AST 248 Lecture Notes - Lecture 23: Burgess Shale, Encephalization Quotient, Cambrian Explosion
1 Aug 2016
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L/t gives the fraction of civilizations that currently exist. N = 6 109 0. 05 1 1 fi 1 l/1010yr. Primary uncertainties in the drake equation fi the development of intelligence. Limited availability of raw materials, forces evolution of complex processes to develop alternate, more reliable, sources example: original organisms relied on limited supplies of. Aerobic photosynthesis and metabolism used more common materials. Specialization in cells: development of eukaryotes and organelles by symbiosis. Sexual reproduction: permits greater genetic variation in offspring. Development of multicellular organisms, probably by symbiosis, triggered cambrian explosion of phyla, as recorded in the burgess shale. Development of nervous system/brain: elimination of dna-length bottleneck. Convergent evolution argues in favor of intelligence as a survival optimizer. The generally increasing maximum encephalization quotient of other mammals, like dolphins and whales, also supports large values for fi. Note, however, that all mammalian species do not show such increases.
