Does the Bronze Age Herald a Major Transformation in Human Dispersal Patterns?

Humans–Homo Sapiens or Anatomically Modern Humans–have been around for about 200,000 years. We have only recently–for the past few thousand years or so–begun making a serious effort at recording human history and figuring out what happened before our own times.

Most of what we know about major migrations and changes among human populations come from three major sources: written records, archaeology, and genetics.

Written records are (usually) the easiest to work with. We know when the Spaniards discovered Cuba because we have written records of the event, for example. Unfortunately, written records go back only a few thousand years–covering a teeny portion of human history–and can be highly unreliable. After all, we thought the entire world was only 6 thousand years old for a while because a book that seemed to say so.

Archaeology lets us peer much further back than written records, but with much less detail. We don’t know a lot, for example, about the folks who made Aurignacian tools–what they called themselves, what sort of rituals they had, what they hoped or dreamed of. Without those details, it’s hard to care much about one culture or another. After a while, pots blend into pots, stone tools into stone tools.

Can you tell which one is Aurignacian, and which is Gravettian?

(Oh, I threw in a Mousterian tool, as well. Those were made by Neanderthals, not H. sapiens.)

I can’t, either.

It is difficult to tell whether a change in artifacts between one layer and the next reflects a change in people or a change in technology. The proliferation of steel artifacts in the archaeological record in Mexico circa 1500 reflects an influx of new people, but the proliferation of television sets in the future-archaeological record of my area merely reflects a technological development. Finding a lot of mass graves in an area is, of course, a tip-off that invasion and replacement happened, but invasions aren’t always accompanied by easily identified mass-internments.

This is where genetics comes in. If we can find some skeletons and sequence their DNA, and then find some later or earlier skeletons in the same area and sequence their DNA, then we can get a pretty good idea of whether or not the later people are descended from the earlier people. This probably doesn’t always work (if the people in question are under some kind of selective pressure–which we all are–then their descendants might look genetically different from their ancestors simply due to evolution rather than replacement,) but it is a pretty darn good tool.

As I discussed back in “Oops, Looks Like it was People, not Pots,” archaeologists have fiercely debated over the decades whether the replacement of Narva Pots with Corded Ware Pots circa 3750 ago represented a population replacement or just a change in pot-making preferences:

    

Corded Ware on the left, Narva on the right.

Luckily for us, genetics has now figured out that the Corded Ware people are actually the Yamnaya, aka the Proto-Indo-Europeans, and that they expanded out of the Eurasian Steppe about 4,000 years ago, replacing much of the native population as they went.

So it’s starting to look like there were quite a few conquering events of this sort.

From, A recent bottleneck of Y chromosome diversity coincides with a global change in culture

from A Handful of Bronze Age Men Could have fathered two-thirds of Europeans

In general, if you see a lot of mtDNA and only a little Y-DNA, that means there were a lot of women around and only a few men. And that generally means those men just killed all of the other men and raped their wives and children.

Which appears to have happened on a massive scale throughout much of the world around 10,000-4,000 years ago.

Just off the top of my head, recent large-scale migrations and at least partial replacements include the arrival of Indians in Australia around 4,230 years ago; replacement of the Thule people by the Inuit (aka Dorset aka Eskimo) around 1,000 ago; successive waves of steppe peoples like the Turks and Mongols invading their neighbors; the Great Bantu Migration that began about 3,500 years ago; the spread of Polynesians through areas formerly controlled by Melanesians starting around 3,000 BC; displacement of the Ainu by the Japanese over the past couple thousand years; etc.

Replacement of the Thule by the Dorset, from The genetic prehistory of the New World Arctic

Paths of the great Bantu Migration

Map is in French. Negative numbers are years BC; positive numbers are years CE.

And of course, we know of many more recent migrations, like the one kicked off by Columbus.

So it looks like people have moved around a lot over the past 10,000 years.

Terms like “bronze age” are a little problematic because people adopted different technologies at different times. So the “bronze age” began around 5,300 years ago in the Middle East, 4,000 years ago in Ireland, and skipped the Inuit entirely (they basically went straight from stone and bone tools to guns.)

Agriculture emerged in the Middle East circa 11,500 years ago; followed by the wheel, 8,500 years ago; carts, 6,500 years ago; and domesticated horses about 6,000 years ago. These technologies made the world ripe for warfare–riders on horseback or in chariots were great at conquering, and agricultural settlements, with their large population centers and piles of food, were great for conquering.

Our conventional views of prehistory are tainted, I suspect, by a mis-perception of time. This is probably basically a quirk of perception–since we remember yesterday better than the day before yesterday, and that day better than last week, and last week better than last year, we tend to think of more recent time periods as longer than they really are, and older time periods as relatively shorter. Children are most prone to this; ask a child to make a numberline showing events like “Last week, my last birthday, the year I was born, and the year mommy was born,” and you’ll tend to get a very distorted number line. Grown ups are much better at this task (we can count the time-distance between these events,) but we’re not perfect.

