I spend all day yesterday at SEAC (Jackson, Mississippi) in the Paleoindian symposium organized by Scott Jones. There were lots of interesting papers -- among the best parts of these kinds of gatherings is being able to sit in a room and watch person after person talk about what they've been doing, what they've learned, what they think is important or interesting, etc. It's not necessarily the best way to get command of all the minutia of the work we do, but it is the best way to get a feel for what's going on across multiple regions, what people in different research programs have been working on, etc.  

One of the interesting aspects of a symposium like this is that you can see patterns of interest emerge -- different people working on different parts of the same problems in different regions.  As the discussant for the session, Joe Gingerich organized his thoughts on the papers along three main lines: landscape, technology, and issues of society. These articulate with one another in all kinds of interesting ways. The papers in the session as well as the "after session" discussions I had at the bar and at dinner made me optimistic that maybe we really are heading into an era where we can have some substantive discussions about Paleoindian societies that make innovative use of all the new data that have been gathered over the last few decades.

Anyway, I think my paper went well. I basically set out to ask if/how we can gain some traction on understanding how Paleoindian societies were organized internally in terms of their constituent "building block" parts: families, foraging groups, maximal bands, etc. This is a question where multiple lines of evidence can be brought to bear. That doesn't mean, however, that it's easy to answer. I think we have enough in front of us now from across the Eastern Woodlands, however, that we can take a hard look at it and try to move the ball forward. Here is a pdf of my presentation. I also put it in on my Academia page.

Also, for the record: as far as I can recall, the Jackson, MS, airport is the only airport I have ever been in where the coffee shop also sells cold bottles of beer. 

I'm currently in Tulsa, OK, at the 2017 Southeastern Archaeological Conference. I took a break this afternoon from papers and talking to hole up in my hotel room and put the finishing touches on the presentation I'll be giving tomorrow. I'm honored to be senior author on a paper with David Anderson (University of Tennessee). Our paper will be last tomorrow in a marathon symposium organized by Shane Miller (Mississippi State University), Ashley Smallwood (University of West Georgia), and Jesse Tune (Fort Lewis College).

I'm really looking forward to the session, which will present summaries, updates, and syntheses of work from across the Southeast. It's intended to be a 20-year update to the work that culminated in the landmark Paleoindian and Early Archaic Southeast volume that was published in 1996. Congratulations are due to the organizers who conceived of the symposium and pulled it off.

I briefly discussed our paper back in September. Significant work has happened since then, and I'm pretty happy with the result. The point of doing a "big" paper like this, in my view, is to attempt to identify and describe patterns that require explanation. We used information from three large datasets -- PIDBA, DINAA, and an always "in progress" compilation of radiocarbon dates -- to investigate patterns of population stability/fluctuation during the Paleoindian period in the Eastern Woodlands.

As of now (rushing through this blog post so I can go out to dinner) I like the result: a six period chronological/geographical model identifying the time/space parameters of population stabilities and fluctuations. As I listen tomorrow to region-by-region updates on what we know about the Paleoindian period in the Southeast, I will almost certainly learn of many things that are wrong. But I will be listening to the results of others' work with a model in mind. That's useful. As the famous quote goes: "all models are wrong, but some are useful." To me, a useful model is a machine for thinking that makes predictions about the world that can be evaluated. So I'm looking forward to seeing what I got wrong. I wish I had a big piece of paper I could spread out on a table so I could take notes time period by time period, region by region.

After this updated photograph of Woody Guthrie, I'll post images of a few key slides from the presentation. I'll put the whole thing on my Academia page tomorrow after the dust settles. [Update 11/13/2017: the presentation is available here.]

I'm happy to announce that my recent paper on the minimum viable population (MVP) size of hunter-gatherer populations is now officially published and available for download from the Journal of Artificial Societies and Social Simulation (JASSS).  JASSS is open access, meaning anyone can access any paper at any time. It's the way to go, and I wish all journals could figure out how to play nicely with the public.

The issue of how many hunter-gatherers it takes to form a population that can sustain itself over a long period of time is relevant to understanding several issues, including: (1) how hunter-gatherer societies colonized empty landscapes; (2) how/why hunter-gatherer societies take on the forms that they do in different environments; (3) how/why/when those societies change in response to factors such as population growth.

