“The fundamental innovation that we see with the Cro-Magnons and their African precursors is that of symbolic thought, and this is something with which language is virtually synonymous. Like thought, language involves forming and manipulating symbols in the mind, and our capacity for symbolic reasoning is almost inconceivable in its absence. Imagination and creativity are part of the same process, for only once we have created mental symbols can we combine them in new ways and ask ‘what if?’ . . .
    [T]here’s little doubt that it is symbolic thought that above all differentiates us . . . not only from every other hominid but also from every other organism that has ever existed. . . . [T]he record seems to show that the early history of modern humans was one of the sequential discovery of the things that symbolic thought made possible. This is, indeed, an ongoing process: even today we are discovering new ways in which to employ and express our unprecedented cognitive abilities.”
   
—Ian Tattersall, The World from Beginnings to 4000 BCE, 2008.