The use of surnames started in France around the year 1100 AD, The Norman invaders brought the practice to Scotland nearly 100 years later. However, the use of surnames was not common for some 50 years or more after this time, or around 1155AD. Prior to this, Malcolm Ceannmor (1057-1093), spouse to Queen Margaret of Scotland directed his subjects to adopt surnames after their territorial possessions. Such was the origin of the first earls of Scotland, such as Leslie, Gordon, Shaw, and Abircrumby among others. Written references to actual surnames are first found during the time of David I, who reigned from 1124-1153AD. One such reference is found for Robertus de Brus (Robert the Bruce).
In light of this understanding about the use of surnames, one can appreciate that the name ANDERSON would not be a Scandinavian name, as the Danes invaded Britain between 997-1014 AD, some 150 years prior to the use of surnames. However, we do recognize that some Scandinavians may also bear the name.
Anderson means "Son of Andrew". Typically, the intent was to denote "servant of Andrew", Andrew being the patron saint of Scotland. The Gaelic form of the name is Gillanders. The Andersons are a diverse group, with no specific place from which the name is derived. Most likely, the name cropped up all over the country over a period of time, with one group of Andersons not necessarily related to another group of Andersons.
Anderson or Ross or Donald?
Occassionally, the Anderson name is affiliated with Clan Ross, which creates some confusion among Andersons. The first five earls of Clan Ross bore the name "Aindrea", and not Ross. They too were "Servants of Andrew". As the title passed to descendants of the female line, the name, Ross, was assumed by the male representatives of the earls as it referred to their territorial origin. The name "Ross" is actually derived from the District of Ross, and is therefore a territorial name. In fact, the Ross's first referred to themselves as do the Andersons: "Andrew's Servants". It is also possible that some descendants of Highland Andersons rightfully share a heritage with what today is the Ross Clan.
Some other Highland "Gillanders" (Servants of Andrew) may be associated with Clan Donald, also through the female line. The Lord of the Isles (Clan Donald) assumed the title of Earl of Ross. In fact it was Donald MacGillandrish who accompanied Moira McDonald of Clan Donald when she became the wife to a McIntosh chief in the 1400's. their descendants became known as MacAndrew (son of the servant of Andrew). This is the origin of the affiliation with Clan Chattan.
A Clan in its own Right
According to the Lord Lyon, there was an Anderson of that Ilk in the 1500's. This specific Anderson is unknown to us today. But this reference verifies that the Andersons are a clan in their own right, despite having a shared ancestry with other groups. The Anderson name shows up in many forms: Andrews, Andirsoone, Andersonne, Andersoun, Andersoune, Andison, Andreson, Andherson, MacAndrews, Endirone, and many others.