The classic papers on the lower size limits of hunter-gatherer populations were published by Martin Wobst in the 1970's. Like him, I employ model-based approach to address the issue of how big a human population has to be to not be threatened by random fluctuations in mortality, fertility, and the ratio of males to females. Very small populations are more sensitive to those random fluctuations because each person makes up a greater percentage of the population. 

My analysis suggested that, under a range of conditions represented in the model, human populations with more than about 150 people were fairly safe over long periods of time.  That's a smaller lower size limit, I think, than a lot of people conceive of.

Here is the abstract:

"A non-spatial agent-based model is used to explore how marriage behaviors and fertility affect the minimum population size required for hunter-gatherer systems to be demographically viable. The model incorporates representations of person- and household-level constraints and behaviors affecting marriage, reproduction, and mortality. Results suggest that, under a variety of circumstances, a stable population size of about 150 persons is demographically viable in the sense that it is largely immune from extinction through normal stochastic perturbations in mortality, fertility, and sex ratio. Less restrictive marriage rules enhance the viability of small populations by making it possible to capitalize on a greater proportion of the finite female reproductive span and compensate for random fluctuations in the balance of males and females."
  

If you're interested in hunter-gatherer theory stuff, have a look and see what you think. This is probably the first paper of several I'll be writing on the topic.

I'm happy to announce the publication of a new paper of mine in The Journal of Artificial Societies and Social Simulation (JASSS). JASSS is an open access journal focusing on the use of computer simulations as a tool for understanding social systems. I love publishing papers that anyone can get to at any time, without requiring logins, subscriptions, or fees. I wish every paper could be open access, and I wish I had the funds at my disposal to throw money at journals like JASSS to support such efforts. If I ever do have the money, that's the direction I'm going to throw it.

My paper, titled "A Model-Based Analysis of the Minimum Size of Demographically-Viable Hunter-Gatherer Populations" will appear in Volume 20, Issue 4 (due to be released on October 31). You can read the paper online here. It should be available in pdf form soon.

If you really want to get into the nitty gritty, the raw model code and an explanation are available here.
​
The focus of the paper using an agent-based model to revisit the question of how large human groups have to be to be demographically viable (i.e., able to survive over the course of many generations). This is a key question for understanding the size and structure of ethnographically- and archaeologically-known hunter-gatherer social systems as well as fleshing out scenarios of hunter-gatherer groups colonizing empty landscapes. Here is the abstract:

"A non-spatial agent-based model is used to explore how marriage behaviors and fertility affect the minimum population size required for hunter-gatherer systems to be demographically viable. The model incorporates representations of person- and household-level constraints and behaviors affecting marriage, reproduction, and mortality. Results suggest that, under a variety of circumstances, a stable population size of about 150 persons is demographically viable in the sense that it is largely immune from extinction through normal stochastic perturbations in mortality, fertility, and sex ratio. Less restrictive marriage rules enhance the viability of small populations by making it possible to capitalize on a greater proportion of the finite female reproductive span and compensate for random fluctuations in the balance of males and females."

My main finding is that, under the varying conditions I investigate with my model, I find no support for the often-repeated idea that a society of about 500 persons is required to ensure demographic viability.  Students of American anthropological archaeology -- especially, I suspect, those of us that went to the University of Michigan or were taught by U of M alums -- will immediately recognize the "magic number 500" as a concept that emerged from the research of Joseph Birdsell and (later) H. Martin Wobst. As I discuss in the paper, I think neither Birdsell nor Wobst intended the number 500 to take on the meaning that it did -- it became a kind of shorthand gloss for setting a general lower boundary on the size of hunter-gatherer social systems.

My modeling results suggest that the number of people required for demographic viability can be safely pushed down south of 200.  In over 67,000 model runs (under varying conditions of mortality, fertility, and marriage rules) where the mean population exceeded 150 people, the population went extinct only nine times.  I'd take those odds.

All the modeling was done under conditions with no logistical constraints to identifying and obtaining marriage partners:  no spatial component to interaction, no impediments to the flow of information. Logically, putting the model systems in space and dispersing the populations across a social/physical landscape would have the ultimate effect of raising the population size required for demographic viability. Would it double or triple it, though? I highly doubt it.  But the great thing about modeling is that we don't have to be satisfied to simply suppose things -- we can model the problem.  Understanding that less than 200 people are required for demographic viability assuming no interaction issues, we can then unpack the issue to ask why hunter-gatherer societies are often much larger. What role does the structure of mobility play? What about the need to maintain a geographically-extensive social fabric to buffer large-scale environmental variability? Here are a couple of paragraphs from my conclusion:
​

It already sounds like a paper title -- just replace what's after the colon with "A Model-Based Approach."

