Roger, you sure make it tough for the rest of us.
“Fitter genes”, or whatever phrase you want to use for them, are only a part of circular thinking if you don’t know how to use math.
Your “so-called” “Fitter Genes” can be defined by means of a time-sensitive calculation:
A) The number of fertile offspring sharing descent from an individual (or individuals)
B) with Genetic Configuration “XYZ” (compared to those with Configuration “ABC”)
C) over a 100 year period (or down to the 4th Generation)
D) in the ecological niche or system “XYAB”,
D) equals “n”.
Depending on the study, the time frame can be longer or shorter, or the generation count can be longer or shorter. It’s pure math, and can be quantified.
And it can even be quantified differently in different ecosystems (which I figure would delight you to read!).
Stating the ecological niche and time frame is important because some trait alleles can have a negative impact on an individual, while having a positive impact on the population at large.
For example, Sickle Cell anemia is usually considered detrimental. But having a percentage of the population that suffers from it tends to help populations with long term exposure to Malaria.
“In 1949 the genetic transmission was determined by E. A. Beet and J. V. Neel. In 1954 the protective effect against malaria of sickle-cell trait was described…”
“The allele responsible for sickle-cell anaemia can be found on the short arm of chromosome 11, more specifically 11p15.5. A person who receives the defective gene from both father and mother develops the disease; a person who receives one defective and one healthy allele remains healthy, but can pass on the disease and is known as a carrier or heterozygote. Heterozygotes are still able to contract malaria, but their symptoms are generally less severe.”
“Due to the adaptive advantage of the heterozygote, the disease is still prevalent, especially among people with recent ancestry in malaria-stricken areas, such as Africa, the Mediterranean, India, and the Middle East. Malaria was historically endemic to southern Europe, but it was declared eradicated in the mid-20th century, with the exception of rare sporadic cases.”
“The malaria parasite has a complex lifecycle and spends part of it in red blood cells. In a carrier, the presence of the malaria parasite causes the red blood cells with defective haemoglobin to rupture prematurely, making the Plasmodium parasite unable to reproduce. Further, the polymerization of Hb affects the ability of the parasite to digest Hb in the first place. Therefore, in areas where malaria is a problem, people’s chances of survival actually increase if they carry sickle-cell trait (selection for the heterozygote).”