Modern evolutionary science is credited, in almost all textbooks, as having grown from a general change of worldview. The old, static view that went back to the Bible and to the worldviews of ancient Greece and Rome, was displaced by a process-based view of nature. Rather than a series of ad hoc events dictated by God, or the idea that the world was static, we realized that things changed over time.
Darwin was profoundly affected by Lyell and if any one thing characterizes Darwin's contribution to the world it was the application of uniformitarianism to life: life was an historical process, not a series of sudden creation events. This view of slow, continuity was absolutely fundamental to Darwin's thinking, as he stressed time and time again.
The idea--nowadays the assumption--that processes here today were perforce operating in the past, has been considered to be one of the founding legacies of the 19th century science largely due to Lyell and Darwin and many other less prominent figures.
But how accurate is that view? In around 170 AD, the Roman Emperor Marcus Aurelius, in his Meditations, was musing about the nature of life.
Pass in review the far-off things of the past and its succession of sovranties without number. Thou canst look forward and see the future also. For it will most surely be of the same character, and it cannot but carry on the rhythm of existing things. Consequently it is all one, whether we witness human life for forty years or ten thousand. For what more shalt thou see?
Treatments we're aware of (the Wikipedia entry for 'uniformitarianism', e.g.) credit this concept to the 18th century when the term itself was coined. They do not go back to the ancients, and indeed, it was only in reading Marcus Aurelius for his general philosophy of life that we stumbled inadvertently across his version.
Evolutionary ideas, crude and terse, were widespread if not dogma to the Islamic scholars of the middle ages, as we've mentioned in previous posts. So the interesting question is the way new facts being discovered, such as collections of specimens from global travelers, somehow led to the revival of these ancient ideas at a time when we -- that is, Darwin -- had the methodological framework to make the ideas more rigorous. For every thing there is a season, or a cycle of seasons.
Yes, when it comes to human ideas, there's nothing new under the sun.....and indeed that quote is itself from Ecclesiastes:
What has been will be again,
what has been done will be done again;
there is nothing new under the sun.
Which antedates Marcus Aurelius by quite some time.
Of course, we can't let ourselves get carried away by uniformitarianism. The important point is the belief in general that Nature is orderly: it has properties or 'laws' by which it works, and the idea is that these are universal and unchanging. Gravity doesn't take days off, and wind and water always erode rock.
On the other hand, what makes life the way it is, is specifically the unique events of mutation and adaptation. It is only by becoming different that life evolves. Humans are the result of continuing, fundamental processes, but we are the result of unique events involving those processes. Worms and oaks are not heading towards a human state.
Indeed, what is unique under the sun, is life itself! Uniformitarianism says that the geological processes have continuity. Mountains don't arise spontaneously out of a momentary blip in physical processes. But life did arise that way, as far as we know.
So we need to recognize the importance of continuity, but also of difference.