Kindly explain the term " Our symbolic mile zero" and its connotations.
It is the scientists of the Middle Awash research project who invited us to begin walking at Herto Bouri, our symbolic mile zero in the Ethiopian Rift—one of the richest human boneyards in the world. This is the famous site where some of the world’s oldest human fossils have been found. Homo sapiens idaltu. Gone for 160,000 years. A big-boned ancestor—a dawn version of us. (from https://www.nationalgeographic.com/magazine/2013/12/out-of-eden/)