How Primate Moms Decide When to Start Weaning Their Babies

Weaning is a difficult thing to study and to quantify.

Because of the multitude of factors involved that a mother cannot control (resources, predation, environmental stochasticity, number of previous offspring, offspring size, and sex), the time to wean could easily be different for each one of her infants.

In fact, the most important variables in the weaning process involve a multitude of individual characteristics about mom herself.

primate breastfeeding
Image by Rajesh Balouria from Pixabay

Weaning is Impacted by the Mother’s Age

The mother’s age makes a big difference in the weaning process; younger moms often must consider their own growth in addition to the growth of their newborns, so they may opt to wean earlier and put a greater level of resources into their own growth and development.

It’s often the case that first-time primate moms are little more than young ladies themselves!

On the other hand, multiparous, older moms do not have as much of a requirement to invest in their future reproduction, and so they may choose to wean their offspring later.

Many human mothers reflect that they weaned their “last” baby at a later age because they knew it would be their last chance to experience breastfeeding.

Was this the case for you? Let me know in the comments!

It’s possible that there could be a similar sentiment in primate mothers. However, most non-human primate mothers continue to produce babies until close to their death. Humans and toothed whales are unique in the animal kingdom in that their reproductive system ages much more quickly than the rest of their body. 

Prevous Parenting Experience Alters When a Mother Weans Her Baby

In mountain gorillas, the inter-birth interval of primiparous (first-time moms) is 20% higher than for multiparous ones. This isn’t surprising, given the steep learning curve of first-time moms.

Survival of first-borns is lower for primiparous mothers as well. Infants born to first-time moms have a 50% higher mortality rate than those born to more experienced ones.

Breastfeeding and weaning are just two of the many practices that are difficult when one is doing them for the first time. Primiparous moms generally have a lower quantity and quality of milk than multiparous ones. This is likely related to both physiological and emotional aspects of each.

Photo by Acharaporn Kamornboonyarush from Pexels

Social Rank and Resource Access Affect When a Mother Decides to Wean

A mother’s social rank most certainly plays a role in the weaning time of her offspring. High-ranking mothers have priority access to high-quality foods. This makes them more likely to attain their pre-baby energy stores more quickly than low-ranking ones.

It’s been show for some cooperatively breeding primates that mothers receiving help in the form of allonursing and infant care tend to wean their offspring much more quickly than those who do not.

As with most aspects of life, low-ranking mothers have limited access to high-quality foods. They are more likely to experience ill-health themselves. For these moms, there is a more difficult trade-off between supplementing their infants and supplementing themselves.

Image by Rajesh Balouria from Pixabay

The Weaning Process is Partially Determined by Mom’s Personality

There is a great deal of diversity in mothering style with respect to how much mothers encourage independence of their offspring.

Macaque mothers will play games with their infants as a way to introduce them to independence. They will place their babies on the ground, just a few feet away and then encourage them to make their way over to them.

Moms may make familiar gestures or sounds so that their infants begin to understand what is expected of them. Macaque mothers begin these games as early as the infant’s first week of life.

Female olive baboons, yellow baboons, and Hamadryas baboons all do something similar: put their babies on the ground, sometimes as early as the day they are born, and take a few steps away before making familiar retrieval vocalizations.

Mother chimps take their tiny infant’s hands and help them to take their first steps while walking bipedally backward. This is done much in the same way that human mothers help their infants.

Photo by Sebastian Voortman from Pexels

Perhaps it’s not surprising that the females who encourage independence of their infants from an early age tend to have offspring that wean earlier and have more adventurous personalities.

Maternal encouragement is also sensitive to the competence of individual offspring.

When it comes to weaning and the encouragement of infant independence, there is no easy way to summarize or conclude that “that’s how primates do it.” Some babies are simply ready before others, and all mothers must ultimately make this decision based on each infant’s ability to thrive on their own.


This post is an adapted excerpt from my book “Wild Moms: Motherhood in the Animal Kingdom

11 Comments

  1. I watch a few channels out of Cambodia with long tail Macaques. There is a mother that is still nursing and weaning her juvenile 14 month old daughter. But has a 3 month old baby boy she is also nursing. Many say it’s unheard of but the juvenile was severely injured as a baby and i believe this is why she is not weaned yet. Is this normal?

