Darwin's Predictions
Evolution by natural selection must have a mechanism.
Darwin knew in his heart that evolution by natural selection happened, but he didn't know how. In fact, he proposed a mechanism of heredity that proved to be dead wrong, something he called pangenesis. Ironically, the actual mechanism of heredity—genetics—was revealed in Darwin's lifetime, though he never knew it. Working with pea plants, the Austrian priest Gregor Mendel discovered the fundamental laws of genetics in 1865. But Mendel's work was neglected until 1900, and it wasn't until the 1940s that scientists identified DNA as the genetic material (here, Francis Crick's first sketch of DNA's double helix structure). Today, the clear focus of the revolutions now under way in genetics, medicine, and other fields is on the genomes of living organisms.