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History From the Beginning

A Classic Example of the Scientific Method Successfully Applied

Gregor Mendel, born in 1822 in what is now Czechoslovakia, grew up on his father's farm. His father taught him much about agriculture and how to care for different kinds of fruit trees and plants. After his college studies in both physical and natural science, while teaching as a Catholic priest in a high school, he became curious about the manner in which different characteristics of plants were inherited from generation to generation. The study of inheritance is called genetics, and little was known of the subject when Mendel started posing questions and imagining possible answers.

Gregor Mendel did more than speculate and ask questions, however. He carefully planned a long and laborious series of experiments aimed at answering his questions about the laws of biological inheritance. It seems probable that from his many years of observation of various kinds of plants he had in mind some insights, possible explanations for what he had observed. His program of experimentation was designed to lead to a correct understanding of inheritance by testing his explanations or hypotheses.

A scientific hypothesis is an educated guess aimed at explaining what has been observed. If the results of Mendel's experiments supported any of his hypotheses, fine. On the other hand, even if the results overthrew his ideas, they might lead to other, correct answers to his questions about inheritance. Being trained in physical science and mathematics, Mendel believed that a mathematical analysis of how particular characters are passed from generation to generation might reveal the laws of inheritance. Famous biologists concerned with inheritance had never thought of this approach to studying genetics. They tended to believe that living things would not function in a manner which could be described mathematically as do inanimate things such as chemicals, magnets and electricity. But as it turned out, these great scientists were wrong and the unknown Augustinian priest was right.

The industrious Mendel planned his research in minute detail. He wisely chose the familiar garden pea as the material with which to do most of his experiments. He first selected eight true-breeding varieties of peas, each of which had an easily recognizable peculiar character or trait. His plan was to cross-pollinate the different varieties and see what characteristics successive generations of the resulting hybrid peas displayed.

During eight years of experimentation he raised many thousands of hybrid pea plants and meticulously recorded the numbers of each type of plant which he found in each succeeding generation of pea plants. Mendel carried out a mathematical analysis of the results. Finally he was ready to publish his results and announce to the scientific world his theory of inheritance which he had developed and tested so thoroughly. His theory is now referred to as the Laws of Mendelian Inheritance. But when he delivered two lengthy technical lectures to the members of a small scientific society in 1865, none of his audience understood him. His paper was published in the little known journal of the society, and he sent a copy to a prominent German scientist who also was studying inheritance in plants. The two men carried on correspondence on the subject, but the older, eminent scientist simply dismissed Mendel's research and theory as unimportant.

No scientist would listen seriously to the man who had made the greatest single discovery in the history of the science of genetics, the science of which Mendel is now considered to be the founder. None of them really knew anything profound about genetics, and a brilliant piece of scientific research lay before them which revealed the fundamental laws of biological inheritance. Nevertheless, they were utterly incapable of recognizing the truth when they saw it proved by irrefutable evidence! Gregor Mendel had to go on to other duties after he was appointed the director of his school, but he remained confident that one day the importance of his discovery would be acknowledged.