So, it occurred to me the other day that I knew very little about the development of human history.

All I really knew was that modern humans have been dated to about 200,000 years ago (give or take a few millennia) but the rise of modern civilization only began about ~10,000 years ago. It seemed impossible to me that humans could have existed in the modern genetic form and spend almost ten times as long doing absolutely nothing to improve their lot, and then suddenly rising exponentially from hunter-gatherer tribes to what we know as modern civilization today.

So I set out to find out why.

As it turns out, Earth suffered from a very long (by our standards) period of glaciation, stretching from about 115,000 years ago until just about 12,000 years ago. The climate during this period would have caused major desertification across the habitable regions, and obviously most of the planet’s surface toward the poles were covered by four-kilometer thick (!!) sheets of ice. This would have reduced all of the living human subspecies (which included Homo sapiens, Homo neanderthalensis, and possibly others) to subsistence living. There was no way during this period for civilization to arise — there was just not enough available arable farmland and the climate was not reliable.

However, starting at about 130,000 years ago and leading up to the next period of glaciation (at 115,000 years ago) there was an inter-glacial period called the Eemian era. As it turns out, this one was even warmer than ours (which is known as the Holocene, incidentally). Modern humans existed during this time, right alongside Neandertals and probably the Denisovans.

Interestingly enough, we have almost no indication of what things were like during this time period. There seems to be very little speculation as to the reasons that, given a period that has a lot of similarity to our own interglacial period, civilization never arose during the Eemian era while it did for ours.

The general consensus seems to be that the climate was perhaps more unreliable, preventing the rise of agriculture, because of a lack of regular seasons. However, this is mostly because we don’t really have a lot of artifacts from the Eemian era — it’s very difficult to tell what was going on when you only have some bones and a few decorative shells.

As I was thinking about this, it occurred to me that the slow, inexorable crush of glaciation — which is powerful enough to destroy rock formations and distribute them across a wide area — and then the massive flooding that comes during the next period of warming would be incredibly destructive to anything that might have been there. The weight of four kilometer-thick ice sheets would be enough to pound just about anything into dust, in my estimation.

As a fiction writer, it is of course my realm to speculate, and to speculate wildly. I find it very hard to believe that, given a period of warmth where modern humans (and others!) existed, that humankind would have stagnated for 15,000 years without improving at all, even given an unreliable climate.  I have to wonder whether civilization did begin to arise, somewhere in there. It might have taken longer, and almost certainly did not reach the level that we have today, but somehow Robert E. Howard’s Hyborean world doesn’t seem so far-fetched to me… something like that. Entirely different cultures, languages and histories.

It’s mostly interesting thinking. Obviously, it’s quite possible that there were indeed reasons that civilization never rose past the hunter-gatherer tribal period, but I prefer to think that any possible evidence was entirely destroyed by the movement of the glaciers and the flooding. I don’t think it’s really that far-fetched a thought, either.

I might venture into some speculative historical fiction, at some point.

That might be fun.