Note: Nowadays, people are more likely to state 300,000 years ago as the start, since a cranium from a site in Morocco was called H. sapiens.
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| https://www.nhm.ac.uk/discover/news/2017/june/oldest-known-homo-sapiens-fossils-discovered-in-morocco.html |
So, here we are. We're at the point in time with "Sapiens that looked just like us" and who, around 70,000 years ago, spread into the Arabian peninsula and "quickly overran the entire Eurasian landmass". Again we're told that "scientists also agree" on this, which is good for adding nuance.
But it also doesn't come close to conveying why there is agreement. And I don't mean why he can say there is agreement. Forget the details for a moment. Forget the evidence, or not, for there being agreement. I'm talking about why there would be agreement, as a phenomenon, at all in science.
It's not because the truth is apparent! You don't have to agree with someone that a fossil exists, or that you're holding a fossil in your hand where you can both see that there is a fossil in your hand. Facts don't really need agreement. That's shared reality.
In science, agreement is always about the more-than-meets-the-eye interpretation of what is plainly visible in hand, of the facts. Agreement is the construction of a shared reality. And sometimes that constructed shared reality becomes the facts themselves. Sometimes that's because new discoveries have been established as facts that no one disagrees are facts and so agreement is based not on interpretation anymore but of the facts themselves. But sometimes agreement becomes fact even though the agreement is still based only on interpretation and yet people act like the agreed upon interpretation is the fact. But what happens when people forget that it's an interpretation?
They do exactly that when interpretations are presented as the facts without any nuance or context. And without anyone but the scientists knowing what facts and theories go into those interpretations. One of the many results of this phenomenon is that science ceases to exist in the public. They see it only as a set of facts rather than a perspective on the world and a way to find out about the universe. When we see it as the latter, then we see the imperative to learn how to do it, even in a world where we have easy access to "the facts" in our pockets.
(Too many thoughts today. Carl Sagan, read by Cary Elwes, is still haunting me, having just finishing re-reading the magnificent D-HW—in which even Sagan tells some evolutionary tales!)
And, with the human evolutionary past, two things are always working to shape agreement, either by confirming what was already agreed upon or by shifting what is agreed upon to something different, even if slightly:
(1) New fossil and archaeological findings are always filling gaps in space-time and affecting how scientists agree and on what they agree.
(2) The fossil and archaeological record is necessarily incomplete. If everything preserved, then we wouldn't exist. Old molecules are recycled into new organisms. The deeper in time we go, the worse the preservation gets, the more empty space in the fossil and archaeological records. That leaves room for more interpretation, and more agreement or disagreement.
These time estimates (150,000 and 70,000 years ago) have not only been revised and shifted and refined and debated since Harari's time of writing (and we won't bother to nit-pick because it doesn't affect his narrative), but they are absolutely affected by preservation bias. And preservation is biased towards the present and the very recent past. It's biased against the deep past.
And on top of that? This part of the story that Harari is telling is affected by how scientists categorize hominin fossils. As we've discussed a bit already, species are made up. Labeling fossils is not a 100% objective exercise because people are forced, by the conventions of science and language, to decide where to cut up a continuum of continuous variation, the unbroken thread, into slices of life that we call species.
Within reason, there's no necessary right or wrong species label for a fossil hominin. So, as long as you're calling that fossil head from Morocco up there a hominin, and not a dinosaur, you're good. Keeping it in the genus Homo as opposed to Australopithecus? You're good there too, because it's more like you and me than it is like Lucy's kind. Calling it H. sapiens, and not some other Homo, is purely a judgment call, not a fact. And, if you're lucky, people will agree with you. If not, then you'll sweat it out once or twice a year when you have to face them at conferences. And you'll yell a swear word or many whenever you review their papers and grant proposals. That's how reality gets constructed above and beyond the facts themselves.
There is enough variation over time and space in the hominin record over the last 500,000 years that there is no purely objective reason for all scientists lump it into Homo sapiens. Just as there is no purely objective reason for all scientists to split it up into many species. Right now, most aren't lumping. That's why there are "Neanderthals" and "Archaics" and "Homo heidelbergensis" and "Denisovans" and etc. etc. They could all be Homo sapiens if people wanted them to be, especially now that ancient DNA has linked us now to many of those fossils from the past.
