I remember a novel (or multiple novels?) set on a planet that is in a binary system. From time to time it is switching the orbit to the other sun, resulting in a long winter. The planet is inhabited by a bioengeneered civilisation, that can turn to long sleeps to survive the winter. Also these people have some sort of genetic memory, they can remember the stuff their ancestors remembered.
Has anyone an idea which novel(s) this are?
Edit: Some more elements I remember. The civilisation was humanlike, but not humans. I think at the end some humans came to the world. There was a second race, more like apes and very primitive, but somehow they were important for survival, don't remember how.
The first part (or novel) told about a civilisation with cars and stuff like that, tech-level like early 20th century. Second part had a more basic civilisation, and I think only in the second part they had genetic memory. I think they smoked something to get in trance and relive memories of their ancestors.
It was claimed, these biology was engineered somehow by another alien race.