Decades ago the geneticist Conrad Waddington pointed out that the most perfectly adapted organisms on Earth must surely be bacteria. They are able to thrive and multiply in the most inhospitable places on the planet. If adaptation was the single driving force behind evolutionary change through time, he said, then more complex, multicellular life forms should never have evolved because bacteria are so capable (find reference…). This is an important observation that should have had many evolutionary biologists scratching their heads and looking for alternative causal explanations in addition to adaptation and natural selection. It did not, and I will never understand why, but it is time to move on.
My favorite example of what passes for a causal evolutionary explanation is the classic story of “industrial melanism.” The story has been passed along to countless biology students, but it has a fatal flaw in that it is not an example of evolution. Back in the 1800s, during the Industrial Revolution, the story goes, coal-fired factories were pumping out massive quantities of nasty particulates. As the soot settled out of the air much of it landed on the white trunks of the birch trees, darkening them. Out in the birch groves there lived a little moth, the pepper moth, Biston betularia. The common form of this moth had white wings with a few peppery dark spots. In the predominantly white-winged populations a few individuals with dark brown wings occurred naturally. As the trunks of the birches became darkened with soot, the white moths stood out against the blackened bark, making them easier for their bird predators to see. As the numbers of white moths declined, the dark morphs, now better hidden as they mated and rested on the trees, increased in numbers because they were eaten less often. After a time, the darker form became the dominant phase and the white winged moths were uncommon. This, we have been told for several generations, is an example of evolution by Natural Selection.
I have heard another version of this story that says the light colored form of the moth didn’t begin to die out from increased bird predation, but because it was more susceptible to a particular disease than the darker moths. Either way, this is not an example of evolution, but only of shifting numbers in an existing population that already included two morphs. Nothing new was generated in this little fable. Natural selection did not “create” a dark form of the moth whose cryptic coloration kept it hidden from its predators – the dark moths already existed. The only thing this example illustrates is shifting numbers of the two moth forms – dark moths became more common while the numbers of light moths declined. The story fails to explain, or even address, anything very interesting. It tells us nothing of how there came to be birch trees, moths or birds, and these are the true questions of interest. It is not possible to create something new beyond one end of the bell-shaped curve by whacking off the other end, unless magic is invoked.
The aspect of this story that has always surprised me most is that anyone ever took it seriously as an example of evolution. For a long time as a student I though I must have been missing something – how was this an example of evolution? I had the same problem with population genetics. There were just a lot of calculations that didn’t make any explanatory sense. Over time I came to the conclusion that these examples really were empty. Natural selection is a variation decreasing force – its only role is to kill things off. The appearance of new forms cannot arise by the destruction of older forms. This is a logical impossibility. Natural selection did not create dark colored moths for they already existed. The theory of natural selection says that this force works on the living manifestations of random genetic mutations (some would say on the genes themselves), knocking out that which is “unfit” and leaving the “better adapted” to reproduce. If we look at this explanation in terms of the covering law model, joining the initial conditions of random mutation to the natural law of selection, the bridge principles would reasonably take us to the event of different proportions of moth morphs. But this begs the question of evolution because it tells us nothing of how moths might come to exist in the first place. Given nothing more than this superficial theory, the event of speciation is left unexplained. All the important questions are ignored today as they have been for 150 years.
Reproduction has been much studied by evolutionary biologists, and they see sex as playing a central. Reproduction, whether it happens by bacterial fission, vegetative rhizomes in plants or sex among mammals, is an initial condition because replication is one of the defining features of life. Perhaps some researchers consider sex to be of the utmost importance because humans in general think sex is important. The real questions aren’t about maximizing “fitness” or getting your two bits into the gene pool. The question is why self-replication is a property of living systems, and how speciation works through ontogeny, the development of individuals. How are these systems emergent? My dear old professor from UBC, Jack Maze, has explored these questions for a number of years. He has been kind enough to have me as a collaborator. Our work together and his work with others interested in alternate theories of evolution will be explored in more depth in later sections.
Stan Salthe (ok to add a link?) has compiled a detailed critique of all aspects of neo-Darwinian theory, but Salthe does more than point out logical and observational flaws. He has also contributed valuable ideas on hierarchical organization, to be explored later. My old friend and fellow student of Jack’s, Mishtu Banerjee, once offered a quote (I’ll have to ask Mishtu for the source) that sums up my opinion of neo-Darwinian theory. It’s one of my favorites: “The application of calculus to a bad idea doesn’t help.”