Andy White Anthropology
  • Home
  • Research Interests
    • Complexity Science
    • Prehistoric Social Networks
    • Eastern Woodlands Prehistory
    • Ancient Giants
  • Blog
  • Work in Progress
    • The Kirk Project >
      • Kirk 3D Models list
      • Kirk 3D Models embedded
      • Kirk 2D images >
        • Indiana
        • Kentucky
        • Michigan
        • Ontario
      • Kirk Project Datasets
    • Computational Modeling >
      • FN3D_V3
    • Radiocarbon Compilation
    • Fake Hercules Swords
    • Wild Carolina >
      • Plants >
        • Mosses
        • Ferns
        • Conifers
        • Flowering Plants >
          • Grasses
          • Trees
          • Other Flowering Plants
      • Animals >
        • Birds
        • Mammals
        • Crustaceans
        • Insects
        • Arachnids
        • Millipedes and Centipedes
        • Reptiles and Amphibians
      • Fungi
  • Annotated Publications
    • Journal Articles
    • Technical Reports
    • Doctoral Dissertation
  • Bibliography
  • Data

Hunter-Gatherer MVP Size Paper Published and Available (Open Access)

11/6/2017

0 Comments

 
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.
Picture
0 Comments

Information, Division, and the Internet: A Simple Complex Systems Problem?

7/5/2017

2 Comments

 
I don't remember who was talking, but I recently heard some TV pundit remark that it was both a surprise and disappointment that the internet has contributed to fostering cultural/social/political divisions rather than promoting unity. 

Disappointment? Yes.

Surprise? No.

Complex systems models have demonstrated over and over again that disunity (i.e., cultural polarization, geographic segregation, etc.) can emerge in systems within which information flows freely. The lesson is that having a high degree of information flow doesn't guarantee homogeneity at the scale at which the information is flowing. Two simple models demonstrate this point nicely.

First, the Schelling Model. If you're a fan of complex systems theory, you've probably heard of the simple simulation model that Thomas Schelling constructed and explored in the early 1970's and published in Micromotives and Macrobehavior (1978).  The original model was implemented using coins and graph paper rather than a computer. It demonstrated how relatively small preferences about the characteristics of ones' neighbors can result in complete segregation of neighborhoods. Actors in the model make decisions about whether to stay put or move based on on information about their immediate surroundings. Through a multitude of individual, localized decisions, large-scale patterns of segregation emerge in the absence of any intent or authoritative control.
Picture
Figure by Sebastian Schutte (2010) showing results from a computer-based implementation of the Schelling Model (source: http://jasss.soc.surrey.ac.uk/13/1/2.html).
Second, Robert Axelrod's (1997) adaptive culture model (see here). If you want a simple complex systems model . . .  it doesn't get much simpler than this one.  The model demonstrates how polarized cultural regions can develop even though the only mechanism for interaction in the model is one of convergence (i.e., the actors can only become more, not less, like their neighbors).
Picture
Figure showing polarization in Axelrod's Adaptive Culture model (source: https://computationallegalstudies.com/2010/03/12/the-dissemination-of-culture-axelrod-1997-model-now-available-in-netlogos-community-model/).
The short version of my argument (which is all I have time for today) is that complex systems approaches will provide an actual chance to figure some of this stuff out. You're not going to be able to write a mathematical formula to do it, as straight math can't handle emergent phenomena (show me a formula that captures this kind of flocking behavior and I'll admit I'm wrong). And you're not going to be able to sort it out by comparing two or three variables at a time ("white males between the ages of 18 and 22 in this county voted for X, which the same demographic in this county voted for Y").