We show this same tendency when thinking about human history. Our written documents barely go back past 3,000 years, and as far as most people are concerned, this is the beginning of “history”. Nevermind that humans have been around for 200,000 years–that’s 197,000 years of human history that we tend to condense down to: humans evolved, left Africa, and invented agriculture–then came us. We tend to mentally assign approximately equal chunks of time to each phase, which leads to things like people thinking that the Basques–who speak a language isolate–are an ancient, archaic people who hail directly from the first humans, or Neanderthals, or somesuch. Neanderthals disappeared around 40,000 years, and the Indo-European language expansion probably cut the Basques off from their fellow-language speakers about 3,000 years ago. Of course, the Basques could have been cut off since the Neanderthal age, but that’s a jump of 37,000 years (or more) on very little evidence. Likewise, we tend to assume that people just spread out from their original African homeland, got to where they were going, sat down, and never moved again. With the exception of Columbus and his European co-ethnics, everyone is sort of assumed to have gotten where they are now about 100,000-40,000 years ago. (Or the equivalent time period for people who think humanity is much younger or older than it is.)

But the emerging picture is one of conquering–lots of conquering, at least in the time periods we’ve been able to get details on. But go back more than 10,000 years or so, and the records start petering out. We’ve got no writing, far fewer artifacts, and even the DNA breaks down. The technology we’ve developed for extracting and sequencing ancient DNA is amazing, but I suspect we’ll have a devil of a time trying to find any well-preserved 40,000 year old DNA in the rainforest.

So what did the human story look like between 200,000 and 10,000 years ago? Have humans been conquering and re-conquering each other from the beginning? Is it ethnic group after ethnic group, all the way down? Or did lower population density in the pre-agricultural era make it easier to spread out and avoid one’s neighbors than to bother fighting with them? Certainly armies would have spread much less slowly before the domestication of the horse and invention of the chariot. (Not to mention that they require quite a bit of food, which is a tough sort of thing to get in large, easily-transportable form if you’re a hunter-gatherer.)

Certainly prehistoric peoples slaughtered (or slaughter) each other with great frequency–we can tell that:

It doesn’t take a lot of technology to go put a spear into your neighbor’s chest. Even bands of chimps go smash other bands of chimps to bits with rocks.

We also have genetic evidence emerging from further back, ie, An Older Layer of Eurasian Admixture in Africa. As Dienekes summarises:

The authors propose that a genetic component found in Horn of Africa populations back-migrated to Africa from Eurasia ~23 thousand years ago. … For a time, there was a taboo against imagining back-migration into Africa; in a sense this was reasonable on parsimony grounds: Africans have most autosomal genetic diversity and the basal clades of mtDNA and Y-chromosomes; a model with Out-of-Africa is simpler than one with both Out-of and Into-Africa. However, we now know that pretty much all Africans have Eurasian ancestry, ranging from at least traces in theYoruba and Pygmies (to account for the Neandertal admixture) to intermediate values in East Africans, to quite  a lot in North Africans.

Eurasian admixture in Africa seems to be general, variable, and to have occurred at different time scales. It’s still the best hypothesis that modern humans originated in Africa initially and migrated into Eurasia. However, it is no longer clear that Africa was always the pump and never the destination of human migrations.

Whether this was “conquering” or just wandering remains to be discovered.

As for me, my money’s on horses and agriculture making warfare and dispersal faster and more efficient, not fundamentally changing our human proclivities toward our neighbors.

These are a few of my favorite things (Indian DNA)

People often make the mistake of over-generalizing other people. We speak of “Indians,” “Native Americans,” or better yet, “Indigenous Peoples,” as though one couldn’t tell the difference between a Maori and an Eskimo; as though only two undifferentiated blocks of humanity existed, everywhere on the globe: noble first people who moved into the area thousands upon thousands of years ago, sat down, and never moved again, and evil invaders who showed up yesterday.

In reality, Group A has conquered and replaced Group B and been conquered and replaced in turn by Group C since time immemorial. Sometimes the conquered group gets incorporated into the new group, and years down the line we can still find their DNA in their descendants. At other times, all that’s left is an abrupt transition in the archeological record between one set of artifacts and skull types and another.

Even “Indigenous” peoples have been migrating, conquering and slaughtering each other since time immemorial. The only difference between them and Europeans is that the Europeans did it more recently and while white.

When we take a good look at the Indians’ DNA, we find evidence of multiple invasion waves, some of them genocidal. The Sururi, Pima, and Chippewyans are clearly distinct, as are the Eskimo and Aleuts:

DNA of the Eskimos and related peoples

DNA of the Aleuts and related peoples

(all of the charts are from Haak et al’s charts:

Please note that Haak’s chart and the chart I have at the top of the blog use different colors to represent the same things; genetic admixture of course does not have any inherent color, so the choice of colors is entirely up to the person making the graph.)

