If you act under the assumption that a man owns his tools, his shelter, his wife/wives and his children, as is evidenced in many cultures, you don't need agriculture to be part of the arrangement.



From everything I've read, the idea of property/ownership is fairly universal, and wherever there is property or ownership, there are interpersonal relationships that could be called marriages that were usually handled as contractual transactions. The idea being a man who wanted to procreate, or to have a secondary food source in the form of a gatherer or agricultural laborer, would approach another group that had extra women of a young enough age to be both physically able to work and likely to bear multiple offspring because infant mortality rates have been staggering for most of human history. Sometimes the transaction was peaceful and involved an exchange of resources (tools, food, hunting land, etc.) for the woman, other times it was handled as a raid where the more aggressive group would simply take the woman/women, making them that man's property by force.

From what I've read, there is evidence of this kind of transaction before agriculture became the norm, and after as well.

Then again, I'm an amateur in this realm. Ask me about politics... there I'm a professional!