This expression generally refers to the apostasy of Adam and Eve in the Garden of Eden, which introduced the human family to heartache, disease, and ultimately death (Gen. 2:17; 3:16ff; Rom. 5:12).
Since that awful day when our race was murdered (Jn. 8:44), we have been a planet in rebellion. The biblical concept of "the fall" stands in direct opposition to the evolutionary notion that man has climbed upward from a brutish past.