I'm coming up on the end of my second year in South Carolina. I think it takes a few annual cycles before you start to "get" the rhythms and tempos of seasonality in a new environment. Prior to coming here I had lived in the Midwest for most of my life, so there's a lot to learn. 

As an archaeologist, I don't try to understand the environment just so I can give it a round of applause (if I had to pick what to applaud here, however, it probably would be the birds, flowers, and insects). Human societies and natural environments are inter-linked in numerous and  complex ways -- figuring out those linkages and understanding how the "social" and "natural" parts of those coupled systems affect one another is an intrinsically interesting and profoundly important part of understanding how human societies work and how they changed in the past.

My point in writing this isn't to compose a fully-formed, well-researched argument, but rather to jot down a few observations/ideas/questions that have struck me since I transplanted myself into a region of the country with environments that are, in many ways, dissimilar from those of the Midcontinental interior with which I am most familiar (i.e., the Ohio Valley, the Till Plains, the Great Lakes). I don't have time to pull all these strings yet -- I'm just noting them.

First, the Deer . . .

Early on, I commented on what must be differences in the demography and behavior of a key Holocene large game species (white-tailed deer) across the different regions of the Eastern Woodlands. One would expect that those regional differences -- whatever they are -- would have articulated somehow with the behaviors of the human populations that exploited them.  Generally, we presume that periodic (i.e., seasonal) aggregations of hunter-gatherer populations are useful to those societies for a number of demographic and social reasons. Logically, aggregations of large numbers of people have to take place when and where the resource base can support them. I would guess that most archaeologists in the north have a "fall aggregation" model in their heads, based in part on when deer are the fattest and least cautious. Are those conditions different in the Southeast, where the seasonal gradient is much less severe than in the north?  Do deer populations go through boom/bust cycles? If so, are those linked to periodicities in mast production? Do those periodicities differ from region to region in the Eastern Woodlands? Deer hunting isn't everything, but it's surely something.

​Second, the Sea . . .

At some recent conference, I had a conversation with a colleague who has been working in this region for a long time. It was clear he had had a few drinks, so he was probably telling me the truth. He said that the rhythms and tempos of hunting and gathering on the coast are very different than in the interior. I've never done coastal archaeology -- when I go to the beach it's usually to let the kids play, watch birds, and look for shells.

We were at Edisto last year during the time when the loggerhead sea turtles come ashore to lay their eggs. These are big animals, with adults weighing about 300 pounds (up to about 1000 pounds). The females come ashore at night during the summer to lay about 120 eggs in a nest in the sand. 

Watching the Edisto turtle patrol identify and check nests every morning, I became curious about how turtle nesting behavior articulated with prehistoric coastal hunter-gatherers in this region. The nests are easily spotted by the tread-like path that turtles leave as they move across the sand. Caught in the act, the adult turtles are large packages of meat, sitting in the open, defenseless. Presumably a couple of people could flip one on its back and return later for an on-the-spot feast or to butcher the animal.

How much archaeological evidence is there of sea turtle exploitation on the Carolina coast? Does it change through time? Where would sea turtles rank in terms of a seasonally-predictable resource that could be used to support periodic aggregations? Were sea turtles part of coastal Carolina hunter-gatherer cosmology (perhaps in connection with the summer solstice)? I don't know the answers to any of these questions.

Third, the Air . . .

The birds here are beautiful, plentiful, varied, and constant. Of the 914 species of birds documented in the United States, over 400 occur in South Carolina. That's a lot of birds. Some sing all year round. Some even sing at night. It's fabulous.

One bird I have learned about since I moved here is the Mississippi Kite. It is a smallish, grey raptor that winters in South America but breeds in the southeastern United States.

These birds eat mostly flying insects, and you can see them circling over my neighborhood during much of the summer. Their appearance in the region seems to coincide with what I interpret as the "high" insect season -- the cicadas are hatching in force and there are things buzzing around everywhere. They're a signal of a season change here, perhaps much in the same way as the yearly arrival of Turkey Vultures north of the Ohio River. 

