Macromutation

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Most biologists believe that adaptation occurs through the accumulation of small changes, such as the slight differences between parents and their children, some of which can result from mutations. However, an alternative that has been suggested for this process is macromutation, essentially when a sudden large-scale mutation produces a characteristic. This theory has generally been disregarded as the major explanation for adaptation, since a mutation on this scale is regarded as more likely to be detrimental than beneficial.

While macromutations appear to be the only explanation for differences such as the number of body segments among arthropods, at the genetic level where the original change occurs, very few changes to genes may actually be necessary to result in the large physical change. Some genes control other genes and the higher the level of control, the larger the change it can make (see Homeobox). Biologists make a distinction between changes to the genotype(the recipe for a body encoded in genes), and the resulting body structure resulting from those genes phenotype.

For example, Polydactyly individuals have a large resulting change in their body structure (extra toes), but can result from a small change their genotype. This is not the only possible cause of such changes. They can also result from errors during development, but such non-gene changes are not inherited by future generations.

Macromutation in Chromosomes

Instantaneous biological adaptation must occur when a non deleterious or rarely useful change occurs in the number of chromosomes in the organisms phenome. This must have occurred when the ancestral ape produced offspring which possessed 46 instead of 48 chromosomes, leading to the eventual evolution of humanity.

This change cannot have taken place slowly as odd numbers and partial chromosomes in diploid creatures are not reproductively viable. Arguments that the possibility of finding a similarly endowed mate to enable reproduction are unlikely are wrong, as this must sometimes happen, albeit between siblings, as this must have happened in the case of the mutant form of Great Ape that led to humanity. This must also have happened in every other case where related species possess different numbers of chromosomes, such as horse/donkey.

This does not invalidate adaption taking place as a result of slowly developing variation acted on by Natural Selection, as the genetic sequencing changes wrought by Natural Selection may lead to chemical instability of the genome concerned causing fusion ,splitting of ther chromosomes, usually deleterious, but very occasionally useful.