There remains, however, the previously unsuspected connection between advanced dendritic branching and manual dexterity, which Dr. Hotton tackles in his sixth chapter. This concept has caused a revolution in paleoanthropology. We are now forced into the uncomfortable realization that Pithecanthropus robustus , formerly dismissed as a large-jawed, vegetable-chewing ape, was probably far more intelligent than Homo sapiens. CAT-scans of the recently discovered Tanzanian fossil skeleton, nicknamed "Leonardo," reveal a Pithecanthropus skull-ridge obviously rich with dendritic branching. It has been suggested that the pithecanthropoids suffered from a heightened "life of the mind" similar to the life-threatening, absent-minded genius of terminal neural chernobyl sufferers. This yields the uncomfortable theory that nature, through evolution, has imposed a "primate stupidity barrier" that allows humans, unlike Pithecanthropus , to get on successfully with the dumb animal business of living and reproducing.