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

ForagerNet3_Demography (Version 3): Description and Code Available

11/29/2016

1 Comment

 
Picture
I devoted yesterday afternoon and most of today to (finally) producing the updated documentation for Version 3 of the ForagerNet3_Demography model, one of the agent-based models that I've been working with. You can read all about it on this page, and you can even download the raw code if you like. Files and citation information for the model are also available on OpenABM.org.

I used a version of this model (implemented in Repast J rather than Repast Simphony) in a recent paper published in Uncertainty and Sensitivity Analysis in Archaeological Computational Modeling (edited by Marieka Brouwer Burg, Hans Peeters, and William Lovis).

Over the summer I used to model to generate data for a paper on the minimum viable population (MVP) size of human groups. That's in the editing stages now -- hopefully I'll be able to get it done and submitted somewhere before the Christmas break.

​Onward.

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

Looking for Quantitative Data on Children's Productivity in Domestic Work

11/3/2015

1 Comment

 
After having set computer modeling aside (out of necessity) for the past year, I'm ready to start getting back to that component of my research.  I'm hoping to get things ramped back up this semester and be doing some fairly hardcore computational work by next semester.  I've got some technical and logistical issues to address, and I'll surely  have to spend some time getting back up to speed with Java and Repast.  But it shouldn't be too bad
One of the things I'd like to do when I get up and running again is take another look at how the children's labor might affect the dependency ratio and household-level calculations about family size, etc. (see this paper for my first attempt to address the issue). In the models I'm currently using (e.g., the ForagerNet series), I represent a child as either a "producer" or a "non-producer" by comparing the child's age to the value of a parameter that specifies the age at which children become producers. Clearly that's a significant simplification of reality: children do not magically become "producers" overnight on their 8th birthdays or their 12th birthdays, etc.
Picture
I was watching my two boys (ages 4.7 years and 2.2 years) shell beans at the kitchen counter over the weekend, and it got me wondering what kind (if any) quantitative data are available about age-based changes in the proficiency of children in doing various kinds of productive tasks. Watching my two kids, there was a huge difference in the proficiency (and interest level) of the older and younger boys.  The older one stuck with the task until we ran out of beans and, while not as fast as an adult, was really pretty good.  Despite an equal contribution of energy (at least in the beginning), the productivity of the younger one was much lower.  Part of that had to do with the desire to do a victory dance for each single bean that he managed to pull from a pod. 

What would the age-based "proficiency curve" of bean processing look like?  A linear progression? A rapid increase in proficiency between ages 2 and 6?  At what age do individuals reach "full proficiency" in processing beans?  

​Are there ethnographic data available that would allow me to understand how proficiency at processing various kinds of plant foods changes with age? How about tasks related to gathering?  Or planting?

There has been an increase in interest in the lives of children in hunting-gathering societies (see this paper by Nurit Bird-David), and I'm hoping that some quantitative data are available from recent ethnographic studies (e.g., see this 1994 paper by Blurton Jones et al., this 2004 paper by Raymond Hames and Patricia Draper, this 2009 volume edited by Barry Hewlett and Michael Lamb).  I'm less familiar with possible sources for quantitative data relevant to modeling age-based changes in children's work proficiency in agricultural societies.  Maybe there are government agencies or NGOs that monitor that sort of thing (the site of the International Labour Organization discusses children's domestic work, for example).

Anyway, this blog post is just a placeholder. I'm interested in tracking down some data if they're available (if you know of any, please let me know!).  

If there are not suitable data already out there, I might have to generate some of my own through some controlled experimentation.  Let me know if you like beans.  We may soon be producing a surplus at my house. And I may soon ask to borrow the participation of children of various ages.

