https://rowman.com/ISBN/9781498514279/Impact-of-Tectonic-Activity-on-Ancient-Civilizations-Recurrent-Shakeups-Tenacity-Resilience-and-Change
This posting has been revised and incorporated in a published book as of August 2015 (link above)
Quantified
spatial analysis of tectonic boundaries vs. ancient
complex cultures
Eric
R. Force (eforce@email.arizona.edu)
I have previously described the tectonic
environments of the “great” ancient civilizations in the old world (1). It
is impressive how closely associated most of them are with tectonically active
plate boundaries, despite the seismic and volcanic dangers involved. The
association is most obvious in the spatial relation at several scales, between
the originating sites of these civilizations and the tectonic boundaries
(Force, 2008, fig. 1; Force and McFadgen, 2010, figs. 1, 2), though its
significance is supported in other ways. In othert posts I analyze
various aspects of the dynamics of the relation (2).
First, however, I need to quantify the strength
of the apparent spatial relation, in order to address the possibility that it
is some sort of coincidence. Then it may be possible to select subsets, both
geologic and cultural, and compare their behaviors in order to provide clues to
the meaning of the relation and link these to archaeological-historical
observations.
Quantification
of the basic spatial relation.--Since the originating sites of the ancient
civilizations are map-points whose distance from the nearest tectonic-boundary
line can be approximated, we have the basis for finding an approximate
probability that this distance is random for the available space where such
sites are possible. In my paper of 2008, I performed this calculation
excluding two ancient civilizations, China and Egypt, as exceptions because I
did not see any particular connection to tectonic boundaries.
Subsequently (3), I placed these civilizations in tectonic environments that
permit inclusion, albeit at greater distance, and omitted Assyria as a separate civilization, bringing the
number of treated ancient civilizations to twelve. In this post I redo
the calculation to incorporate these changes in variables.
Note 4 lists the distances used to calculate
average distances of ancient civilizations from active tectonic boundaries.
The average distance is about 100 km. In other words the
civilizations lie in a belt averaging only 200 km wide, with the southern
boundary of the Eurasian plate and related plate-tectonic boundaries defining
the center of this belt, which contains an area of 4.4 million square
kilometers. In contrast the theoretically available land area for origination
of these civilizations in Eurasia and Africa was 85 million square kilometers,
suggesting that the ancient civilizations crowded into the 5.2 percent of
available land that is adjacent to tectonic plate boundaries. This might
seem an unrealistic percentage given that northern Siberia and other extremely
unsuitable areas were included as available areas, so to exclude these I have
used a figure of 77 million square kilometers in the calculation as being
available (5).
It may also be misleading to measure to the
nearest fault that represents a plate boundary where the boundary is partitioned
among two or more main faults, as in the Zagros Mountains and Baluchistan.
To accommodate this ambiguity, I have used a double-width of 290 km, which
along most of the boundary is a generous overestimate. This combination
gives a percentage of 8.3, or about 1 in 12 (6) as the fraction of available
land where ancient civilizations originated adjacent to active
continental-scale tectonic boundaries.
Next is the calculation of the probability that
this distribution is random (7), given that the area of the belt is about 1/12th
of the available land areas. Because there are now no exceptions, this is
an easy calculation. The chance of random distribution given the observed
distribution is one in twelve to the twelfth power, using the binomial
probability distribution formula (given in Force 2008). Technical
points of the calculation need not be repeated here, but readers who do some
gambling may enjoy an analogy that makes it easier to visualize.
Computing this probability is the same as computing the probability in roulette
of a ball landing on the same number twelve times in a hypothetical roulette
wheel that has twelve numbers. These readers will not be surprised
to learn that this calculated probability is one in 8.92 trillion.
Thus the probability that the civilization distribution is random relative to
tectonic boundaries is so small that the spatial relation is like those we
accept instinctively. It is far beyond any need for statistics.
In my 2008 paper I also varied another factor in
order to see whether the probability of random distribution could be increased,
in a sort of sensitivity analysis. Four civilizations IN the belt were omitted
on the grounds that some authorities would lump them with other civilizations
or not recognize them as “great.” In the equivalent calculation of this
“worst-case scenario” using the above figures, the probability of random
distribution was still one in 282 billion. The conclusion that these
ancient civilizations are spatially related in some way to tectonic boundaries
is robust. In other posts I present probability calculations that confirm various
different aspects of the relation (8).
Looking
at assumptions, constraints, and definitions.—Perhaps the outcome of
quantification was pre-determined by the design of the experiment, which
involves a certain time period and a certain half of the world. I
think it’s pretty obvious that “constraining” to the period of antiquity from
the beginning of the Bronze Age to about A.D. 500 (about 4000 years) and “constraining”
the area considered to the whole eastern hemisphere gives ample scope to
variation! Times and areas outside
those boxes are considered in other posts. They present
interesting stories of their own, consistent with the conclusions drawn thus
far, suggesting in fact that they have broader application.
Perhaps most critical is the term civilization,
in the sense of “great ancient civilization.” This is a term not much in
favor among anthropologists of our day, and for some good reasons.