And of course there's no such thing as a "simple" complex systems problem. But complex systems theory has helped us understand a thing or two about human cultural/social/political behavior that we wouldn't be able to understand otherwise. And some of that understanding has come from some relatively simple models.  I'm sure there has already been work done extending models like Schelling's and Axelrod's to represent media influences, complex structures of interaction (i.e., different network topologies, etc.), variable demography, etc. The smart money will pay attention to that work to help identify and understand the characteristics of our system that exacerbate divisions (and can be used to widen those divisions).
2 Comments

Periodicity and Sync in Coupled Socio-Natural Systems: Some Fastform Thoughts

6/26/2017

7 Comments

 
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.
PictureMigration and range of the Mississippi Kite (map from www.allaboutbirds.org).
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.
7 Comments

Three for Thursday: Demography, Swords, and Trophy Bases

3/16/2017

4 Comments

 
Following the spring break hiatus, the Broad River Field School will be back in session tomorrow. We'll be shifting gears a bit to carefully work our way into what appears to be a buried Late Archaic/Early Woodland component. I'm also anticipating continued work on the deeper deposits at the site. Hopefully it will be an eventful day. It's supposed to be sunny and in the mid 60's. I'll just leave it at that.

Here are a few quick updates on other things for those playing along at home: a new modeling paper about the minimum size of demographically viable hunter-gatherer populations, new Fake Hercules Swords en route, and an identification of last Friday's whatzit. 

Picture
How Small is Too Small?

I'm happy to announce that a paper I submitted to the Journal of Artificial Societies and Social Simulation (JASSS) has been accepted for publication.  The paper ("A Model-Based Analysis of the Minimum Size of Demographically-Viable Hunter-Gatherer Populations") uses computational modeling to systematically investigate how large hunter-gatherer populations have to be to survive over long periods of time. Spoiler alert: my results suggest that populations much smaller than the "magic number" of 500 are demographically viable over several centuries under the conditions I explore with my model (in this case, FN3D_V3). JASSS is open access. I'll let you know when the paper becomes available.

Picture
Two New Swords on the Way

Two new Fake Hercules Swords should arrive at my office any day now. Alert #Swordgate enthusiast Hartman Krug spotted these swords, which are currently being produced in Italy. Because the company doesn't ship to the U.S., I asked a relative in Germany to purchase them for me and ship them to South Carolina. After arriving in New Jersey a few days ago, they are currently listed by the USPS as "in transit to destination."

It will be really interesting to have a look at this and delve into the history of the company making them. Could this finally lead us back to the original Mother of All Fake Hercules Swords?

The purchase and shipping of these swords was supported by your contributions to Woo War One. There's still a positive balance there, but it's dwindling. If you'd like to help keep the pressure on and get to the bottom of this, please consider contributing.

Picture
The Whatzit: A Trophy Base?

The "what the heck is this" post I put up last Friday was fun. Within a few minutes of asking the question to an artifact group on Facebook, someone suggested that the item is a base for a trophy. That explanation made sense to me (you can see some new ones for sale here).

Following the post, the owner of the artifact told me he returned to the same creek where he found the original artifact and found another one (left) that lacks the rounded corners of the first one (right). What these things are doing in a creek in Tennessee I do not know.

If you've got a whatzit, send me some photos and maybe we can get it figured out.

Finally, following up on yesterday's post about Against Me!, I would like to encourage you to listen to the song "Rebecca" if you like the rock'n'roll music. It's on repeat in Andyland. 
4 Comments

Repast Simphony Batch Runs: Note to Self

2/15/2017

0 Comments

 
I've found that the notes I make on my website are much easier for me to find later than the things I scrawl on pieces of scrap paper. The shoe fits, so I'm going to wear it whether or not it's interesting or useful to anyone else.

I've spend much of my time since Monday working to get the agent-based model I'm currently messing around with (version 3 of ForagerNet3_Demography) to work in version 2.4 of Repast Simphony. Something went awry with my previous installation (2.0) and it made sense to start trying to fix things with the most current version. After many frustrating loops of install/uninstall/reinstall, I finally got a good installation of 2.4 and got my source files moved in and working.

