The Theory That Changed Everything: “On the Origin of Species” as a Work in Progress

Book Preface

The more we learn, the more it becomes evident that the insights and observations conveyed in On the Origin of Species continue to guide our understanding of biology, evolution, and how we might act in matters of general interest, some bearing on our very existence.

Charles Darwin was a keen, curious observer who possessed a quality of mind that enabled him to see the connections among seemingly unrelated natural phenomena and human endeavors. His voyage on HMS Beagle was, as he put it, “the most important event in my life, and has determined my whole career.” Darwin came in contact with the indigenous people of Tierra del Fuego, who lived in circumstances far removed from those of his prosperous family and acquaintances, but he nonetheless discerned the qualities that made it clear to him that all people are brothers and sisters. He saw animals and plants outside the range of what is found in England and Scotland and the fossil remains of creatures that no longer live on earth.

When Darwin first boarded the Beagle on December 27, 1831, he firmly held to the belief that God had created the world and all its forms of life. On his return to England four years later, he started on the journey in his mind’s eye that led to the theory that changed how we view the evolution of all forms of life and their place in nature. His theory was controversial from the day of its publication in 1859 and remains so today. Darwin departed from the view that God had created the world and all forms of life in a week or else had set in motion a master plan that over time produced new forms of life, extinguishing others. The course of evolution instead was happenstance based on variation and chance. No two beings are identical. Variation always marks the creatures or plants that constitute a species, including the individuals who constitute the human species, Homo sapiens. Darwin did not know how or why variations occurred—why some roses were redder than others or why some people were taller or could run faster—but he thought that natural selection was the primary mechanism for the “transmutation” of species: evolution.

Natural selection is a simple concept. Any heritable variation that results in a living organism’s having more descendants tends to be preserved, providing a “selective advantage” in the “struggle for existence.” However, ruthless competition and brute strength were not the keys to success in the Darwinian struggle for existence, a concept that has been misinterpreted and misused to justify exploitation and greed. Cooperation yields benefits, and, as Darwin stressed, small changes can drive natural selection. One of the incremental results of natural selection is evident on the shelves of your supermarket. If your ancestors lived in a culture that herded cows, sheep, or goats, you will most likely skip the lactose-free selections because natural selection has conferred on you adult lactose tolerance. Being able to add milk to our diet conferred an advantage in the “struggle for existence”—making some individuals and their children more likely to survive. If your ancestors did not live in such a dairy culture, you may need to purchase lactose-free products.