The Karitiana are one of those mixed horticulturalist/hunter-gatherer tribes from deep in the Amazon Rainforest who have extremely little contact with the outside world and are suspected of having Denisovan DNA and thus being potentially descended from an ancient wave of Melanesians who either got to the Americas first, or else very mysteriously made it to the rainforest without leaving significant genetic traces elsewhere. I’m going with they got here first, because that explanation makes more sense.

The Pima People of southern Arizona had extensive trade and irrigation networks, and are believed to be descended from the Hohokam people, who lived in the same area and also built and maintained irrigation networks and cities, and are probably generally related to the Puebloan Peoples, who also built cities in the South West. An observer wrote about the Puebloans:

When these regions were first discovered it appears that the inhabitants lived in comfortable houses and cultivated the soil, as they have continued to do up to the present time. Indeed, they are now considered the best horticulturists in the country, furnishing most of the fruits and a large portion of the vegetable supplies that are to be found in the markets. They were until very lately the only people in New Mexico who cultivated the grape. They also maintain at the present time considerable herds of cattle, horses, etc. They are, in short, a remarkably sober and industrious race, conspicuous for morality and honesty, and very little given to quarrelling or dissipation … Josiah Gregg, Commerce of the Prairies: or, The journal of a Santa Fé trader, 1831–1839

Linguistically, the Pima speak an Uto-Aztecan language, connecting them with the Soshoni to the north, Hopi to the east, and the Aztecs to the south (and even further south, since the family is also spoken in Equador):

Map of Uto-Aztecan language distribution

The Aztecs, as you probably already know, had a large empire with cities, roads, trade, taxes, etc.

In other words, the Pima were far more technologically advanced than the Karitiana, which suggests that the arrow of conquering here goes from Pima-related people to Karitiana-related people, rather than the other way around.

Now, obviously, the Pima did not travel down to Bolivia, kill a bunch of Karitiana people living in Bolivia, rape their women, and then head back to Arizona. More likely, the ancestors of the Karitiana once lived throughout much of South and Central America, and perhaps even further afield. The ancestors of the Pima then invaded, killing a bunch of the locals and incorporating a few of their women into their tribes. The Karitiana managed to survive in the rainforest due to the rainforest being very difficult to conquer, and the Pima failed to mix with other groups due to being the only guys interested in living in the middle of the Arizona desert.

The Chipewyan people (not to be confused with the Chippewa people, aka the Ojibwe,) live in northwest Canada and eastern Alaska, and are members of the Na-Dene Language family:

 

Map of Na-Dene Language family Distribution

Those guys in the southern branch of the family are the Navajos and Apache. These languages are speculated to be linked to Siberian languages like the Yeniseian.

(I think the Chilote people are from Chile.)

The Algonquin people (of whom the Ojibwe are part,) come from the North East US and Canada:

Map of Algonquian Language Family distribution

There also exist a couple of languages on the California coast which appear to be related to the Algonquin Family, possibly a case of Survival on the Fringes as a new wave of invaders migrated from the Bering Strait.

The Algonquins appear to have been semi-nomadic semi-horticulturalists. They grew corn and squash and beans, and also moved around hunting game and gathering wild plants as necessary.

Where we see red admixture in Haak’s graph, that means Siberian people. Where we see dark blue + orange + teal, that’s typical European. Most likely this means that the Algonquins in Haak’s data have some recent European ancestors due to a lot of inter-marriage happening over the past few hundred years in their part of the world. (The Chipewyans live in a much more isolated part of the continent.) However, some of that DNA might also have come with them when they migrated to North America years and yeas ago, due to their ancient Siberian ancestors having merged with an off-shoot of the same groups that modern Europeans are descended from. This is a likely explanation for the Aleuts and Tlingit peoples, whose dark blue and teal patches definitely look similar to those of other Siberian peoples. (Although, interestingly, they lack the red. Maybe the red was a later addition, or just didn’t make it over there in as large quantities.)

The Eskimo I have spoken of before; they appear to have wiped out everyone else in their immediate area. They live around the coastal rim of Alaska and northern Canada.

The Aleuts likely represent some kind of merger between the Eskimo and other Siberian peoples.

 

My summary interpretation:

Wave One: The Green People. Traces of their DNA appear to be in the Ojibwe, Eskimos, and Chileans, so they may have covered most of North and South America at one time.

Wave Two: The Pink People. They wiped out the vast majority of the Green people throughout North America, but as migration thinned their numbers, they ended up intermarrying instead of killing some of the Greens down in Central and South America.

The Green People only survived in any significant numbers deep in the rainforest, where the Pink People couldn’t reach. These Greens became the Karitiana.

