Food
"For three million years we were hunter-gatherers, and it was through the evolutionary pressures of that way of life that a brain so adaptable and so creative eventually emerged. Today we stand with the brains of hunter-gatherers in our heads, looking out on a modern world made comfortable for some by the fruits of human inventiveness, and made miserable for others by the scandal of deprivation in the midst of plenty."
―Richard E. Leakey
