Last names came about when the population grew to such a size that people needed to find ways to differentiate between two individuals who shared the same first name. At that point, identifiers were added such as a father's name, a physical description or an occupation. That's how you get last names such as Miller – a person who worked in a grain mill – or Johnson, meaning "son of John." You can usually trace the origin of a last name using an online genealogy service, and then use DNA studies to link it to a specific nationality.
Learn Your Name's Meaning
You can run a free name-origin search at Ancestry.com whether or not you subscribe to the site. Simply navigate to the search tool, type the name into the search box, and read the instant results to learn the meaning of your last name. Descriptive or occupation-based meanings won't help you very much; the surname "Russell," for example, indicates that your ancestor had red hair. It won't tell you where he came from. Location-based meanings, on the other, are extremely helpful since they pinpoint precisely where your ancestors lived. The surname "Wakefield," for instance, references a specific city in Yorkshire, England.
Study People With the Same Name
Since 2012, genealogy website Forebears has been mapping the last name nationality of 11 million surnames. If you type the last name into its search function, you'll receive a map showing the countries where the name appears with the highest concentration. There's also information on what the name means and a list of popular variants, such as "Dhavis" and "Tdavis" for "Davis," which might give some additional clues. If you click the "Show All Records" button on your results page, you'll also get an easy-to-read ethnicity breakdown.
Join a DNA Surname Study
DNA surname studies trace members of a family who share a common surname. Because last names are passed from father to son in most cultures, and DNA is passed from father to son, people with the same surname can take a DNA test and share their DNA results with the study to determine if they share a common ancestor. If there's a match, you'll see quite clearly where your ancestor came from.
Some participants get a DNA match with people with a different surname. This is valuable information, since it suggests that your family adopted a different surname at some point, perhaps due to an immigration event. If you are looking for your ancestors overseas, knowing their original family name can provide some vital clues.
Network With Same-Name People
RootsWeb's Surname Resources page has links to research tools for thousands of surnames. Just click the letter of the alphabet for your name, find your name from the list, and see what information comes back. If you subscribe to the surname mailing list, you'll receive emails from other people with the same surname. It's a good way to share information, and you might find that someone has already traced the nationality of your last name. Navigate to the page with your surname on RootsWeb, then click the link to subscribe to the mailing list.
Focus Your Research
Since many surnames are shared between multiple nationalities, be sure to match the information you've uncovered to the known birthplaces of your ancestors. Go through the genealogical research with a fine-toothed comb, looking for locations that your family line has in common with the last name nationality you've turned up in your research. This could help you to determine where your earliest known ancestor likely lived.