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OUR ancient ancestors are off the hook about contributing to climate change. About 6000 years ago, levels of atmospheric carbon dioxide rose – and until now slash-and-burn by the 12 million humans on the planet at the time has been blamed.

Now these early farmers have been absolved. The 20-parts-per-million rise in CO₂ concentration which occurred between 7000 and 500 years ago wasn’t their fault, say at the University of Bern in Switzerland and his colleagues (Nature, ).

The team extracted air bubbles from an Antarctic ice core to identify the origins of CO₂…