Stepping Out Of Eden

Science has manipulated DNA, mapped the human genome, and cloned both plants and animals. They estimate that humans share 99 percent of their DNA with chimps, but the 1 percent difference enables humans to create art, literature and religion.

We often wonder, what makes humans innately human? Is it our biological differences, our lack of body hair, the size of our brains, opposable thumbs or our ability to walk upright? What was the catalyst that spurred the transition from tree-dweller to a...