“The Evolution of Evolution”, 2019-12-01 (; similar):
In the past, most biologists, myself included, did not think of evolution as changing over time. The wonders of natural selection were always at hand and went into operation once there was life. However, with a little reflection it becomes obvious that evolution has changed—there has been an evolution of evolution.
Evolution can be separated into 4 phases, or eras, that may or may not overlap. The first era starts with the evolution of life on earth, which led to single cells that multiply asexually. The second era takes advantage of the invention of sexual reproduction as evolution could now gallop forward because of a richer fare of diverse offspring for natural selection. The third era begins with the introduction of multicellularity.
In the fourth era there is a radical innovation: the nervous system that arises animals by standard Darwinian selection. This has allowed major rapid changes to proceed, such as language that led to all the rapid progress we call civilization; a true revolution, and one that does not depend on the slow genetic changes of all other standard gene-controlled evolutionary steps.
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