- I Read It for You: On the Origin of Species (Introduction)
- I Read It for You: On the Origin of Species (Ch.1: Variation Under Domestication)
Chapter 1: Variation Under Domestication
Chapter 1 opens with general overview of how animals differ from one another under domestication and yet in many cases come from one source species. He claims this as a promising place to look for explanations of how so many species came to be.
It’s interesting what a paltry sample he has to draw from in conducting his analysis; scientists today have a crushing wealth of taxonomies, specimens, numbers, research going back dozens of generations about species Darwin never knew existed. So he is wrong in some of his assumptions about domesticated animals (for example, he guesses that dogs are so varied as to likely come from more than one ancestor), and about the sources of some of the variation (like drooping ears in some domesticated animals arising simply from disuse of the ear muscles).
I do not believe, as we shall presently see, that all our dogs have descended from any one wild species….
That’s right: there are many things Darwin was wrong about. (Creationists love to chuckle and point at these places, as if they’re the ones who discovered his errors through their own research and the arrogant scientists don’t know about it yet.) This is what’s so great about science: when science is wrong about something, it gets disproven and is no longer believed to be true.
Anyway. Darwin goes on to notice that strange correlations exist between traits — like blue eyes and deafness in cats — but knows little or nothing about the reasons for these correlations. Because genes hadn’t been discovered yet.
Strange fact of history: Gregor Mendel was actually discovering genetics at the same time Darwin was working on natural selection. There’s strong evidence Mendel read Darwin’s work at some point during or after his famous work with pea-pods, but he was a reclusive monk and apparently they had no contact with each other or mutual influence.
He focuses on pigeons, his specialty, and deduces that they all came from a wild ancestor of the rock pigeon, because breeding wildly different varieties of domesticated pigeons often produces rock-pigeon characteristics, seemingly out of the blue. (Like a white and a black pigeon producing brown mottled young’uns, and then one of the third generation being a bright blue spitting-image rock pigeon.)
He notes that breeding two clearly distinct varieties together doesn’t usually produce something evenly in between; rather, you get a shotgun spread of variations, and have to do your best to breed the ones you like together for a VERY long time to get any permanent desired intermediate. This to him indicates that all the lasting distinct variations now existing within a single species must have taken quite some time to form, or else have descended from different ancestors.
I Don’t Want to Believe It, Therefore It Isn’t True
He makes a point of acknowledging the resistance of breeders to this general concept (a prescient foreshadowing of the eerily similar resistance of “design” proponents) due to the fact that in their own breeding efforts, only minor, incremental alterations can be seen. In other words, he clearly perceives the Argument from Personal Incredulity (I can’t believe a thing like that is true, therefore it isn’t) and rebuts it. How sad that 250 years later the black weeds of it still take root in untended minds.
He wraps up the chapter by concluding that selection is the predominant mechanism which shapes the variations of species which are under human domestication. Why? Because it is the ability to reproduce that determines the propagation of a trait! He acknowledges that varieties can be obtained by deliberately (or accidentally, or naturally) crossing different species, or different varieties—but the results are unpredictable: often sterile and even more often of no benefit. He rules such a mechanism “greatly exaggerated.” Traits strengthening or disappearing due to use or disuse of the relevant feature (like ears getting floppy when the muscles aren’t used) is another mechanism, but he doesn’t give it a lot of weight. No, in order to steadily improve a species under domestication, the bulk of all divergence is best attributed—whether by design, as in breeding, or simply as a byproduct of tending the “best” animals—to the domesticators’ guidance of which animals get to reproduce. In other words, selection.
Watch this amazing video to see this in action:
This ends the chapter. In this way, the author has introduced the concept which is now often used as a layman’s definition of the word “evolution”: slow change over time. He correctly identifies the process of selection—deciding which animals get to breed and which do not—as the chief driver of variation along the lineage of a domesticated species.
If this is true—and to think otherwise would be as bizarre an act of denial as denying that heat comes from the sun—then what must inevitably follow is natural selection. For the struggle to survive in a world of predators, scarce food, varied climates, and otherwise competitive environments is a kind of selection guided not by the hands of human domesticators, but by the mere fact of surviving while others die. But by opening the book with a safe and undeniable example of selection at work in the world of animal breeding, he has successfully taught us the concept without threatening our pride or our religious accounts of how man and other animals came to be.
tl;dr: Creatures are slightly different from their parents. Breeders of domesticated animals select the ones they like and allow them to breed. Breeders picking the traits they like, generation after generation, leads to animals which are eventually quite different from the original ones. Darwin calls this process selection.