    • It sure is normal. 10-14 months is the typical age at which a young macaque is fully weaned, injured or not. BTW, if you remain interested in monkeys I would suggest checking out channels such as Vervet Forest or Arroz Marisco’s Monkey Hill. The Cambodian VOs are (for the most part) exploitative and present a badly skewed narrative if not outright lies.

  2. I watch the macaque monkeys in Cambodia and there is a girl monkey(Janna) that is almost 21 months old and still nursing. She has an 8 month old brother and it’s being said that the mother is pregnant again. Is this normal. The 21 month old was bitten by a dog as an infant and has some spinal deformity. She hangs around her mom all the time too nurse. She’s jealous of her brother and fights, bites and pulls their mom’s nipples from his mouth when he’s nursing. She sometimes but not always cries and throws fits if her mom doesn’t allow her to nurse or if her brother nurses too long. Once the 8 month old switched to the other nipple and the 21 month old had a fit.

    • If the mother is low ranking, it is very common to nurse longer. The mother, would know if her milk is satisfying or not. If it isn’t she will nurse for longer, as her food, will be what the high rank don’t want. High rank and 1st time mothers, will wean them off quicker, In the high rank case, she must be one of the 1st, to fall pregnant again. In the 1st time Mum, she is still growing, and knows she needs more, to survive, feeding her baby full length, puts damage on her still growing body. There is no firm, weaning time in Macaques. Many females will infact Nurse multiple offspring, especially if they are female,As they are needed, for a strong healthy breeding Troop.

      • That has little to do with it in regards to the long tailed macaques at Angkor Wats that these people here are referring to (the “Cambodian macaques”).
        These macaques, no matter what their rank is in the societal hierarchy, have access to more food than they could ever need (which is also why so many of them are morbidly obese). For a very long time, far longer than there were VOs filming there for YouTube channels, that site receives thousands of visitors and tourists every single week and the majority of them feed the macaques, there definitely is an overabundance of food available to them.

    • Not really. All they know is their security and food source is being removed. Many fight their mothers in order to continue to nurse. Some mothers start the weaning processing within the first week of life and on rare instances, some mothers never wean and continue to feed up an into early adulthood. There have been cases where pregnant offspring will still go back to their mothers to nurse. As for seeing their babies again. Most offspring follow the mother, even though they are weaned, for years. Their mothers are there first and only source of safety. Babies that are removed from their mothers to become ‘pets’ suffer for the rest of their lives. Many suck their thumbs, toes or anything else that hangs off of them or other monkeys. Also, the weaning process can be pretty violent. Many baby monkeys are left with cuts and burses on their faces.

    • Of course they still see their mothers!! If they are female then they usually have a lifelong relationship with not only their mom but often also their grandmother, maternal aunts and their sisters and younger siblings. Often males emigrate to another troop once they reach sexually maturity but not as often as researchers used to think. It has been found that some do not move away to another troop and some move away and then return to their natal troop! In those cases the males will still remember their families and maintain a relationship with them.

  3. Great article, how much milk does an infant macaque need per day? Why do some moms wean a newborn for a period of time while periodically checking their butt? Does this have a correlation with their first vowel movement?

    • Lol…you mean their first bowel movement? Actually it has absolutely nothing to do with that and though you are a bit confused I can see why you might think that!
      First, they are never “weaning” their newborns just as when they are refusing to allow a baby of 5 or 6 months to access their breast at the moment they are not actually weaning them. It is simply a matter of needing a break occasionally from them nursing (regarding the newborns) though an attentive and non-abusive mom will usually allow a newborn to pretty much nurse on demand. With older babies they are just teaching them that they cannot just nurse whenever they want.
      When you see a mom turning them upside down and “checking” their rear ends it is actually usually just to get them off of their nipple at the moment for whatever reason without having to scold or be “mean” to them! A newborn cannot easily find moms nipple again when they are being held upside down!!

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