Scientific Issues and Problems with Traditional Evolution
Theory
Darwin's idea that current species are descended from different earlier species
is now overwhelmingly confirmed by steadily increasing observational evidence
and no longer has scientific opposition. Darwin's evolutionary
mechanics theory, essentially survival of the fittest or natural selection, also fits the vast
majority of observations. His idea was that mutational changes occasionally
occurred in individual organisms. Sometimes the changes were inheritable.
Sometimes inheritable changes improved the ability of individual organisms
possessing them to survive longer (and thereby reproduce more) or to otherwise
reproduce more, thus propagating their altered design in a population. According
to traditional mechanics theory, any evolved organism characteristic must
therefore
improve the ability of individual organisms to live longer or reproduce
more.
However, the traditional evolutionary mechanics theory, now known as neo-Darwinism or The Modern Synthesis, conflicts with some observations as described below. Because such a large proportion of observations conform, Darwin and many subsequent theorists assumed that conforming explanations for the relatively few conflicts would eventually be found. As time passed that did not happen and additional issues and conflicts surfaced leading to development of the alternative evolutionary mechanics theories beginning in 1962. Principal areas of conflict are listed below. This issue is absolutely critical to theories of biological aging because such theories are essentially determined by evolutionary mechanics theory.
Life Span
The extreme variation in life spans between similar species was immediately noted as a conflict following publication of Origin. If species were designed to have a species specific life span, a design that purposely limited life span, that observation conflicted with traditional mechanics. If not, why did similar species have different life spans? Wouldn't evolution be pushing for ever increasing life span such that species (at least similar species) would all have the same life span. If fundamental unavoidable natural forces limited life span would they not apply equally at least to similar species?
Biological Suicide
Various plants and animals were observed to die suddenly following reproduction. Semelparous organisms die following their first reproduction and include a mammal, the male marsupial mouse, which dies following mating. Salmon and octopus have similar behavior. Biological suicide represented a more explicit violation of traditional mechanics theory. There was no way to blame this behavior on fundamental deteriorative processes.
Darwin responded regarding the above conflicts that there must be some hidden compensating benefit that offset the adverse nature of a design-limited life span. He did not specify the benefit. Theorists have been looking for and arguing about the compensating benefits ever since.
Altruism
Biologists noted that some animals had behavior patterns leading them to protect unrelated members of their species at the expense of personal risk. According to traditional mechanics an animal should only defend itself, its mate, and its direct descendents in order to best propagate its personal design so this behavior conflicted. This is the "dog eat dog" or "red of tooth and claw" aspect of traditional mechanics theory. For some reason animal altruism, an obscure behavior of wild animals, has historically attracted more interest than the other discrepancies.
Delayed Sexual Maturity
Many animals, especially males, have sexual maturity that occurs at a late age relative to what appears to be biologically necessary from a functional, growth or development perspective, a reproductive disadvantage. In animals that nurture or protect their young, this could result in compatible compensating benefit to direct descendents because older animals would be more able to perform those functions. In animals that do not nurture or protect young, purposely late male sexual maturity appears to conflict.
Sexual Reproduction
Sexual reproduction is massively reproductively adverse relative to asexual reproduction. Only females can bear young (instead of all the organisms), reproduction requires the additional effort of finding a mate and mating. If as traditional theory suggests the goal of every organism is to propagate its personal design, sexual reproduction appears to be a step backward. Because it is sharing genetic responsibility with a mate, its descendents do not express its personal design to the extent they would under asexual reproduction. And yet sexually reproducing organisms evolved from asexually reproducing organisms. Theorists have been arguing for 150 years as to the origin and purpose of sexual reproduction.
Inheritance Mechanism Issues
Inheritance mechanisms are critical to any evolutionary mechanics theory because mutational changes occur in a single individual and then propagate into a population by means of biological inheritance. Genetics, or the study of mechanisms whereby organisms inherit their designs has advanced enormously since Darwin. Some genetics discoveries (some of them recent) suggest that the ways that mutational changes are handled by inheritance mechanisms affect the evolution process. Two of the three categories of alternate mechanics theories (evolvability and gene-oriented mechanics theories) specifically propose that these discoveries support alternative theories. See How Genetics Discoveries Affect Evolution Theory.
Evolvability Issues
Traditional theory assumes that all organisms posses the capacity for further evolution and that this capacity is a constant that does not vary between populations or species. There is growing evidence (much from recent genetics science) that this is not true leading to evolvability theories of evolutionary mechanics.
Science Schism Regarding Evolutionary Mechanics
The observations described above have resulted in a schism in the bioscience community regarding evolutionary mechanics. Some theorists still insist on the validity of traditional mechanics and contend that the relatively small number of conflicting observations can be explained within that framework. Non-programmed theories of aging are part of this effort.
The other faction believes that the combined net effect of all of the apparently conflicting observations demands at least some adjustment to traditional mechanics and has produced proposed alternative mechanics theories including dependent theories of aging (the programmed theories). Needless to say, both factions cannot be simultaneously correct. Major efforts by the second faction only started in 1962. Recent trends have been toward more observational evidence that conflicts with traditional mechanics and supports alternatives. However, there is no current consensus among this faction as to which or which combination of alternative theories is correct. For more see: Evolution Controversies and the Theory of Aging.
Alternative Evolutionary Mechanics Theories
None of the alternatives suggest that survival of the fittest (natural selection, individual fitness) is not the most important factor directing the evolution process, rather they suggest that other factors also participate in the process. The three categories of alternative theories are listed below.
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