James F. Crow

Early life and education

Crow was born in 1916 in Phoenixville, Pennsylvania, where his father was a teacher at Ursinus College. The family moved to Wichita, Kansas, two and a half years later, in 1918, where Crow was part of the 1918 flu pandemic. He went to school in Wichita, then to Friends University, at the time a Quaker school, also in Wichita, graduating in 1937.

At school, he enjoyed physics and chemistry, but pursued chemistry more strongly at university. He picked up biology as well, and double majored in chemistry and biology. A genetics course in his junior year was his first exposure to that field, even though the syllabus omitted the modern synthesis.

Delaying the decision of whether to become a biologist or chemist, Crow applied for graduate fellowships in both biology and biochemistry. He took up the first positive reply, a position with H. J. Muller at the University of Texas at Austin, in spite of knowing that Muller was in Russia at the time. It turned out that Muller had no intention of returning to his position in Texas, and so J. T. Patterson became Crow's supervisor there. Under the influence of Muller, Patterson was starting to switch to Drosophila genetics, having previously worked on the embryology of the armadillo, and so it was that Crow came to study the genetic isolating mechanisms in the Drosophila mulleri group. This included a combination of doing mating crosses between species and looking for chromosome rearrangements using polytene chromosomes. (Polytene chromosomes are large aggregations of actual chromosomes which, once appropriately stained, facilitate the discovery of chromosome rearrangements through an ordinary light microscope. Polytene chromosomes are mostly found in the salivary glands of some species.) In his studies of pre-mating isolation, Crow was one of the first to study genetic reinforcement, and also observed that species occurring together were sexually isolated, while those living apart were not.

A great influence on Crow at the time was W.S. Stone, who encouraged him to learn more mathematics, while he himself knew none. Later on, Crow admitted to struggling with some of the advanced maths and physics courses he took as a result, but also said they had been rewarding.

Dartmouth College and the war

Crow graduated with his PhD in 1941 and moved to Dartmouth College just prior to the American entry into World War II, where he remained until 1948. The original plan had been to get a postdoctoral fellowship to work with Sewall Wright at the University of Chicago, but this proved difficult just at the start of the war.

His appointment in Dartmouth was to teach genetics and general zoology, but as faculty were drafted off into military endeavors, Crow took on an increasing number of courses. Crow particularly delighted in being able to teach embryology and comparative anatomy. When it seemed likely that he himself would be drafted, Crow took a course in navigation, at which, owing to his mathematical training, he proved so adept that he was asked to teach it. As parasitology became relevant to the war (as it did on the opposing front, where Willi Hennig was active in this area), he was asked to also teach parasitology and haematology. Not long after, he was also teaching statistics. It may be that, having to teach many hours each day, Crow discovered his love for teaching at this point. He later recounted that there were several students all of whose courses were taught by him.

He, like many of his colleagues of the era, had college-time involvement with pacifist groups that had communist leanings. During WWII, he tried to enlist, but was deferred until the end due to his teaching commitments.

Race and IQ controversy

Crow wrote "Genetic Theories and Influences: Comments on the Value of Diversity," an article in the Harvard Educational Review reprinted in the review's reprint series^[12] responding to Arthur Jensen's 1969 article, "How Much Can We Boost IQ and Academic Achievement?"

Paternal age effect on DNA

Crow also did research and writing in how DNA in sperm degrades as men age, through repeated copying, and can then be passed along to children in permanently degraded form, which they likely then pass on as well. As a result, he said in 1997 that the "greatest mutational health hazard to the human genome is fertile older males". He described mutations that have a direct visible effect on the child's health and also mutations that can be latent or have minor visible effects on the child's health; many such mutations allow the child to reproduce, but cause more serious problems for grandchildren, great-grandchildren and later generations^[13] A 2009 review prematurely concluded that the absolute risk from paternal age for genetic anomalies in offspring was low, and stated that "there is no clear association between adverse health outcome and paternal age but longitudinal studies are needed."^[14]

However, newer studies supported Crow's claims. A study in 2006 of 132,000 Israeli adolescents discovered men in their 30s are 1.6 times as likely to have a child with autism as men under 30, with men in their 40s having a sixfold increase in risk ^[15] Further studies in Sweden (2.6 million children),^[16] Denmark (2.98 million),^[17] and an international dataset of 5.7 million children ^[18] showed a definite link between increased paternal age and autism risk. A widely-referenced Icelandic whole-genome sequencing effort led by Kári Stefánsson of DEcode Genetics and published in Nature also concluded similarly.^[19]