|Mitochondrion. Source: US NIH|
" So what about sex, or the nucleus, or phagocytosis? [...] If each of these traits arose by natural selection – which they undoubtedly did – and all of the adaptive steps offered some small advantage – which they undoubtedly did – then we should see multiple origins of eukaryotic traits in bacteria. But we don't. This is little short of an evolutionary 'scandal'. "
Nick Lane – The Vital Question (2015)
In my previous post I commented on the first part of Nick Lane's book, which deals with the proton-motive force and the origin of life. This second post focuses on the second half of the book, which explores the origin of complex life (i.e. eukaryotic cells).
If the first half of the book was equally part history of the field and part new hypotheses, the second half leans clearly more towards hypothetical ideas – albeit including many facts, and backed with rigorous thinking. Lane's big idea is the following. Most traits that differentiate eukaryotes from prokaryotes (cell and genome sizes, nucleus, introns, sexual reproduction) ultimately follow from a single and singular event: the endosymbiosis event that created mitochondria. For Lane, the organelles that power respiration in all eukaryotic cells are the one special ingredient that permitted the development of cellular complexity.