One thing that I wasn't able to make functional in the last version was the batch mode.  Batch mode lets you run jobs in batches, speeding up computation by farming out the computational workload to different processors or machines, etc. (doing runs in parallel rather than serial). It wasn't too troublesome that I couldn't get the embedded batch mode working before, as the model I'm working with isn't terribly demanding. There are bigger things coming down the road, however, so I was happy to see the batch mode appeared to be active and ready to go with the new installation.

I spent most of yesterday trying to figure out how to use the batch mode while preserving the data output format that I've created on my own and that works for me. The way I've written the model, it produces a summary data file at the end of each run. The file (just a simple .txt file that I can open in a spreadsheet) preserves information on all the parameter settings used in the run as well as data on the outcomes. In the Repast/Eclipse batch mode, however, that .txt file wasn't getting produced. I was frustrated to learn that I apparently had to redo all the data capturing in the model so that the software could use something called a "file sink" to collect information. I was then relieved to learn that there was a workaround to using the "embedded system:" you can specify an "Optional Output File Pattern:"
Picture
The "Pattern" is the name of the file produced by the model. I changed the file name to "TestBatchMode.txt" in my code for the purposes of experimenting with where and under what circumstances the file would be created. The "Local Path" is what you want the file to be called that the batch mode creates (it will appear in the output directory specified above). Check the "Aggregate" box so that it saves the output from each run and then gloms it all together in a single file. I left "Has Header" unchecked because my data doesn't have a header.

Repast seems to be picky about the settings in the "batch_params.xml" and "parameters.xml" files, wanting them to match. I get null pointer exceptions when I clear everything but the random seed out of the files, so I just left a parameter in to keep the software happy (it does nothing, as it's a constant and doesn't affect any of the settings in the model). 

I'm still testing out the batch mode and the model to make sure everything is working properly. My plan then is to modify version 3 to create version 4, which will include some different mortality settings (which, in turn, will necessitate rewriting some of the code that calculates age-specific mortality outcomes). After all that's done, I'm planning on doing some new modeling work to formally follow up on some preliminary observations I presented at the SAA meetings a few years ago.
0 Comments

Three-Headed Research Monster: A Brief Update

9/8/2016

1 Comment

 
Picture
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).
Picture
Drawing of the deposits exposed in profile. The numbers in the image are too small to read, but the (presumably) Middle Archaic zone is the second from the bottom if you look at the left edge of the drawing. Woodland/Mississippian pit features are also exposed in the profile nearer the current ground surface.
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.
Picture
​In the "creeping along" department is the Eastern Woodlands Radiocarbon Compilation. My daughter did some work on the bibliography over the summer, so that was helpful. I'm still missing data from big chunks of the Southeast and Midwest. I've got some sources in mind to fill some of those gaps, and I've also got a list of co-conspirators. Our plan is to combine everything we've got ASAP and make it available ASAP.  I don't really have a timeline in mind for doing that, but for selfish reasons I'm going to try to make it sooner rather than later: I'm going to be using information from the radiocarbon compilation in the paper I'm going to give at this year's SEAC meeting in October. So . .  Georgia, Alabama, Arkansas, Missouri, Indiana, Illinois . . . I'll be coming for you.
Picture
I've got two undergraduate students working on processing the Larry Strong Collection, a large collection of artifacts (mostly chipped stone projectile points) from Allendale County, South Carolina.  Mr. Strong, who gathered the materials himself over the course of decades, donated the collection to SCIAA in the 1990's. Large surface collections such as this have significant research potential. I'm most interested in this collection for two reasons: (1) it provides a large sample of Kirk points from a single geographical area made from a single raw material, improving the possibility of teasing apart functional, stylistic, and temporal dimensions of variability (the large majority of 3D models of Kirk points I've produced so far have come from the Larry Strong collection for just this reason); (2) it provides a basis for making robust statements about the relative frequencies of various point types. When you have an n in the many thousands, you can have some confidence that the patterns you're seeing (such as drop in the numbers of points following the Kirk Horizon) are real. That will also factor into my SEAC paper. Curation of the Larry Strong collection is being funded by a grant from the Archaeological Research Trust.
Picture
Finally, in the "paused" category there is the Eastern Woodlands Household Archaeology Data Project. That effort has been on hold since early last year (I have money to support it and I had an assistant hired, but she moved on to a greener pasture). I'd really like to get this going again but I need to find someone who can work on it more-or-less independently. And I need a bit more office furniture and another computer. Hopefully I can get the EWHADP moving again after things stabilize with my new crop of employees and I have time to take a trip to the surplus building and see what I can scrape up.

