Officially, we’re in what’s known as the Holocene, the geological epoch that began at the end of the last ice age. But the influence of human activity on the Earth’s ecosystems has become so extreme that it now seems to be the central driver of environmental change, leading some scientists to argue that we should think of ourselves as living in a new epoch called the Anthropocene. Usage of the term is still being debated, though, and one of the central disputes is when the start of this new epoch would be. The mid-twentieth century? The Industrial Revolution? Or might it be earlier than that—say, when agriculture took hold as a dominant feature of human life?

A new study suggests that