Trillions of solar neutrinos passed through your body in the time it took to read that last sentence. Bacteria, for example, are prokaryotes, meaning they don't have membrane-enclosed nuclei. We might be talking aliens of the smooth, scaly sort; they might boast the large muscles of the predators from the Alien movies, or the cute waddle of an E. After all, mixing and matching a genome is a crapshoot, said Sally Otto, director of the Biodiversity Research Centre at the University of British Columbia. Well, maybe not many planets can offer the long-term TLC required for complexity and smarts to evolve. When he left, she pointed at her stomach, at him and then at the sky, implying she would have his child somewhere in outer space. Also, forget what those cartoons showing apes marching toward a proud, pants-wearing future may suggest; there's no "arrow of progress" inherent in evolution. Perhaps such characteristics are rare for rocky worlds in the habitable zone. They rarely survive the breeding season. The hermaphroditic C. There are more subtle possibilities in play as well. Frank N. Chapter 1: Where Is Everybody? Nobody knows. God loves us that much! Chimps, ravens, dolphins, sea otters, octopi, and a number of other species are smart enough to use tools, but only humans have built radio transmitters, spaceships, and wheely shoes.