Did Evolution Create God?: It makes sense to me; those who were most gullible and could believe in an afterlife reproduced more sucessfully than those who were perpetually anxious due to their discovery of their own mortality. The Chicago Tribune (free reg. req.) reports:

...Hamer, a behavioral geneticist at the National Institutes of Health and the National Cancer Institute, stands by research he says shows that spirituality -- the feeling of transcendence -- is part of our nature. And he believes that a universal penchant for spiritual fulfillment explains the growing popularity of non-traditional religion in this country and the presence of hundreds of religions worldwide.

"We think that all human beings have an innate capacity for spirituality and that that desire to reach out beyond oneself, which is at the heart of spirituality, is part of the human makeup," Hamer, 53, said in an interview at his home.