Cultures can be complex in different ways, and the complexity of “GAC”s as
conventionally defined requires recognition of characteristics that can be
preserved in archaeological and historical records, with particular emphasis on
public architecture and preserved writing (10). Postings listed above
have recorded some of the accomplishments of GACs that have convinced previous authorities
(and me) of their greatness, in the sense that their complexity has many
dimensions and far exceeds that of the neighboring cultures of their times.
But it would be desirable to get beyond both the term “great
civilization” to give cultural complexity a more rigorous basis.
Some historians and anthropologists think that
attempts to quantify cultural comparisons are to be avoided (but see note 11).
For my purposes, a list of the characteristics of GACs by Childe (12) that
is still highly regarded (and which has been discussed and slightly modified
for 60 years) seems the best basis. The assemblage of ten characteristics
listed by Childe is that which more or less defines GACs as they are
conventionally accepted and which seems to correspond to the spatial
relationship I’ve documented. Thus a rough “quantification” of my use of GAC
corresponds to Childe-scores of eight or more.
The correspondence invites, indeed demands,
exploration independently of reactions to “great civilizations”. That is, the
correspondence of Childe-scores of cultural complexity with tectonic boundaries
is telling us something about the emergence of this assemblage of cultural
traits in a tectonic context.
In Mar. 4, 2014 I aggregate Childe’s criteria to construct
cultural complexity “transects” at continental scale; the resulting
distributions justify confidence that the “GAC” designation is meaningful and
that it corresponds spatially to tectonic boundaries.
It seems safe to conclude that ancient cultures sufficiently complex to have
been called “great ancient civilizations” show a remarkable spatial
relationship to active tectonic boundaries, especially the southern boundary of
the Eurasian plate and closely associated structures. Though apparent in
map view, the relationship is resoundingly supported by quantitative probability
analysis. The next and more interesting steps are to probe the meaning of
the relationship.
Notes
1.
June 27, 2014, June 16, 2014, May 18, 2014, and May 8, 2014)
2. Mar. 4, 2014, Feb. 1, 2014, Jan. 7, 2014, Dec. 11,
2013, Nov. 26, 2013, Oct. 16, 2013, Aug. 29, 2013, July 17,
2013, June 3, 2013, and May 10, 2013
3. May 8, 2014
4.
Distances in km used to calculate average—Rome 130, Etruria 150, classical
Greece 10, Mycenaeans 25, Minoans, 60, SW Asia 25, Mesopotamia 150, Indus 90,
Persian 30, Aryan India 100, China 300, India 130. These values are
discussed in posts describing individual civilizations, and in some cases are
themselves averages for civilizations of composite origination.
5.
Subtracting areas north of 60 degrees and a few extremely mountainous areas.
6.
cf. Force 2008, rows 3 and 4 of table 1)
7.
To calculate probabilites, I used the binomial distribution formula, which
requires that the outcome of each “experiment” be independent of previous ones.
The people founding ancient civilizations of course knew nothing about plate
tectonics, but they were cognizant of earthquakes and volcanoes. If we’re
trying to increase the probability of random distribution, the question is
whether such phenomena in previous civilizations influenced them in founding
new sites of civilizations in similarly active locations. It seems
unlikely that they would choose locations on this basis, which to them seemed
to hold only disadvantages. A related consideration is whether the
location of the previous civilization has preempted a significant share of the
length of the plate boundary. On this subject remember that the
occurrence in question involves only the founding sites for each civilization,
i.e. only a point on a line. But if such preemption should occur, the
probability of random occurrence would be decreased, not increased. Thus
if exceptions to independence occur, they would seem to strengthen the spatial
relation.
8. Jan. 7, 2014, Dec. 11,
2013, and Nov. 26, 2013
9. Jan. 7, 2014, and Oct. 16, 2013).
10.
Questions remain where the evidence has been erased. For example, only
scraps of either the civic architecture or the language and literature of the
Etruscans have been preserved. Would we regard Etruscan civilization as
“great” had it not been for their funerary arts and architecture, and the
evidence from other cultures (and the plaques of Pyrgi) that they did have a
literary corpus?
11.
Ian Morris (2010) on the other hand, has tried to use quantification methods
that avoid cultural baggage, with an index that includes energy capture, urbanism,
and ability to wage war.
12.
Childe (1950). These are cities, occupational specialties, concentrated
food surpluses, monumental public architecture, capabilities for planning and
organization, record-keeping and writing, practical science, arts, trade, and
some sort of ideological solidarity.
References
Childe, V. G., 1950, The urban revolution: The town planning review, v. 21, p.
3-17
Force, E. R., 2008, Tectonic environments of
ancient civilizations in the eastern hemisphere: Geoarchaeology v. 23 p.
644-653.
Force, E. R., and McFadgen, B. G., 2010,
Tectonic environments of ancient civilizations: opportunities for
archaeoseismological and anthropological studies, in Ancient Earthquakes, M.
Sintubin, I. S. Stewart, T. M. Niemi, and E. Altunel, eds.: Geological
Society of America Speical Paper 471, p. 21-28.
Morris, Ian, 2010, Why the West rules—for now: Ferrar,
New York
