“Before Adam” by Jack London
“Before Adam is a mixture of sound science and sci-fi speculation. It is based around Darwin’s theory of evolution and the idea of racial memory.
The main character lives in the current world but has dreams and nightmares that he relives the pre-stone age life of one of his proto-human ancestors.
Those who are scientifically inclined may enjoy this novel more than fans of “standard” science fiction such as Edgar Rice Burroughs. (Summary by Tom Weiss)”
London takes us back to the Pleistocene when we still lived in the trees. Written in the first person, the story revolves around the vivid, interlocking dreams from childhood that involve racial memories and the knowledge of his prior existence as a man-like creature named Big Tooth.