State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, the Chinese Academy of Sciences, Kunming 650223, China; 2. Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
The metabolism of organisms is carried out through a series of metabolic pathways. How these ingeniously regulated and collaborated metabolic pathways evolved has been a fascinating and important question for some time. Since the ‘retro-evolution hypothesis’ was first put forward in 1945, there have been seven main hypotheses concerning the evolution of metabolic pathways, including ‘retro-evolution of pathways, ‘semi-enzymatic theory’, ‘forward development model’, ‘enzyme recruitment hypothesis’, ‘specialization of multifunctional enzyme’, ‘pathway duplication’, and ‘de novo invention of pathways’. Among them, the most popular hypotheses are ‘retro-evolution’ and ‘enzyme recruitment’, and recently greater attention has been paid to the ‘specialization of multifunctional enzyme’ hypothesis, due to its strong theoretical basis and experimental evidence. Here, all of the seven hypotheses were reviewed, and the development prospect of this field analyzed.