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). 
Picture
How big does a human population have to be to remain demographically viable over a long span of time? Perhaps not as big as we think. The numbers along the bottom axis code for marriage rules (which will be explained in the paper). Generally, the rules get more strict from left to right within each category: 2-0-1 basically means there are no rules, while 2-3-8 means that you are prohibited from marrying people within a certain genetic distance and are compelled to choose marriage partners from within certain "divisions" of the population.
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.
1 Comment

Memory Leak Plugged, FN3_D_V3 Model Performing Again

3/30/2016

1 Comment

 
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.
Picture
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. 
1 Comment

Friday Digest: Fringe Utopia, Memory Leaks, the Sword, and an Open Invitation to "The Walking Dead"

3/25/2016

4 Comments

 
I've been hard at work rolling a boulder up the Repast Simphony learning curve.  Computer modeling is a basic element of my three-headed "Shovels, Collections, and Code" research agenda. The other two are on track: I'm planning future survey/excavations at a natural levee system that appears to contain buried Archaic components, and I've started my collections work with an ambitious data-gathering effort oriented toward understanding the Kirk Horizon.  The computer modeling part of my work is an important part of building an interpretive framework that allows us to integrate the small-scale behaviors we can document at individual sites with the large-scale patterns we can describe through pan-regional collections work.  More on that later.

Call me crazy, but I find writing and debugging computer code to be relaxing.  It can be frustrating, of course, when you can't figure out the source of some problem or error, but overall the process of building and tuning a model is engaging and strangely soothing. The parts make sense, represent something, and work together. And there are rewards for elegant design. It's fun. During my dissertation work I sometimes had the luxury of taking full days (not 9-to-5 days, but 24 hour days) to focus on uninterrupted programming.  Those days are gone, but I still find myself enjoying the times when I can block out a few hours, close my door, and get into the code.

The rest of the world doesn't stop, however.  So I have a few things I wanted to briefly talk about today.
​
Picture
Amazing Tales of a Fringe Utopia in Northeast Illinois

A reader of this blog emailed me some links to material that, for all I know, is familiar ground to those who closely watch "fringe" theorists.  I had never heard of E. P. Grondine's manuscript He Walked Among Us, however, so I presume that others also have not.  The work (available in three parts here), details the history, philosophy, and inter-personal interactions of "fringe" figures (including David Hatcher Childress) in a small town in northeastern Illinois. Thus far I have only skimmed through parts of it (it will go on my summer reading list).  Check it out and see what you think. 

I don't know E. P. Grondine and am not yet very familiar with his work. He has commented on this blog at least once.
​

Plugging Memory Leaks

I've succeeded in getting one of my models (ForagerNet3_Demography_V3) operational in Repast Simphony. Repast Simphony operates a little bit differently than Repast J (the platform that I used to write the model), so I had to learn something about those differences, write some new code, and re-configure some other sections of the code.  Though I've still got some testing to do to make sure the model is behaving the same (i.e., it's doing the same thing it did before the conversion), everything seems to be working within the model itself.

The issue I'm trying to solve now is getting the model to run in batch mode.  Running a model in batch mode means that the computer performs a series of model runs (a "batch") automatically.  One of the great benefits of computational modeling is that you can do systematic experiments and determine cause and effect. You can hold everything about the model constant except for the value of single parameter, for example, and see how changes in that parameter affect the outcomes. You can run the model as many times as you want -- tens, hundreds, or thousands -- to flesh out those cause-effect relationships. Running the model in batch mode automates that process.  Ideally, I can start a batch running on Friday afternoon and return to my office on Monday morning with a large dataset ready to analyze.