​

1 Comment

The Dependency Ratio in Human Evolution

5/15/2015

3 Comments

 
As far as I know, humans are unique among animals in having an extended period between weaning and being able to subsist on their own.  We call this “childhood.”  The long period of post-weaning dependence provides our large brains with a lot of time to mature.  It also requires a lot of parental investment (in terms of time, energy, calories, etc.) and means that we would have to wait a long time between offspring if each one had to independent before the mother could have another.   We don’t do that, tending to have a shorter interval between subsequent births (the inter-birth interval, or IBI) than other great apes.  The long period of childhood dependence and the short IBI mean that, as a species, humans tend to have multiple, dependent offspring of different ages at the same time.  Speaking as a parent of multiple, dependent offspring of different ages, I can tell you that this is often no walk in the park.  This peculiar human strategy has a lot of costs.

Understanding when, how, and why this distinctly human reproductive strategy developed is a great evolutionary question.  Reducing the IBI increases the potential fertility of human populations, but also creates new demands on the energies of parents and families.  Human families today often offset those extra energy demands by getting help (evolutionary anthropologists call it “cooperative breeding”).  A new paper in the Journal of Human Evolution titled “When Mothers Need Others” by Karen Kramer and Erik
Otárola-Castillo tries to further our understanding of where cooperative breeding comes from, using an “exploratory model” to try to understand the selective pressures associated with the evolution of human-like patterns of reproduction and child-rearing.  The goal of the paper “is to develop a model to predict those life history transitions where selective pressure would have been strongest for cooperative childrearing” (pg. 5). 

Kramer and
Otárola-Castillo call their model the “Force of Dependence Model.”  Their model is a simple one, calculating “the net cost of offspring as a function of dispersal age, birth intervals and juvenile dependence” as a 3-dimensional surface (Supplementary Online Material  from Kramer and Otárola-Castillo 2015).  The authors use several different combinations of settings to represent a range of conditions from “ancestral” (juvenile independence at age 10, IBI of 6 years, and a dispersal age of 14) to “most derived” (juvenile independence at age 20, IBI of 3 years, and a dispersal age of 20).  Their graphs show that “net costs” within a domestic group (a mother and her offspring) are lower when offspring are spaced further apart and become independent at a younger age.  When offspring hang around past the age of juvenile independence, there is a net benefit to the domestic group as their productive capacities can be used to offset the drain of their younger siblings. The authors find that the strain points – where selective pressures for assistance would be greatest – occur in domestic groups with the most derived set of characteristics: late juvenile independence and a low IBI (lots of children who remain dependent for a long time).   

As I understand it, the “net cost” in this model more-or-less mirrors the dependency ratio (the ratio of consumers to producers) of a domestic group or family, something anthropologists have been interested in understanding for a long time.  The higher the ratio of consumers to producers, the higher the dependency ratio, and the higher the “cost” to each producer supporting the family.  The dependency ratio changes through the lifespan of a family in a patterned way: every domestic group that has children goes through a “pinch” period when the dependency ratio is highest, and the pinch period logically corresponds to the time when there are a lot of dependent offspring.  As I wrote in my 2013 paper in the Journal of Anthropological Archaeology (“Subsistence Economics, Family Size, and the Emergence of Social Complexity in Hunter-Gatherer Systems in Eastern North America,” available here):

“the duration and amplitude of the ‘pinch’ is affected by the rapidity of the addition of offspring and how quickly those offspring turn from consumers into producers.  The rapidity of addition of offspring will depend on factors such as fertility, infant and childhood mortality, and the number of wives. The productive potential of children will be affected by the presence and distribution of resources that can be procured by children and the foraging strategies that are employed to exploit those resources” (White 2013:128).

The main part of that paper used an agent-based model (ABM) to try to understand how the distribution of family size changes when the age at which children become producers (the “age of juvenile independence” in Kramer and
Otárola-Castillo’s model) decreases and there is an incentive for polygynous marriage.  In addition to the ABM, I used a simple spreadsheet model to show how the dependency ratio changed through the course of the developmental cycle of an individual family in cases where the age at production was low (8 years old) and where it was high (14 years old).  In this simple model, I used an IBI of 3, a dispersal age of 16 for females and 20 for males, and a female reproductive period spanning ages 20-35 years (giving a total fertility of 6 offspring).

