Nothing in Biology Makes Sense Except in the Light of Evolution
Theodosius Dobzhansky · 1973
"By the mid-20th century, genetics (Mendel's discrete units) and natural selection (Darwin's mechanism) had been fused into a single coherent framework — the Modern Synthesis — that made evolutionary theory the organizing principle underneath every other branch of biology."
For decades after Darwin, genetics and evolution were seen as separate, even conflicting fields. Dobzhansky's famous 1973 essay title stated the resolution as settled fact: they were never actually separate at all.
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Experiments on Plant Hybridization
"Traits are passed from parent to offspring as discrete, countable units — not as a smooth blend of parental characteristics — following statistical ratios predictable enough that Mendel derived the basic laws of inheritance from pea plants alone, decades before genes or DNA were known to exist."