Happy Birthday, Gregor Mendel

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Genetics is a buzzword of the modern era. Controversial as it is powerful; it is not a question of if it will change the world, but when. However, its roots are far older than Dolly the sheep or the Human Genome Project. The first principles of inheritance were theorised by an Austrian friar at the Abbey of St Thomas in Brno.

The friar’s name was Gregor Mendel, and today would be his 189th Birthday. His parents were a family of farmers, but he had risen to study Philosophy and Physics at the University of Olomouc before training as a priest in 1843. His physics teacher recommended the Abbey in Brno, in the modern day Czech Republic, because it had excellent research facilities. This included a 2 hectare experimental garden. After several years breeding bees and plants he was sponsored to study at the University of Vienna, and when he returned in 1856 he set to work growing peas.

At the time, the study of inheritance was based upon observed characteristics or phenotypes. The widely accepted theory of inheritance was known as Blending. It stated that offspring were the product of random traits from each of their parents. At first this appears to make sense, but there were too many anomalies for the theory to be the whole story. For example, two white sheep can produce a dark-wooled lamb; two black cats can have ginger kittens and so on. The study of inheritance seemed to be hit and miss, so the only way to get meaningful results was to study large populations for simple traits. Plants were far easier to study in this way and so Mendel was in an ideal position to study inheritance using the research garden at the abbey and peas. Lots of peas.

He began by interbreeding purebred peas with wrinkled and smooth shells. He then counted all the peas from the offspring, and recorded his results. All the offspring produced were smooth shelled. However, when he interbred these offspring, some the plants produced some peas that were wrinkled and some smooth. Blending would state that all the peas must be smooth, as none of the parent plants had wrinkled peas. When he counted the peas, the numbers came very close to a 3:1 ratio in favour of smooth peas. He then repeated the experiments looking at two traits instead of one, plant height and pea type. He found that when breeding the first generation together, all tall and smooth, the offspring were arranged in a more complex but no less regular ratio.

Mendel repeated the process of interbreeding and recording over the next 7 years, cultivating some 29,000 pea plants in the process. He drew two conclusions from his work, known now as Mendel’s Laws of Inheritance. The first law, of Segregation, states that each offspring receives two copies of a trait, one from each parent. It can also only pass one random copy to its offspring. The second law, Independent Assortment, states that that the trait that is inherited is independent to all the other traits that may be passed on, for example if a pea plant is tall it has no greater or lesser chance to have wrinkled peas than a short plant. These simple beginnings are the cornerstones of the modern study of inheritance, genetics. Of course, genetics now encompasses many other aspects of science, but it was first a study of how traits are passed on. It would take almost 100 years before DNA was found to be the medium these inherited traits are transported in, and since James Watson and Francis Crick deciphered its structure in 1953 the field of genetics has grown exponentially. However, it was not until the early 1900s that Mendel’s groundbreaking work was acknowledged.

In fact, it was more of a rediscovery as it had taken two other scientists to publish the same theory for the importance of his work to come to the forefront. He became known as ‘The Father of Genetics’ and is far more recognised than he was when he published his results. They were widely disregarded by the scientific community and Mendel went back to his work with physics and meteorology instead. He became abbot in 1868 and his new responsibilities prevented him from continuing his scientific work. He died aged 61 in 1884. Charles Darwin’s theory of Natural Selection, though published in 1859, was only combined with Mendel’s Laws in the 1930s. Darwin had tried to popularise the theory of Pangenesis (that inheritance was in flunked by every body cell) over Blending, but Blending stayed the dominant theory until the turn of the century.

Despite being all but ignored in his time, Mendel’s work opened the door for modern theories of inheritance and evolution. As medicine begins to harness genetics to diagnose and treat inherited diseases; to treat cancer; and develop new drugs, one cannot help but feel that the Austrian friar would be proud to know that his work was being put to such good use.

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  • http://www.facebook.com/earivir Harry Parkhill

    Thanks for this article. You’ve made learning about the history of genetics quite interesting :)