ution and fluidity has occurred so that none of the organism species that existed 'then' is likely still around now (10:258). DNA in all living things persists, of course, although its understanding is barely as old as a human generation. Still, evolving DNA analyses of the prokaryotes as a group is redefining the field of microbiology.
Starting with the single-celled, simply structured, bacterial organisms still known as the prokaryotes, all living things began to evolve from an inorganic, primordial sea-soup between three billion and four billion years ago (11:160). Today's life forms, including the remaining prokaryotes, other simple plants and animals, and eukaryotes from mosses to mammals continue to evolve, with bacteria reproducing and mutating hourly to daily (10:262). In a third form of evolution, micro-biologists are changing their techniques and their textbooks as fast as they can to explore and recount the four thousand millennia of what has gone on and to predict--even participate in--what is going to happen next.
The Historical Rise and Evolution of the Prokaryotes. Fascinating as four billion years of history are, they can be dismissed fairly quickly here. They occurred, and from 3.8 billion years ago until about 1.2 billion years ago, the prokaryotes were apparently here alone, some becoming aerobic only 2.2 billion years ago (11:160). A detailed journey through the miasma of early inorganic chemistry of the planet and the early autotrophic life forms is given by Postgate (10:241-64) (whose dates are somewhat different from Rao et al. (11) but whose prose is far superior). The prokaryotic bacteria that developed back then are, in many (newer) forms, still here, and in profusion.
Continuing Evolution of Bacteria, as Revealed in Modern DNA Studies.
Bacteria change in a variety of ways, adding and subtracting characteristics even while remaining within the same species as their parent. Mutations occ...