Neuronal Death and Neurotrophic Factors

Abstract

The tyranny of theory over the evidence is nowhere more glaringly evident than in the history of the delayed discovery of neuronal death during normal development. The tyranny in this case was imposed by the theory that both ontogeny and phylogeny are progressive, from lower and less organized to higher and more organized nervous systems. Evidence of neuronal death during normal development was reported but was ignored because it was in conflict with the idea of progressive development. Reports of neuronal death were buried in the literature, to be unearthed much later as curious historical relics. Such reports come back to haunt us as they haunted previous generations who could not accept evidence that conflicted with their cherished theories.

Men make their own history, but they do not make it just as they please; they do not make it under circumstances chosen by themselves, but under circumstances directly encountered, given and transmitted from the past. The tradition of all the dead generations Weighs like a nightmare on the brain of the living.

Karl Marx (1818–1883), The Eighteenth Brumaire of Louis Bonaparte, 1852

According to tradition, the development of the vertebrate nervous system has hitherto seemed to proceed straight on in a gradually ascending path, without turnings, temporary expedients, or regressive changes. As a consequence none were looked for and none were found.

John Beard (1858–1918), The History of a Transient Nervous Apparatus in Certain Ichthyopsida, 1896