Pinter et al., on a paper recently published in Quaternary Science Reviews, have reviewed several studies about the changes in vegetation and fire patterns in the Americas between 13.000 and 8.000 yr BP. The transition from the Pleistocene to the Holocene saw a climate change that marked the end of the last glaciation. During the Holocene, the ice melted, the see level raised and, of course, the vegetation changed. Therefore, the changes in paleoecological records of this period - like pollen and charcoal in lake sediments – have been interpreted as exclusive evidence of climate change. However, the problem is that during this same period of climatic change, people colonized America and also transformed the environment. We know that people can have a negative impact on the environment. Pinter et al. report several examples: “In Australia, human colonization ca 50,000–45,000 BP was accompanied by extinction of 90% of large fauna and the rapid decline of rainforest gymnosperms and other fire-intolerant plant taxa and by sharp increases in charcoal […] Tasmania was colonized 5–10 kyrs later than mainland Australia, and megafaunal extinctions and fire-driven devegetation and erosion also occurred 5–10 kyrs later.”
Why should it have been any different in America? People used fire and hunted large herbivores, maybe bringing them to the extinction. The extinction of the megafauna and the use of fire had an important impact on the vegetation. So, the main conclusion of their review is that climate is not the “universal independent variable” determining environmental change. People also played an important role.
But where and when? And here comes the importance of archaeological research and the study and reconstruction of past human-environment interactions. We need to set the geographical and chronological limits of human presence in the Americas in order to be able to interpret the paleoecological archives with any accuracy. This is extremely important in the Amazon Basin, where evidence of early human occupation is scarce. We need to address a fundamental question: Were there no people living in Amazonia 10.000 yr. BP or have we simply been unable to find their archaeological remains yet?