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This is a re-posting in a slightly different form, of an essay originally published in 2009.
I present several arguments in Cancer Selection in favor of my theory, and devote an entire chapter to what I consider the strongest. It’s Chapter Five.
The argument is based on two, to coin a phrase, megafacts about the history of the Bilaterians – the complex animals – that now exist or that existed in the past.
This is the first megafact: No Bilaterian animal that bred—no animal that left behind any descendants —died as a juvenile. Not a single one. Juvenile animals—by definition—are incapable of sexual reproduction, therefore every one of those breeders—all the ancestors of every animal alive today, every ancestor of every dinosaur or other extinct animal—survived into adulthood. Every breeder, in other words, was the beneficiary of meticulous—perfect—development. [See Note.]
Here’s the second megafact: Evolution happened. Some of the gene pools that produced the Cambrian Explosion’s fossilized animals were transformed over hundreds of million years into the gene pools that produce all of today’s complex animals, animals spectacularly different from their Cambrian ancestors. Nothing even remotely like, say, an African elephant lived on the floor of Cambrian seas, yet all evolutionists would agree: every elephant now grazing on the savanna was produced by a gene pool that descended directly from one of those long-ago Cambrian entities.
We can use these two megafacts to illuminate the puzzle that any serious theory of animal evolution must solve:
All the changes needed to effect the great transformation from Cambrian ancestor to today’s animals were expressed perfectly—without catastrophic failure—in every single breeder.
How did their gene pools manage that spectacular efficiency? How over hundreds of millions of years in trillions of specimens in millions of lineages were all the transformations needed to turn the gene pool producing, for example, the earliest marine arthropods into those producing today’s insects invariably expressed with precision in every breeder? The earliest vertebrates into dinosaurs and, much later, into elephants? For hundreds of millions of years in millions of lineages these “chains of perfect development” were never broken. Every single breeder was meticulously constructed.
Here is my explanation: perfect development of the breeders could not have occurred without selection pressure generated by developmental failures in the non-breeders, by deaths of imperfectly developing juveniles. Some juvenile deaths resulted from mal-development of tissue and from imperfectly formed vital organs and some were caused by errors at the level of individual somatic cells, errors that led to the initiation of cancer that killed the developing animals.
The alternative explanation, which is implicitly embedded in conventional Neo-Darwinism, is that lethalization of error at the level of individual cells was not necessary for the origin or evolution of complexity in animals. Here's an accurate summary of what the accepted theory implies:
Successfully-constructed animals bred and left behind offspring, but animals with lethally damaged tissue or ill-formed organs did not leave any offspring. Selection pressure from breeding by the "perfects" and the mortality of the ill-formed was sufficient: there is no need to introduce into evolutionary theory a “quality control” mechanism, a "feedback mechanism," functioning at the level of individual cells. Although the number of different types of somatic cells increased dramatically in many Bilaterian lineages (to about 200 in humans) the perfectness of individual somatic cells in breeding animals throughout evolution requires no selection-based explanation. It just happened.
How do I know that that explanation is implicit in Neo-Darwinism? Because evolution textbooks don’t mention cancer, because their theory offers no evolutionary mechanism exclusive to Bilaterians that was capable of changing gene pools as the result of something that happened to developing animals and because it states—implicitly but emphatically—that all complex animals came to exist through mechanisms also found in the far simpler cell colonies. According to that theory, all complex modern animals, including humans, are products of the same mechanisms found in jellyfish.
Note: No doubt some animals survived development with non-fatal malformation of some body parts and upon reaching maturity successfully bred. We can presume that such occurrences were as rare in the past as they are in modern times and thus had no significant impact on evolution.
At this site you will find links to additional material including my original Letters to the Journal of Theoretical Biology and the 1992 Nature review of my book.
Copyright 2009, 2014 by James Graham
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