It is speculated that two factors of our development as a species differentiate us from other primates: 1) opposable thumbs; and 2) larger brain size. Anthropologically, anthropomorphically, and paleontologically the opposable thumb and the larger brain size is theorized to come about because of the following: A. Opposable Thumb development stems from an evolutionary adaptation of the need to develop refined tools (for hunting) from stone, copper, bronze and iron in order to survive being eaten by either our Neanderthal or the tiger. B. Larger brain development came about as our waning need to have a larger mandible (chewing mechanism) to masticate bone or as a defense. As we began to genetically trigger development of smaller mandibles, our skull capacity for larger brains increased the development of cerebral structures and material conducive to the development of "consciousness." That's a new way of appreciating the epithet: "hand to mouth existence."