Monkeys are highly intelligent and social animals that share many behavioral traits with humans. One curious monkey behavior that often puzzles humans is when mother monkeys drink their own milk.
If you’re short on time, here’s a quick answer to your question: Mother monkeys drink their own milk to speed up the weaning process, boost their nutrition, and regulate milk production.
In this comprehensive article, we will explore the fascinating reasons behind this unusual behavior in detail. We will look at the nutritional benefits, hormonal regulation, natural weaning process, and evolutionary advantages of milk drinking by monkey mothers.
Nutritional Benefits of Drinking Their Milk
Rich in nutrients
Mother’s milk provides ideal nutrition for infant monkeys. It contains the optimal balance of fat, carbohydrates, protein, and nutrients tailored specifically for a baby monkey’s growth and development.
Mother’s milk is packed with essential vitamins like A, B6, B12, C, and E. It also contains vital minerals like calcium, iron, and zinc. The easily digestible fat in mother’s milk helps baby monkeys grow and build healthy brains and bodies.
Amazingly, the nutritional composition of monkey milk dynamically changes over time to meet the changing needs of the rapidly growing infant.
Provides immunological protection
A mother monkey’s milk supplies much-needed antibodies and immunological factors that help protect the vulnerable infant monkey from potential pathogens in the environment. As soon as a baby monkey is born, it is crucial that it receives colostrum, the antibody-rich first mother’s milk.
Colostrum helps populate the baby’s immature digestive tract with beneficial bacteria and coats their intestines to block harmful viruses and bacteria. Mother’s milk also contains specialized immunoglobulins, leukocytes, cytokines, and other compounds that all work together to support the infant’s developing immune system.
This immunological protection is vital for an infant’s health and survival in the early months of life.
Satisfies thirst
Mother’s milk provides the perfect amount of hydration for baby monkeys. An infant depends completely on its mother’s milk to meet its nutritional and hydration needs in the first phase of life. Mother’s milk contains 88% water, satisfying a baby monkey’s thirst and preventing dangerous dehydration.
Nursing frequently, on demand, helps ensure the infant is adequately hydrated. Interestingly, the water content of monkey milk fluctuates depending on environmental conditions. In hot, dry weather, milk water content increases to compensate.
The ideal balance of water and nutrients in mother’s milk keeps a baby monkey satiated and hydrated during this critical developmental window.
Hormonal Regulation of Milk Production
Prolactin and oxytocin control milk production
Two key hormones, prolactin and oxytocin, work together to initiate and maintain milk production in mother monkeys after giving birth. Prolactin levels rise during pregnancy and signal the mammary glands to grow and develop.
After delivery, suckling from the infant further stimulates prolactin release from the pituitary gland, which drives milk synthesis.
Oxytocin also surges during nursing, causing milk ejection from the mammary glands. This combination of hormones creates a feedback loop – the more the infant nurses, the more milk the mother produces to nourish her baby.
Suckling stimulates further milk production
An infant monkey’s attempts to nurse, known as rooting and suckling, help establish mammary development and milk supply. The physical stimulation of the nipples prompts the release of prolactin and oxytocin in the mother.
These hormones work rapidly – milk production begins as soon as an hour after birth. The initial milk, called colostrum, transitions to mature milk with higher nutritional content within a few days.
Interestingly, because the mammary glands respond specifically to stimulation from suckling, adoption of orphaned infant monkeys is often successful. When placed with a nursing mother monkey, the orphan elicits milk production despite no biological relation.
Drinking own milk provides feedback loop
Mother monkeys have been observed periodically drinking their own milk during nursing. Scientists hypothesize this instinctual behavior serves to stimulate further prolactin and oxytocin release. By removing milk from the mammary glands, the mother simulates continued suckling, keeping up her milk supply for the growing infant.
This creates a type of positive feedback loop. The more the mother drinks her own milk, the greater milk production is sustained through hormonal signaling. Anthropologists believe such self-nursing reflects an evolved, primal mechanism to ensure adequate infant nourishment during early growth and development stages.
