Asian Girl With Full Breasts

Milk production unrelated to pregnancy can also occur. This condition, called galactorrhea, may be an adverse effect of some medicinal drugs (such as some antipsychotic medications), extreme physical stress or endocrine disorders. If it occurs in men it is called male lactation, and is often classified as a pathological symptom due to its strong correlation to pituitary disorders. Newborn babies are often capable of lactation because they receive the hormones prolactin and oxytocin via the mother's bloodstream, filtered through the placenta. This neonatal liquid is known colloquially as witch's milk.
Other suggested functions
Zoologists point out that no female mammal other than the human has breasts of comparable size, relative to the rest of the body, when not lactating and that humans are the only primate that has permanently protuberant breasts. This suggests that the external form of the breasts is connected to factors other than lactation alone.