However the annual long-distance migration/breeding pattern of the kites evolved, I would guess that the dense insect populations of the Southeast are a key to making it viable. That got me thinking about the effects of longer-term periodicities, particularly the those of the 13-year and 17-year periodical cicadas. The emergence of buhzillions of cicadas at the same time would surely make for easy living for the kites, as well as for game animals with an insect-based diet (e.g., turkeys). The periodical cicadas tend to damage trees, however, which reduces mast production (and hence could have a suppressing effect on deer populations). Did any of this factor into the characteristics (social, behavioral, cosmological, etc.) of the prehistoric human societies of this region? I don't know.

Finally, from the Periodic to the Anomalous . . .

The completion of my second year in Columbia will be marked by a total solar eclipse that I'll be able to experience from my backyard on August 21 at 2:41 p.m. I've never seen a total eclipse before, and I may never see one again. Most people don't see one in their lifetime. I'm really looking forward to it. Thankfully I won't have to stay up late at night to see it.

Obviously, it's now old hat for us to predict these "anomalous" astronomical alignments with a great deal of accuracy (business depends on it). Given how infrequently these things occur and the low probability of any one person accidentally being in the right place at the right time to witness it, it's natural to wonder what prehistoric peoples would have made of this sort of phenomenon. I'm really curious as to what it will feel like to experience it firsthand (I'd also like to know what's it like to be in a hurricane, to break the sound barrier, to be close to a tornado, to fly at the edge of the atmosphere, to experience zero gravity, etc., in case your looking for ideas for my birthday).

So What?

Somewhere in all this mess, there's a question to be crystalized about how human societies "tune" themselves to the predictable and unpredictable fluctuations in their environments. What are the feedbacks? What are the dampers? What are the common denominators? What is the range of risk/variability that societies create cultural rules or behaviors to respond to? What happens when the needle moves outside of that range? Which parts are robust? Which parts break? How do responses scale to the size and predictability of perturbations across time and space?  I have no answers right now, just questions.

And now I've got to move on and do other things.

I've loaded a pdf version of my 2016 SEAC presentation "Social Implications of Large-Scale Demographic Change During the Early Archaic Period in the Southeast" onto my Academia.edu page (you can also access a copy here). Other than a few minor alterations to complete the citations and adjust the slides to get rid of the animations, it's what I presented at the meetings last Friday. I tend to use slides as prompts for speaking, so some of the information that I tried to convey isn't directly represented on the slides. There's enough there that you can get a pretty good idea, I hope, of what I was going for.

One of the major things I took home from this conference was that there has been an important broadening of enthusiasm for subjects that used to be considered bizarre, baseless, unscientific, and even too political for archaeology. I got the impression that talking about ritual, symbolism, and belief systems (hot topics for decades among those who focus on the materially-rich Middle Woodland and Mississippian "florescences" of the Eastern Woodlands) is now also quite common among those who work on the Paleoindian and Archaic periods.  I saw numerous papers asking new questions about material remains, and they were fascinating.

The session that really brought the point home was a symposim titled "A Ritual Gathering: Celeberating the Work of Cheryl Claassen" (Session 3 in the program).  Claassen, a professor at Appalachian State, has been pushing the boundaries of the archaeological conversation in the Eastern Woodlands for decades (you can see some of her work on her Academia.edu page). The papers in this session (many by her students) evoked responses in me ranging from "what a profoundly interesting thought" to "are you sure about that?" to "get off my case."  It was great.

(As an aside, I wish that some of my friends on the "fringe" could have seen these papers. Perhaps if you witnessed a professional archaeologist discussing how the skeletal remains of immature bird wings in a feature were connected to the astronomical scheduling of seasonal ritual aggregation events, you'd have a better appreciation both for the kinds of questions that actual archaeology can address and the level of work it takes to convincingly address those questions. The claim that archaeologists are afraid to say anything new or different is preposterous.)

I want to state clearly that, in my opinion, the expansion of thought that was on display in the Claassen session is a positive thing with a lot of potential upside.  As an advocate of a complex systems approach to understanding human cultures in the past, it makes perfect sense to me that ritual and belief are involved in both "bottom up" and "top down" aspects of human societies. I see no logical or analytical reason to assume that ritual and belief are epiphenomenal or unimportant compared to other domains of social, economic, and political life. It all matters, and it's all fair game for trying to flesh out the past as best we can and trying to explain, using all the tools at our disposal, how those societies worked and why and how they changed. 

