• Tue. Feb 27th, 2024

How a scholarly spat shaped a century of genetic research

How a scholarly spat shaped a century of genetic research

William Bateson (left) and Raphael Weldon had different ideas about the nature of inheritance.Credit: John Innes Archives, courtesy of the John Innes Foundation

Contested inheritance: the battle against Mendel and the future of biology Gregory Radick University of Chicago Press (2023)

Between 1856 and 1863, an Austrian monk named Gregor Mendel conducted a series of pioneering experiments with plant breeding. Using garden peas (Pisum sativum), he demonstrated that seed color and plant height are transmitted to the next generation in a 3:1 ratio—for example, three plants with yellow peas for every one green pea. Mendel proposed that unknown particles, which he called elements, were the source of this pattern. The type of element each offspring inherits determines whether it will have a ‘dominant’ majority or a ‘recessive’ minority trait. Monk died before the term gene was coined, but his theories became known as Mendelian genetics.

Inn Disputed inheritance, historian of science Gregory Radick provides a scholarly, detailed, and perceptive analysis of why Mendelian genetics has long dominated our approach to understanding heredity, despite bold attempts to propose alternatives. The answer lies in the fierce competition between the two scientists in the early days of the field.

Radick divides his analysis into three parts: Before, Battle, and Beyond. The first part draws together the threads of mid- to late-nineteenth-century studies that analyze heredity using a range of approaches, from breeding experiments to statistical analyzes of trait variation. These comparisons demonstrate how different thinking about evolution and heredity was at the time.

Two opposing views

Mendel’s findings gained attention after they were repeated by a group of botanists in 1900. The attention of many biologists turned to a newly proposed element, which in 1909 was named the gene. Some have argued that Mendel’s ideas about the inheritance of these particles could explain how each trait was passed down from generation to generation. But others were not satisfied. Mendelian thought did not allow for the influence of environment, natural selection and other considerations in heredity.

Radick presents a battle over the nature of heredity—the foundation of all future studies of biology. Both groups were led by English zoologists William Bateson of Cambridge University and Raphael Weldon of Oxford University. They were friends as undergraduates who were separated by competition. Bateson was an influential advocate of Mendelian genetics. But Weldon viewed variation in traits as a spectrum—influenced by genes, yes, but also by development, environment, and the ancestral history of each species.

Common pea, Pisum sativum, Pois ordinarye, 53. Hand-colored copperplate engraving of botanical illustration.

garden peas, Pisum sativumHe was instrumental in Gregor Mendel’s research on heredity.Credit: Alamy

Radick describes how these two men and their supporters fiercely defended their positions in public debates, soirées, journals, and extensive correspondence. The engagements were often brutal. When Bateson was elected to a committee of the Royal Society in London, he used his influence to change the rules to prevent the research of Weldon and other committee members from being published in its journals. Outraged by what he saw as a deliberate attempt to silence scientific progress, Weldon founded an independent publication, Biometrica, along with his supporters – eugenicist Francis Galton and his protégé Carl Pearson. Bateson devoted half of his 1902 book to Mendel’s principles of inheritanceAttack Weldon’s research directly.

A debate about coat colors in rodents has arisen on several topics Nature Since 1902. The coloring of some mice did not follow traditional Mendelian patterns – the offspring had blotchy coats instead of inheriting uniformly colored fur from their parents. The dispute continued at a meeting of the Zoological Society of London, before which Weldon wrote to a supporter, “We will all take our biggest and sharpest knives and have a row.”

Radick paints a picture of the increasingly tortured logic Bateson and his supporters use to defend Mendel’s laws as experimental data increasingly suggest a more complex reality involving environmental and other influences. The battle continued even after Weldon’s death in 1906 – leaving behind his book, Heredity theory, Unpublished.

A long standing tradition

In the final part of his book, Radick extends his discussion to the 1940s. By this time, biologists were turning to extensive studies of the processes influencing heredity, namely the role of different versions of the same gene – known as alleles – in the effects of genes at the population level. However, no single system of inheritance was sufficient to replace Mendelian genetics.

Radick also includes an extensive analysis of what the history of genetics might look like Heredity theory Published. He uses a ‘what if’ approach. Most historians of biology condemn this approach, but some have used it in the past. For example, in his 1989 book Wonderful life, Stephen J. Gould suggests that rewinding and replaying the tape of life might produce a different result. and Peter Bowler’s 2013 book Darwin deleted Arguing that no one else could construct the theory of evolution as Charles Darwin did.

Radick uses reverse history to perform an experiment. He designs a curriculum for an introductory biology class that does not begin and end with Mendelian inheritance, but instead emphasizes developmental contexts. Students who took this class — experimented with by Radick at the University of Leeds in the UK — came away with a gene-centered and more investigative approach to biology than those who took a Mendel-centered course (A. Jamison & G. Radick science education 26, 1261-1290; 2017).

The syllabus is commendable and the experiment is fascinating. A caveat is that many biologists have sought alternatives to Mendelian genetics since Weldon’s death. Focusing on Weldon and his unpublished book, Radick presents these actual histories in favor of what might have been.

Take Conrad Waddington, who in 1942 proposed that traits change before genes. This happens, for example, when fruits fly (Drosophila melanogaster) upon contact with the ether, a second thorax with wings develops where the wingless abdomen should have been (CH Waddington evolution 10, 1-13; 1956). Selective breeding of these flies results in offspring that develop a body with two wings without further ether exposure. Waddington named this phenomenon ‘epigenetic inheritance’ – epigenetic means ‘above the gene’. That this idea has been rejected over the decades is a testament to the firm hold of Mendelian inheritance.

We know that epigenetic inheritance occurs due to changes that affect gene expression, such as adding heritable molecular ‘tags’ to the histone proteins that wrap the DNA, without changing the DNA sequence. These tags can be inspired by environmental changes, which brings us back to Weldon and emphasizes the environment.

The discovery of epigenetic inheritance reveals a more nuanced theory of inheritance than Bateson acknowledges. Describing how scientists’ debates shaped the field of genetics, Disputed inheritance The work of the last century provides a basis for understanding, leading to a richer understanding than Mendelian genetics could have provided in the previous century.

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