Our genus is characterized by a unique dependence on technology, which is first seen in the mid-Pleistocene and becomes more sophisticated through time. The trend towards increasing encephalization appears to accelerate once tools have been acquired, coincident with a focus on meat-eating. This chapter reviews later Pleistocene species, including the Neanderthals, with whom we share many behavioral adaptations. However, there appear to be several critical differences, especially in the potential for language and possibly figurative expression, that may have made the difference over millennia, so that by 25,000 years ago we were the only human species left on Earth.