Manuel de Landa, A thousand years of non linear history

(…) sudden mineralization, and a new material for constructing living creatures emerged: bone. (…) far from having been left behind as a primitive stage of the earth’s evolution, fully coexisted with the soft, gelatinous newcomers. Primitive bone, a stiff, calcified central rod that would later become the vertebral column as vertebrates, belong, it never forgot its mineral origins: it is the living material that most easily petrifies, that most readily crosses the threshold back into the world of rocks. For that reason, much of the geological record is written with fossil bone.

The human endoskeleton was one of the many products of that ancient mineralization. Yet that is not the only geological infiltration that the human species has undergone. About eight thousand years ago, human populations began mineralizing again when they developed an urban exoskeleton: bricks of sun-dried clay became the building materials for their homes, which in turn surrounded and were surrouned by stone monuments and defensive walls. This exoskeleton served a purpose similar to its internal counterpart: to control the movement of human flesh in and out of a town’s walls.