The Murder of Adam and Eve - William Dietrich
The Murder of Adam and Eve finds sixteen year old Nick Brynner exploring an old abandoned fort on a forbidden island for a school project. He is then being chased in a deserted village by something that he thinks is a gargoyle. He escapes with the help of another teen, Ellie, and the pair are then sent to prehistoric Africa by an alien race called the Xu. The race is on to find Adam and Eve.

It's definitely an interesting and thought provoking read.