Darwin’s Five Major Theories of Evolution
Mayr recognized that Darwin’s theory really consisted of five components. Summarized from his book “What Evolution Is” (2001), they are as follows:
1. The non-constancy of species (The basic theory of evolution)
Today this is commonly referred to as change over time.
2. The descent of all organisms from common ancestors (branching evolution)
Also known as “common descent”. It refers to the fact that evolutionist believe that all living things, from fish to fungi, to fruit, to bacteria, to birds, to humans, to trees and any other thing you can think of regardless how different – all of them arose from a single ancestor. Put another way, evolutionists truly believe we are all distant cousins to worms, roaches and snakes.
3. The gradualness of evolution (no saltations, no discontinuities)
A saltation is a jump or other discontinuity in a line of descent. Darwinian evolution says such things do not happen. This is in contrast to the theory of punctuated equilibrium as proposed by Eldridge and Gould, who believe evolutionary changes can occur in bursts of activity or jumps.
4. The multiplication of species (the origin of diversity)
This is the observation that the number of species increases over time.
5. Natural selection
“What Darwin called natural selection is actually a process of elimination” Mayr acknowledges. Natural selection removes information. As opposed to selection by an intelligent breeder making selective choices to develop or remove characteristics he or she is interested in, natural selection happens without intelligence, by natural processes. (This is the illustration Darwin used.) The process is a two-step one – first there is variation. In today’s understanding such change is typically brought about by a chance mutation (This is a modern understanding. Darwin did not know about genetics or mutations. The theory that includes mutations is thus referred to as “Neo-Darwinism.” (“Neo” means new)). This step is such an important one, that some evolutionist break it out as a separate step. Once there is variation, then there is a change which may be beneficial or not. This is where survival of the fittest comes in: those variations which better position a creature to survive will do so, while those less beneficial or detrimental to the creature will cause it to perish. In theory, over multiple generations, this will result in evolution that can change and multiply species.
To see Paul Nelson’s definition of Neo-Evolution, see here.