South American peopling and neotropical savannisation
By Valentí Rull
Northern South America is covered by extensive savannas whose natural or anthropogenic origin is debated. Currently, these savannas are in expansion to the detriment of the surrounding rainforests due to fire management by humans. Knowing the origin and historical development of these savannas is needed for optimal conservation planning. Past ecological studies based on pollen and charcoal analysis of sediments suggest that the joint action of arid climates and fire may have played a major role in the origin of neotropical savannas. However, the natural or anthropogenic origin of fires is still unknown. The oldest fires recorded so far in the region correspond to the Younger Dryas cold-arid phase occurred between about 13,000 and 11,500 years before present, shortly after human entrance in South America via the Panama Isthmus. These first colonisers were nomadic hunter-gatherers largely depending on currently extinct megahervivores for food supply, and may have been involved in the initial deforestation and the subsequent savannisation of Neotropical South America.