I read this book back in the 80's, so it is from that era or before. I think that the book was an omnibus printing of the original trilogy.
As to the story line. There is an attack on Earth, and humans are kidnapped by aliens. On the way back to the aliens home world the human hero finds, and interacts with the aliens ( which are very lobster/crab like to the human eye ) and another alien race ( They have also been kidnapped by the lobster like aliens ) that is very similar to humanity. Save differences like having narrower faces, one extra finger, breasts slightly lower on the chest. But close enough that they would pass as human at first glance.
The human ends up very close to one of the female aliens, and between them they manage to arrange a rebellion and take over the ship they were on and kill off the lobster like aliens on the ship. They then alert their governments to what happened. ( lobster aliens have much higher tech than either of their species )
Book goes on, they raid some of the lobster planets and recover some previously kidnapped members of both species, which the aliens had surgically altered to look like they did.
They continue to explore, finding the location of the main world of the lobster aliens, as well as stumbling across a weird humanoid like race... at which point some hormone causes all of them to breed. Which produces the progenitor species of alien, that had created the 3 "human" races by splitting their DNA and making so that when they met, they would breed and recreate their species. ( genetic memory being a given in this book )
It turns out that the lobster aliens had originally been pets to the progenitor race, that had faced some unnamed enemy so terrifying that they had created the human races and "hid" till it was safe to come back out. The humans end up revealing proof of this to the lobster aliens, which all but destroys their society, as they were convinced they were the 'gods' favorites and chosen. Finding out that they were just genetically altered chihuahuas ( which the rulers of the lobsters already knew, and kept hidden ) shattered their psyche.
As to the story line. There is an attack on Earth, and humans are kidnapped by aliens. On the way back to the aliens home world the human hero finds, and interacts with the aliens ( which are very lobster/crab like to the human eye ) and another alien race ( They have also been kidnapped by the lobster like aliens ) that is very similar to humanity. Save differences like having narrower faces, one extra finger, breasts slightly lower on the chest. But close enough that they would pass as human at first glance.
The human ends up very close to one of the female aliens, and between them they manage to arrange a rebellion and take over the ship they were on and kill off the lobster like aliens on the ship. They then alert their governments to what happened. ( lobster aliens have much higher tech than either of their species )
Book goes on, they raid some of the lobster planets and recover some previously kidnapped members of both species, which the aliens had surgically altered to look like they did.
They continue to explore, finding the location of the main world of the lobster aliens, as well as stumbling across a weird humanoid like race... at which point some hormone causes all of them to breed. Which produces the progenitor species of alien, that had created the 3 "human" races by splitting their DNA and making so that when they met, they would breed and recreate their species. ( genetic memory being a given in this book )
It turns out that the lobster aliens had originally been pets to the progenitor race, that had faced some unnamed enemy so terrifying that they had created the human races and "hid" till it was safe to come back out. The humans end up revealing proof of this to the lobster aliens, which all but destroys their society, as they were convinced they were the 'gods' favorites and chosen. Finding out that they were just genetically altered chihuahuas ( which the rulers of the lobsters already knew, and kept hidden ) shattered their psyche.
I came here eight years ago, looking for a short story. They found it immediately, and I've never left. Once in a while, even I get to find something for someone. Stick around and see what else we can do! 
