Heredity
Year of Discovery: 1865
What Is It? The natural system that passes traits and characteristics from one
generation to the next.
Who Discovered It? Gregor Mendel
Why Is This One of the 100 Greatest?
Gregor Mendel conducted the first serious study of heredity. His findings, his methods, and his discoveries laid the foundation for the field of genetics and the study of genes
and heredity. The discoveries of genes, chromosomes, DNA, and the decoding of the human genome (completed in 2003) are all direct descendents of Mendel’s work. The medical
breakthroughs in the fights to cure dozens of diseases are offshoots of the work begun by
Gregor Mendel.
Finally, Mendel’s discovery, itself, provided great insights into the role of inherited
traits and into the ways those traits are passed form generation to generation.
How Was It Discovered?
The wide fields and gardens of the Austrian Monastery of Bruun stretched up gently
sloping hills surrounding the monastery complex. Tucked into one corner of the monastery’s garden complex stood a small 120-foot-by-20-foot plot. This small garden laboratory
was used by one of the monks, Father Gregor Mendel, for his experiments on heredity; that
is, on how individual traits are blended from an individual through successive generations
into a population. In May 1865, he planted his sixth year of experimental pea plants.
English scientist Charles Darwin explained evolution but hadn’t successfully addressed how characteristics are passed down through the generations, some to dominate
(appear) in every generation—some to randomly pop up only every now and then. That was
what Mendel wanted to study.
Mendel crossed a strain of tall pea plants with one of short pea plants. He produced a
row of all tall plants. And when he planted the seeds of those tall plants he got mostly tall
with a few short plants. The short trait returned in the second generation.
Similarly, he crossbred yellow peas with green peas and got a generation of all yellow
peas. But in the next generation he produced mostly yellow with a few green peas. But never
a yellow-green. The green color trait returned but the traits never mixed. The same happened when he crossbred smooth-skinned with wrinkled-skinned peas.
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