Pacific rats trace 2,000 years of human impact on island ecosystems

June 4, 2018, Max Planck Society

Chemical analysis of the remains of rats from archaeological sites spanning the last 2000 years on three Polynesian island systems has shown the impact of humans on local environments. The analysis by an international team of scientists allowed the researchers to reconstruct the rats' diets—and through them, the changes made by humans to local ecosystems, including native species extinctions and changes to food webs and soil nutrients.

The Earth has entered a new geological epoch called the Anthropocene, an era in which humans are bringing about significant, lasting change to the planet. While most geologists and ecologists place the origins of this era in the last 50 to 300 years, many archaeologists have argued that far-reaching human impacts on geology, biodiversity, and climate extend back millennia into the past.

Ancient human impacts are often difficult to identify and measure compared to those happening today or in recent history. A new study published in the Proceedings of the National Academy of Sciences by researchers at the Max Planck Institute for the Science of Human History in Jena and the University of California, Berkeley advances a new method for detecting and quantifying human transformations of local ecosystems in the past. Using state of the art methods, researchers searched for clues about past human modifications of island ecosystems from an unusual source—the bones of long-dead rats recovered from archaeological sites.

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