Matthew H. D. Chapman is an English-American journalist, author, screenwriter, director and science activist. As the great-great-grandson of Charles Darwin, he has had a particular interest in the American creationism versus evolution controversy. He has written and directed six films, written two books and numerous screenplays, had articles published in Harper's Magazine and National Geographic among others, and blogged for the Huffington Post.

Matthew Chapman grew up in an English family that attended church and his parents sent him to "schools that mandated daily prayers." His father, Cecil Chapman, was the son of the noted physicist and astronomer, Sydney Chapman, responsible for early research on the nature of the ozone layer. His mother, Clare, was the daughter of the philosophy professor and author Francis Cornford and poet Frances Cornford (née Darwin), the daughter of Francis Darwin.

Growing up in Cambridge, England, Chapman did not give much consideration to the fact that he was the great-great grandson of Charles Darwin. He did feel the pressure to be an academic success. However, he was "a boy who refused to be educated and was kicked out of several schools." Chapman left school at age fifteen. After that, he held various jobs until landing an apprenticeship as a film editor.

According to his book Trials of the Monkey—An Accidental Memoir, Chapman began praying nightly at the age of 7. As fodder for his lengthy prayer sessions, he found magazine and newspaper articles provided "an endless and astonishing vein of human misery from which to mine the elements for [his] nightly pleas." This awareness of human suffering led him to consider becoming a missionary to help others. He decided to read the entire Bible as a first step toward that goal.

When he had read as far as the Book of Leviticus, he was dismayed to discover that God tells Moses to kill homosexual men. At that point in his life, Chapman found his gay uncle, Ben Duncan, and his partner to be "the only truly civilized and loving couple [he] knew." By the age of 9, Chapman had discovered that Leviticus 20:13 was often used by clergy and politicians to justify the incarceration of men like his uncle.

In the 1980's, Chapman moved to the US and became aware of believers in creationism challenging schools over teaching evolution. His interest in this issue grew and led him to write his first book in 2001, Trials of the Monkey—An Accidental Memoir.

In 2005, Harper's Magazine asked Matthew Chapman to cover the Kitzmiller v. Dover Area School District case. In that court case, eleven parents successfully sued the school district to prevent creationism (also called intelligent design) from getting equal footing with instruction on evolution in science classes taken by 9th graders. The ruling in the case, issued by Republican Judge John Jones, reprimanded "the [Christian] fundamentalists and their scientific supporters for their intellectual dishonesty.”

During the trial, a journalism colleague from a Harrisburg newspaper reported on the fact that Matthew Chapman was a descendent of Charles Darwin. This led to Chapman being "invited to homes and churches in the area to talk about [his] views, and on a couple of occasions to endure attempts at conversion." He encountered many people who, having been indoctrinated with religious beliefs from childhood, would "choose faith no matter how good the contradictory evidence was." Chapman says that when he left Pennsylvania after the conclusion of the trial, his "journey to atheism [was] complete."