For me, however, my positive regard for the role of belief and ritual in human societies (and for the appropriateness of including it in our discussions) doesn't alleviate concerns about how we study it in the past tense. I know that I'm not alone here. I think several legitimate worries underlie uncertainties about both the approaches and the conclusions reached by those focused on belief and ritual.

One concern that's out there -- perhaps the major one -- is a feeling that the "ritual" people are jumping outside the established lines of scientific process in a way that undermines confidence in their conclusions. Talking with a few of my colleagues about this, I got the sense that people are not closed to the questions so much as they are skeptical of the methods (or the perceived lack of methods) used to address those questions. 

I conceive of science as an inductive-deductive loop. On the inductive side, you create an explanation to fit a bunch of data.  On the deductive side, you collect new information to test an expectation derived from your explanation. Ideally, the two sides of the loop are exploited together to create (eventually) a credible explanation that fits all the available information and makes further predictions about the world that are falsifiable but not falsified. As long as you get yourself into this loop, you're doing science. It doesn't really matter what the starting point is or where an idea comes from as long as you're willing to follow through and ride the inductive-deductive roller coaster around the track for as long as it takes.

Are there ways to skeptically evaluate ideas about Archaic ritual and belief systems and make sure we're utilizing the full power of the inductive-deductive loop?  I'm sure that there are. What I'm less sure of, at this point anyway, is the presence of an appetite for the deductive side of the loop that matches the robust enthusiasm for climbing up the inductive side. No matter how interesting or appealing an interpretation is, you still have to put on the skeptic glasses and try to find the seams you can follow to figure out whether you're right or wrong.  

The inductive-deductive loop is critical in archaeology because of all of our equifinality problems: there's usually more than one way something could have happened, so how do you know what the real cause was? You have to do the work to assemble independent lines of evidence, build theory, collect data, construct and test hypotheses, etc. You can't skip all that and just hug an assertion. Well, you can, but I won't buy what you're selling.

That leads me to a second concern: the burden of proof. Who's is it? Does it have to reside in one domain of inquiry, or is it the responsibility of the person making the claim no matter what the claim actually is? At one point in the session I heard the phrase "can you prove it's not a ritual assemblage?" I take the point of the question (which was used mainly, I think, to argue that we should always consider ritual as a possibility), but I'm uncomfortable with the notion that we should accept/assume that something is related to ritual unless we can prove it's not.  I think we all realize that people's lives are often not partitioned neatly into "ritual" and "non-ritual" components, but that doesn't mean all activities should be presumed to be ritualistic in nature unless we can prove they're not. That seems to me to be out of bounds of the way good science is done.  There has to be a positive case made for a claim, whether it's about ritual or not.

And that brings me to my third concern: the appeal to human "universals" to gird claims about past ritual behavior. Several times, in several different papers, I heard the assertion that all humans share a basic set of experiences in the material world and therefore all belief systems share a similar set of components tied to that material world: fire transforms, the sky is above and the earth is below, water goes down and smoke goes up, etc. This seems logical and may well be true (I haven't yet read through the arguments to evaluate them on my own).  My concern is not that such universals don't exist, but that playing the "universal" card as the basis for analysis rather than an empirical problem may do two counter-productive things: (1) short circuit the inductive-deductive cycle by introducing a powerful, unvetted assumption; and (2) actually bland out the kind of contextual variability that could potentially be very interesting and analytically useful.

This last point is somewhat ironic.  Many of the issues that the pursuit of ritual and belief articulates with have a particularly "post-processual" flavor. One of the main critiques leveled at the processual archaeology of the late twentieth century was that it didn't account for the meanings of objects in their contexts. Symbols and objects do not mean the same things in different cultures: context matters. It seems to me that by falling back to "universals" as explanation we're actually ignoring context altogether -- if something is present everywhere, what meaning does it actually have?

One of my professors at Southern Illinois University was fond of repeating the phrase "playing ethnosemantic tennis with the net down" (if my memory serves me right, he used the phrase in connection with criticisms of Claude Levi-Strauss).  If we lay down a foundation of presumed "universals" and then build an analysis based on those, I worry that we're lowering the net significantly if not taking it down altogether. Opening things up is great for generating discussion and new approaches, but at some point the net has to go back up so we can have some mechanism for discriminating between credible and non-credible explanations. 

