The Organization of Chipped-Stone Economies at Piedras Negras ...

An analysis of CE:M ratios and blade widths indicates that there were indeed
variable reduction strategies and changes in efficiency over time. Table 7.2 reveals how
CE:M ratios decrease, indicating that obsidian was reduced more efficiently in earlier
times than later on. A number of explanations can be made for this pattern, such as: (1)
obsidian became increasingly available over time; and (2) the general skill-level of
knappers in the city declined over time. This pattern seems counterintuitive, because
there is less evidence that percussion-prepared cores were imported to the site at the onset
of the Chacalhaaz phase. Fewer eccentrics were made out of percussion blades and flakes
with original percussion scars on their dorsal surfaces, and one would expect that blade
efficiency would increase if the cores were imported to the site already reduced by
pressure. However, this does not appear to be the case. Skill level appears to decline,
according to CE:M ratios, and the cause may be more widespread reduction of blade-
cores, by less-skilled laborers, in the city center during the Chacalhaaz phase.
Another interesting pattern is that blades from producing household groups tend
to have a higher CE:M ratios. One possible reason, other than higher skill-level, is that
sturdier blades may have been more valuable in trade interactions, and smaller, thinner
blades may have been less valuable and, hence, were retained for use within the
producing household. The correlation is tight for Chacalhaaz times, but the Yaxche phase
reveals no such pattern. Anomalies in the CE:M ratio for Yaxche are difficult to
understand, and may be due to smaller samples for this time period. In any case, the
correlation between CE:M and producing residential groups may be significant, but this
idea requires further study.
278