Unlike most mammals, primates have only two teats positioned high on the chest. This is directly linked to single-infant births and the nursing posture — the infant clings to the mother's ventral fur and reaches up to feed.
Monkey milk is remarkably dilute at only 3–5% fat, compared to 20–25% in bears or 35–50% in whales. Because infants have continuous ventral access and nurse dozens of times per day, milk does not need to be energy-dense.
Most Old World monkeys nurse for 12–24 months or longer. Lactation suppresses ovulation, naturally spacing births. The nursing relationship also reinforces social bonding between mother and infant within the troop.
Colostrum produced in the first days is protein-rich and loaded with immunoglobulins. Over weeks it transitions to mature milk with higher lactose. Fat content rises slightly toward weaning as nursing frequency declines.
Thin and watery with a mildly sweet flavor from high lactose — more similar in consistency to human breast milk than to the thick, oily milks of cetaceans or bears. Pale white in color with a faintly nutty aroma.
Composition closely mirrors human breast milk, reflecting shared primate evolutionary history. High lactose (~7%) fuels the rapidly developing brain. Rich in taurine and DHA, critical for neural and visual development in large-brained primates.
Moderate calcium and phosphorus support slower skeletal growth compared to ungulates. Significant vitamin D and iron. Colostrum is exceptionally rich in secretory IgA immunoglobulins, transferring passive immunity in the first critical days of life.
Because primate infants nurse on demand throughout the day and night, milk volume stays low and dilute rather than concentrated — the opposite strategy from bears or cetaceans. Social context also matters: infant distress calls prompt immediate nursing, and allonursing (feeding another's infant) is documented in some species.