And the small-brained fossils of the most recent era are easier to set aside as other species, outside Homo sapiens, like Homo floresiensis and Homo naledi. Though, what we might imagine (or not) about these hominins' behavioral capacities is biased by their exclusion from H. sapiens, isn't it?
What's in a name? "They're not like us," that's what.
And now, after all that, I'm ready to face the main point of the pages, today: the different models for Sapiens origins. This is about where in space and time Sapiens first emerged and what happened between then and now as this single species spread far and wide all over where there were other hominins (as known from the fossil record).
The overwhelming consensus by European and American schools of thought is that Sapiens first emerged in Africa. That's based not only on the fossil record but on analyses of living human genomes. The most genetic diversity exists in living Africans, everyone else is a subset of that variation. That tells us that the human genome has had the longest time to accumulate variation (as it always is doing, generation to generation, parent to offspring) in Africa compared to everywhere else.
But even people who agree on that idea may hold very different views about what happened before and after and so there have been different models of the before and after proposed and debated. At first they were extreme opposites: the "Multiregional" model versus the "Out of Africa" or "replacement" model. The former thought that once Homo dispersed across Africa and out into Europe and Asia that gene flow kept evolving lineages reproductively linked, and that, over time, biogeographic diversity emerged, as it does, which helps explain present biogeographic variation. Essentially it put Sapiens back two million years. The latter saw Sapiens as only as recent as the genetic and archaeological evidence points: within the last 300,000 years (earlier it was much more recent like around 200,000 max) and since then, there had been no interbreeding with any hominins we call other names, like the Neanderthals and later Homo erectus.
And I'd say that most people who debated these things believe that the models are valuable because debating them gets scientists as close to knowing as possible, like through agreement, via disagreement. They still won't know, but they'll have constructed a shared reality through agreement. (Whether this should be considered "science" is a whole other conversation. For now, it is and so we carry on, here.)
The subjectivity and debate involved in species designation in the fossil record is one reason that different models of human origins have been difficult to parse over the years. And still another obstacle has been the racism—real, perceived, plucked from, and projected onto—the different models. And still another, which is hardly ever explicitly stated is that the models have run they're course, they've done their jobs, they've gotten us closer to the truth but showing us that they're not the truth.
When I began grad school in 1999, genetics had just begun to have a huge impact on paleoanthropology and so it was playing a major role in the field's debate between two opposing models of human origins: the Multiregional Hypothesis on one hand and "Out of Africa" or "Replacement" on the other.
The Multiregional model was an underdog from the start. The names had been named and so things were already established to be separate. How to think about them as actually just one big interconnected gene pool going back further in time than the first agreed upon Sapiens, is asking a lot, then. Not only that, but it sounds like old ideas of polygenesis. That different human races evolved independently or separately was a mainstream belief among some of the earliest evolutionary thinkers, but famously excluding Charles Darwin who believed that all humans shared one origin, as in "monogenesis." But the Multiregional model is not polygenesis. (And monogenesis is not the antidote to racism.)
The Multiregional model is about how the evolutionary phenomena that contribute to biogeographic variation today (selection, drift, and gene flow, or lack thereof) must have occurred for as long as hominins have occurred. As hominins spread further around Africa and then, especially, across other continents, these processes would have been involved in how the local populations changed over time, as lineages. And if they all retained the ability to interbreed with other lineages, then that means, under the biological species concept, that they are one species. So, thinking with this model means that perhaps Sapiens extends to who people have long called Neanderthals, and to other hominins over the last million or even two million years ago. Remember, species change over time, and must include change over time, or else we're ignoring the reality of constant change over time. So species don't only contain variation over space, but also over time.
So, a Multiregional model of human origins would link modern Europeans to fossil Neanderthals, modern Asians to fossil hominins there, and modern Africans to fossil hominins there.
Lots of evolving going on in lots of places, going back further in time than 150,000 (or 300,000) years ago, perhaps back to two million years ago!
Again, to many people this seems racist perhaps because it's rooting the fact of contemporary biogeographic variation deeper in time than 300 kya or 150 kya or 70 kya. But why would a deeper origins of biogeographic variation be any more racist than people already are? The fossils don't have IQ or agression or sex drive or laziness or all the bullshit behavioral stuff people believe to be in the blood and bones of different "races" so it really shouldn't matter how old we label "Sapiens" and, in fact, it doesn't because it's a made up label. We cannot win over the racists with any model of human origins because science cannot falsify racism, it's an unscientific faith-based phenomenon! Science cannot falsify that which is based on faith.
