The narrative of President Obama’s family embedded in the American psyche gained a new layer this week as a team of genealogists found evidence that he is most likely a descendant of one of the first documented African slaves in this country.

The link to slavery, which scholars of genealogy and race in America called remarkable, was found 400 years back in the lineage of Obama’s mother, Stanley Ann Dunham. It was discovered by a team of four genealogists from Ancestry.com who worked for two years on the findings released in a report Monday.

Using property and tax records, the team uncovered “a lot of context and circumstantial evidence” that points to an enslaved black man named John Punch as Obama’s ancestor, said Joseph Shumway, one of the genealogists who worked on the report.

Because his father emigrated from Kenya and his mother was born in Kansas, Obama was thought to have no direct links to American slavery.

“His tree is one of the most dynamic that we’ve seen as far as diversity,” said Shumway, whose company also helped uncover the president’s Irish ancestry and that Obama is a distant cousin of Warren Buffett.

The link between Obama and Punch was first reported by the New York Times from an early copy of Ancestry’s report. Punch is a significant historical figure, who has long been a subject of research. In 1640, he and two European-American indentured servants were arrested for running away from their masters in Colonial Virginia. The two white men, a Dutchman and a Scot, received four additional years of servitude, but the black man, Punch, was to “serve his said master … for the time of his natural life,” said Peter Wood, a professor emeritus of history at Duke University. Punch is thought of as the first black slave in Virginia.

“We often need specific names to help us understand sweeping social changes. Punch gives us the story of a real person who endured the beginnings of a huge social shift,” Wood said of Punch’s significance.

The discovery comes at a time when Americans have been digging into their family trees. It was such familial research that led the team at Ancestry.com to make the connection between Punch and Obama’s family line. They first traced Obama’s mother’s heritage through her maternal grandmother to the Bunch family, who at one time lived in Virginia and “passed for white” and “intermarried with local white families,” according to the report. Members of the modern Bunch family, who had already begun to dig into the family’s heritage, had already conducted DNA testing that found that the family had an ancestor from Africa, and posted that information on a family Web site. Shumway and his colleagues set out to find that black ancestor.

The records eventually led them to Punch, who was one of only 150 Africans living in Virginia in the mid-1600s, and fathered a free child by a white woman. That the family name changed to Bunch was not uncommon in an era when there was no standardized spelling, Shumway said.