Symbiogenesis is a theory of evolution. It argues that symbiosis is a primary force of evolution, because acquisition and accumulation of random mutations or genetic drift are not sufficient to explain how new inherited variations occur. According to this theory, new cell organelles, new bodies, new organs and new species arise from symbiosis, in which independent organisms merge to form composites. This challenges some standard textbook ideas of how evolutionary change occurs. To some degree, Darwin emphasized competition as the primary driving process of evolution, symbiogenesis emphasizes that co-operation can also be important to the process of evolution.
It is now very reasonable to propose four major events of symbiogenesis:
1. The origin of double-membrane (gm neg) bacteria.
2. The origin of the eukaryotic cell.
3. The origin of mitochondria.
4. The origin of chloroplasts.
And there is a conceptual logic involved with all this. The gram positive bacteria front-load the appearance of the gram negatives and the eukaryotic cell, which in turn front-loads the appearance of modern eukaryotes complete with chloroplasts and mitochondria. I have previously provided independent evidence for the front-loading of mitochondria , and I have also noted the conceptual connections between photosynthesis and aerobic respiration. Everything is connected.
We are beginning to see the blurred outlines of evolution as a rational process that entails key steps of unfolding. This then leads me to a new prediction that extrapolates from this trend – the origin of metazoan life itself was dependent on symbiogenesis. I have provided plenty of evidence to support the front-loading of metaozoan life, so it is now time to take it to the next level.