I'm excited by what I saw and heard at SEAC. We've still got a long way to go to address many basic space-time issues for some of the questions that I and many others are interested in. That doesn't mean, of course, that we can't think about other additional things while that's going on. I bought Claassen's (2015) book Beliefs and Rituals in Archaic Eastern North America at SEAC. I look forward to seeing what's inside and comparing it to my own views and knowledge about the eastern Archaic. Nothing that I've said in this post should be construed as pointing at the content of the book, which I have not read yet. I anticipate the book will be a stimulating read. Should be fun!

Archaeological conferences serve several purposes. For me, there are three main attractions, all selfish: (1) meeting people; (2) learning about things I didn't know that I didn't know about; and (3) clarifying and catalyzing my own research. Conferences are fun, but they're also a bit mercenary -- I want something from them.

This year's Southeastern Archaeological Conference (SEAC) is in Athens, Georgia, which I hear is very nice. I put together a small symposium titled "Hunter-Gatherer Societies of the Late Pleistocene and Early Holocene Southeast" (session 35 in the program). I originally wrote about the idea last April. We ended up with papers by seven presenters: Al Goodyear, Doug Sain, David Thulman and Maile Neel, Kara Bridgman Sweeney, Joe Wilkinson, Sarah Gilleland, and me. Here is the symposium abstract:

"Societies are groups of people defined by persistent social interaction.  While the characteristics of the late Pleistocene and early Holocene hunter-gatherer societies of the Southeast certainly varied, archaeological data generally suggest that these societies were often geographically extensive and structurally complex.  Patterns of artifact variability and transport, for example, demonstrate that small-scale elements (e.g., individuals, families, and foraging groups) were situated within much larger social fabrics. This session aims to explore the size, structure, and characteristics of early Southeastern hunter-gatherer societies, asking how patterns of face-to-face interactions at human scales “map up” to and are affected by larger social spheres." 

I decided to use my contribution to think about the issue of a possible abandonment of the deep south during the later portion of the Early Archaic period. Here is the abstract for my presentation, titled "Social Implications of Large-Scale Demographic Change during the Early Archaic Period in the Southeast:"
 
"Previous studies of radiocarbon and projectile point distribution data have suggested the possibility of a significant shift in the distribution and/or behaviors of human populations during the later portion of the Early Archaic period (i.e., post-9000 RCYBP). This paper considers the evidence for an “abandonment” of large portions of the Southeast following the Kirk Corner Notched Horizon and explores (1) possible explanations for large-scale changes in the distribution of population in the Early Holocene and (2) how those demographic changes, if they occurred, might have articulated with social changes at the level of the family, foraging group, and larger societies."  

I first became interested in the Early Archaic abandonment issue while reading Ken Sassaman's (2010) book Eastern Archaic, Historicized. Working on this presentation was fun because it forced me to try to think through some of the issues about how we would recognize a large-scale abandonment, what the abandonment process actually would have been like, and what the social ramifications might have been for the people and societies involved in that process. I'll tweak the presentation before I give it, but it's pretty close to done.

​The first question is to ask is whether or not there was a large-scale abandonment of parts of the Southeast. On the surface (at least), I think the case is fairly compelling. Following the example of Faught and Waggoner's (2012) paper about Florida, I started compiling radiocarbon data from across the Eastern Woodlands to evaluate the idea. At 9,500 dates and counting, the radiocarbon database that I'm working on clearly supports the idea that there are far fewer than expected dates from 9000-7000 radiocarbon years before present (RCYBP) in the deep south:

A chi square easily defeats the null hypothesis: there just aren't as many radiocarbon dates from 9000-7000 RCYBP below the southern corner of South Carolina as you'd expect by chance. The pattern holds when you consider the number of dates during that period in the entire Atlantic Plain vs. the other major physiographic regions of the eastern United States (the Appalachian Highlands and the Interior Plains). 

The idea of a large-scale abandonment is also consistent with the distribution of post-Kirk lobed/bifurcate projectile points, which (unlike Kirk), does not extend into Louisiana, Florida, and southern Mississippi, Alabama, and Georgia.