There is apparently a built in batch configuration in Repast Simphony, but for some reason I haven't yet been able to get to it in the software. Maybe I need to reinstall.  For the time being, I've been using a simple little parameters file that just tells the software how many iterations of the model to perform and what random seed to use.  The model runs for the first 40-50 runs before throwing an "Out of Memory" error and locking everything up. It seems to run slower and slower with each iteration, which suggests to me there is a memory leak somewhere in my code. The model creates a bunch of objects (people, households, social links between people) during each run. Each of those uses memory. At the end of each run, all the object associated with that run should be tossed out to free up all the memory for the next run (when the model resets and starts fresh).  If some of the objects are "leaking through" and being retained in the memory, the progressive accumulation of those unused objects will eat more and more memory until there's none left.  I'm pretty sure I've got the model tossing all the people, households, and links (the three agent classes) out, so it may have something to do with copies of the spatial world and/or what's called the "context."  The structure of the "world" in Repast Simphony is different from that in Repast J, so I need to figure out how to make sure I'm getting rid of all the unused parts between each model run. That's my goal for today. Hopefully I can find and plug the memory leak and set my computer to work for me over the weekend.
​
Picture
The "Sword Report"

I still haven't been able to muster the combination of time and interest to read through J. Hutton Pulitzer's "sword report." What I know about the contents of the report I know from comments on Facebook pages (e.g., The Fraudulent Archaeology Wall of Shame and Fake Hercules Swords), this blog post from last week, and Jason Colavito's post about the report. My two main impressions are these (please correct me if I'm wrong):
​
The report contains no new information about the alleged "Roman sword from Nova Scotia." Pulitzer does not provide his XRF data that he claimed proved the sword was a "100% confirmed" Roman artifact. He spent months crowing about his XRF results, and, in fact, said he would release them "the next day" after Brosseau's results were aired on television. He has not done that. Why?  Remember when he said the exposed brass on the sword was actually gold? Whatever happened to that claim?

The report is an argument against Brosseau's interpretations, not her results.  Pulitzer seems to have abandoned the argument that his XRF results are correct and Brosseau's results are wrong, and is arguing that the metals identified by Brosseau are consistent with those produced by Romans.  He actually made this pivot some time ago (I wrote about it back in January). Sometime after Brosseau's results were aired, he decided that he had a better chance making a case for the antiquity of the sword based on Brosseau's results (which are well-explained and documented) than his own (let us never speak of those XRF results again?).  Apparently, the "case" for the Roman antiquity of brass with 35% zinc is based on the same sleight-of-hand he tried in January (see this post) with the added puffery of 70+ pages lifted more-or-less directly from this online study by David Dungworth.   Here is a direct quote from that study:

"Forty percent of all Roman alloys had at least 5% zinc. The distribution of zinc in all Roman alloys is fairly flat between 5 and 25% (Figure 31). This apparently even spread of zinc contents is an over-simplification. Zinc content varies with time - high zinc alloys belonging to the early Roman period. In addition zinc is strongly correlated (inversely) with tin (see Figure 34). The alloy type classification discussed below (see Figure 35) defines brasses as those alloys with 15% or more zinc. The method of brass production at this time was the cementation method (Craddock 1978) which could yield brass with a maximum zinc content of c. 28%. The paucity of such alloys (those with more than 23% zinc) in all the samples analysed here is striking."
​
Can anyone out there show me a single authentic Roman brass artifact with 35% zinc content?  I'll wait.

No matter how many times you assert that the sword is Roman, and no matter how long of a document you put together, evidence still matters. I still see no evidence that this is a Roman sword. I see continued monkey business, sleight of hand, and silliness.  Can we move on to the next "smoking gun that will re-write history" now please?  The sword is boring.
​

An Invitation for The Walking Dead to Enjoy Springtime in South Carolina

The Walking Dead is my favorite television show.  The program has had its ups and downs, but I think this season is pretty strong and I'm enjoying it. I'm a couple of episodes behind right now, so don't spoil it for me.

