punctuated equilibrium
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betting it all on a spin and toss?
Yeah, in a way.
This graphic from Wikipedia illustrates very nicely what punctuated equilibrium is.
The horizontal x-axis is morphology. That means body-form. (Small x distances mean small differences in body-form, big distances big ones.) The vertical y-axis is time.
Gradualism imagines that body forms are continually changing, and speciation occurs when these gradual changes bifurcate and different populations start changing in different ways, becoming increasingly dissimilar.
Punctuated equilibrium imagines that changes in body form happen rapidly over short periods of time, so that speciation is sudden and new physically dissimilar populations appear suddenly in the fossil record. Then these new forms might survive relatively unchanged for long periods.
The fossil record provides illustrations of both gradualism and punctuated equilibrium, so both seem to happen.
In both cases, the new morphological variants would have to find new ecological niches where their differences are indeed adaptations and not birth defects. So there's an element of rolling the dice in both cases.
But given that punctuated equilibrium imagines much larger morphological variants appearing more rapidly, the element of risk would seem to be greater.
The question arises: what would explain a sudden speciation event such as punctuated equilibrium imagines? That explanation might perhaps be found in developmental biology. Many of the genes in which mutations can occur regulate fetal development. So a small change in a single gene might cause dramatic differences in how a fetus develops.
Imagine dwarfism genes. A small chemical hiccup, and short legs suddenly appear without all the intermediate leg-length morphological variants that gradualism imagines. Now imagine that there are some niches where dwarfism is a positive benefit, so that these variants enjoy an advantage. If the new variants survive and pass on their genes, a new species might be observed to suddenly appear in the fossil record. And if the new variant is well adapted to its new mode of life, it might not change again for a long time.