From the geological period identified as the Holocene, which followed the Pleistocene, emerges the Anthropocene—the age when humans, a very new animal indeed, have a geological and ecological impact that is planetary in scale. Researchers at the University College London, reports Science Daily, have marked the beginning of this period at around 1610. The reason for selecting this point near the start of the second half of the second millennium is that it meets two requirements for the definition an epoch: One, lasting change must be recognizable in the natural record (things like "rocks, ancient ice or sediment from the ocean floor") and, two, a sudden globally significant event (a "golden spike") must also be marked in this natural record.

Around 1610, the researchers contend, there was an unprecedented exchange of life forms between two continents (the New World and the Old World). This "cross-ocean exchange" has had a lasting impact on the history and development of the biosphere—which is one of Earth's layers. The second marker resulted from the death, during this period, of an estimated 50,000,000 humans in the New World. Diseases transported from the Old World were responsible for the dramatic crash of this population; and fewer humans on the continent meant a massive reduction in agricultural activities, which then resulted in a rebound of forests (or tree cities), and this rebound reduced atmospheric carbon. A record of this reduction is found in Antarctic ice.

One would think a more human Earth would mean a better world for humans. A city of humans is much more comfortable for this animal than a city of trees. There are no chairs or tables in a forest; leaves are not good pillows. But globally significant human activity is not making Earth more familiar but more strange. We have, it seems, created a monster that the current governor of Florida refuses to name. That monster is, to use the language of the ecological philosopher Timothy Morton, a hyperobject identified by the scientific community as global warming. This massive and anthropogenic object is as real as the sun in the sky, the black hole at the center of the galaxy, and the bacteria on your eyelashes. Ignoring its name will not, sadly, make it go away. The age of humans also means the age that will be the most strange to humans.