Power, sex, suicide Mitochondria and the meaning of life

Mitochondria are tiny organelles inside cells that generate almost all of our energy in the form of ATP, regulate numerous cellular functions, and possess their own complement of DNA. There are hundreds within each cell, ten million billion in the human body. Once free-living bacteria, they adapted to life inside larger cells two billion years ago, making complex life possible. Lane (University College London) claims that these larger eukaryotic cells evolved here on earth just once in a "deeply improbable chain of circumstances," circumstances that would make complex life on other planets equally improbable. This implies that the evolution of complexity cannot be explained by natural selection alone, but requires mitochondrial symbiosis in addition. Mitochondria "seeded complexity in the eukaryotes, placing them at the beginning of the ramp of ascending complexity." Once begun, however, increasing complexity was almost inevitable. This well-written, up-to-date account of mitochondria sheds light on subjects ranging from human prehistory, evolutionary innovation, and genetic disease to metabolic efficiency, the origin of the sexes, and apoptosis--the enforced suicide of cells, with its implications for aging and death. The book's organization, glossary, diagrams, and illustrations make it a sound introduction to a complex and important topic. ^BSumming Up: Recommended. Lower-level undergraduates and above; general readers. R. M. Davis emeritus, Albion College