Editing Symbiosis (section)

=== Symbiogenesis ===

{{main|Symbiogenesis}}

One hypothesis for the origin of the nucleus in [[eukaryotes]] (plants, animals, fungi, and [[protists]]) is that it developed from a [[symbiogenesis]] between bacteria and archaea.<ref name="Moran-2006"/><ref>{{Harvnb|Brinkman|Blanchard|Cherkasov|Av-Gay|2002}}</ref><ref>{{Harvnb|Golding|Gupta|1995}}</ref> It is hypothesized that the symbiosis originated when ancient archaea, similar to modern methanogenic archaea, invaded and lived within bacteria similar to modern myxobacteria, eventually forming the early nucleus. This theory is analogous to the accepted theory for the origin of eukaryotic mitochondria and chloroplasts, which are thought to have developed from a similar endosymbiotic relationship between proto-eukaryotes and aerobic bacteria.<ref>{{cite book |last=Margulis |first=Lynn |author-link=Lynn Margulis |year=1981 |title=Symbiosis in Cell Evolution |pages=[https://archive.org/details/symbiosisincelle00marg/page/206 206–227] |publisher=W. H. Freeman and Company |location=San Francisco |isbn=978-0-7167-1256-5 |url=https://archive.org/details/symbiosisincelle00marg/page/206 }}</ref> Evidence for this includes the fact that [[mitochondria]] and [[chloroplast]]s divide independently of the cell, and that these organelles have their own genome.<ref>"Symbiosis". ''Bloomsbury Guide to Human Thought''. London: Bloomsbury Publishing, 1993. Credo Reference. Web. 17 September 2012.</ref>

The biologist [[Lynn Margulis]], famous for her work on [[endosymbiosis]], contended that symbiosis is a major driving force behind [[evolution]]. She considered [[Charles Darwin|Darwin]]'s notion of evolution, driven by competition, to be incomplete and claimed that evolution is strongly based on [[Co-operation (evolution)|co-operation]], [[Biological interaction|interaction]], and [[mutual dependence]] among organisms. According to Margulis and her son [[Dorion Sagan]], "[[Life]] did not take over the [[Earth|globe]] by [[combat]], but by [[social network|networking]]."<ref>{{harvnb|Sagan|Margulis|1986}}</ref>