I was going to write a review... But, everyone else has said it already. I did, however, keep getting confused with his use of spiritual versus religious. He tended to want to fuzzy the difference and call the religious spiritual, then differentiate them again. Didn't work.

Before this, I read Sam Harris' The End of Faith polemic and Daniel Dennett's Breaking the Spell (both reviewed by me). While Dennett notes as an aside in his book that no such single "god gene" exists, Hamer himself early on admits the same, but acknowledges it's not as catchy a title otherwise. The subtitle needs to be changed too: "How Faith Is Hardwired--in perhaps a significant but not overwhelming percentage of our genetic makeup for some of us." God is not proven or disproven, only that some of us tend to look for the divine more than others, and that this may be biased for some in our neural transporters of monoamines.

Looking into the distinction between believing and belonging, Hamer seems to get sidetracked into other studies that he paraphrases, and finding out who tends towards the spiritual--not the same as organized religion in its more public manifestation--certainly proves elusive. Unless you're a twin, since they get to be tracked by eager technicians in labs across the globe, at least from the evidence summarized in this book, ad infinitum.

In March/April 2006, studies of twins in Minnesota by Dr. Koening seem to back up Hamer but with an added proviso: environmental tendency in childhood being a bit stronger but the genetic tendency towards the spiritual in adulthood gaining power among the admittedly small group analyzed. I have heard it summed up that one may tend to revert back to one's childhood faith as one gets older, a point Hamer brings up if at all only tangentially I reckon.

As one with theological but not biological background, I admit that the middle of the book with its exploration of brain chemistry lost me. But Hamer at other places has a knack for being straightforward and engaging. He may well be accused of dumbing down his book to reach people like me. But there's plenty of recondite knowledge I'm certain has escaped many of his peers.

His chapter linking the DNA findings of the priestly Cohen caste to their biblical time, while intriguing on its own, seems grafted into his study, however. It fits his other points, but either deserved more in-depth study as its own brief book or more integration into the wider implications of his argument. Hamer does raise a fascinating crux: if historically, Jewish women only had a 1:200 rate of exogamy outside the tribe, how did the Jews wind up looking more or less like all of the many peoples among whom they dwelt for as much as two-and-a-half millennia?

Differing from E.O. Wilson's sociobiology, Hamer argues with this Jewish example (although again I wish it was clearer) that his own findings show an inner tendency towards the divine impulse not part of transmitted ritual like circumscision or learned cultural behavior like keeping kosher. Differing from Richard Dawkins (I kept waiting for Dawkins' thesis to be confronted by Hamer, and he does not do so until well on in the book) and his attack on religion as a parasitic meme, Hamer seeks not to prove God, but merely to chart how roughly half of one's makeup might be in some cases genetically predisposed towards the spiritual search. He notes rather depressingly, although it may get lost in the whole argument, that parents have barely a miniscule influence on the religious or spiritual tendencies of their offspring. The behavior and the outward adherence can be inculcated and enforced, but not the interior tug towards what Rudolf Otto nearly a century ago called the numinous.

He does not seem to demolish Dawkins as hard as he could have. Why a parasitic meme would not die out after millenia if religion gave its bearers no advantage seems a bit overlooked. Dennett--whose earlier work on consciousness is not mentioned in Hamer, who wrote this about three years before Dennett's new book--might help. Dennett shows the social and psychological advantages and disadvantages of religious faith for human communities and the indiv

Persinger and Wilson may be deeper, but, let's face it, for most of us Hamer is probably the better guide to the new study of spirituality's biological foundations. He makes a compelling case for the existence of these, in a readable sweep of current thinking on the subject.

His writing slips up from time to time; for example, when he implies that serotonin causes depression when he really means to say the lack of serotonin does. In a survey text like this, that's a venal sin at most.

My greater complaint is that Hamer jumps to some sappy conclusions about the evolutionary advantages of religiosity, willfully dismissing its demonstrated military and reproductive effects to focus instead on the supposedly superior health and happiness of religious people. Biologically speaking, that seems a stretch.

I'm unfairly selecting Hamer's book as a polemic against the recent wave of scientific and reductionist accounts of religion (neurotheology, the god part of the brain, etc.). I'm a doctoral student in philosophy/religious studies and my largest grievance against this new trend is that all of the scientists involved display a complete ignorance of the history of human religiosity in their attempts to "stuff" religion into a framework more genial to Darwinist evolution. Specifically, as Hamer does in his work, religion promotes a feeling of well-being and an assurance of our continuation after death. It seems that he doesn't take into account the history of religious conviction prior to the New Testament and certain of the later texts of the Hebrew Tanakh. Has he ever read Job, for example? Ecclesiastes? The immortality of the soul was a late development in antiquity. The Hebrews never held such a doctrine....it came into their imagination due to diffusion from Persian and LATE Greek religion. The gods previous to this could not be propitiated; their ways were capricious and a source of terrible anxiety to humans. In no way could humans join them in enjoying immortality. Even in Egypt, a person's ba (soul) only existed after death so long as people remembered his/her name. Read Bernstein's THE FORMATION OF HELL to see this development. Only with Jesus did God appear benevolent, as a Father (Abba--daddy). There was 10,000 years of human religiosity prior to that where God/the gods were hardly an assuaging reality to human beings.
Where this biological basis for religion is helpful is in its claim that religion is an irreducible sui generis--a distinct phenomenon and not an epiphenomenon of ideological or politically driven forces/factors which is the pathetic claim of postmodernism and its neo-sophistic outlook.

To start with, the title is misleading. The important parts of the book are about spirituality (as in what Buddhists seek), which has little connection with God or churches. He does a moderately good job of describing evidence that he has identified a gene that influences spirituality. He makes plausible claims that spirituality makes people happy (that part of the book resembles the works of Csikszentmihalyi and Seligman). He makes a half-hearted attempt to argue that spirituality has evolutionary advantages which isn't very convincing by itself, but in combination with the sexual selection arguments in Miller's book The Mating Mind it becomes moderately plausible.
About halfway through the book, he runs out of things to say on those subjects and proceeds to wander through a bunch of marginally related subjects.
His descriptions of psilocybin, prozac, and ecstasy were interesting enough to make me want to learn more about those and similar drugs.
His claims that placebos are effective seem very exaggerated (...)