ALL OF RECORDED HISTORY HAS OCCURRED WITHIN THE LATTER HALF OF THE Holocene epoch. The first written records appear around 5,000 years ago, and the first cities just over 4,000 years before that. They are all contained in a sliver smaller than 4 percent of Homo sapiens’ full history. This is because the Holocene, beginning about 11,700 years ago, brought more hospitable weather patterns, allowing humans to store large-scale agricultural surpluses, which in turn enabled the construction of the world we know today. Those conditions have come to an end. In the 1950s, human population, greenhouse gas emissions, chemical production, and infrastructure development began shooting upward, with biodiversity, cultural diversity, and wild habitat mirroring them downward. Nuclear fallout from bomb testing and ash from fossil fuel combustion spread around the…