Symbiogenesis

Symbiogenesis, also called endosymbiotic theory, is the leading evolutionary explanation for how the complex eukaryotic cell arose from simpler prokaryotic ancestors. It holds that mitochondria, chloroplasts and possibly other organelles of eukaryotic cells descend from formerly free-living prokaryotes that were taken inside another cell in a lasting endosymbiosis; mitochondria are phylogenetically related to Rickettsiales bacteria, while chloroplasts derive from cyanobacteria. The idea traces back to nineteenth century researchers such as Andreas Schimper and was formally set out by the Russian botanist Konstantin Mereschkowski between 1905 and 1910, but it only gained wide scientific credibility after Lynn Margulis presented detailed microbiological evidence in 1967, including electron-microscope comparisons and the discovery that these organelles carry their own DNA. Symbiogenesis reshaped evolutionary theory by proposing that major evolutionary advances, especially the origin of the eukaryotic cell, can arise from symbiotic mergers between organisms rather than only from gradual mutation and competition between individuals, establishing cooperation alongside competition as a genuine driver of evolution. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/