|From the Annals of the World History
|- July 20, 1822 - January 6, 1884|
|Gregor Johann Mendel was an Augustinian priest and scientist, who gained posthumous fame as the figurehead of the new science of genetics for his study of the inheritance of certain traits in pea plants. Mendel showed that the inheritance of these traits follows particular laws, which were later named after him. The significance of Mendel's work was not recognized until the turn of the 20th century. The independent rediscovery of these laws formed the foundation of the modern science of genetics. |
Mendel was born into an ethnic German family in Heinzendorf bei Odrau, Austrian Silesia, Austrian Empire (now Hyncice, Czech Republic), and was baptized two days later. He was the son of Anton and Rosine Mendel, and had one older sister and one younger. They lived and worked on a farm which had been owned by the Mendel family for at least 130 years. During his childhood, Mendel worked as a gardener, studied beekeeping, and as a young man attended the Philosophical Institute in Olomouc in 1840-1843. Upon recommendation of his physics teacher Friedrich Franz, he entered the Augustinian Abbey of St Thomas in Brno in 1843. Born Johann Mendel, he took the name Gregor upon entering monastic life. In 1851 he was sent to the University of Vienna to study under the sponsorship of Abbot C. F. Napp. At Vienna, his professor of physics was Christian Doppler. Mendel returned to his abbey in 1853 as a teacher, principally of physics, and by 1867, he had replaced Napp as abbot of the monastery. Besides his work on plant breeding while at St Thomas's Abbey, Mendel also bred bees in a bee house that was built for him, using bee hives that he designed. He also studied astronomy and meteorology, founding the 'Austrian Meteorological Society' in 1865. The majority of his published works were related to meteorology.
|Mendel began to conduct experiments. He studied the inheritance of seven pairs of traits in garden pea plants and in their seeds. These pairs included tall or short plants and rounded or wrinkled seeds. He bred and crossbred thousands of plants and observed the characteristics of each successive generation. Mendel soon arrived at the conclusion that pea plants reproduced through the union of cells called gametes and that plant traits were being handed down through hereditary elements, now called genes, in the gametes. He worked out that each plant receives a pair of genes for one trait; that is one gene from each of its parents. He also concluded that if a plant inherits two different genes for a trait, one was dominant and the other recessive. It is the trait of the dominant gene that would appear in the plant. For example, if a plant inherits genes for round seeds and wrinkled seeds, it would have round seeds, if the gene for the round seed was dominant. |
Mendelism and the two laws
Yet another conclusion that Mendel drew was that the pairs of genes separated randomly when a plant's gametes were formed. Working backwards, he concluded that a parent plant hands down only one gene of each pair to its offspring. This led to his Law of Segregation. He also claimed that a plant inherits each of its traits independent of other traits. This led to the Law of Independent Assortment. His system came to be known as Mendelism and is considered one of the basic principles of biology. Scientists have claimed there are exceptions to the rules, but in general, the theories have been proved.
Life after the pea experiments
After Mendel completed his work with peas, he turned to experimenting with honeybees, in order to extend his work to animals. He produced a hybrid strain (so vicious they were destroyed), but failed to generate a clear picture of their heredity because of the difficulties in controlling mating behaviours of queen bees. He also described novel plant species, and these are denoted with the botanical author abbreviation "Mendel".
At first Mendel's work was rejected, and it was not widely accepted until after he died. At that time most biologists held the idea of blending inheritance, and Charles Darwin's efforts to explain inheritance through a theory of pangenesis were unsuccessful. Mendel's ideas were rediscovered in the early twentieth century, and in the 1930s and 1940s the modern synthesis combined Mendelian genetics with Darwin's theory of natural selection.
Mendel died on January 6, 1884, at age 61, in Brno, Moravia, Austria-Hungary (now Czech Republic), from chronic nephritis.
Rediscovery of Mendel's work
It was not until the early 20th century that the importance of his ideas was realized. By 1900, research aimed at finding a successful theory of discontinuous inheritance rather than blending inheritance led to independent duplication of his work by Hugo de Vries and Carl Correns, and the rediscovery of Mendel's writings and laws. Both acknowledged Mendel's priority, and it is thought probable that de Vries did not understand the results he had found until after reading Mendel. Though Erich von Tschermak was originally also credited with rediscovery, this is no longer accepted because he did not understand Mendel's laws. Though de Vries later lost interest in Mendelism, other biologists started to establish genetics as a science.
Mendel's results were quickly replicated, and genetic linkage quickly worked out. Biologists flocked to the theory, even though it was not yet applicable to many phenomena, it sought to give a genotypic understanding of heredity which they felt was lacking in previous studies of heredity which focused on phenotypic approaches. Most prominent of these latter approaches was the biometric school of Karl Pearson and W.F.R. Weldon, which was based heavily on statistical studies of phenotype variation. The strongest opposition to this school came from William Bateson, who perhaps did the most in the early days of publicising the benefits of Mendel's theory (the word "genetics", and much of the discipline's other terminology, originated with Bateson). This debate between the biometricians and the Mendelians was extremely vigorous in the first two decades of the twentieth century, with the biometricians claiming statistical and mathematical rigor, whereas the Mendelians claimed a better understanding of biology. In the end, the two approaches were combined as the modern synthesis of evolutionary biology, especially by work conducted by R. A. Fisher as early as 1918.