Argument #1: Transitional Fossils

[Heywood]

Actually, fossil records show major progress in evolution in the entire fauna almost invariably coincide with large environmental upheavals. Earth's environment tend to remain stable, or change only slowly, for long periods, usually many tens of millions of years, punctuated by large disruptive events such as major changes to sea levels, large swings in atmosphere composition or temperature, desertification, sea chemistry changes etc, which tend to occur quickly in comparison, usually last from hundreds of thousands of years to a few million years.

During these times of environment quasi stability, evolution tend to be slow and incremental. Species well adapted to stable environment tend not to suddenly acquire super men's cape with some comic book like mutations. When species are well adapted, these is little room for mutation to improve adaptation over what is already achieved in the fauna.

During these periods of stability, not only do rates of evolution of lineages remain sedate, the composition of the fauna as reflected by the relative abundance of different lineages tend to remain relatively stable.

Only when existing adaptations suddenly become inadequate thanks to environmental upheavals, do you see drastic changes to the composition of the fauna, as well as rapid progress within lineages inside the fauna.

Evolution and mutation tend not to produce comic book superheroes out of nowhere. On the whole they tend to reflect themselves mainly in enabling lineages to adapt to changing environments.

Around 2000, I was playing around with evolution simulators. I would often observe the simulants plateauing or coming into equilibrium. In one instance the equilibrium lasted quite a long time but eventually gave way to another period of changes. In the simulation nothing about the environment changed. It wasn't a variable. I only observed this once but that's when I started to think about the idea of mutations being able to lift populations out of punctuated equilibrium. Here is a link to one of the simulators I used.

Framesticks evolution simulator