From chaos, order: On the nature and measurement of biological aging

What is aging and how to measure it is an everpresent question in the field of aging research. Given the complexity of biology many give up on the task, proclaiming that "we" (either the field or humanity) don't understand aging. I don't. To me, what aging is is clear enough, and we can understand it as a fractal and emergent phenomenon within a system: there's aging of DNA, aging of cells, aging of organs, aging of organisms. To understand aging and measure it we have to be reasonably acquainte...