Origin: A Genetic History of the Americas

Chapter 4
Twenty years ago I took my shoes off and stepped into the Mayan
underworld.
The darkness in the cave rendered my peripheral vision useless—the
only objects I could see were those directly illuminated by the narrow cone
of light from my headlamp, giving me only piecemeal images of the huge
cavern. The archaeologists who were guiding us and supervising our
training called this room the main chamber. Seeing a world through a
headlamp is like looking through the cardboard tube at the center of a paper
towel roll; you focus on one object, shift your head, take in something else,
shift again. I felt like I was piecing together the entire cavernous chamber in
a hundred spotlit gazes.
Against one wall was a cluster of beautiful white columns made up of
fused stalactites and stalagmites. Over thousands of years, the drip of water
from the limestone ceiling formed the flowstone deposits that glittered in
the light of my headlamp.
As I turned my head slightly to the right of the columns, my light
revealed something much younger resting against the wall: a manos and
metate—stones the ancient Maya had used to grind corn.
I shined my headlight down to my feet, clad only in wet woolen socks.
In order to protect both the artifacts and the cave formations, we had left
our shoes outside, and now I was standing in the dark with the other
students, my toes hanging off of the lip of one of countless small travertine
dams that extended outward from the entrance of the main chamber to its
back wall. Each dam was a ledge of calcite encircling small indentations in
the ground, caused by the water that had once dripped from the countless
stone icicles hanging from the ceiling.
The pools were dry now, but they hadn’t been when the ancient Maya
last visited this room, over a thousand years ago. In these pools, on the