The article discusses the evolution of the understanding of evolutionary rates and modes, as outlined in George Gaylord Simpson's classic book *Tempo and Mode in Evolution*. Simpson's work aimed to synthesize paleontology and genetics, addressing topics such as evolutionary rates, acceleration, deceleration, and the conditions of slow or rapid evolution. The article highlights the ongoing debate between gradualists, who favored small, continuous changes over time, and saltationists, who advocated for discrete, large jumps in evolution. This debate was resolved in the early 20th century through the work of R.A. Fisher, J.B.S. Haldane, Sewall Wright, and S.S. Cheverikov, who integrated Mendelian inheritance, natural selection, and biometrical knowledge. The article also reviews the contributions of Theodosius Dobzhansky's *Genetics and the Origin of Species* to the integration of Darwinism and Mendelism, and the subsequent development of modern evolutionary theory. It discusses the impact of molecular biology on the study of evolution, particularly in understanding the history of life over the past three billion years. The article covers various aspects of evolution, including microevolution and macroevolution, human evolution, and the patterns of evolutionary rates. It highlights the importance of molecular methods in studying evolutionary processes and the role of chance events in adaptive evolution.The article discusses the evolution of the understanding of evolutionary rates and modes, as outlined in George Gaylord Simpson's classic book *Tempo and Mode in Evolution*. Simpson's work aimed to synthesize paleontology and genetics, addressing topics such as evolutionary rates, acceleration, deceleration, and the conditions of slow or rapid evolution. The article highlights the ongoing debate between gradualists, who favored small, continuous changes over time, and saltationists, who advocated for discrete, large jumps in evolution. This debate was resolved in the early 20th century through the work of R.A. Fisher, J.B.S. Haldane, Sewall Wright, and S.S. Cheverikov, who integrated Mendelian inheritance, natural selection, and biometrical knowledge. The article also reviews the contributions of Theodosius Dobzhansky's *Genetics and the Origin of Species* to the integration of Darwinism and Mendelism, and the subsequent development of modern evolutionary theory. It discusses the impact of molecular biology on the study of evolution, particularly in understanding the history of life over the past three billion years. The article covers various aspects of evolution, including microevolution and macroevolution, human evolution, and the patterns of evolutionary rates. It highlights the importance of molecular methods in studying evolutionary processes and the role of chance events in adaptive evolution.