The multiregional model still has humans as one big, diverse, genetically-linked species over space time. That's what we are right now and no one is saying that fact is inherently racist. I'm not clear on why starting that process earlier in time and including more weirdos from the past (like Neanderthals and late erectus) in on the fun is inherently racist. Maybe that's because I know that race is the sense we make of human variation and not any inherent system that nature devised. We are born into race, not with race. So, because of that I know that the Multiregional model is only racist if people see it that way, not because its possible truth about human origins would mean that human variation really is what racists believe it to be.
Anyway, there were reasons that model was not popular. But probably the most important reason was that another model was seen as better and so it was the popular one. And, by the way, it's got no less potential for encouraging racism!
That's the "Out of Africa" or "Replacement" model.
And then... and then...
Geniuses developed the methods for amplifying and studying the ancient DNA from the nucleus... the genome of fossil hominins who were preserved in persnickety enough contexts like cold dry caves to still have any of the precious molecules. And, holy fucken shit, the Neanderthal genome is right there in the living human genome. At first, it looked like it was only in Europeans and Asians, but as methods improved it was then shown to be worldwide. We all have a little Neanderthal in us, different parts of the Neanderthal genome, yes, but a little bit is there, nonetheless. And this was the emerging understanding right when Harari was writing Sapiens.
But so far we have no reason to believe he was aware of it. (We will see that he is aware of this on page 16.)
He presents the "Interbreeding Theory" (IT) which is the Multiregional model, I suppose. Though he's done so with a twist. He describes the results of the hypothetical possibility of Sapiens and Neanderthals merging in Europe as "not pure Sapiens". I think he's being cheeky. I think he's saying that if the "Interbreeding Theory" is correct, then it's the Europeans who are "impure," while the Africans whom their ancestors (and many living people today) deemed racially inferior are pure stock.
So, yeah, I think he's being subversive, but he's using pseudoscientific habits of thinking to make his point which severely weakens it, given how I doubt most readers know what he's doing and how so many believe in biological purity. I do think I'm reading this right but, regardless, it's a mistake to use "pure Sapiens" without saying there's no such thing, at least to an American readership! We're a bunch of racists and not too long ago our science journals were all about showing the believed-to-be disastrous effects of "miscegenation".
Anyway, the "Interbreeding Theory" is presented rather neutrally compared to the other one. Brace yourself.
According to Harari, the "Replacement Theory" (RT) is a doozy. It "tells a very different story--one of incompatibility, revulsion, and perhaps even genocide."
And then he says that "according to this theory, Sapiens and other humans [like Neanderthals] had different anatomies, and most likely different mating habits and even body odours. They would have had little sexual interest in one another."
page 15
First of all, the mating habits and odors are imaginary and not knowable, so they're not anyone's scientific theory. But also, it's not clear if he's is only presenting this idea or if he's also endorsing it over the other one. Keep that in mind because it will be a pattern you see again and again throughout the book.
Now, the Replacement Theory, he says, if true, would make us "all 'pure Sapiens'". That time he puts it in scare quotes. I'm not sure how to take that, now.
He says a lot hinges on the debate. He says that if the RT is correct then racial distinctions are negligible but if the IT is correct the racial differences could be really old and saying so could lend power to the racists. Well, I already arrived at this implication and how I see it. Who cares? Race is made up. It's what we're born into not what we're born with, so in a racist world it doesn't matter to racists how old or young the genetic differences are between people. The differences are there and so racists can still be racist.
At the end of this post I'm worried about two things.
1. How long it was. What the hell?
2. That he sets up the Multiregional model/ Interbreeding Theory as the one racists will love, which is (a) not necessarily true and, like I said, pointless to worry about because race/racism is only pseudoscience and can keep going despite the facts or because of them, either way, and (b) because the Replacement Theory is just as lovable by racists. Hopefully we'll have a chance to talk about why in the next post! Wheeee!
Page 16-19 are next. To be continued...
1 comment:
My apologies to anyone who read this just after I posted. That was a rougher draft than I intended to publish! I only found out hours later... thanks to a very helpful reader.
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