We are therefore reduced to the levirate as a proof of the former existence of group marriage.
This is certainly possible, although it rests on the hypothesis of the levirate marriage.
Most marriage was by purchase; the levirate and sororate were common.
The levirate (from "Levir," a brother-in-law, in Sanscrit dvar) is also found operating as a stringent injunction.
In Polynesia the levirate has the force of law, and it is common throughout America and Asia.
By a levirate marriage if a man died without heirs his remaining brother married his widow and raised up heirs to him.
There is absolutely no trace of a levirate system by which the nearest male kinsman must marry his deceased brother's widow.
He regards this rather unfortunately named custom of the levirate as having its root in group marriage.