Food scraps are the key to discovering rainfall patterns from over 40,000 years ago according to a collaboration between Mirarr Traditional Owners and University of Queensland researchers.

Believed to be the leftovers of meals eaten by Traditional Owners up to 65,000 years ago, anyakngarra (pandanus) nutshells were discovered in 2012 during excavations at Madjedbebe rock shelter, on Mirarr Country, in the Alligator Rivers region (now Kakadu) of Arnhem Land.

A five-year investigation saw both parties record and measure the impact of different rainfall patterns on pandanus shells, then compare these measurements to the ancient shells.

Gundjeihmi Aboriginal Corporation CEO Justin O’Brien said the investigation supported the importance of the Madjedbebe site and its “extraordinary depth of knowledge”.

“This research reaffirms the importance of its long-term protection,” O’Brien said.

A modern pandanus nutshell. Photo supplied.

Lead researcher Dr Anna Florin from the Australian Research Council (ARC) Centre of Excellence for Australian Biodiversity and Heritage noted her excitement at the discovery. 

“I think for us this is an incredibly exciting part of the world where people potentially were first entering Australia 65,000 years ago and lived through … these glacial stages, these two quite arid periods in the past,” said Dr Florin.

“We have a very good understanding of what happened more recently, but not so much what happened before 8,000 years ago. So, between 65,000 and about 8,000 years ago we don’t really have environmental records for that area.”

Dr Florin said she and her research team wanted to create an environmental record that allowed them to understand how Traditional Owners were living in and shaping their environment up to 65,000 years ago.

“I think the key finding from our studies is that we were able to use this pandanus … which is the food scraps from people’s meals that have been left in the site in little fireplaces essentially.”

The team examined the isotopic composition of the shells to understand the rainfall patterns in the region at the time.

“One of the interesting things that we found is that the Alligator Rivers region, which is basically the Kakadu region today, may not have been super dry during these glacial stages,” Dr Florin said.

“We know that other parts of Australia, especially Northern Australia were really very arid during these periods, so it would’ve been a very big stress on … communities who were living in these areas.

“What we think might be happening is these areas actually acted like a bit of a refuge for people, and is a place where groups would have thrived during these ice ages.”

Areas surrounding the site also recorded large amounts of stone tools and stone materials, which Dr Florin said suggests higher mobility during dry periods.

“It also might have been changes in … social networks, so people are trading more and have more interconnectedness because they have a higher risk if they aren’t connected to groups around them,” said Dr Florin.

“We get these little glimpses potentially into how people were dealing with these sort of environmental changes in the past.”

By Rachel Stringfellow