The figure below compares Kramer and
Otárola-Castillo’s graphs from their cases with early and late juvenile independence (holding IBI at 3 and dispersal age at 14) with my data on changes in dependency ratio through the developmental cycle in cases with a single reproducing female and an age at production of 8 (top) and 14 (bottom).   My model data are the same as in my 2013 paper (Figure 5), but I have re-graphed them to make comparison with Kramer and Otárola-Castillo’s figure easier.  I have redrawn the graphs from Kramer and Otárola’s Figure 1 (third graphs from the left, top and bottom rows).   The dotted lines on the graphs of my results indicate a dependency ratio of 1.75, which is what I have generally used in my modeling efforts as a “typical” dependency ratio among hunter-gatherers (following Binford 2001:230).
Picture

My results showed the same pattern as Kramer and Otárola-Castillo’s:  the peak of the “pinch” comes earlier and is less severe when children become producers at an earlier age.  Even though our models have some differences (and some of the values of the parameters were different), the correspondence in results is notable. Compare, for example, when the amplitude of the “pinch” (peak dependency ratio in my results, greatest net cost in Kramer and Otárola-Castillo’s results; marked by stars) is greatest and the differences in amplitude between the early and late ages of juvenile contributions to subsistence.

The correspondence between my results and Kramer and
Otárola-Castillo’s is unsurprising.  The idea that the dependency ratio of a domestic group changes through the course of its developmental cycle in a somewhat predictable way is not new (and the idea that the “pinch” comes when you have lots of little kids running around at the same time won’t come as a revelation to anyone who has multiple children).   This is a phenomenon that has been studied for decades (e.g., Chayanov 1966; Donham 1999; Fortes 1958; Goody 1958) and recognized as a key aspect of how hunter-gatherers organize themselves (Binford 2001:229).

So where does this kind of work put us in terms of understanding the evolution of human reproduction, society, and family life?  I think it primarily puts us in a spot where we’re asking some good questions.  Going back to the issue of the origins of monogamous pair-bonding (which I touched on briefly in this post about birth assistance and this post about australopithecine sexual dimorphism), having a two person (male-female) unit forming the core of a domestic group would have a mitigating effect on the strain caused by a decrease in IBI (i.e., you’d be adding another producer into the equation).  If the appearance of male-female pair-bonding was associated with a sexual division of labor (which is I think what most of us would hypothesize), males and females would presumably be focused on procuring somewhat different sets of subsistence resources.  Offspring could be largely “independent” with regards to some of those resources but not to others – think about the difference between collecting berries and running down large game.  A sexual division of labor and an environment where relatively young children could make some contribution to their own subsistence (even if that contribution does not include the full range of resources that are exploited) would go a long way toward easing the “pinch” that comes from having more children spaced closer together.

When does this happen in human evolution?  Of course that’s a tough thing to get at directly.  I think if you took a poll, the winner would probably be “around the time our genus emerges” or “with Homo erectus.”  An increase in total fertility (coincident with a lowering of the IBI) would help explain the population growth that must have been part of the dispersal of our species out of Africa prior to 1.8 million years ago.  It would also fit nicely with the evidence for an increased exploitation of animal resources around that same time.  Maybe Glynn Isaac was right all along to propose the emergence of human-like central place foraging with home bases and a sexual division of labor at the beginning of the Lower Paleolithic?

