The fractal geometry of ancient Maya settlement

Ancient Maya settlement patterns exhibit fractal geometry both within communities and across regions. Fractals are self-similar sets of fractional dimension. In this paper, we show how Maya settlement patterns are logically and statistically self-similar. We demonstrate how to measure the fractal dimensions (or Hausdorff–Besicovitch dimensions) of several data sets. We describe nonlinear dynamical processes, such as chaotic and self-organized critical systems, that generate fractal patterns. As an illustration, we show that the fractal dimensions calculated for some Maya settlement patterns are similar to those produced by warfare, supporting recent claims that warfare is a significant factor in Maya settlement patterning.     

New experimental data on the distance of sling projectiles

The range of stones cast by slings used in the past is debated. In the Central Andes, slings are asserted to be important weapons of prehispanic war, and have been recovered archaeologically. Rolled river cobbles and stones presumed to be slingstones found at fortified hilltop archaeological sites are presented as evidence that slings were used at these fortifications. Yet sling use has not been adequately tested at hillforts. Experiments conducted in Europe by a novice slinger have attempted to illuminate the range of sling cast stones at ancient hillforts. Data acquired from native slingers is necessary to more accurately assess distances achieved by projectiles launched by slings. We present data from sling experiments carried out in Puno, Perú among Quechua-speaking herders who are experienced slingers. The results demonstrate that a prior model of the maximum theoretical distance of sling cast stones underestimates their range. Results also show significant differences in the use of slings by men and women, and by different age groups. These new data permit a better approximation of warfare that has bearing on our interpretation of fortified sites.     

Possible isotopic fractionation of argon in source obsidians and archeological artifacts from Kulkuletti, Ethiopia

Despite uniform geochemistry ⁴⁰Ar/³⁹Ar ages of 0.6, 1.25, and 1.3 Ma on obsidians from a source flow (Worja) and from archeological artifacts at the sites of Kulkuletti (near Gademotta, Ethiopia) have been interpreted to suggest that they derive from different source flows of different ages. A further suggestion is that the magmatic source of the obsidian flows was chemically homogeneous between 1.3 Ma and 0.6 Ma. Chemical analysis of these obsidians indeed suggests that they derive from a single flow. Reexamination of the argon isotopic data reveals that argon isotopes may have been fractionated within the flow, so that the assumption of an atmospheric ⁴⁰Ar/³⁶Ar ratio of 295.5 is inappropriate to use for computing ages. Three groups of data are apparent, and internally all yield ages near 1.3 Ma if the intercept value for ⁴⁰Ar/³⁶Ar from an isotope correlation plot is used for computation instead of using the atmospheric ratio. The Soret thermal diffusion effect provides a possible mechanism of fractionation of argon within the obsidian flow that is of approximately the right magnitude to explain the observations by in-diffusion of already fractionated atmospheric argon.     

Phylogeographic analysis of barley DNA as evidence for the spread of Neolithic agriculture through Europe

Results of analyses of the photoperiod response gene (PPD-H1) and simple sequence repeats (SSRs) in modern landraces of cultivated barley were used as evidence for the mechanism of agricultural spread in Neolithic Europe. In particular, we explored the usefulness of considering adaptive genes as indicators of past selective pressures acting on crops, during their spread through Europe. In some areas, such as the Alpine region, Britain and Scandinavia, we have evidence to suggest that the adaptation of crops to certain climatic conditions may have contributed to the timing of agricultural spread. At the northern fringes of Europe, and in higher altitude locations in central Europe, the introduction of more suitably adapted cereals may have facilitated successful agriculture to trigger agricultural expansion. This research opens up the possibility of investigating other genetic adaptations to climate, which would permit a fuller evaluation of the relative contributions of climate/crop and forager/farmer interactions in the process of agricultural spread.