The history of medical observation is unknown. Astute medical conclusions that self-evidently must have been divined by Australopithecines have yet to be unearthed. One can only presume that, sometime in the last 10 million years, some species became conscious of the fact that concussive brain injury (CBI) often has late effects. More recently, largely due to significant increases in life expectancy after 1900, it has become clear that traumatic brain injuries -- single or multiple -- very often have disabling effects that either persist after injury or appear after a symptomatic caesura. Another relatively modern observation is that, with the passing of time, the waning of vigor, and the accumulation of mutations, old brains change in ways very roughly correlatable with behavioral functionality. What remains profoundly mysterious is whether and how these two observations relate. This chapter essays a slightly ambitious agenda: to consider the late effects of one or more CBIs in the light of basic principles of biology and logic. It is proposed that only by examining time-passing-related brain change free of implausible preconceived nosologies might one devise research strategies that can illuminate that relationship.