It's well known that Charles Darwin's groundbreaking theory of evolution made many people furious because it contradicted the Biblical view of creation. But few know that it also created problems for Darwin at home with his deeply religious wife, Emma.

Darwin held back the book to avoid offending his wife, said Ruth Padel, the naturalist's great-great-granddaughter. "She said he seemed to be putting God further and further off," Padel said in her north London home. "But they talked it through, and she said, "Don't change any of your ideas for fear of hurting me.'"

More than 300 birthday celebrations are planned in Britain alone, where Darwin's face graces the 10-pound bill along with that of Queen Elizabeth II. Shrewsbury, the central England town where Darwin was born and raised, is holding a monthlong festival for its most famous son. And a permanent exhibition re-creating some of his most famous experiments is opening at Down House, his former home near London.

Many more events are planned worldwide, including the Second World Summit on evolution in the Galapagos islands in August. In Australia, the Perth Mint is putting out a special commemorative silver coin.

Bob Bloomfield, special projects director at London's Museum of Natural History, said Darwin was cautious not only because he didn't want to offend his wife, but also because he understood that the concept of man's evolution from other animals was controversial. He didn't want to present it simply as a hypothesis, but as an explanation buttressed by many observations and facts.

Darwin's small, handwritten diaries are on display at a major exhibit at the Museum of Natural History, as well as thousands of specimens he collected. Some came from his fabled five-year trip to South America aboard the Beagle, when he visited the remote Galapagos Islands and saw how some species had adapted to its strange, demanding environment.

The diaries offer insights into Darwin's meticulous, analytical approach. He even lists the pros and cons of getting married.