What Makes Us Human

The dominant theme of the text is the repeated investigation of what makes humans uniquely human. Dozens of traits are examined in considerable detail, from language and art to genocide and drug use. The author nearly always concludes that these traits that are generally considered to be uniquely human are uniquely human only in degree - that is, for every uniquely human trait there are numerous animals that exhibit the trait to a lesser degree. For example, human speech has numerous precursors within the animal kingdom, from singing birds through vocalizing vervet monkeys. Many animals use vocalized communications, yet only humans use language.

The author proposed a concept early in the text, which is thereafter referred to as The Great Leap Forward. The Great Leap Forward is the event or series of events which occurred at some point in the past that allowed modern humans...