In the most recent edition of Soule Kindred, Louise Walsh Throop has an interesting article on the possible Dutch origins of Mayflower passenger George Soule. Part of her argument rests on the premise that four men signed the Mayflower Compact being aged 18-21. Of these, I noted Gilbert Winslow was the only person one could argue that fact since we was but 20 years old. The others Walsh argues are Edward Doty, George Soule, and Edward Leister. Edward Doty is given a probable origins in East Halton, Lincolnshire and a baptism of 3 November 1600.
Of the arguments Walsh makes, I have to disagree with assuming Edward Leister is the younger of the two servants of Stephen Hopkins merely because he was listed second to Edward Dotey. As for George Soule, the entire article is premised with the creation (always a bad idea when doing genealogical research) of a possible George son of a John (in Dutch "Jan"), although there is no primary evidence for such a son. This type of argument starts: if there were a George he would fit in as born ca. 1601 and here's all the supporting arguments for such a premise, including that he could sign the Mayflower Compact despite being less that 21 years old. Genealogy works best when you start with a primary record that shows a person actually existed rather than starting off with a phantom. That's my opinion.
So leaving Soule and Leister behind, let's assume this Edward Doty is the Mayflower passenger. We have two men (Winslow and Doty) born in 1600 that signed the Compact. However, both were born before November 11, 1600 and were therefore each in his 21st year of age. If asked on November 11, 1620 (the date of the Compact) how old are you?, they could have answered truthfully they were in their 21st year of age.
If, as time and research continues, we find good birth dates for the signers, I would argue that 21 was the official age and these two men shaded the truth a bit. One should note that in 17th century death records, most ages are given as "in their xxth year."