I have been excited to write this post since last May. My husband and I were on a weekend trip in State College, PA celebrating our six-year dating anniversary by visiting all the local bookstores as we like to do. In a cute café and bookstore called Webster’s, I came across a uniquely rustic book called The A B C of Evolution by Joseph McCabe. It was $20 which is above the average price for a used book, but something told me I would never find a book like this again, so I bought it. Part of what sold me was the copyright date of 1920; at the time I thought to myself that that would soon be 100 years ago! Since then I’d been waiting for the perfect time in 2020 to look back at where the study of evolution was 100 years ago.
(I know it says 1921 a lot, but I think that the book was originally published in 1920, and that this copy was printed in 1921. We don’t need another endless hunt for the original publication date like we had last week.)
On the author
Joseph McCabe was raised Catholic. He even studied at a monastery and was an ordained priest at age 23, but that was the same year when McCabe renounced his faith and began writing. From then on, he was “bitterly anti-Catholic,” and he devoted the rest of his life to secularism. He wrote 122 “Big Blue Books” and 121 “Little Blue Books,” including The A B C of Evolution. I really encourage you to read more about him (if you don’t already know about him; it seems he’s pretty well known and I just had no idea). His Goodreads page is very informative, and if you want to fall even deeper into a rabbit hole, there are links to even more articles about him at the bottom of that page.
With his dedication to reason and scientific literacy, McCabe’s little blue book on evolution was enjoyable, informative, and quick. It summarized evolution pretty succinctly at only 124 pages. But for all of the author’s careful research, The A B C of Evolution wouldn’t make such a good introduction to the topic in 2020.
100 years of scientific progress
What I appreciated most in this book was McCabe’s intellectual honesty. He knew that there were several scientific topics that hadn’t been studied enough yet and were still being disputed, and he wasn’t afraid to admit it. In regards to the origin of life, he wrote:
Where did the first living things come from, and what were they like? That is a more interesting question. Unfortunately, science is not yet able to give a confident answer. This is hardly surprising. Man is at least half a million years old, but science is only about two centuries old; and to expect it to take a very wonderful and complex change that occurred a hundred million years ago and tell us confidently ‘all about it’ is to expect too much. We can only speculate.Joseph McCabe, The A B C of Evolution, p. 28
As I’ve been saying for years, I’m no scientist. I’m not an expert in any of this. But as I was reading, I paid careful attention to scientific ideas that are outdated and whose answers have since been discovered or better researched. I think that reading this book has made a great opportunity for me to look back on how far science has come in the last 100 years! We can consider, in a sense, that I’m bringing McCabe up to speed on a few questions that have been answered since he wrote this.
Now, [natural selection] may not prove to be an explanation of everything in living nature. There are certainly many features of animals and plants that it does not easily explain. In any case, it does not go far enough, because it throws no light on the living machinery (the embryonic machinery) which causes the variations at birth.Joseph McCabe, The A B C of Evolution, p. 11
It is with great irony that an amateur science enthusiast tries to explain embryology to a professional science writer. However, if I may give it my best shot, I will say that natural selection has everything to do with embryonic machinery. By the time that the embryo forms, natural selection has already influenced it. By this, I mean that the fact that the parent survived long enough to reproduce means it was already “selected”. In reproduction, as we now know, the parent is not passing down physical traits themselves but the genes that determine what features the embryo will form and take on in life. To learn more about this, I recommend the chapter called “You did it yourself in nine months” in Richard Dawkins’ The Greatest Show on Earth.
But first we have to introduce life itself. It appeared at a very remote date in the warm, shallow ocean of the primitive earth. How long ago that was we cannot say. Most geologists would say between fifty and a hundred million years ago. There is, however, a new school which professes that what are called the ‘radio-active’ minerals (minerals whose atoms break up, like those of radium) in the older rocks show that the earth must be more than a thousand million years old. There is really no reason why we should be in a hurry to decide how old the earth is. It is enough that the story of life on it began at least tens of millions of years ago.Joseph McCabe, The A B C of Evolution, p. 28
It was really fun to see which things were new in McCabe’s time, like radiometric dating, which had only been discovered 13 years prior to this book’s publication. As it turns out, it was radiometric dating that determined for us that the earth is in fact 4.5 times older than McCabe (and his contemporaries) estimated. What’s more, life is now thought to have begun 3.7 billion years ago—37 times longer ago than McCabe thought.
During this Cretaceous (Chalk) Period there was a slow transformation of the world of life. The great reptiles disappear; and most of the smaller types, the survivors of that powerful dynasty, retire into the tropics. This obviously means a chill. The north is too cold for them, food is less abundant, and leaving eggs to the care of nature is no longer possible. Cold killed the reptilian monsters.Joseph McCabe, The A B C of Evolution, p. 69
It’s understandable that McCabe might not know much about the time of the dinosaurs. He says once that “It was the age of the Brontosaur, which was photographed and described in all our newspapers a year ago.” I have a hard time understanding this, as the only name I’ve ever heard similar to “brontosaur” is “brontosaurus” which has been renamed to “apatosaurus”. Regardless, it’s now widely believed that the impact of a meteorite ended the dinosaurs’ reign not 15 million years ago, as McCabe says elsewhere, but approximately 66 million years ago.
We saw that wings are developed frequently in the course of evolution. . . . You might almost say that the same thing is happening under our eyes in England to-day. Man is struggling to rise out of his congested roads and travel in the free air.Joseph McCabe, The A B C of Evolution, p. 77
This may not be classified as natural science, as the rest of these snippets are, but it ages this book and reminds the reader to not take things like air travel for granted (like we used to). The Wright brothers flew their first plane only seventeen years before the publication of The A B C of Evolution, and it wasn’t until over thirty years after its publication that the first jet airliner would successfully take off.
Progress in paleoanthropology
I have . . . mentioned a prehistoric human skull that was found at Piltdown, in Sussex, in 1911. It must have been buried something like 400,000 years ago.Joseph McCabe, The A B C of Evolution, p. 112
Not a lot was said in this book about human evolution, and for good reason. Only a handful of ancient human fossils had ever been discovered, most notably Java Man, which was at the time classified as Pithecanthropus erectus but is now the type specimen for Homo erectus. Rather than lingering on Java Man, McCabe spent more time speculating about the more recently discovered Piltdown Man which had taken the paleoanthropological world by storm. I won’t refute his age estimation of 400,000 years, because instead the Piltdown Man never existed at all. If you want to be technical, the orangutan mandible was about 500 years old, and the human skull was of medieval age (although I can’t find a more precise age for it).
The entire field of paleoanthropology took off in the last hundred years. I don’t even have the time to tell you how many fossils have been discovered, and how many times the human family tree has been updated, since the publication of this book. The most famous fossils, however, are probably those of the ≈3.5 million year old Australopithecus afarensis Lucy, found in 1974 by Donald Johanson.
Looking back at where evolutionary thought was one hundred years ago makes me even more keen to learn more about what else has been discovered since then. But what’s most exciting is just thinking of where science will be one hundred years from now.