@G H,
Quote: This doesn't even touch upon the added magnitude of lucky circumstances falling into place in order for complex organisms to arise. After 4.54 billion years, it wasn't until the last fifth of that that a glimmer of the latter even arose on a planet like Earth.
Is it therefore, in your mind, the large time difference between simple life and complex life and finally hominims that impress you?
The basic assemblages of respiration, synthesis,and reproduction are all present in basically similar genetic formulae from amoebas to australopithecenes. Also Adaptation and reproduction are prime directives in species development and evolution. It appears , from the earth's geologic history that the appearance of the "Next higher orders" in the bush of life , come curiously after (and apparently associated with) fundamental changes in the
edapho's , the part of the environment upon which life persists. C12 came on the scen only after the earth cooled enough and water could be seen to be present in the Isua Formation of theEoarchean(your LHB?). The presence of the C12 , as a signal that "life had indeed begun" was in concert with the Law of equivalent surfaces throughout the Eoarchean world.
Later "rises" of the etent of life from a protist state to more complex seemed to follow the sudden presence of a contaminant chemical that somehow life achieved other adaptive levels (like photosynthesis). Then, well before the Ediacaran, the availability of alkali elements in seawater paralleled the rise of "complex" life, (meaning nothing more than oragnisms in multi segments and sporting calcareous tests)
As I proposed before, this is merely a logical progression of a mathematical series where each evolutionary step reduces the possibilities of the outcomes of successive steps. That seems to be the way life has progressed
Why hasnt this occured on other planets in other systems? Im not sure anyone can say either way but why isnt it possible? We know fairly well the progression of elements formation