1. Pleistocene, 2.6 million to 11,700 years ago
The very best time on Earth. Extremely recent as far as geologic time goes, the Pleistocene was momentous. It’s also the last chapter in which Earth’s climate was untarnished by human changes. Modern humans were around then, though, and we were busy interbreeding with Neanderthals and the Denisovans. The Pleistocene saw the first art, and, perhaps most importantly, woolly mammoths and adorably armored glyptodonts bopped around the cooler stretches of the planet. There were also cave bears, marsupial saber-toothed tigers, and giant ground sloths. At one point, the recent northern glaciers reached as far south as Manhattan. The Pleistocene is a fascinating liminal space between our recorded history and deep time, one that holds many clues to how humans ended up the way we are today.
