Ancient DNA evidence for genetic continuity in arctic dogs

The domestic dog fulfills many functions for their human companions, such as hauling, guarding, and protection. Consequently, humans have taken dogs to nearly every corner of the globe. Recent translocations of Western dogs stemming from the Victorian era dog fancy have erased some of the ancient genetic signatures of these earlier migrations. Here we used DNA of ancient and modern dogs from the North American Arctic of Alaska and Greenland to assess their genetic continuity in time and space. We successfully sequenced 23 archaeological (ca. AD 1250–1910) and recent (ca. AD 1930–1990) surface-collected Canis bone and tooth samples and compared them to 51 modern Inuit Sled Dogs and to published sequences of modern Alaskan Malamutes (and additional Inuit Sled Dogs) to test for evidence of lineage replacement or genetic continuity through time. Ancient samples from Alaska and Greenland and modern sequences from Greenland all contained a high frequency of haplotype A31, which was previously described only in modern North American Arctic dogs. Thus, A31 was a common thread tying the entire North American Arctic together prior to European colonization and, in the Eastern Arctic, indicates genetic continuity between past and present dogs as well. However, A31 is rare in modern Alaskan dogs, consistent with post-colonization replacement by Eurasian matrilines.     

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.