But what if monogamous pair-bonding and a sexual division of labor appeared much earlier – with australopithecines or even some pre-australopithecine like Ardipithecus?  If those things came along with bipedal locomotion, would a decreased IBI and increased fertility have followed automatically?  Maybe not.  Perhaps those earlier hominids just didn’t have the wherewithal to exploit their environments like later hominids did – perhaps the diversity of the resource base they could exploit wasn’t great enough to really leverage a sexual division of labor until animal products became readily attainable.  That may have required a suite of anatomical adaptations for daytime exhaustion hunting (loss of body hair, skin pigmentation, greater body size, stiffer foot) and cognitive/behavioral adaptations for making and using stone tools to process carcasses.  The date of the “earliest” proposed use of stone tools continues to be pushed  back (now it’s at 3.3. million years ago), but as far as I know the density of stone tools and butchered animal bones that appears at about 1.8 million years ago is unlike anything that precedes it.

More modeling work will be required to really understand how changes in the dependency ratio might have articulated with changes in reproductive, social, and technological behaviors deep in human prehistory.  In order to understand what changes in reproduction might have meant in terms of social interactions, however, we’ll need a different grade of model than that used by Kramer and
Otárola-Castillo.  Of course I’m going to say that complex systems modeling is the way to go on this:  it will let us get past the limitations of deterministic inputs and help us understand how constraints, costs, and interactions would have played out within a society.   In order for “others” to help with raising and provisioning multiple dependents, those others had to have existed within these small-scale hominid societies and (again, speaking as someone involved in raising multiple small kids) there wouldn't have been some inexhaustible Plio-Pleistocene babysitting pool of “others” out there just waiting to step in and provide extra calories for a few years.  A different kind of modeling effort with broader scope will let us get at the group- and society-level contexts in which family-level changes in child-bearing and child-rearing would have played out. Stay tuned.
References

Binford, Lewis R.  2001. Constructing Frames of Reference: An Analytical Method for Archaeological Theory Building Using Hunter-Gatherer and Environmental Data Sets.  University of California Press, Berkeley.

Chayanov, A. V.  1966.  A. V. Chayanov on the Theory of Peasant Economy.  University of Wisconsin Press, Madison.

Donham, Donald L. 1999.  History, power, ideology: Central issues in Marxism and anthropology.  University of California Press, Berkeley.

Fortes, Meyer.  1958.  Introduction.  In The Developmental Cycle in Domestic Groups, edited by Jack Goody, pp. 1-14.  Cambridge Papers in Social Anthropology.  Cambridge University Press, London.

Goody, Jack.  1958.  The Fission of Domestic Groups among the LoDagaba.  In The Developmental Cycle in Domestic Groups, edited by Jack Goody, pp. 53-91.  Cambridge Papers in Social Anthropology.  Cambridge University Press, London.
ResearchBlogging.org
Kramer, K., & Otárola-Castillo, E. (2015). When mothers need others: The impact of hominin life history evolution on cooperative breeding Journal of Human Evolution DOI: 10.1016/j.jhevol.2015.01.009
3 Comments

Data from "Functional and Stylistic Variability in Paleoindian and Early Archaic Projectile Points from Midcontinental North America"

3/3/2015

1 Comment

 
Picture
I have added an Excel file of the basic dataset for my 2013 paper in North American Archaeologist to the "Data" section of the website.  The file contains basic information on provenience (county), UTMs (county center), typological category, and morphometric data for the 1,771 Paleoindian and Early Archaic projectile points that I used in that study.  Like the 2014 AENA paper, the NAA paper was produced from a portion of the analysis in my dissertation. 

The samples I used for the morphometric analysis in my dissertation and in the NAA paper were identical, so the data in the Excel file are also in the appendices of my dissertation.  I'm hoping that providing the data in an electronic format will save someone a great deal of time doing data entry, and will encourage the use of the dataset that took me who-in-the-hell-knows-how-many hours and miles to collect, compile, and produce.  The measurements used, as well as the procedures for taking them, are defined in the paper and in my dissertation.

