The endosymbiont theory explains the origins of

Endosymbiotic Theory Introduction. ... Endosymbiotic theory, that attempts to explain the origins of eukaryotic cell organelles such as mitochondria in animals and fungi and chloroplasts in plants was greatly advanced by the seminal work of biologist Lynn Margulis in the 1960s.

There is no scenario shared.

Explanation:

Large lungs could represent that smoking can cuase serious problems