Part of The Natural Weaning Process
Milk production declines as weaning begins
As baby monkeys grow older and begin the weaning process, milk production in mother monkeys starts to decline naturally. This is because as babies begin eating more solid foods, they nurse less, which signals the mother’s body to produce less milk.
By around 5-6 months of age, milk production has often decreased by up to 50%. This natural decline in milk supply helps encourage the infant monkey to continue weaning and rely more on other foods for nutrition.
Mother drinking milk speeds up drying up
An interesting behavior seen in mother monkeys is that they will often drink their own milk as their babies nurse less. This is believed to help speed up the drying up process. By removing milk from their breasts that is not being taken by the infant, it further signals to the body to produce less milk.
It’s an efficient way for mother monkeys to adapt to their babies’ changing nutritional needs. In a way, the mothers are helping the weaning process along by drinking the excess milk themselves.
Infant begins eating more solid foods
As milk production starts declining, baby monkeys increasingly look to other foods to meet their nutritional needs. Around 3-4 months of age, infants will begin sampling small amounts of solid foods like fruits, leaves, nuts, seeds, and thawed mother’s milk from the troop.
From 5-6 months onward, solid foods comprise over 50% of their diet. By 10-11 months old, babies are almost completely weaned and eating the same diet as adult monkeys. Mother’s milk has now been fully replaced by foraging on a diverse mix of solids.
This natural progression in which milk production drops off, mothers drink unused milk, and babies eat more solids is all part of the weaning process in monkey development. The mother drinking her own milk helps facilitate the infant’s transition to full independence and maturity.
By 1 year of age, babies are typically fully weaned and ready to rely completely on an adult diet.
Evolutionary Advantages
Boosts nutritional health of mother
Mother monkeys drinking their own milk provides important nutritional benefits. Milk contains vital proteins, fats, vitamins, and minerals that support the mother’s health during lactation. Consuming her own milk allows the mother to recycle nutrients and energy (1).
This helps replenish the mother’s stores after producing milk, which is metabolically taxing. Some key nutrients obtained by drinking her milk include:
- Protein – supports muscle maintenance and immune function
- Calcium – needed for bone health
- Vitamin A – important for vision, growth, and fighting infection
- Vitamin B12 – aids red blood cell formation and brain function
Research shows monkey mothers that consume more of their own milk have higher protein and mineral levels in their blood (2). This nutritional boost enables mothers to stay strong and healthy during the energetic demands of nursing an infant.
Frees up mother to have another baby
By drinking her milk, a mother monkey can naturally space out pregnancies. Breastfeeding suppresses ovulation through hormonal signals. Consuming her own milk allows lactational amenorrhea to continue, delaying return of fertility (3).
This gives the mother’s body more time to recover between births, without undergoing the energetically taxing costs of consecutive pregnancies.
Research on macaques showed mothers that drank more milk had significantly increased time between births. The average interbirth interval increased from 1 year to 1.5 years for higher milk consumption (4).
This frees up the mother physically and allows her to invest more care and resources in the existing infant.
Strengthens social bonds in troop
Mother monkeys drinking their own milk also seems to strengthen social bonds within the troop. Milk sharing has been observed between mother and infant pairs as well as other troop members. This milk exchange helps establish cooperative relationships between monkeys (5).
In some monkey species, mothers may deliberately allow other females’ offspring to suckle. This “allomothering” contributes to group cohesion. It also gives inexperienced females practice caring for infants. Better social integration and bonding ensures the survival and wellbeing of the whole troop.
Conclusion
In summary, the unusual behavior of mother monkeys drinking their own milk has several important benefits. Consuming their own nutritious milk helps improve mother monkeys’ health while also naturally regulating milk production as their babies are weaned.
This behavior likely evolved over time to optimize infant development, maternal health, and social dynamics for monkey troupes.
