The so-called "grandmother hypothesis", based on studies of African hunter-gatherer groups, suggests that infertile women are vital for successful child-rearing despite being unable to produce children themselves.
Child-rearing should not involve childless women.
( z1 recommend :ARG1 ( z2 involve :polarity - :ARG1 ( z3 woman :ARG0-of ( z4 have :polarity - :ARG1 ( z5 child ) ) ) :ARG2 ( z6 raise :ARG1 z5 ) ) )