Sawyer (Flashforward; Factoring Humanity), a Canadian, is one of contemporary SF's most consistent performers. His new novel concerns the appearance at the Royal Ontario Museum in Toronto of a spiderlike alien paleontologist named Hollus. The alien has come to Earth to study the five great extinction events that have hit our planet over the eons, the best known being the asteroid collision that wiped out the dinosaurs. When the museum's head paleontologist, Tom Jericho, consults with the alien, he is shocked to discover that Hollus has proof that her own planet and that of another alien race suffered a similar series of five catastrophic events at virtually the same times as Earth did. More surprising still to a 21st-century disciple of Darwin like Jericho, both alien races see this synchronicity, along with other scientific evidence, as proof of the existence of God. Much of the novel is relatively cerebral, as Jericho and Hollus argue over the scientific data they've gathered in support of God's existence, but Sawyer excels at developing both protagonists into full-fledged characters, and he adds tension to his story in several ways: Jericho has terminal cancer, which gives him a personal stake in discovering the truth of the alien's claims, and lurking in the background are a murderous pair of abortion clinic bombers who have decided that the museum's Burgess Shale exhibition is an abomination that must be destroyed. Finally, there's the spectacular, if not entirely prepared for, climax in which God manifests in an unexpected manner. This is unusually thoughtful SF.