A new study provides the earliest evidence to date that humans significantly altered entire ecosystems with llamas. The artifacts examined by the researchers are of the type produced in Africa in the Middle Stone Age, a period that dates back at least 315,000 years .
The study combines archaeological evidence – dense groups of stone artifacts dating back 92,000 years – with palaeoenvironmental data on the northern shores of Lake Malawi in East Africa.
Pollen and carbon counts
Archaeological data was collected from more than 100 wells dug hundreds of kilometers from the alluvial fan that developed during this time. Palaeoenvironmental data is based on pollen and charcoal counts that were deposited to the bottom of the lake bed and then recovered in a long sediment core drilled from a modified barge.
According to the researchers, the data revealed that there was an increase in carbon accumulation shortly before the flattening of the region’s species diversity – the number of distinct species that inhabit it.
Despite the lake’s consistently high levels, which imply greater stability in the ecosystem, species richness deflated after the last arid period based on information from fossilized pollen extracted from the lake bed.
The increase in archaeological sites after the last arid period, along with the increase in charcoal and the absence of forest, suggests that people were manipulating the ecosystem with fire. The scale of their long-term environmental impact is typically associated with farmers and herders, rather than hunter-gatherers. In other words: humans have always been impacting the environment , and before, percentage-wise, we did it much more aggressively: