It is the whole meaning of life. Continuing propagation and raising up the kids.
I respectfully disagree. The sole purpose of our existence is to glorify God - in everything that we do.
Propagation of the species is certainly important - especially since it is among the first of God's commands to his creation.
To suggest however, that procreation is the whole meaning of life is to allow that a pagan family with 10 children has a more meaningful existence (giving more glory to God) than a missionary couple who've had the misfortune of being childless all their lives.