What caused life's major evolutionary transitions?

Join us as we explore the fascinating transition from early cells to multi-celled animals. This transition, as well as several other major evolutionary transitions, dramatically increased the complexity of lifeforms on our planet. If you enjoyed the show, please consider supporting us at patreon.com/statedclearly to see the animation on bees, go here: https://www.youtube.com/watch?v=J83qyLXAsN4 ------------SOURCES------------ OVERVIEW OF MAJOR TRANSITIONS This animation was based on a paper by Stuart West et al called Major Evolutionary Transitions in Individuality which can be accessed free here: http://www.pnas.org/content/112/33/10112.full.pdf Dr West's paper defines major transitions in a slightly narrower way than earlier workers on the subject. For a broader definition see the book by John Maynard Smith and Eörs Szathmáry on the topic: https://en.wikipedia.org/wiki/The_Major_Transitions_in_Evolution MITOCHONDRIA The paper by Dr Margulis (Sagan) on the origin of mitochondria. Note that in it she presents several ideas cautiously as hypothesis. While some aspects of the paper are now known to be incorrect, she was spot on about the origin of mitochondria: http://web.gps.caltech.edu/classes/ge246/endosymbiotictheory_marguli.pdf VIROIDS The free living genes discovered by Dr Diener were made of RNA. Here is a paper on them: http://www.sciencedirect.com/science/article/pii/0042682271903424 Here is an excellent Wikipedia article on them I suggest looking over first. It includes a schematic of the species Diener found: https://en.wikipedia.org/wiki/Viroid EXPERIMENTS SHOWN IN THIS ANIMATION Phagotrophy by a flagellate selects for colonial prey: A possible origin of multicellularity: http://link.springer.com/article/10.1023/A:1006527528063 Experimental evolution of multicellularity: http://www.pnas.org/content/109/5/1595 Auto-/heterotrophic endosymbiosis evolves in a mature stage of ecosystem development in a microcosm composed of an alga, a bacterium and a ciliate [what a catchy title!]: https://www.ncbi.nlm.nih.gov/pubmed/19162125