Haldane's Dilemma

IntroductionMy argument will rely on demonstrating that Haldane's calculations made a number of severely incorrect assumptions that do not accurately reflect nature nor the evolution of humans from a primate ancestor. Instead of just focusing on my opponent's calculations (I will address them in a later round if necessary), I will detail the main parts of Haldane's Dilemma and show where he went wrong. First I will detail the various assumptions Haldane made, and then proceed to refute them.The ImplicationsI confirmed that all of these existed in the actual document used by my opponent before using them.1) Before Haldane begins his calculations, he states that "a sudden change occurs in the environment." The change is supposed to be detrimental and leads to a harsher, more exacting environment. At the same time he assumes a constant population.2)At the same time he states that the "reproductive capacity is lowered."3) Haldane generates a 'cost of substitution' which is supposed to assign a constant to the amount of individual organisms needed to produce a beneficial substitution. Although he does not clearly state what the cost represents, it can be inferred that it is the number of deaths needed before a 'good' change happens in the DNA AND becomes common in the overall gene pool. He uses the number 30, meaning that 30 times the population must die before a good change is permanently added. Ex. Pop.=1000, Cost=30 `58; 30000 deaths before change4)He links this substitution cost with the overall fitness of the population. This means that once a beneficial mutation first appears, the overall fitness of ALL other individuals goes down and the 'new' one stays constant.5) His '300' number that my opponent used in his argument is not backed up by any calculations. Haldane says, "I think n=300... is a more probable figure." He does this to generate in his calculations a low intensity of selection.6) Haldane assumes that changes due to genetic drift and gene changes happening simultaneously are uncommon in evolution and does not account for them in his assessment.Assessment1) An important thing to note is that in the last 10 million years, the environment has not undergone rapid changes, such as a meteor strike or massive volcanic eruption. It has remained relatively constant, with the exception of several climate shifts and ice ages. However, Haldane assumes from the beginning a deteriorating environment. This does not accurately reflect nature, nor evolution. The majority of change occurs similarly to 'soft selection' where good genes find their way into the gene pool gradually, and do not necessarily 'compete' with others.2) For some reason, Haldane assumes the reproductive capacity is lowered. His calculations show he placed it around 1.1, meaning each individual would produce, on average, 1.1 children. However, most mammals can sustain a stable population in an ancient (non-deteriorating) environment with a ratio of close to 2.3) There are various issues with Haldane's substitution cost. One is that as population increases, the cost should go down. This has to do with simple probability and also increased competition that would promote widespread but slow change. Additionally, the cost does not account for sexual recombination, which causes fixation faster. This would reduce both the '30' and '300.' Finally, it doesn't account for simultaneous changes. Here, if two good changes were approaching fixation, and an organism without either dies, it would have died for two changes, not one. Therefore, the cost would be halved during simultaneous changes.4) As previously stated, the majority of selection happens from a process similar, but not exactly, soft selection. Just because an organism has a higher chance of survival with a new gene does not mean that all the others will suddenly become less adapted to the environment. Their chance of survival remains constant, and this is not represented in Haldane's work.5) The obvious problem here is that 300 comes from nowhere. He comes up with the number to make his calculation prettier, and in a way where he changed a dependent variable to fit an independent variable. There is absolutely no definitive scientific reason why the number should be 300.6) Genetic drift (selection caused not by advantage, but random events) actually accounts for a more significant portion of the changes than Haldane assumed. Moreover, simultaneous fixation is, in fact, extraordinarily common. This occurs when certain genes are fixated at the time. Due to sheer amount of nucleotides, this is very common, and often occurs with more than one nucleotide. However, Haldane completely ignores it, even though it would greatly change the outcome.Additional Arguments1) Genes are not passed down individually. They are attached to each other, so recombination is more efficient. This means that some 'meaningless' changes would be passed on with the same efficiency as 'good' ones.2) There is possible no dilemma at all. Because DNA decays relatively quickly, we cannot recover any from our primate/common ancestors. Even if we assume that Haldane is correct, 1667 may be enough nucleotides to cause a difference. Besides, because our other ape cousins evolved from this ancestor, their would be 3333 differences between us and them. This may be the case. The only major difference between humans and other apes is a structural difference in one acid: sialic acid, which resulted from only 92 nucleotide deletion. This acid has major roles in various developments in primates, so it could account for the majority of our difference.ConclusionMy main points:1) There is no deteriorating environment. 2) '300' has no basis.3) The substitution cost is unreliable.4) Haldane doesn't account for genetic drift nor simultaneous substitution. 5) There may not be a dilemma.I mainly used this round for a general assessment of Haldane's work to show its overall unreliability. I will answer, to my best ability, any specific objections raised by my opponent in the final two rounds.