How do you get from here to there?
600 Years ago common people like ourselves did not own books. One of the more common things you’d have found in the collections of those who did own books would be a bestiary, basically a book describing all of the mythical animals which supposedly lived on far islands or in far Asia. Like the “beneficial mutation” leading in the direction of a change in animal kind, the creatures of the bestiary did not actually exist.
Remine: Nearly three decades ago, new techniques allowed measurement of genetic variation for the first time. The results were a surprise. In most populations, each gene has many versions (known as alleles). In fact, there is much more genetic variation than can be reconciled with the classical selection theory. This unanticipated result prompted various theoretical developments to accommodate it.
The selectionists modified their theory by adding several mechanisms for actively maintaining genetic diversity. These mechanisms are called heterozygote advantage and balancing selection. These special types of selection work to keep variation.
Remine: substituted traits are simple changes having arisen by mutation, which include DNA inversion, gene duplication, or deletion, or a new location of a gene on a chromosome but, according to the neo-Darwinian synthesis, are typically a new version of a gene - an allele. The new substituted gene typically differs from the old gene by one newly mutated nucleotide.
The “COST” of the scenario above was 50,000, i.e. the birth rate you’d have to have to do it.
Haldane tried to resolve the problem by supposing that the cost of substitution is being paid in installments rather than having one woman have 100,000 kids.
This involves picturing a hose or pipeline representing 10,000,000 years, with apes walking in at one end, and humans walking out at the other.
Aside from the question of intermediate fossils, there is also the question of why we do not see creatures of all stages of such a process still walking around…
Remine cites a number of problems with the simplistic scenario above:.
+ Mutation Deaths
+ Segregation Deaths
+ Balancing Deaths
+ Substitution Deaths
+ Random Deaths
B -1 =PM+ PX + PB+ PS + PR
B = births per survivor
PS =B - 1 - PM - PX - PB -PR
The quantity PS is the relative number of births available to pay the cost of substitution, i.e. it is what remains of the birth rate after subtracting all other payments. The other P quantities represent the average payments made each generation toward the costs of mutation, segregation, balancing, and random death, respectively.
In summary, the cost of substitution is 30 and it is paid off in installments of 0.1 each generation. At that rate it takes 300 generations to pay the cost of substituting one gene. Haldane's conclusion was clear: over the long term, the average rate of gene substitution is no better than one gene every 300 generations.
This is the source of the 1700 substitutions in 10,000,000 years figure you read, and of the use of the term “quadrillions of years” in the literature.
Let’s take a bit more of a look at that idea of a “balancing death”…..
From “Biotic Message:
“If 2000 overdominant loci are segregating, each with 1% heterozygote advantage, and if the selection is carried out by premature death of less fit homozygotes, each individual must produce on the average roughly 22,000 young in order to maintain the population number constant from generation to generation. (Kimura)
One, it’s a pure pseudoscience; advocates actually claim that the lack of evidence (all the missing intermediate fossils) validates the theory since that is what would be expected.
Similarly, Cotton Mather claimed that the fact that nobody had ever seen or heard a witch was proof they were there (if you could SEE them, they wouldn't BE witches...). This kind of logic is less inhibiting than the logic they used to teach in American schools. For instance, I could as easily claim that the fact that I'd never been seen with Tina Turner was all the proof anybody should need that the two of us were secretly married. In other words, it might not work terribly well for science, but it's great for fantasies...
Five, for any number of reasons, you need a minimal population of any animal to be viable. This is before the tiny group even gets started in overwhelming the vast herds. A number of American species such as the heath hen became non-viable when their numbers were reduced to a few thousand; at that point, any stroke of bad luck at all, a hard winter, a skewed sex ratio in one generation, a disease of some sort, and it's all over. The heath hen was fine as long as it was spread out over the East coast of the U.S. The point at which it got penned into one of these "peripheral" areas which Gould and Eldredge see as the salvation for evolutionism, it was all over.
Such is the quasi official replacement doctrine for classical Darwinian gradualism….