NEW YORK — Millions of people in recent years have sent off samples of their saliva to DNA-testing companies such as 23andMe and Ancestry.com hoping to find out where their forebears came from and whether they have mystery relatives in some distant land or even around the corner.
The trend itself can be traced to an Italian physician and geneticist, Luigi Luca Cavalli-Sforza, who died Aug. 31 at his home in Belluno, Italy, at 96. He laid the foundation for such testing, having honed his skills more than 60 years ago using blood types and 300 years of church records to study heredity in the villagers of his own country.
Dr. Cavalli-Sforza was a pioneer in using genetic information to help trace human evolution, history, and patterns of migration. The founder of a field that he called genetic geography, he was renowned for synthesizing information from diverse disciplines — genetics, archaeology, linguistics, anthropology, and statistics — to explain how human populations fanned out over the Earth from their original home in Africa.
David Reich, a professor of genetics at Harvard Medical School, said in an interview that Dr. Cavalli-Sforza was the first scientist to predict that there would be “enough information in genes to determine where people came from in the world and who they’re most closely related to.”
“A fair number of reasonable people,” he added, “thought it wouldn’t be possible.”
Dr. Cavalli-Sforza was a professor at Stanford University from 1970 to 1992 and continued to do research for more than a decade after retiring.
Described by colleagues as endlessly curious and fearless about venturing into unexplored zones, he studied fruit flies, bacteria, Italian marriage records, human blood groups, African Pygmies, and the political and religious views of American college students and their parents, analyzing his own findings with merciless statistical rigor. Cultural traits and how they spread fascinated him, and late in life he began to study variations in hand gestures in different parts of Italy.
With Marcus Feldman, a biologist and colleague at Stanford, he founded a field called cultural evolution, which treats language, values, customs, and other social phenomena as traits that evolve, just as physical traits do.
Cultural evolution “exploded into a legitimate discipline,” Feldman said in a telephone interview. “There’s now a cultural evolution society.”
Dr. Cavalli-Sforza also studied genetic changes in the Y chromosome, the determinant of male gender, which is passed from fathers to sons.
His work, along with that of colleagues, indicated that genetically there is no such thing as race: Individuals within a population group differ genetically from one another just as much as they differ from people in other groups. He denounced efforts to suggest that superficial traits such as skin color or hair texture had any underlying connection to intelligence, behavior, or character.
Dr. Cavalli-Sforza came under fire from some quarters after proposing, in the 1990s, what he called a Human Genome Diversity Project. The plan was to collect blood, hair, or saliva to provide DNA from populations all over the world, including aboriginal groups that were declining in numbers. The project would create cell lines that could be stored and used later by researchers.
Although many scientists favored the plan, opponents said it smacked of colonialism, racism, and “biopiracy” — meaning that if the samples led to medical or pharmaceutical breakthroughs, the people who donated their DNA would never see the health benefits or the profits.
Some critics even maintained that the samples could be used to create biological weapons that might target specific ethnic groups.
But Dr. Cavalli-Sforza stuck to his guns. The project went on, although not on the scale that he had planned. He had hoped for 10,000 samples but wound up with about 1,000 samples from some 50 populations; the samples are stored in Paris at the Center for the Study of Human Polymorphisms.