to L. J. Stadler working independently , who published on barley 1 year later [2]. The primary interest and focus of Muller's work was the construction of genetically marked stocks useful for increasing the detection of mutations and the subjection of these mutations to genetic manipulation as a means of unraveling the structure and function of the gene. After Muller's discovery he became quickly sensitive to the possible genetic hazards of ionizing radiation and strove to bring these hazards to the attention of both the medical profession and the public at large [3]. It may not be entirely coincidental that he was awarded the Nobel Prize for this work in 1946, one year after international consciousness of the possible long-term consequences of ionizing radiation was aroused by the explosion of atomic bombs at Hiroshima and Nagasaki. Almost all histories of genetics regard the work of Müller and Stadler as the first "breakthroughs" in the area of radiation-induced mutagenesis [4-6]. But an earlier demonstration using quantitative genetic methods of the effect of ionizing radiation on heredity was reported by James Watt Mavor, a professor at Union College in Schenectady, New York, in 1921, 6 years before Muller's report [7]. Earlier workers had found radiation effects on chromosome structure (see citation in reference [8]), but Mavor was the first to demonstrate that X-rays induced changes that were truly genetic in the sense of being transmissible to The author is indebted to James W. Mavor, Jr., for providing personal papers and documents of his father; to George Wise for reviewing historical files of the General Electric Research Laboratory; to Elof A. Carlson for suggestions; and to L. B. Clark, C. W. Hundey, George Scott, and W. T. Winne for sharing their recollections ofJames Mavor. *Bureau of Maternal and Child Health, New York State Department of Health, Albany, New York 12237 and the Department of Pediatrics, Albany Medical College, 12208.© 1986 by The University of Chicago. AU rights reserved. 003 1 -5982/86/2902-0474$0 1 .00 278 I Ernest B. Hook ¦ James Walt Mavor later generations of individuals. He noted evidence for three categories of genetic phenomena: radiation-induced X-chromosome loss [7], nondisjunction [9, 10], and effects on crossing-over [11, 12]. A review of Mavor's life reveals a number of unexpected aspects. He was primarily an experimental fish and marine biologist with no previous research experience in genetics. He made his discoveries using relatively simple methods that could have been applied by any of a number of geneticists at the time. While contemporaries in genetics appear to have been aware ofhis work, its publication may have slowed subsequent discoveries in radiation genetics. And Mavor appears to have been motivated initially more by practical and perhaps social concerns about the effects of ionizing irradiation than was Müller. Indeed there are two major puzzles about Mavor's work. The first concerns why he originally entered this field, which was outside of the mainstream of his own research. The second, an even greater mystery, concerns why, after a spurt of extraordinary productivity within an 8year span [7, 9-23] he ceased not only work in this area but essentially all biological research whatsoever. A review of Mavor's life thus provides a window on a problem that today still results in a significant loss to science and society as a whole: the cessation of active research in midcareer by men and women of talent and achievement. James Watt Mavor was born in Scotland, December 13, 1883 [24, 25]. He moved to Canada at an early age, when his father, an eminent political economist [26], took a position at the University of Toronto. He returned to the United Kingdom as a student and received an A.B. at Trinity College, Cambridge in 1905. His father had wanted him to go into a business career [27], but the boy was...