Genealogy (from Greek: γενεά, genea, "generation"; and λόγος, logos, "knowledge") is the study of families and the tracing of their lineages and history. Genealogists use oral traditions, historical records, genetic analysis, and other records to obtain information about a family and to demonstrate kinship and pedigrees of its members. The results are often displayed in charts or written as narratives.

The pursuit of family history tends to be shaped by several motivations, including the desire to carve out a place for one's family in the larger historical picture, a sense of responsibility to preserve the past for future generations, and a sense of self-satisfaction in accurate storytelling.

Hobbyist genealogists typically pursue their own ancestry and that of their spouses. Professional genealogists may also conduct research for others, publish books on genealogical methods, teach, or produce their own databases. They may work for companies that provide software or produce materials of use to hobbyist and other professional genealogists. Both try to understand not just where and when people lived, but also their lifestyles, biographies, and motivations. This often requires—or leads to—knowledge of antiquated laws, old political boundaries, migration trends, and historical socioeconomic or religious conditions.

Spencer Wells (born April 6, 1969 in Georgia, United States) is a geneticist and anthropologist, an Explorer-in-Residence at the National Geographic Society, and Frank H.T. Rhodes Class of '56 Professor at Cornell University. He leads The Genographic Project.

Wells grew up in Lubbock, Texas. He obtained a Bachelor of Science in Biology from the University of Texas at Austin in 1988, and a Ph.D. in Biology from Harvard University in 1994. He was a postdoctoral fellow at Stanford University between 1994 and 1998, and a research fellow at Oxford University between 1999 and 2000.

Wells did his Ph.D. work under Richard Lewontin, and later did postdoctoral research with Luigi Luca Cavalli-Sforza and Sir Walter Bodmer. His work, which has helped to establish the critical role played by Central Asia in the peopling of the world, has been published in journals such as Science, American Journal of Human Genetics, and the Proceedings of the National Academy of Sciences.

He wrote the book The Journey of Man: A Genetic Odyssey (2002), which explains how genetic data has been used to trace human migrations over the past 50,000 years, when modern humans first migrated outside of Africa. According to Wells, one group took a southern route and populated southern India and southeast Asia, then Australia. The other group, accounting for 90% of the world's non-African population (some 5 billion people as of late 2006), took a northern route, eventually peopling most of Eurasia (largely displacing the aboriginals in southern India, Sri Lanka and Southeast Asia in the process), North Africa and the Americas. Wells also wrote and presented the PBS/National Geographic documentary of the same name. By analyzing DNA from people in all regions of the world, Wells has concluded that all humans alive today are descended from a single man who lived in Africa around 60,000 - 90,000 years ago, a man also known as Y-chromosomal Adam.