What's amazing about Ponter Boddit isn't just that he appeared from nowhere inside a sealed experimental tank two kilometers underground. That would be strange enough. But the real news is that Ponter is a Neanderthal—a physicist, no less, from an advanced Neanderthal civilization.

Ponter and his partner, Adikor, had been building a quantum computer. A quantum computer can execute obscenely complicated tasks, because its memory is a quantum state, which permits the superposition of many different numbers at once. This superposition uses copies of the computer in recently split-off parallel universes. When Ponter and Adikor told it to factor a ridiculously large number, the computer's demand for parallel registers spread into a universe split off much further back—ours, the one where Homo sapiens, not Homo neanderthalensis, survived. Ponter, who was on the computing floor while the machine was still processing, accidentally passed through where only numbers had gone before.

Unfortunately, he crossed into that sealed tank. Almost drowned and suffering head trauma, Ponter is rushed to a hospital, where X-rays reveal the impossible. Mary Vaughan, a paleologist, is called in to confirm the findings. She welcomes the diversion—she's still recovering from having been sexually assaulted a few days before.

Meanwhile, grief-stricken Adikor is accused of murder, an unheard-of crime in Neanderthal society. Naturally non-violent, all Neanderthals also have networked implants in their bodies that record everyone's movements. Adikor and Ponter, however, were deep underground, off the net. The woman prosecuting Adikor feels he must have killed Ponter, body or no body. Without a recorded alibi, Adikor has no defense.

In our world, word has leaked out about Ponter, who's becoming a celebrity. But he succumbs to an illness for which he has no immunity, causing Ponter, Mary and her associates to be sealed in quarantine indefinitely—just as Adikor faces the penalty suffered by all criminal deviants: sterilization.

An alternate alternate history tale

Alternate history usually explores what would have happened if some key event had come out another way—if FDR had lived, if Napoleon had won at Waterloo, if John Hancock's pen had run out of ink. Here's the ultimate what-if, going way back beyond the origins of human society to when humans and Neanderthals coexisted. What if they went on to build civilization, and not us? What would modern Neanderthal society be like?

In his works to date, Robert J. Sawyer's strength has been in pondering the logical consequences of theories and abstractions. Here, Sawyer develops a full-fledged Neanderthal world based in part on what little we know about them. In particular, their tremendous physical strength is, intriguingly, the basis for a society that, knowing violence annihilates, has rooted out aggression in a conscious, collective effort to survive. Without war and conflict, Neanderthals over time built a sophisticated culture in which reverend elders oversee everything from the conception of the next generation to scientists' contributions to society.

Inevitably, Ponter is amazed and disgusted by what Mary tells him about human society, even as they grow close. The very fact that Mary's sexual assault impedes their nascent romance feels like an indictment of humanity. The danger in telling Ponter's story is in veering too far into social commentary. It's too easy, after all, to have a naive alien unacquainted with war, poverty or environmental exploitation scorn our everyday evils. Sawyer harvests that disdain, but uses it to deepen Ponter's character and to develop the poignancy of his relationship with Mary and the others.

Again, a Utopian Neanderthal society would be too facile a contrast, and Sawyer is clever enough to crack the looking glass. For example, thanks to the networked implants, the Neanderthals have no privacy and distrust what hasn't been recorded. And then there's their punishment for apparent genetic defects related to violence. Adikor's frustration at facing sterilization despite his innocence adds a human taint to this seemingly perfect world, leaving us rooting against Utopia just this once.