This novel won the Nebula Award in 1982. It is about a man who travels back in time to two million years ago before homo sapiens had appeared. The structure of this novel is very similar to Moorcock's Behold The Man, i.e. there are two narratives intertwined: one which starts with Joshua Kampa time-travelling back two million years to Africa where mankind was supposed to originate; the other chronicles his life leading up to the point where he time-travels.
It is difficult to make the plot sound very interesting and, indeed, the book is a bit of a slow starter. But ultimately it is an enjoyable novel. Bishop's novels tend to be fairly long and he takes his time to move the plot along - but it has been worth it, so far with other novels of his. It is also worth noting that these novels are not typical of the SF genre and, therefore, are not predictable.
