On the Origin of Species by Charles Darwin

This is the book in which Charles Darwin explains his theory of natural selection. First published in 1859, it changed the way we look at the natural world. Although scientists had begun to come to the conclusion that the plants and animals that live on the earth are not fixed and unchanging, this was the book that contained a coherent theory for how organisms could change and how we could end up with the many different species we see across the planet, each well adapted to their way of life. As well as explaining the theory, Darwin is attempting to convince the reader that his theory is true, by providing arguments and evidence for the theory, and by tackling the main objections.

I could tell when reading this book that Darwin was writing for his fellow naturalists and scientists. He does assume some knowledge that he would have expected his peers to have. For example, he often uses the latin names for the species he’s discussing, and he refers to geological time periods and expects the reader to know when these occurred in relation to one another. It does make it a bit hard to follow, and the writing style is a little overly wordy and old fashioned. It’s a fairly challenging read, but you will get a sense for how Darwin’s mind worked, and how carefully he had thought about his theory before publishing it.

Darwin talks a lot about domesticated species and how they have been altered through selective breeding. Even when not explicitly trying to create certain characteristics in our domesticated animals, simply by allowing the most useful animals or plants to breed, humans have shaped their evolution. He’s then able to draw the analogy with species in nature, arguing that the same mechanism must account for changes in species there, but acted on by “natural selection” i.e. the environment in which the organism lives in nature, and the competition (and cooperation) with other organisms in that environment.

One thing that struck me was the number of experiments that he personally performed in order to help validate his theory. For example, an argument against his theory was the distribution of some species around the world. With species like birds and bats, we can understand how they might be able to fly across the ocean and end up populating an isolated island somewhere. But how do plants, or animals that can’t fly, get there? Some of Darwin’s experiments were to do with investigating whether mud from ponds contained viable seeds that could travel, by being stuck to the feet of birds, to remote lands. Another experiment tackles how long certain seeds or creatures can survive in salt water, to simulate a voyage across the ocean. In doing these experiments, he sures up his theory against its detractors at the time.

One of the things that must have frustrated Darwin, and made his theory weaker and less convincing to his peers, was that he didn’t understand the exact mechanism by which characteristics were passed down from parents to offspring. DNA wasn’t discovered until much later. He knew there was a mechanism though, and he does his best to construct his theory without it. He comes up with basically the right answer when considering examples like the social insects, where clones work hard for the collective without the prospect of producing offspring themselves. Nowadays we know that their genes are identical to those that get passed on, so from the gene’s perspective the clones are still helping to propagate those genes by sacrificing their own ability to reproduce, in favour of allowing their identical siblings to do so.

This is not the best book to read if you want to learn about evolution for the first time. I think our modern understanding of evolution based on passing DNA from parent to offspring, with mutations introducing differences that natural selection can then act upon, can be better explained elsewhere. As a snapshot of the thinking at the time though, and as a way to understand how Darwin himself constructed and explained his theory, this book is really interesting to read.