The Wander Years
Earth is 4.5 billion years old, we’re told. Roughly. Everything in geologic time is rough.
This has been divided into four eons, which have varying lengths, delimited by events. The current eon, the Phanerozoic, began around 540 million years ago when the first hard-shelled creatures appear in the fossil record. It marks the beginning of the Cambrian era, but I’m getting ahead of myself.
Eons are subdivided into, in descending order, eras, periods, epochs, and ages, with essentially the same criteria used to mark them.
So, our current era is the Cenozoic, which began around 66 million years ago when the dinosaurs went extinct.
Our current age is interesting. It’s called the Meghalayan, which is the name of a state in northern India where sediment cores were taken. This began 4200 years ago with a great drought, which lasted a century and disrupted civilizations from Egypt to China, devastating trade and creating a Dark Ages for several centuries. It’s the only one of these subdivisions named for an event that is notable for its effect on humans.
It’s part of the Holocene epoch, which began roughly 11,700 years ago, when the last glacial period (the Ice Age) ended.
It’s been suggested that we start a new epoch around 1950 called the Anthropocene, marking the beginning of human effect on climate. I have no opinion on this.
The period we’re in is called the Quaternary, beginning around 2.5 million years ago, beginning a period of glaciation that has not ended, a true Ice Age that we’re still in. We’re in an interglacial, when it gets warm and the ice sheets withdraw, which began 11,700 years ago. Interglacials in the past tend to last 10-20,000 years, although now it’s anybody’s guess as to when or if it gets cold again, considering we’re messing around with Mother Nature now.
Around 2.5 million years ago is when the first hominins show up (essentially primates who walk upright, beginning with Australopithecines, i.e., “Lucy”). Again, this is a really rough estimate on my part, but my point is that we’ve always existed in the cold. The fact that we arose on the only continent to straddle the equator doesn’t negate that we live in an ice age, and we always have.
Homo erectus, the most successful human species ever (lasting well over a million years), were probably the first humans to leave Africa (approximately 1.8 million years ago), and they really left; we’ve discovered remains as far as east Asia (“Peking Man”) and island southeast Asia (“Java Man”). We are born wanderers.
I don’t know why this subject, human migration, intrigues me, but it’s been a long time in development. My first interest in world maps and globes was imagining how someone could walk around the world, long before it occurred to me that someone had.
Our cousins the Neanderthals made it to northern Europe, but also as far south as Gibraltar and as far east as Central Asia. It’s believed by many that they made sort of a last stand on the Iberian peninsula, but they disappeared around 35,000 years ago.
When modern humans arose in east Africa, some began to leave and got as far as Israel and even Georgia, before dying off or returning to Africa; this was a little over 100,000 years ago, when the Sahara was green but getting progressively arid, and game would have been following water (and humans following game, most likely).
It would take around 50,000 years for the humans who would be the ancestors of all non-Africans to leave, most likely crossing the (much narrower and shallower) Red Sea onto the Arabian peninsula.
And then we took off. We were in Australia so quickly that it would take us another 15-20,000 years to reach Europe and Siberia. In another 20,000 years, give or take (and not only is this rough, but it’s a huge point of controversy as to exactly when, something that doesn’t matter at all as far as I’m concerned), we crossed the land bridge known as Beringia between Siberia and Alaska, becoming the first indigenous Americans.
Three things: 1) Sorry for the info dump, but now I don’t feel compelled to do it again; 2) this is very general, and, again, very rough timelines; and 3) I wrote all of that without notes.
As much as it’d be cool for that to demonstrate my awesome intellectual powers, it’s entirely about having time to study interesting subjects, and a compulsion to learn so I can re-package it into something fun to read and write about. It’s happened a million times in my life; I’ll retain this until I get bored, and then good luck asking me about the Cambrian explosion.
I obviously will be working on the fun part.
I don’t think I’m liable to come up with a universal truth from all of this, but it helps understanding, at this late date, why I do what I do.
And why, even though I admire all sorts of statesmen, scientists, military leaders, etc., the only profession that automatically inspires respect is astronaut. We do like to wander.
