This is an older treasure (original publication 1988) from one of our science fiction greats. It's got Golden Age sense of wonder, a contemporary attitude about gender equality, and an optimism that's been hard to find in the last decade or so.
That's on top of the excellent writing, world-building, and character development.
The People have been living underground in the Cocoon for 700,000 years, ever since the fall of the Death Stars ended the civilization of the Great World and brought the Long Winter to Earth. They've had to limit births, and send their aging tribe members out into the desolate cold to die at the limit age of thirty-five, but it has been overall a comfortable life, and a good one. Now, though, omens of change surround them. Thaggoran, the tribe's "old man," or chronicler (and the only member not subject to the limit age), detects signs that, as predicted by the chronicles, the giant ice eater worms are approaching through the rock and ice below the cocoon. When they reach it, the cocoon will be destroyed. Riyyig Dream Dreamer, a strange-looking creature with no fur, no sensing organ/tail, awakens and announces the coming of the New Springtime, and then dies.
Koshmar, the tribe's chieftain, overrides all doubts, and prepares her tribe to leave the cocoon forever and venture out into world.
What follows is an exploration and an adventure. The world has changed in seven hundred thousand years, and the end of the Long Winter doesn't change the fact that all the plants and animals they encounter are new, completely unknown to either their experience or anything the chronicles can tell them.
They also meet some survivors of the long-dead Great World--the hjjk-men, insectoid beings who are the only (other?) survivors of the Six Peoples: the hjjk-men, vegetals, mechanicals, sapphire-eyes, sea lords, and humans.
The People know that they're the humans, destined to inherit the world after the end of the Great World civilization, now that the New Springtime has come.
There are wonderful characters in this book. Koshmar is proud, ambitious, but dedicated to the welfare of her people. Torlyri, the offering-woman, is gentle and deferential, and a major source of strength both for Koshmar, and for the tribe as a whole. Hresh, a young boy often called Hresh-full-of-questions, learns to ask uncomfortable questions and find answers the tribe needs, as he grows into manhood. Harruel, the senior warrior of the tribe, is a complicated character filled with ambition, violence, and self-will, but willing to face real hardships for the tribe, and with an instinct for some risks that others miss.
This is a rich world well worth exploring, and some great characters to do it with.
I received a free electronic galley from the publisher via NetGalley.