Punctuated equilibrium, that is. This one’s from 2020 but still worth a look. Author Renee Ducksworth is an evolutionary biologist at the University of Arizona:
When things did settle back down, the pace of evolution would return to a virtual standstill. That’s the pattern we observe in the fossil record: disruption, change and then long periods of stasis. However, it took many years for scientists to accept this pattern. It contradicted the Darwinian paradigm, where evolution should occur through slow and gradual changes. Under the Darwinian view, the diversity of life can be explained by simply adding up many, many small inherited changes over a long period of time. Such gradualism was believed to be a necessary part of adaptation by natural selection – the process by which some variants of traits are lost each generation, because their bearers leave no offspring. The evolution of something new, such as eyes or feathers, requires a heck of a long waiting time But this persistent focus on natural selection as the sole mechanism of adaptive evolution has always been a sticking point. It can’t properly explain how anything new arises. After all, natural selection is a process that eliminates unfit variants – it doesn’t create, but changes the prevalence of what’s already there. Instead, novelty must come from the purely random process of genetic mutation. The problem is that when new mutations appear, they’re usually not a good thing. They are more likely to disrupt well-adapted systems than to improve them, especially if they have a big effect. The upshot is that the evolution of something new, such as eyes or feathers, requires a heck of a long waiting time. Not only is there a long wait for a beneficial mutation to come along, but then there’s the long process of accumulating enough of them to build up, step by step, a complex new structure.
Fortunately for the Darwinian paradigm, geological time gives evolution millions and billions of years to work with. Yet in the 1970s, the American palaeontologists Stephen Jay Gould and Niles Eldredge proposed that the pattern of stasis and disruption might be something more than just imperfections in the fossil record. This punctuated equilibrium, as they called it, might reflect the uneven way that evolution actually unfolds. If Gould and Eldridge were right, then natural selection on random mutation suddenly had a much shorter timescale in which to accomplish major evolutionary changes. Because of this, punctuated equilibrium was initially met with scepticism.
However, there’s been a growing acceptance of this pattern among evolutionary biologists and theorists over the years, as new studies and techniques reveal it again and again across diverse organisms. For example, Stevan J Arnold, an evolutionary biologist at Oregon State University, and his colleagues looked at patterns of body size evolution in vertebrates using three different types of data that span vastly different timescales: long-term field and museum studies that compare changes over tens to thousands of years, fossil measurements that assess changes over 100,000 to around a million years, and comparative data that can detect divergence among species (estimated using genetic data) over a period of tens of millions of years. They found that bursts of body-size evolution occur only on the order of every million years or so.
Renee Duckworth, “Catastrophes and calms” at Aeon (August 13, 2020)
Punctuated equilibrium is what we observe but it isn’t popular. Punk eek makes it even less likely that life develops due to unintelligent random processes. It just does not allow anywhere near enough time.
You may also wish to read: He Said It: As A Butcher Eyes A Sheep, So The Darwinists Eyed Paleontologist Steve Gould (1941-2002)