This week, Disney and Marvel warned Georgia Governor Nathan Deal that they will stop filming in the state if he signs a so-called "religious liberty" bill that many say will legalize anti-gay discrimination (here's the story in The Washington Post).  

I applaud Disney and Marvel for their stance, and hope that AMC follows suit and moves the filming of The Walking Dead out of northern Georgia. Given what's going on in North Carolina right now, the logical choice is to put the show in South Carolina.  There are signs this state is moving in the right direction (e.g., the removal of the Confederate flag last summer), and your business would be a nice encouragement. Having traveled up and down I-20 and 301 a few times now, I can tell you that you won't have any difficulty finding good locations for filming. You can enjoy the palmettos, azaleas, crepe myrtle, and Carolina wrens. We have some room at our house, so I can provide accommodations for at least two cast members (Glen and Maggie? Carol?).

Just think it over. You don't have to answer now. If you can't make it here this spring the flowers will still be blooming all year round. And there are butterflies.

4 Comments

Repast Simphony: There's Light at the End of the Tunnel

3/18/2016

1 Comment

 
This is just a quick post to commemorate the progress I've made this week in getting my main agent-based models (ABM) to work in Repast Simphony. I wrote all my model code in Repast J for my dissertation work and had access to help and some pretty powerful computing infrastructure while I was at the University of Michigan.  I had to largely put that part of my work aside after I was no longer a student. I didn't have full access to U of M's resources anymore, and I didn't have time with my job at Grand Valley anyway. So the modeling work has been on hold for a while.

One of my main goals this year (my first year at South Carolina) was to get my modeling work up and running again. I'm behind where I wanted to be at this point, but I'm happy to report that I've spent the week dealing with a lot of the main challenges (I think) of getting my Repast J code to work in Repast Simphony. The Java language stuff is the same, but there are some differences in how the models are structured (what controls what, etc.) and how you get it to schedule actions, put things in a spatial world, etc.  I've got the latest generation of my non-spatial model (ForagerNet3_Demography_V3) more-or-less up and running: people are forming households, reproducing, dying, forming and dissolving links to one another, etc., just like they used to. With those nuts and bolts operational again, I can move on to tinkering with model to streamline the code, figuring out batch mode, figuring out how to have it compile data outputs, and figuring out how to put the whole system back into a spatial framework again.  And then the fun really begins. But first: Miller Time.
Picture
1 Comment

Free Access to My New Essay: "Chaos, Complexity, and a Revitalization of Four-Field Anthropology?"

9/22/2015

2 Comments

 
Picture
My essay in Reviews in Anthropology that I wrote about here is behind a Taylor & Francis paywall.  I just found out this morning, however, that I get 50 free "eprints" that I can distribute however I like.  Given that the essay isn't supposed to be a secret, I thought the simplest thing to do would be to make those copies available to whoever wants them:  my understanding is that the first 50 people to click this link can download my essay for free.  It's not open access, but better than nothing.

Please let me know if you try it and it doesn't work (or if you try it and it does work).  Happy reading!


2 Comments
<<Previous

    All views expressed in my blog posts are my own. The views of those that comment are their own. That's how it works.

    I reserve the right to take down comments that I deem to be defamatory or harassing. 

    Andy White

    Follow me on Twitter: @Andrew_A_White

    Email me: andy.white.zpm@gmail.com

    Enter your email address:

    Delivered by FeedBurner


    Picture

    Sick of the woo?  Want to help keep honest and open dialogue about pseudo-archaeology on the internet? Please consider contributing to Woo War Two.
    Picture

    Follow updates on posts related to giants on the Modern Mythology of Giants page on Facebook.