The ultimate goal of the two analyses (raw material and morphometric) was to produce a quantitative description of the apparent sequence of material culture change from homogenous (Early Paleoindian) --> regionalized (Late Paleoindian) --> homogenous (Early Archaic) that characterizes the Pleistocene-Holocene transition in the Midcontinent.  A quantitative description allowed an "apples to apples" comparison with data from model experiments, providing a basis for evaluating some alternative scenarios explaining the regionalization as a result of various changes in social network structure.  As the time to my defense was ticking away, I had to sacrifice some of the modeling work in order to get finished.  I was able to draw some conclusions, but a satisfying analysis of the "social boundary" question is still in the future.  Once I get set up at my new job I'll be able to restart the modeling work, add data from the southeast to my dataset, and reboot on the question of the social networks of early hunter-gatherers in eastern North America.


1 Comment

All the Cool Kids are Doing it (whether they know it or not)

4/17/2014

2 Comments

 
Picture
I just got back reviews for a (rejected) grant application.  It didn’t surprise me that the grant was rejected, as demand for research dollars far outweighs supply and the large majority of these proposals are not funded.  Rejection isn’t the best feeling, but you take it and move on.  I’ll find some other way to do the work and address the questions at some point in the future.   

What struck me about the reviews was not the rejection but the skepticism about the model-based analysis of archaeological data that I advocated.  I wasn’t asking for money for that part of the work, so I didn’t spend much of the limited space I had to detail the approach I would take.  But I did mention that I’d be using agent-based modeling as an analytical tool to try to connect patterns in household-level archaeological remains to the gendered activity patterns that might have been associated with those households.  (To be clear:  I’m under no illusions that this will be a simple thing to do, but it is something we’ve got to continue to wrestle with.  We say over and over again how important the sexual division of labor is to hunter-gatherer families and societies, but we don’t really seem to be too worried about it in terms of its archaeology).  

One reviewer wrote that I was arguing that I could simply “model my way out of the problem.”  This is an interesting thing to say.  First, I think it communicates a strange hostility/skepticism toward the particular kind of modeling that I do.  Based on previous experience, I would guess that this kind of negative reaction to agent-based modeling is probably rooted in ignorance or misunderstanding about complex systems methods and theory.  That’s fine – that’s part of the professional battlefield that I chose for myself.  What bugs me more is that the statement seems to signal a fundamental misunderstanding about the existence and roles of models in archaeology in general.

A model is a representation of something, plain and simple.   A model can specify how variables fit together, how one part of a system connects or affects another, what behaviors produce a certain kind of material signature, etc.  It is an abstraction of reality that captures some aspect of reality.  The distinction between an archaeologist who is “using models” and one who is not is a false one: all archaeologists use models.  We use models to make the leap between the static remains we have in front of us and the human behaviors that produced those remains.  We are all trying to “model our way out of the problem:”  the problem is that we cannot directly observe the people, societies, dynamics, and behaviors we are trying to understand.  That's archaeology.

The real distinction is not based on whether one uses models in archaeology, but rather what kind of models one chooses to use.  Many of the models that archaeologists use are mental models that are based on logic or some intuitive understanding of how things “should” be related.  Joshua Epstein (2008) makes a useful distinction between implicit models and explicit models: 

“. . . an implicit model in which the assumptions are hidden, their internal consistency is untested, their logical consequences are unknown, and their relation to data is unknown. But, when you close your eyes and imagine an epidemic spreading, or any other social dynamic, you are running some model or other. It is just an implicit model that you haven't written down (see Epstein 2007).”

The paper from which that quote is taken is available from JASSS here.  It is short and non-technical.

Humans (and other creatures) use implicit models constantly to navigate the world.  When you look down the street and see a truck coming, you decide if you have time to safely cross the street before the truck gets there based on a model that lets you relate the key variables to one another (the truck’s distance, speed, acceleration, your speed, the width of the street, etc.).  You can do all this without knowing the precise values for the variables or doing all the division and multiplication in your head:  the model is a representation that gives you an estimate that is “good enough” (your life depends on it, after all).  Similarly, a dog does not need to do the vector math in order to catch the Frisbee from the air:  she uses a mental model to determine how/where to intercept the Frisbee. 

