“Of those body plans that had originally appeared in that great, explosive diversification, one became predominant — the tube with a head at one end, a spinal cord, and, eventually, paired limbs. Soon the spinal cord was encased in a backbone — an interesting solution, so unlike that of my own ancestors. An age of fishes gave way to an age of amphibians, then one of reptiles. Brain-body ratios increased as time went by. It seemed clear that eventually, joyously, intelligence would arise on t...he Crucible as well. Before it did, though, a new form appeared, living in the shadows of the reptiles, tiny furred creatures that nursed their young. It was wonderfully, terribly clear what was happening. Both the reptiles and the mammals were on their way to intelligence, and at about the same rate, too — the ratio of brain size to body size was increasing on a simple curve through time, and the scale-clad and fur-bearing creatures were both at the same point on that curve.MoreLessRead More Read Less
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