Extreme climate changes, both wet and dry, corresponded with the population decline of a Maya settlement in central America according to new research out of McGill University that looked at indicators left behind by ancient human waste. .
Benjamin Keenan, a PhD candidate in McGill's Department of Earth and Planetary Sciences and the study's first author, says human remains don't last very long in tropical rainforest environments — but the molecules present in human waste do.
By looking at the concentrations of fecal stanols that were preserved in the mud of the lake adjacent to the settlement, the team was able to paint a picture of population change over a period of 3,300 years.
Itzan is the "perfect setting" to use fecal stanols to glean information on the relationship between changes in population over time and extreme climate events, Keenan told CBC News. .
The climate change of the past was different from today's, which is due to human-caused greenhouse gas emissions, says Peter Douglas, an assistant professor with McGill's Department of Earth & Planetary Sciences and the senior author on the study.
While it may have been human-induced to some degree — by heavy deforestation that caused soil erosion or dried-out soil, for example — many experts say climate extremes in the Maya era were likely produced by El Niño.
"Based on what we know, the climate change that we can expect in the next 100 years is going to be, at least on a global scale, much stronger," says Douglas. .
"[This study] builds up the case that yes, when climate change happens people have to adapt and they adapt by changing their societies and moving.".
"The [Maya], they never really talked about the weather as being particularly unusual," says MacEachern, who adds that this makes it challenging for scientists to determine whether climate events caused their population decline.