The legacy of the germ line-maintaining sex and life in metazoans : Cognitive roots of the concept of hierarchical selection

Abstract

The metazoan germ line is often referred to as nothing else but another organ or tissue that needs no different treatment in research compared to other somatic organs such as liver, kidneys, skin, brain or blood. However, the germ-line concept was established during the 19th century by August Weismann and was recognized since to be tightly linked with the role of maintaining sexual reproduction. By far more profoundly, Stephen Gould only recently documented how August Weismann and Charles Darwin gained insight into evolution driven by multiple levels of selection - not natural selection as the only level, each playing its particular and significant role in understanding a different aspect of evolution from the level of molecules to cells, man, societies up to the complexity of ecosystems. This chapter represents a single argument pinpointing the historical and current cognitive foundations at the grass-roots level with links to present concepts of sexual reproduction. Feeding back on this, sexual reproduction and genetic recombination including meiosis are part of the glue linking all the levels of hierarchical selection. Finally, this essay briefly sketches a tie to modern frontiers, in particular to the nuage germ plasm organelle. The nuage is recognized as an ancient key platform mediating genome encoded sex-related developmental circuits as well as germ-line-related control of transposon driven (epi)genome instability. © 2007 Springer-Verlag Berlin Heidelberg.