This is the third planned post about human evolutionary history, preceded by Who you aren’t and Who you are. This time, it’s about good ol’ Homo sapiens. My nefarious plan is to reorient the topic away from an origin myth.
Here’s some good reading from almost thirty years ago: Roger Lewin’s Bones of Contention, itself inspired by Misia Landau’ graduate work. The thesis is that the whole sweep of studying human evolution has been tainted, even co-opted, by standard heroic-origin mythmaking. Terms like “evolved” and “adapted” are simply inserted into the basic story of an unusual child who shows great promise, undergoes early trials and testing, achieves heroic status, and ultimately recognition and cultural prominence. Note the core feature of the myth: that human biological history is unlike all others in being a matter of effort and will, resulting in a special and different result, the “uniquely unique” creature. Everyone else had selection happen to them; we selected ourselves.
To put it in into the terms of this blog, discussion of human evolution shifted at the outset from an investigation of how we’re an animal into an achievement-arc of why we’re not. Which is to say, such discussion isn’t evolution or even biology at all.
That’s not really a surprise. A great deal of effort even within biology has been exerted to exempt ourselves from it, despite the remarkable power of William Lawrence’s initial lectures (1814-1819), in which he introduced “biology” to the English language and quite pointedly placed us well inside it with no exempting permitted. Arguably evolutionary theory would never have been accepted by British establishment culture unless it had been massaged accordingly. Although Charles Darwin and Thomas Huxley never succumbed to it, everyone else did.
Most “evolution” most people know today, even scientists, is from Alfred Russell Wallace and Herbert Spencer, both human exceptionalists and the latter about as far from being a biologist as one can get.
I’ve already written about one severe misstep in the course of human-fossil scientific history as well as the crucial issues of mosaic evolution, relict status, and tricky issues of selection including “survival.” Here I can try however hopelessly to extricate Homo sapiens from the allure of being ever-so-adapted, with its implications of “matched” and “finished” – and yet without falling into the other pit of exceptionalism which exempts us from all biological processes and replaces the vague/inaccurate justifications of specialness by natural selection with the equally flawed justifications of specialness by culture.
Here’s the thing: sure, we have plenty of features which are probably directly affected by selection. But whether they are – for lack of a better word – uplift adaptations is the broken narrative I’m trying to get you past. Furthermore, lots of them “belong to” if you will, i.e., they originated in, species besides our own, and let’s not forget that our species was around for a long time, with its combo of features, before we did the stuff we’re so proud of. Which is to say, we didn’t evolve the capacity to write “so that” we could write, nor in the context of writing conferring such reproductive benefit that it became more common via selection.
You know the words “sapient” and “sentient,” right? Sure you do; most readers here are science fiction/fantasy readers and that subculture is deeply committed to stories of humanity “gaining” qualities called by those names. But what they mean in real-life science language is something else entirely. Sentience = flooded by and responsive to sensory input, allowing for limitations of range; sapience = responsive in a goal-oriented fashion, allowing for limitations of range. Which to say, every living being on the planet. This ties back to my earlier points that studying our genus’ speciation history is too easily co-opted into a search for a fictitious “human moment,” when the mists cleared from our eyes and we started being, you know, thinky. Moral. Self-aware. Important. (/sarcasm)
We’re still an ape, man! I haven’t yet presented my thoughts on what culture really is, and since my upcoming book goes into that in some detail, I’ll hold off. But for now, I’ll preview by saying (i) that nothing real is ineffable, no exception for culture; and (ii) that it’s a cumulative effect, not a quality or core-causal entity.
All that said, we do get to enjoy an impressive example of single-species dispersal. The timelines for it still undergo debate and refinement but you can see that although these two depictions vary in timing, what happened is not controversial at all.
Why they call it “migration” I don’t really know, unless it’s the same reason we call human organs the appendix and thumb whereas in other creatures they’re the caecum and hallux. Migration means going back and forth in a seasonal or annual sense; dispersal means extending or transferring the species’ range into new areas.
You may remember from the 1980s and 90s, there was a dust-up between the multi-regional vs. out-of-Africa narratives of H. sapiens‘ origin. Fortunately that’s resolved now – it’s both-ish and not like either narrative as originally framed. There are multiple regions in and out of Africa across which very close relatives are found, close enough to have lived much like we did at the time, and H. sapiens “proper” if you will, originated in eastern and somewhat northern Africa.
One thing you can take from that is not to get too excited about specialness based on this dispersal history; at least two other species of Homo wandered far and wide and arguably could have done more so given geologically-momentary opportunities like the frozen-over Bering Straits.
Now for the part everyone’s skirting around. I could have put it off for another post but I’m getting tired of saying that all the time. So, a brief look anyway, at ethnic diversity.
- The major “arrows” of dispersal were not short-lived single-group events but a long-term, many-times repeated, ongoing set of events in each case.
- Minor features of human appearance became more common within each one
- There is no “African” ethnicity; instead, almost as much change of this kind occurred among the dispersals to various parts of Africa as to the rest of the world
- The variables most informative about this history include
- Facial proportions
- Nuclear and mitochondrial DNA
- Linguistic subdivisions of language (that’s not redundant)
- BUT NOT skin/eye pigmentation
- No selective history for any of these variables has been validated nor is indicated by prior plausibility – I consider them strictly the result of founder effects
The single major point is that ethnic diversity is a matter of outcomes, both for the broad-sweep variables and for the more minor ones that mix & match across later, smaller-scale human dispersal. No one knows either what the earliest individuals of Homo looked like in these terms, although my bet’s on “mainly beigey-brown with a few regional variants” just like today. Nothing about human ethnicity tells us anything about the populations beginning and throughout those large-scale dispersals.
All excited now? Good. Now I’ll say, more for a later post. Sweet dreams.
Next: Circle of nitrates