Thursday, October 20, 2011

"The rhythm of existing things"

Here are some idle thoughts triggered by a chance discovery.

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.

Charles Lyell
In the early 19th century, the geologist Charles Lyell, following on some recent British predecessors, advanced the 'uniformitarian' theory of geology, displacing ad hoc, catastrophist kinds of views of the geological processes like the building of island chains, lifting and erosion of mountains, change in coastlines, and so on.  Rather than sudden events, or events ordained by God, forces we can see today can be extrapolated back into the dark depths of history.  Individual events are unique, but the process is the same, and we can extrapolate it into the future, too.

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?
Marcus Aurelius
It cannot but carry on the rhythm of existing things.  It had to be.  The context of Aurelius' thought had to do with keeping human affairs during one's own lifetime in perspective.  We're not classicists and aren't able to mine the classical literature for other such musings, though it's not surprising that most basic thoughts were raised by those sage ancestors.  But the idea of history as a steady stream seemed obvious to Marcus Aurelius, as it seems obvious to science today.  Indeed, this may be the more remarkable because we often blame the stodgy Middle Ages on fundamentalistic Biblical Christianity.  But ideas of uniformitarianism were not new.  Given that Christian scholars knew very well the deep reaches of human history, it is rather surprising to us that uniformitarianism had so patchy a history and that the 19th century awakening to it seemed, as told by subsequent historians at least, so transforming.

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.


Arjun said...

Responding to the claim made in the last paragraph:

From an Earth systems perspective, biological phenomena are just as necessary to the functioning of the planet as any geological process. In essence, the former represents a subset of the latter.

According to one perspective (which guides most of my own thinking), life began as (and in a sense, remains) a far-from-thermodynamic equilibrium autocatalytic chemical network wrought by the energy gradient imposed on Earth by the sun.

Though I ramble, the point I attempt to convey is that from a physical standpoint life is not as exceptional as we would like to believe it to be, and that from a biogeochemical perspective mountains arose just as spontaneously as life did due to Earth's persistent far-from-equilibrium state.

This begs the question-- which view of life is more fundamental to its comprehension, life as a collection of discrete species that come and go subject to the course of evolution, or life as a subset of a grander global biogeochemical process?

Ken Weiss said...

The thermodynamic argument about life has been made many times, as a response to objections to natural selection. I'll send you a very recent paper related to that, by David Krakauer. I studied with someone named Leslie White, a cultural anthropologist, who used thermodynamic arguments in a similar way to suggest how culture evolves.

One can debate the uniqueness of life and whether or how one would reasonably argue for uniformitarianism in that context (that is, without being mystical).

Even ideas like Gaia hypothesis get at the question of the relatedness of the particular to the whole. Clearly the biosphere has its evolutionary history tied to the earth's, but is made of separate subdifferentiation due to local temporary conditions. Similarly in a sense the organ structures within us. And our different cultures around the world.

What 'uniformitarianism' means today if anything beyond the obvious is different, I'd say, from the past when such arguments were related to religious contexts and offered with much less information or scientific method than we have today.