This week marks the 400th anniversary of the arrival of enslaved Africans in England's American colonies. In 1619, a group of Angolans were taken as captives by the Portuguese, who had colonized Angola and converted some of the population to Catholicism.

They were loaded onto ships bound for what's now Mexico. But on the way, the ships were intercepted by British pirates, who took some of the enslaved Angolans. They were brought to Virginia and sold to colonists from the Jamestown settlement. The event marks what we see as the beginning of slavery in the United States.

Historian Ric Murphy is a Massachusetts native who traces his ancestry to that first group of Africans. His research has led him to the controversial view that when they reached Virginia, which at that time had no slave laws, the Angolans were treated not as slaves, but as indentured servants. WGBH Radio's Arun Rath spoke with Murphy about his ancestry. This transcript has been edited for clarity.

Arun Rath: What was it like for them at the moment when they're getting off that boat in Virginia? What's the world they're stepping into?

Ric Murphy: The English had surplus labor. So when they came here, they had no intentions of enslaving, nor were they looking to bring Africans in, because they hadn’t needed surplus labor that they had.

When the Africans came here, it was by accident, not by design. They were not looked upon as enslaved. They came at a time when the colony was an absolute failure, and the various plantations that were here, none of them had made a profit prior to the Angolans coming. And every plantation that the Angolans went to after that made a profit, because the English had no idea about animal husbandry, agriculture — particularly in a semi-tropical environment — and the Angolans did. Between 1607 and 1619, there was a well-developed indentured servitude contract, and after so many years, depending on your age, you were set free. So these Angolans eventually became free.

Rath: From what I understand — and it could be a popular misconception — but I think most African-Americans have a difficult time tracing their history earlier than the 19th century. But you go a lot farther than that.

Murphy: I do. You're correct. Many African-Americans, or as I like to refer to us, Americans of African descent, have had challenges over the many years in terms of making those connections.

Rath: Can you talk about what you know about your family history coming to America?

Murphy: Fortunately, I come from a long New England family, and we were most fortunate that in New England, birth, death and marriage certificates were captured back in the mid-1600’s. So on my mother's side of the family, we were able to document our European ancestry and our African ancestry back to the early 1700s. On my father's side, the family that came from Virginia, through genealogical research I began to realize that we were documenting them also in the early 1700s.

The process is very different. They didn't collect birth, death and marriage certificates, but what they did was land deeds, where you would often find information about your family. And when land was passed from one generation to another, oftentimes through the wills and the deeds, somewhat of a family pedigree was created, because it would explain what land was given to what child. So that's how I began to realize my ancestry through Virginia, and strictly by accident, found that I was descended from the very first documented Africans that came in August 1619.

Rath: Can you tell us about your relative?

Murphy: I am directly descended from John Gowen and Margaret Cornish. And who would have thought that a kid from Boston would find out that he was descended from the first Angolans that came here in 1619. And that discovery was purely by accident. It was not something that I sought to look for, because I didn't know anything about it. So when I found out that I was descended from these folks, you can only imagine what I thought.

Correction: An earlier version of this story misspelled John Gowen's surname.