Beyond Perfection — Jerry Travis

Hundreds of years from now, modern civilization has utterly collapsed and the Earth's population has been reduced to about what it was during the time of the ancient Greeks and Romans. Humanity is in the midst of building a new civilization based largely on technology leftover from our civilization, some of which has managed to survive into the future. The time travelers from the first two books of the Safety Factor trilogy try to make a home for themselves there, but are confronted by enormous changes in society, science and the human psyche. They are plunged into a world rife with the aftereffects of global warming, and where genetically engineered animals are bread as "workers." What will our refugees from the past do when they see humanity once again making the same mistakes that ended our civilization?