    Archives

    January 2023
    January 2022
    November 2021
    September 2021
    August 2021
    March 2021
    June 2020
    April 2020
    March 2020
    January 2020
    December 2019
    November 2019
    October 2019
    September 2019
    May 2019
    April 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    September 2014
    August 2014
    June 2014
    May 2014
    April 2014
    March 2014

    Categories

    All
    3D Models
    AAA
    Adena
    Afrocentrism
    Agent Based Modeling
    Agent-based Modeling
    Aircraft
    Alabama
    Aliens
    Ancient Artifact Preservation Society
    Androgynous Fish Gods
    ANTH 227
    ANTH 291
    ANTH 322
    Anthropology History
    Anunnaki
    Appalachia
    Archaeology
    Ardipithecus
    Art
    Atlantis
    Australia
    Australopithecines
    Aviation History
    Bigfoot
    Birds
    Boas
    Book Of Mormon
    Broad River Archaeological Field School
    Bronze Age
    Caribou
    Carolina Bays
    Ceramics
    China
    Clovis
    Complexity
    Copper Culture
    Cotton Mather
    COVID-19
    Creationism
    Croatia
    Crow
    Demography
    Denisovans
    Diffusionism
    DINAA
    Dinosaurs
    Dirt Dance Floor
    Double Rows Of Teeth
    Dragonflies
    Early Archaic
    Early Woodland
    Earthworks
    Eastern Woodlands
    Eastern Woodlands Household Archaeology Data Project
    Education
    Egypt
    Europe
    Evolution
    Ewhadp
    Fake Hercules Swords
    Fetal Head Molding
    Field School
    Film
    Florida
    Forbidden Archaeology
    Forbidden History
    Four Field Anthropology
    Four-field Anthropology
    France
    Genetics
    Genus Homo
    Geology
    Geometry
    Geophysics
    Georgia
    Giants
    Giants Of Olden Times
    Gigantism
    Gigantopithecus
    Graham Hancock
    Grand Valley State
    Great Lakes
    Hollow Earth
    Homo Erectus
    Hunter Gatherers
    Hunter-gatherers
    Illinois
    India
    Indiana
    Indonesia
    Iowa
    Iraq
    Israel
    Jim Vieira
    Jobs
    Kensington Rune Stone
    Kentucky
    Kirk Project
    Late Archaic
    Lemuria
    Lithic Raw Materials
    Lithics
    Lizard Man
    Lomekwi
    Lost Continents
    Mack
    Mammoths
    Mastodons
    Maya
    Megafauna
    Megaliths
    Mesolithic
    Michigan
    Middle Archaic
    Middle Pleistocene
    Middle Woodland
    Midwest
    Minnesota
    Mississippi
    Mississippian
    Missouri
    Modeling
    Morphometric
    Mound Builder Myth
    Mu
    Music
    Nazis
    Neandertals
    Near East
    Nephilim
    Nevada
    New Mexico
    Newspapers
    New York
    North Carolina
    Oahspe
    Oak Island
    Obstetrics
    Ohio
    Ohio Valley
    Oldowan
    Olmec
    Open Data
    Paleoindian
    Paleolithic
    Pilumgate
    Pleistocene
    Pliocene
    Pre Clovis
    Pre-Clovis
    Prehistoric Families
    Pseudo Science
    Pseudo-science
    Radiocarbon
    Reality Check
    Rome
    Russia
    SAA
    Sardinia
    SCIAA
    Science
    Scientific Racism
    Sculpture
    SEAC
    Search For The Lost Giants
    Sexual Dimorphism
    Sitchin
    Social Complexity
    Social Networks
    Solutrean Hypothesis
    South Africa
    South America
    South Carolina
    Southeast
    Stone Holes
    Subsistence
    Swordgate
    Teaching
    Technology
    Teeth
    Television
    Tennessee
    Texas
    Topper
    Travel
    Travel Diaries
    Vaccines
    Washington
    Whatzit
    White Supremacists
    Wisconsin
    Woo War Two
    World War I
    World War II
    Writing
    Younger Dryas

    RSS Feed

    Picture
Proudly powered by Weebly