Implicit models work great a lot of the time for doing archaeology.  But they are not all we need.  They can help us avoid getting hit by a truck, but are not so good for sending people to the Moon and back. Some problems require a different kind of modeling.

Archaeology is stuck in several spots.  In many cases, we’re hampered by equifinality problems (multiple processes produce the same outcome).  Maybe getting at gender in the archaeology of hunter-gatherers is one of those spots.  How do we move forward?  I suggest that abandoning models as altogether useless would be a much less effective strategy than adjusting the kind of model you’re using.  How about trying something that fits the problem and gives you a chance to break the logjam?  If you want to get a screw out of a piece of wood, try picking up a screwdriver rather than a hammer.  I know it is a time-honored tradition to bang on the screw with a hammer and then give cautionary tale talks about how you shouldn't do that, but there may be room for another approach.  Just a suggestion. 

Yes, I’m going to try to “model my way out of the problem.”


2 Comments

Brachiosaurus for Sale; Will Trade for Access to HPC

4/8/2014

0 Comments

 
Picture
I’m a fan of metaphors.  A good metaphor can be a tool for clarifying a complicated idea.  And I find that the process of finding that good metaphor  -- that metaphor that so simply captures and communicates subtleties that get lost in a long explanation --  is also worthwhile.  It is a process of distillation:  your brain pares away the clutter until only the most important or meaningful elements of an idea remain.  Sometimes it’s just as difficult as it is important to get to the essence of an idea.  Metaphors help with that.

I’m going to make a renewed effort to sell my brachiosaurus sculpture.  Have a look here at how I built it: started without much of plan, completed in fits and starts over about a year.  It is sitting in my back yard now, perhaps eight feet (2.5m) tall at the head and who knows how heavy.  Weathering is making it look better, I think, taking some of the gleam off the chrome and dampening the brightness of the painted pieces.

My brachiosaurus feels unfinished to me, and I think it probably always will. (The brachiosaurus drawing to the right, which I like, is not by me, but by this person.)  I built it to come apart to make it easier to move (both out of the garage and from place to place).  I’m still patting myself on the back for recognizing early on that it would either need to come apart or be moved outside horizontally.  But the choice to make the legs detachable – to build in some functional flexibility – meant that I couldn’t construct them with the kind of fluidity and fullness that I wanted.  And that has always bummed me out a little.  The moment of triumph was getting out of the garage.  Since then, the personal affection has faded. 

So I’m going to try to sell it. I’ve flirted with the idea several times over the last two years, and two times there has been enough expression of interest that I was optimistic that we’d consummate the deal and Betty would find a new home.   So far it hasn’t happened. But maybe this is the year – maybe this is the year that someone pulls the trigger and decides that, yes, it is time we had a large metal dinosaur in the garden.  Trust me - it's the right call. Buy now and avoid a lifetime of regret.  Do it.

Do it for science.  I would put the money toward a high performance computer that I could use as a dedicated machine for running computational experiments.  Running these experiments is a significant aspect of my work.  Some of the models I’m using are not that computationally expensive to run, but some are.  Space and population size are the keys.  Small populations in non-spatial models, like some of the demographic models I've been working with lately, aren't that bad.  But fill an area the size of the Eastern Woodlands with hunter-gatherer populations at a reasonable density and the millions of probabilistic calculations that take place each step slow the action down to sub-glacial speeds.  Models like the ones I used in my dissertation – with detailed, spatially-situated representations of birth, death, marriage, mobility, kinship, social networks, and social learning – take a long time to run and use a lot of computer power.  I don’t have the resources available to me right now to run those.  Thus my research using those high amperage models is on hold until I can find a way to create or tap into the infrastructure I need.  There are advantages to not being a graduate student anymore, and then there are disadvantages.  This is one of the disadvantages.

