Gregor Mendel was living the quiet life of a monk/scholar when he read a German translation of Darwin’s Origin of Species in 1862. Mendel was aware of the controversy caused by the book and spent much time making notations that reveal his intense interest in Darwin’s work. The annotations Mendel made to this and other of Darwin’s texts particularly show his annoyance with the poor techniques used by Darwin in cross-fertilization experiments.
Natural Selection Questioned
While Charles Darwin felt secure in the validity of his evolution theory, he was less certain of the process of heredity. Darwin knew that his theories of inheritance, how traits were passed from one generation to another, were the weak link in his theory of natural selection. He confronted these questions in the middle chapters of Origin of Species.
Darwin went along with the commonly held view of the day that theorized inheritance to be a blending process similar to mixing two separate colors to achieve a third color. The problem with this theory was that successful characteristics would be diluted away until they were not noticeable at all within a generation or two. The trait that gave an organism an advantage would ultimately disappear. These problems explaining inheritance proved to be a source of great criticism for Darwin’s theory of natural selection.
Darwin and Natural Selection
Darwin was occupied searching for a more precise process that supported natural selection, one that produced minor variations in each successive generation. Darwin thought he had found this with the theory of pangenesis, one that required no mathematical calculations at all. In this theory cells give off particles, which Darwin called gemmules, that multiplied and moved throughout the human body, finally collecting in the reproductive areas which then contained particles from all parts of the parent.
Darwin’s theory of pangenesis was developed in part due to his shortcomings in mathematics. His mind, which was so adept at observing and developing theories about the natural world, failed him when it came to understanding the role ratios and fractions played in inheritance.
While Darwin had successfully convinced the scientific world of the validity of evolution, there continued to be a great deal of skepticism about the untestable theory of natural selection which remained under constant attack. It was one of Darwin’s own supporters, Francis Galton, who while attempting to prove Darwin correct, performed an experiment that failed to produce the results predicted and ended pangenesis as a viable theory of heredity.
Mendel Defines Natural Selection
Here lies the importance of Gregor Mendel’s work. Mendel articulated a solution to the problem of heredity that Darwin had struggled with after publishing Origin of Species, one that explained how traits were passed on to successive generations.
Mendel had discovered that heredity was not a blending process at all but was instead a process where different traits were dished out in small units, passed from one generation to another without ever being blended or diluted away in some genetic mixing bowl. This way any trait, useful or not, remains in the gene pool where it can resurface in some future generation.
From the mathematics of his research Mendel could see that the traits sorted themselves out randomly, as though the seven traits he had selected for his plant-breeding experiments were seven coins tossed into the air. Mendel proved that inheritance was particulate. Averageness was not the ultimate destiny of an organism. Instead any particular trait could crop up in a future generation as if from out of nowhere.
Mendel Goes Public
Mendel presented his research to the Brunn Natural Science Society in 1865 which published the results of his work. A copy of the paper was sent to Karl Wilhelm von Nageli, a Swiss botanist also involved with plant-breeding experiments. Nageli and Mendel corresponded for several years with Nageli advising Mendel that more research into heredity was required.
Historians speculate Nageli was reluctant to promote Mendel’s research more enthusiastically because of the criticism Darwin faced from the publication of Origin of Species, causing Nageli to take a cautious approach to the subject.
Mendel’s research remained relatively obscure until 1900 when Hugo de Vries, another researcher in plant-breeding, stumbled across his papers. Only then did the Monrovian Monk begin to receive the credit due him for his pioneering work in the emerging field of genetics.
Sources:
Carlson, Elof Axel. Mendel’s Legacy, The Origin of Classical Genetics. Cold Spring Harbor, N.Y.: Cold Spring Harbor Laboratory Press, 2004
Gribbin, John, and Mary Gribbin. Mendel in 90 Minutes. London: Constable, 1997
Henig, Robin Marantz. The Monk in the Garden: The Lost and Found Genius of Gregor Mendel, the Father of Genetics.
Iltis, Hugo. Life of Mendel. New York: W.W. Norton & Co., 2004
McClellen, James E. III, and Harold Dorn. Science and Technology in World History. Baltimore: The Johns Hopkins University Press, 1999
Mills, Cynthia. The Theory of Evolution. New Jersey, Wiley & Sons, 2004
Lawrence Koppy - Lawrence Koppy is an Oregon native living in the high desert of Central Oregon. He has been a small business owner for many years ...
Join the Conversation