RESUMEN
We develop an efficient three-stage algorithm for simulating multiple acoustic scattering by two-dimensional configurations comprising large numbers of penetrable scatterers. Our approach is based on a boundary integral equation reformulation of the Helmholtz transmission partial differential equation, and a reduction of the boundary integral system for computationally efficient evaluation of wave interactions between scatterers. A key ingredient of our algorithm is to represent the interactions between scatterers using expansions of cylindrical wavefunctions. For large numbers of scatterers, this approach facilitates the application of the fast multipole method, leading to linear complexity of the algorithm with respect to the number of scatterers. Numerical results demonstrate the efficiency of our algorithm for configurations containing a few hundred to hundreds of thousands of individual scatterers.
RESUMEN
Archaeological evidence attests multiple early dispersals of Homo sapiens out of Africa, but genetic evidence points to the primacy of a single dispersal 70-40 ka. Laili in Timor-Leste is on the southern dispersal route between Eurasia and Australasia and has the earliest record of human occupation in the eastern Wallacean archipelago. New evidence from the site shows that, unusually in the region, sediment accumulated in the shelter without human occupation, in the window 59-54 ka. This was followed by an abrupt onset of intensive human habitation beginning ~44 ka. The initial occupation is distinctive from overlying layers in the aquatic focus of faunal exploitation, while it has similarities in material culture to other early Homo sapiens sites in Wallacea. We suggest that the intensive early occupation at Laili represents a colonisation phase, which may have overwhelmed previous human dispersals in this part of the world.
Asunto(s)
Arqueología , Migración Humana , Humanos , Historia Antigua , Migración Humana/historia , Sedimentos Geológicos , África , Animales , FósilesRESUMEN
The insular region of Wallacea has become a focal point for studying Pleistocene human ecological and cultural adaptations in island environments, however, little is understood about early burial traditions during the Pleistocene. Here we investigate maritime interactions and burial practices at Ratu Mali 2, an elevated coastal cave site on the small island of Kisar in the Lesser Sunda Islands of eastern Indonesia dated to 15,500-3700 cal. BP. This multidisciplinary study demonstrates extreme marine dietary adaptations, engagement with an extensive exchange network across open seas, and early mortuary practices. A flexed male and a female, interred in a single grave with abundant shellfish and obsidian at Ratu Mali 2 by 14.7 ka are the oldest known human burials in Wallacea with established funerary rites. These findings highlight the impressive flexibility of our species in marginal environments and provide insight into the earliest known ritualised treatment of the dead in Wallacea.