Ever Since Fish: Traversing the Change-Time Continuum
Recently, I was talking to a researcher about a particular virus, and he mentioned that it has infected us “since fish.” Yes, fish have a time dimension. In two words, he had communicated reams of information: this virus has infected vertebrates ever since the divergence of the common ancestors of fish and mammals - somewhere around 395 million years ago. That implies that all of the species descended from those ancestors should have their own strains of the virus, which will have co-evolved alongside their host species. “Since fish” is a point in time, a testable prediction about present conditions, and a suggestion of how things might change in the future.
The immensely powerful organizing framework that makes that kind of shorthand possible is, of course, Charles Darwin’s theory of evolution. Besides spawning an argot that includes phrases like “since fish” (which would be a great name for a band, by the way), Darwin built one - or perhaps two - of the most useful conceptual structures in all of science.
I’ve been thinking about this lately, because I’m reading Origin of Species. Like many biologists, I never got around to it in college. That’s a common problem in the sciences, where later work inevitably supersedes the founding publications in a field. It’s the same reason few physicists read Newton, and most chemists cannot quote Lavoisier: their time is better-spent keeping up with the current state of the field.
Still, rewinding the story to the beginning can provide an interesting perspective, especially when the beginning is as stunningly well-argued as Origin of Species. For example, it’s easy to toss out flippant comments about how Darwin simply lifted an idea from the lesser-known Alfred Wallace and rushed it to press, but that charge disintegrates the moment one cracks open the original work. Yes, the concepts of natural selection, speciation, and evolution can be summarized in a few sentences, and they seem somewhat obvious in retrospect, but the mountain of painstaking scholarship Darwin put into testing his theories reveals that he’d been thinking about these issues for decades.
Reading Darwin also provides a potent reminder of just how incomplete biology was before he put things in order. Linnaeus had devised a way to classify organisms, but that still left huge swaths of unresolved problems. For starters, how are species connected to each other, how do they arise, and how do we explain the vast diversity of extinct forms in the fossil record?
Considered this way, Darwin is to biology what Einstein is to physics. Each approached a set of questions that appeared to be unanswerable in the field’s existing framework, and responded with a wholly new framework that changed the world. Just as physicists now speak in terms of space-time, biologists now speak in terms of change-time, and this view of life underlies every modern biological innovation, from polio vaccines to the human genome sequence.
Origin of Species itself has an interesting structure. Rather than starting with observations of nature, like a proper 19th-century naturalist, Darwin begins the book discussing domestic animal breeding. He describes the results of genetic experiments in these easily manipulated systems, then uses those results to predict what we should see in the natural world. Only then does he go outdoors, so to speak, arguing the case for speciation through natural selection.
While he may have chosen to structure his book that way for rhetorical reasons, it happens to be an ideal strategy for laboratory biologists. Today, researchers study mice, fish, worms, and even yeast, then use the results from these easily manipulated systems to make predictions about what they’ll see in nature or in the clinic. Evolution gives us the framework for understanding why this approach works (similar species will have similar biology), and Origin of Species illustrates how to do it. It’s easy to see why so much modern research follows the same pattern: it’s been working, well, since Darwin.