There are several “good” metaphors lurking in all of this, but I have yet to sort them out.  I know, however, that it’s time to commit and move on.  My kids like the metal sculptures (more at this unmaintained website), and they will be sad to see the brachiosaurus go.  For them it is a tangible and symbolic thing that makes our backyard different from all the others.  I like it for that reason, too.  But for me it is also other things.  It is a symbol of how you can build something from nothing, how the joy can come from the process rather than the result, how the necessity of compromise can produce lingering dissatisfaction, and, perhaps, how effort in one currency can be used to bootstrap capacities in another.  Maybe the “good” metaphor will crystalize when it’s gone.

0 Comments

Neandertal "Families," Mortality, and the OY Ratio: SAA 2014

4/3/2014

0 Comments

 
I decided to formally wade into the cloudy waters of the Middle Paleolithic at this year's SAA meetings with a presentation titled Marriage, Mortality, and Middle Paleolithic Families: Implications of a Model-based Analysis (the abstract is here). I'm using an agent-based model (ABM) to probe how the harsh adult mortality regimes suggested for the Middle Paleolithic might have affected the behavioral conditions under which human populations were demographically viable.  The model I'm using is the same as the one used in the AJPA paper with the addition of an age-specific mortality schedule that more-or-less mimics that suggested by fossil assemblages from Atapuerca and Krapina.  If you're interested in the nitty-gritty of the model, full code and description are available at openABM.org.

I became interested in the OY ratio (the ratio of older to younger adults) after reading Caspari and Lee's (2004) paper and the debate that followed.  While my results in the AJPA paper showed that there were clear relationships between the demographic characteristics of living populations (in the model) and the OY ratio of assemblages of dead individuals from those populations, thousands of model runs under widely varying conditions of fertility and mortality did not produce OY ratios nearly as low as those reported by Caspari and Lee for pre-Upper Paleolithic samples. But the representations and parameters in the ABM were based on data from ethnographic hunter-gatherers. 
What happens if we impose a mortality regime like that suggested by Atapuerca and Krapina?

Under a regime of high mortality (mortality schedule 3; MS 3 in the figures - the dotted lines are following José Maria Bermúdez de Castro & María
Elena Nicolás' 1997 paper), model populations are still "viable" if fertility is high enough.  And lower OY ratios (i.e., in the Neandertal range) are associated with higher fertility populations.  All things being equal, however, significantly larger population sizes are required for viability when we impose a harsh mortality regime.  This makes logical sense, of course, but it also seems possibly at odds with some of the peculiarities of the Neandertal fossil/archaeological record.  So I'm using the model to investigate the effects of behavioral differences (in terms of pair-bonding behaviors, "family"-like organization, etc.) on demographic viability. 
Picture
Picture
Picture
Picture
I'm still working my way through the model data.  I hope to be done with the presentation early (wouldn't that be a novel idea) so I can put it up here before the meetings, but I'm not sure I'll get there.  The presentation will be in the afternoon session on Paleolithic Europe on 4/26/2014. 
0 Comments

Complex Systems Science: Archaeology's New Kung Fu?

3/31/2014

0 Comments

 
Picture
I am an advocate for integrating complexity science into anthropological and archaeological research.  I think it is a box full of tools that significantly enhances our ability to understand the past.  I an unequivocal about that: I think it is the path to much better archaeological kung fu.  I just added content to the section of this site discussing what complexity science is and why it is useful for the kinds of archaeological questions I'm interested in.  I will polish it up in the future.  For now I'm going to have to be content with simply nailing it to the church door and moving on.

LATE ADDITION:  In a related story, I just learned on the radio that today is Angus Young's birthday.  Happy birthday, Angus!  Hay un largo camino hasta la cima, si tu quieres rock n' roll. That's perhaps the most useful thing I learned all day.

0 Comments

    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