By M.G. Lord

Two hundred years after his birth, English scientist Charles Darwin, author of "On the Origin of Species," is a powerful global brand. To commemorate his bicentennial, the "Darwin industry" -- as Cambridge historian Martin J.S. Rudwick terms it -- has been in high gear, generating books, papers, greeting cards, T-shirts, car ornaments and, of course, fresh scholarship. Surprisingly, it has not generated much controversy -- except in the United States, which has a stubborn contingent of religious fundamentalists who maintain that the Earth is only 6,000 years old.

Yet they too may soon be won over, if Michael Dowd, author of "Thank God for Evolution," has his way. Dowd is a Christian evangelical minister; his wife, Connie Barlow, an atheistic science writer. Their marriage evokes a Hollywood romantic comedy. After being "born again" and receiving a master of divinity at Eastern Baptist Theological Seminary, Dowd met Barlow, author of two books with "evolution" in their titles, at a cosmology lecture. Against all odds, they fell in love and found a mission: to travel around the country preaching that evolution is indeed God's plan.

Today the couple has no permanent residence. Dowd thumps "Origin of Species" as ardently as the Bible. His movement's logo is a Christian fish smooching a Darwin amphibian (which, if you can bear its cuteness, can be purchased on a baseball cap at ThankGodForEvolution.com).

Dowd's writing has the cheesy tone of a self-help book; his gooiest chapter is a workbook of "Evolutionary Integrity Practices" that parallel the "steps" of 12-step recovery programs. Yet one can forgive such tackiness if Dowd persuades but a single extremist to heed physicist Sean B. Carroll: "Biology without evolution is like physics without gravity."