Darwin’s Evolution: 1859–1980

“So imperfect is our view into long-past geological ages, that we see only that the forms of life are now different from what they formerly were,” said Charles Darwin. In describing the history of the Earth by analyzing its surface and interior, geology seems that it should be a sedate area of science. But geological arguments lie at the heart of three of the most dramatic paradigm shifts that have affected human thinking. A major objection to the theory of evolution was that geological evidence suggested the Earth could not be old enough for evolution to have occurred. The rejection of continental drift made it difficult to understand the evolution of the planet. And there is still a vociferous minority of dissenting scientists who do not believe the impact of an asteroid was responsible for the extinction of the dinosaurs, a key event that opened the way to the evolution of humanity. These are prime examples of science in action and its interaction with society. In each case a scientist proposed a theory that faced adamant opposition not merely from society at large, but also from the scientific community. Each theory rests on observations of distant events where direct experiments are not possible. In each case, the accumulation and acceptance of evidence to overcome opposition took decades. Now this trio of threads comes together to relate human evolution to the history of the planet. Perhaps climate change will be a fourth leg.