Kathy D,
Human breasts are actually the second pair, the first pair in the milk line
are axillary, actually in or just outside the armpits.  This is familiar to
all of us LC's who have seen women with supernumary (SP?) breasts, the most
common place is at the axilla, or on the lower chest.
        Is there any correlation with parenting style for species that have
persistence of only anterior mammary glands rather than posterior?  The
species you mentioned as maintaining cranial teats are those mammals with
longer term infant dependency and more intensive parenting...
Catherine Watson Genna, IBCLC  NYC  [log in to unmask]