If we presume that a post-Kirk abandonment/marginalization of the Atlantic Plain did occur, we can move on to the "why" and "how" questions. Regarding the "why" question: the limited environmental data I've looked at (e.g., the 1980 pollen core from White Pond, South Carolina) suggest that the period 9000-7000 RCYBP was one of significant change.  Oak and hickory decreased and pine increased. In simplest terms, this shift may have been related to a decrease in mast production, perhaps affecting the density of white-tailed deer (probably the primary game species for early Holocene hunter-gatherers in the Eastern Woodlands).

But how would an abandonment actually take place? I can think of several ways that populations could shift out of an area. My gut is that an abandonment of the Atlantic Plain during the late Early Archaic would have most probably involved a contraction of populations into the Appalachian Highlands and Interior Plains. One of my favorite of Lew Binford's papers is his (1983) discussion of how hunter-gatherers often make extensive use of the landscape. Keeping his examples in mind, it's easy to imagine how "abandonment" could actually be the end result of a long-term process involving segments of the population getting "pulled in" to better quality environments in the course of normal decisions about movement.

Assuming population size stayed constant, this shift would have necessarily involved changes in mobility. If (based on Midwestern data) we assume that Kirk "bands" had a group mobility radius of about 200 km, there would have been room for about 18 such "bands" in the Eastern Woodlands. If you took that same population and crammed them into an area 33% smaller (i.e., the Eastern Woodlands minus the Atlantic Plain), the scale of group mobility would have to be reduced by 17% (mobility radius of 165 km) to keep everything else the same.

That level of population contraction would have almost certainly had ramifications up and down the levels of those post-Kirk societies. Residential moves would have decreased in frequency and/or distance, there may have been shifts in logistical vs. foraging strategies, and the lowered "cost" of maintaining extra-local inter-personal relationships may have de-emphasized gift exchange and inter-group marriage as mechanism for creating and maintaining distant social ties. 

It's possible to develop a suite of hypotheses and archaeological expectations to evaluate the idea of a large scale abandonment. 

Make no mistake: these are long-term propositions.  My entire dissertation, for example, was focused on using a combination of modeling and archaeological data to try to understand how changes in patterns of variability in material culture were related to changes in the characteristics and properties of social networks. It's not trivia, and it's not easy. 

For me, this presentation was a machine for thinking. I can't "prove" anything, but going through the process of committing to an idea and preparing a presentation has forced me to attempt to think through some complex, interesting issues. I'm hoping I'll get some good feedback on my ideas ("interesting" and/or "you're full of it"), which obviously involve an extensive geographic area that I make no claim to have mastered. 

I also hope to take full advantage of my hotel and at least quadruple my supply of ink pens. Every little bit helps.

We're now into the fourth week of the semester here at the University of South Carolina. As usual I've been writing for this blog less than I'd like (I have several unfinished draft posts and ideas for several more, and there's currently a backlog of Fake Hercules Swords). A good chunk of my time/energy is going into the Forbidden Archaeology class (you can follow along on the course website if you like -- I've been writing short synopses, and student-produced content will begin to appear a few weeks from now). Much of the remainder has gone into pushing forward the inter-locking components of my research agenda. This is a brief update about those pieces.

Small-Scale Archaeological Data

At the beginning of the summer I spent a little time in the field doing some preliminary excavation work at a site that contains (minimally) an intact Archaic component buried about 1.9 meters below the surface (see this quick summary).  Based on the general pattern here in the Carolina Piedmont and a couple of projectile points recovered from the slump at the base of the profile, my guess is that buried cultural zone dates to the Middle Archaic period (i.e., about 8000-5000 years ago).​

My daughter washed some of the artifacts from the site over the summer, and I've now got an undergraduate student working on finishing up the washing before moving on to cataloging and labeling. Once the lithics are labeled we'll be able to spread everything out and start fitting the quartz chipping debris back together. Because I piece-plotted the large majority of the lithic debris, fitting it back together will help us understand how the deposit was created. I'm hoping we can get some good insights into the very small-scale behaviors that created the lithic deposit (i.e.,perhaps the excavated portion of the deposit was created by just one or two people over the course of less than an hour).

When the archaeology faculty met to discuss the classes we'd be offering in the spring semester, I pitched the idea of running a one-day-per-week field school at the site. Assuming I can get sufficient enrollment numbers, that looks like it's going to happen. The site is within driving distance of Columbia, so we'll be commuting every Friday (leaving campus at 8:00 and returning by 4:00). The course will be listed as ANTH 322/722. It's sand, it's three dimensional, and it's pretty complicated -- it's going to be a fun excavation. I'll be looking to hire a graduate student to assist me on Fridays, and I'll be applying for grant monies to cover the costs of the field assistant's wages, transportation, and other costs associated with putting a crew in the field. 

