Descent and Distribution: History
Look at the discussion in Balch v. Stone, 149 Mass. 39, 20 N.E. 322 (1889), which traces the history of the law of descent and distribution. It is clear from the discussion in that case that as early as 1805 an intestate's property descended to his children, without any preference for the eldest son. The case does cite, however, Chapter 36 of the Acts of 1783 that provided that upon a man's death his property would descend to his children in equal shares, except that the eldest son will have two shares.
1 A spouse did not become a statutory heir until 1902. See the discussion in Seavey v. O'Brien, 307 Mass. 33, 29 N.E.2d 196 (1940).
2 The case indicates that the 1805 statute was simply a codification of the prior law, so the rule seems to even predate the statute.