Discussion. Human influence comes of age : Nature News Human influence comes of age Geologists debate epoch to mark effects of Homo sapiens. Nicola Jones Humanity's profound impact on this planet is hard to deny, but is it big enough to merit its own geological epoch? This is the question facing geoscientists gathered in London this week to debate the validity and definition of the 'Anthropocene', a proposed new epoch characterized by human effects on the geological record. "We are in the process of formalizing it," says Michael Ellis, head of the climate-change programme of the British Geological Survey in Nottingham, who coordinated the 11 May meeting. He and others hope that adopting the term will shift the thinking of policy-makers. "It should remind them of the global and significant impact that humans have," says Ellis. But not everyone is behind the idea. "Some think it premature, perhaps hubristic, perhaps nonsensical," says Jan Zalasiewicz, a stratigrapher at the University of Leicester, UK, and a co-convener of the meeting. Zalasiewicz, who declares himself "officially very firmly sitting on the fence", also chairs a working group investigating the proposal for the International Commission on Stratigraphy (ICS) the body that oversees designations of geological time. The term Anthropocene was first coined in 2000 by Nobel laureate Paul Crutzen, now at the Max Planck Institute for Chemistry in Mainz, Germany, and his colleagues. It then began appearing in peer-reviewed papers as if it were a technical term rather than scientific slang.