Large-Scale Archaeological Data

Some parts of my quest to assemble several different large-scale datasets are creeping along, some are moving forward nicely, and some are still on pause.

Complex Systems Theory and Computer Modeling

Complex systems theory is what will make it possible to bridge the small and large scales of data that I'm collecting. Last year, I invested some effort into transferring my latest computer model (FN3_D_V3) into Repast Simphony and getting it working. I also started building a brand new, simpler model to look at equifinality issues associated with interpreting patterns of lithic transport (specifically to address the question of whether or not we can differentiate patterns of transport produced via group mobility, personal mobility between groups, and exchange).  

As it currently sits, the FN3_D_V3 model is mainly demographic, lacking a spatial component. Over the summer I used it to produce data relevant to understanding the minimum viable population (MVP) size of human groups. Those data, which I'm currently in the process of analyzing, suggest to me that the "magic number of 500" is probably much too large: I have yet to find evidence in my data that human populations limited to about 150 people are not demographically viable over spans of several hundred years even under constrained marriage rules. But I've just started the analysis, so we'll see. I submitted a paper on this topic years ago with a much cruder model and didn't have the stomach to attempt to use that model to address the reviewers' comments. I'm hoping to utilize much of the background and structure of that earlier paper and produce a new draft for submission quickly. I also plan to put the FN3_D_V3 code online here and at OpenABM.org once I get it cleaned up a bit. I also discuss this model in a paper in a new edited volume titled Uncertainty and Sensitivity Analysis in Archaeological Computational Modeling (edited by Marieka Brouwer Burg, Hans Peeters, and William Lovis). 

It will be a relatively simple thing to use the FN3_D_V3 model in its non-spatial configuration to produce new data relevant to the Middle Paleolithic mortality issue I discussed at the SAA meetings a couple of years ago. I'm also going to be working toward putting the guts of the demographic model into a spatial context. That's going to take some time.

I've been spending most of my discretionary work time over the last couple of weeks grinding through the process of getting my computer models up and running again. The main challenges have involved converting my models from Repast J to Repast Simphony. While the Java components are the same, the "world" of the models is structured differently in Simphony. So I've had to try to figure out how to re-connect the various parts of the models using what Simphony calls "context."  I can't yet say I fully understand how "context" works, but I got my ForagerNet3_Demography_V3 (FN3_D_V3) model up and running by trial and error and looking at examples of code from other models.   

Since I haven't figured out to configure the model to use the batch run GUI (I haven't even been able to find it yet, although it apparently exists somewhere in Eclipse), I've been using a primitive parameters file to do batch runs. As I wrote on Friday, these batches would throw an "Out of Memory" error and freeze up around the fortieth run. That suggested some kind of memory leak where object produced during a run were not being deleted before the next run. The gradual accumulation of unused objects eats up the memory until there isn't any left to use to run the model, then it dies.

After going through the code several times and trying a bunch of options, I think I finally found the culprit(s) and made the corrections.  I set the model to run 500 times a couple of days ago, and things seemed to be chugging along just fine (when I got to my office this morning it was at run number 720-something, so clearly I didn't have the "stop" command implemented correctly).  Anyway, I've  now got a batch of new data that I can compare with data produced by the model when it was implemented in Repast J.  The figure below compares old model data (left) with new model data (right).  It is gratifying to see the model is behaving the same.

The data on the left are from a paper of mine ("The Sensitivity of Demographic Characteristics to the Strength of the Population Stabilizing Mechanism in a Model Hunter-Gatherer System") that will be published in an upcoming volume titled Uncertainty and Sensitivity Analysis in Archaeological Computational Modeling (edited by Marieka Brouwer Burg, J. H. M. Peeters, and William A. Lovis; Springer).

I'm happy that this model is back in business. I'll do some more testing to make certain everything is working, then I'll clean up the code and make it available on this website and under my profile at OpenABM. I plan to use this model for some work on the demographic viability of small populations and, perhaps, to push ahead with exploring demography, mortality, and fertility during the Middle Paleolithic.