In writing my 1992 book Cancer Selection I had several objectives. I wanted to introduce to a wider audience the essential core of my peer-reviewed theory—that defenses against lethal juvenile cancer enabled precise construction of complex animals. My theory says that if cancer did not exist the Bilaterians would not exist. I also wanted to argue vigorously in favor of its acceptance as a major amendment to evolutionary theory, hoping for its adoption. Finally, I wanted to extend the theory, explain why I thought certain phenomena no one else associates with cancer actually originated as defenses against it. I wrote that sleep, animal senescence and the human brain originated largely because they defend against lethal juvenile cancer.