Disease: A Hitherto Unexplored Constraint on the Spread of Dogs (Canis lupus familiaris) in Pre-Columbian South America

Although debate continues, there is agreement that dogs (Canis lupus familiaris) were first domesticated in Eurasia, spreading from there to other parts of the world. However, while that expansion already extended as far as Europe, China, and North America by the early Holocene, dogs spread into (and south of) the tropics only much later. In South America, for example, the earliest well attested instances of their presence do not reach back much beyond 3000 cal. BC, and dogs were still absent from large parts of the continent – Amazonia, the Gran Chaco, and much of the Southern Cone – at European contact. Previous explanations for these patterns have focused on cultural choice, the unsuitability of dogs for hunting certain kinds of tropical forest prey, and otherwise unspecified environmental hazards, while acknowledging that Neotropical lowland forests witness high rates of canine mortality. Building on previous work in Sub-Saharan Africa (Mitchell 2015) and noting that the dog’s closest relatives, the grey wolf (C. lupus) and the coyote (C. latrans), were likewise absent from South and most of Central America in Pre- Columbian times, this paper explores instead the possibility that infectious disease constrained the spread of dogs into Neotropical environments. Four diseases are considered, all likely to be native and/or endemic to South America: canine distemper, canine trypanosomiasis, canine rangeliosis, and canine visceral leishmaniasis caused by infection with Leishmania amazonensis and L. colombiensis. The paper concludes by suggesting ways in which the hypothesis that disease constrained the expansion of dogs into South America can be developed further

Human–environment interactions during the early mid-Holocene in coastal Ecuador as revealed by mangrove coring in Santa Elena Province

Coastal environments of the early mid-Holocene provided challenges and opportunities for agriculturalists living in the Santa Elena Peninsula, Ecuador (Santa Elena Province, formerly southwestern Guayas Province). Cores extracted from swamps in three river outflows, namely, the Río Verde/Río Zapotal drainage (Chanduy estuary), the Río Grande (Punta Carnero locality), and the Río Valdivia, provided pollen, phytolith, sedimentary, and elemental sequences relevant to documenting vegetation and agriculture. The Chanduy record documented maize and other cultigens from 3200 to 500 cal. BC, providing evidence for intensive cultivation of alluvial lands. The Punta Carnero core provided the first evidence for occupation of the peninsula during the ‘hiatus’ between the Vegas and Valdivia periods, as maize was present in a stratum dating to 4857 cal. BC. Records documented mid-Holocene sea-level stabilization, development of low-energy depositional environments, and variation in rainfall attributable to El Niño-Southern Oscillation (ENSO) by 5000 cal. BC. There was no evidence that the region was either markedly wetter or drier in the early mid-Holocene, suggesting that climate controls similar to those of today were in place