Children of Time, by Adrian Tchaikovsky

This book is a fantastic example of why I love Science Fiction: alien cultures, developments over loooong time spans, humans at the very edge and beyond their understanding and horizon. I loved it. It's half fascinating and never dry spider civilization worldbuilding and half about the last humans trying to survive in an ark ship; the way they mirrored and played off each other was great, but the contact moments were the best.

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