In the September Scientific American, devoted to human evolution, paleoanthropologist Ian Tattersall discusses how a capacity for toolmaking and other cultural developments worked in conjunction with luck to foster the success of Homo sapiens. Luck came in the form of the climate shifts that served to accelerate the rate of evolution and the adaptation of beneficial traits among certain of our archaic forebears.

In the video here Tattersall describes how his field has changed since he first entered it nearly 50 years ago. Students of human evolution long believed that the story of our species origins was linear, “from primitiveness to perfection.” Scientists now know that the evolutionary path from apes to modern man was far more convoluted, populated with many rival hominins (the group including modern humans and their extinct relations) whose survival was periodically challenged by unpredictable climate shifts.

He also speaks of what makes Homo sapiens special. That our species is the only surviving hominin in the world is testament, he says, to how exceptional we are. We are unique in that we use symbols to represent the world, moving them around and recombining them to create “alternatives to existing reality.” This cognitive faculty also means we are able to ponder where we came from. The study of human evolution, Tattersall notes, holds “a special fascination for human beings, who, of course, are a very egotistical species.”