The findings, which incorporate several lines of past archaeological evidence, suggest even large, resilient, and cooperative coastal communities can easily go out with the tide.
When analyzing and dating a series of prehistoric shell 'mountains', known as sambaquis in the local language, researchers noticed some significant changes in southwestern Brazil about 2,500 years ago.
At this time, the size and frequency of sambaqui sites suddenly began to decrease, possibly indicating the dissolution of what were, for millennia, dense and stable shellfish-eating populations.
Other research in the area has also identified a rapid reduction in sambaquis around this time, but some researchers think these changes mostly occurred from the rise of ceramics and crops. The use of this new technology meant populations didn't need to rely as much on fish or mollusks, leading to a reduction in shell piles.
However, the new study found the decline of shell middens started before the introduction of pottery. So why, then, were sambaqui practices abandoned?
The answer might have to do with an extreme, retreating tide. By reassessing human and animal remains from Babitonga Bay – home to Brazil's largest concentration of sambaquis – researchers have put forward a new timeline.
According to more than 400 radiocarbon dates, the spread of ceramics in Babitonga probably started around 1,200 years ago. READ MORE...
