Children of Time
Children of Time by Adrian Tchaikovsky
Adrian Tchaikovsky trained in zoology before he ever wrote fiction, and you can feel it here. He has said he wanted to build an alien civilization that actually felt alien instead of humans in a costume, so rather than invent something from scratch he went looking at what already exists. He landed on jumping spiders of the genus Portia, which are tiny predators with brains the size of a pinhead that still manage to plan routes, stalk other spiders, and change tactics mid hunt based on what their prey does. The question the whole book seems to grow out of is pretty simple. What happens if you take a mind like that and give it a few thousand generations and a shove? The answer won him the Arthur C. Clarke Award and turned him into one of the biggest names in modern science fiction.
The setup goes like this. A scientist named Avrana Kern is in orbit above a freshly terraformed planet she fully intends to name after herself. The plan is to drop a cargo of monkeys onto it along with a nanovirus engineered to accelerate their evolution, and eventually have a species down there smart enough to talk back to her. Back home, though, things are falling apart. Anti technology factions consider this kind of genetic tinkering an abomination, and one of them has an operative on her station.
It all comes apart at once. The station is sabotaged, Kern runs for an escape pod, and the capsule carrying the monkeys burns up on the way down. The virus lands just fine. With no primates to work on it goes hunting for other hosts, and among the ones it finds are the spiders. Kern ends up stranded in orbit, waking and sleeping across an unthinkable stretch of time, slowly realizing that the radio noise from humanity has gone quiet.
Thousands of years later, people have clawed their way back from almost nothing on a wrecked Earth, scavenging technology from a lost civilization they only know as the Old Empire. The biosphere is dying, the damage from that ancient war finally catching up, and a ship called the Gilgamesh sets out carrying what might be the last of the species. They are headed for Kern's World expecting to find it empty.
From there the book runs two clocks at completely different speeds. On the planet, spider society climbs from instinct to language to chemistry to something you would have to call philosophy, with knowledge handed down through inherited genetic memories they call Understandings. On the ship, centuries of cold sleep and mutiny and slow desperation grind the crew down, mostly seen through Holsten Mason, a historian who keeps waking up to find things have gotten worse. Kern is still up there too, no longer particularly sane, guarding her experiment like a god who has forgotten what she was guarding it for.
When the two finally meet, the obvious ending is that everybody dies. Both sides are cornered, both are sure the other cannot be reasoned with, and it has the exact shape of a prisoner's dilemma. What makes the book stick with you is that the way out does not come from weapons. It comes from the side that spent thousands of years accumulating the understanding that working together tends to outlast winning.
It is a big, patient, genuinely odd novel about deep time, empathy across an enormous gap, and the uncomfortable idea that we might not automatically be the heirs to anything.