Wave Three: The Brown people. These guys wiped out all of the Pink people in northwest Canada and Alaska, but as migration to the east thinned their numbers, they had to inter-marry with the local Pinks. This mixed group became the Algonquins, while the unmixed Browns became the Chipewyans.

Few Browns managed to push their way south, either because they just haven’t had enough time, or because they aren’t suited to the hotter climate. Either way, most of the Pink People went unconquered to the south, allowing the Pima and their neighbors to flourish.

Wave Four: The Eskimo, who wiped out most of the other people in their area.

 

Theory: the inverse relationship between warfare and homicide

That whole myth about hunter-gatherers being peaceful and non-violent probably got its start because hunter-gatherers tend not to be as good at organized warfare as the Germans.

Homicide is an act of disorganized impulsive passion; warfare is an act of organized dispassion; the two are inverse of each other. Thus we see the highest homicide rates in the world’s least developed countries, and the lowest rates in its most developed countries.

 

Note that it is not an absolutely perfect correlation; many Latin American or Caribbean countries have higher homicide rates than even less-developed countries in Africa, but broadly speaking, the pinks and reds are poorer than the blues. (Russia excepted, ‘cuz Russia.)

Also, as you may recall:

Share of violent deaths, non-state societies vs. state societies

Countries involved in the world’s biggest wars:

WWI:

Nuclear stockpiles or programs by country:

(South Africa used to have nukes, but they got rid of them before the end of Apartheid.)

Here’s another graph that makes the size of the arsenals clear:

Source: SMTKS

And here’s another graph that says about the same thing, but is a wonderful example of how to display data:

Source: SMNTKS

I’m pretty sure this graph means we’re all going to die.

And likewise, space programs by country:

Also a nicely done graphic.

You might have heard about India’s space program:

Test launch of India’s GSLV Mk III

But have you heard of the Congolese space program?

To be fair, it’s more “One guy with a rocket-building hobby” than a real space program, but I understand where he’s coming from. Rockets are cool.

The point of all of these maps and graphs is that homicide rates tend to be highest, both today and throughout history, in the places with the lowest levels of social organization/complexity.

Even in our own society, convicted criminals are overwhelmingly lacking in the ability to handle complexity. It looks like they aren’t really all that much more retarded (note: PDF) than the general population (the truly intellectually impaired are often pretty highly supervised and lack the ability to execute many crimes, but are often victims of violence,) but they are drawn disproportionately from the dumber half.

According to respondents in the AR15.com forum thread “Cops and Lawyers – What percent of criminals/clients are retarded?” (Note: I know nothing about this forum or its reliability)

“Not retarded per se. My personal experience is most criminals stopped developing emotionally at about 3 or 4. They live life for the moment, think only of themselves, have no impulse control, can’t control their emotions, throw temper tantrums when they don’t get their way, can’t think past the next 10 minutes, don’t understand consequence, etc……. They are basically little children in adult bodies. Of course, most 3 or 4 year olds are better behaved than the average criminal, but you get the point.”

“I found that better than 90% of them were functionally illiterate, so when they say reading is fundamental, they aren’t kidding!”

“With the advent of welfare, it became profitable to squirt out children.It relegated men to the status of semen injectors. No men, no fathering. down the spiral 40 odd years and we’ve got multiple generations of female children “raising” children.
The results aren’t retarded, they are more like Comanches or Lakota, they have regressed several thousand years.
It is painful to watch good officers try to “reach” these kids. Watching with an unsympathetic eye, it is plain that most of these kids don’t even understand what the officers are talking about.
That’s the brutal truth that no one wants to face. These kids aren’t just lost-they are damned in our society.”

Recall our discussion back in Two Kinds of Dumb–just because someone has a low IQ, doesn’t mean they are retarded. But anyone who is illiterate (in our society) with the emotional maturity of a 3 or 4 your old is not very bright or capable of thinking through the results of their own actions.

The art of killing large numbers of people, by contrast, requires organization. One guy with a pointy stick might kill a few dozen guys who don’t have pointy sticks, but one guy who convince a thousand other guys to stand next to you with their pointy sticks, and you get this:

Source: Chapleton

The Romans didn’t conquer an empire by poking barbarians with pointy sticks; they did it by organizing themselves into an unstoppable war machine.

Armies do not generally fund themselves; they depend upon a vast support structure producing weapons, food, transportation, shelter, technology, etc. The bigger the army and more advanced the weaponry, the bigger the support structure has to be. Nukes take far more people to produce than pointy sticks, from the farmers making the food to feed the scientists working out the details to the structural engineers building the research labs to the guys building the rockets or planes to drop the bombs.

Complex organization requires large numbers of people working in close proximity without punching each other; it requires that people be able to suppress their own personal desires in pursuit of the group goal. All of this requires being less violent, less impulsive, and less inclined toward murdering each other.