Orangutan mothers gradually adjust how much food they share with their offspring to help them learn quicker and become independent, scientists in Germany reveal.
The researchers, from Max Planck Institute of Animal Behavior in Konstanz, analysed behaviour between orangutan mothers and infants in Sumatra, Indonesia.
The researchers claim that they have discovered the first proof of orangutan mother’s active participation in their children’s development of new skills.
Orangutan mother orangutans forage to ‘tailor’ their behavior to their children’s abilities and age, which helps their young learn.
The mothers are able to reproduce once the infants of the orangutan have become independent. It is also possible for them to adapt their behavior in this manner.
Orangutans are similar to humans in that they rely on their mothers for life skills, such as where and what to eat. A female orangutan holds a baby.
The researchers state in their paper that “Immature Orangutans develop their eating skills over several years via independent and social learning.”
“So far it remains uninvestigated whether orangutan mother are involved in this learning process.
“We concluded that mothers of orangutans play a greater role than we thought in skill acquisition for their offspring.”
There are four living classifications of great apes or ‘Hominidae’ – Orangutan, Gorilla, Pan (consisting of chimpanzee and the bonobo) and Homo, of which only modern humans remain.
Humans today are fundamentally different from the other great apes – most notably because we live on the ground, walk on two legs and have much larger brains.
Researchers say that orangutans, in terms of motherhood are an animal of distinction.
An orangutan mother will stay in close contact with her baby for up to nine years – longer than almost all mammals other than humans.
Much like humans, orangutans rely on their mothers to learn life skills – such as what to eat and where to find it – before they finally reach independence.
However, it was not clear that orangutan mother were able to learn from their kids’ learning like humans. It was thought that orangutan mother were passive role models and not active teachers, until now.
During the eight to nine year weaning period, immature orangutans must learn how to recognise and process more than 200 food items, many of which require several steps before they can be eaten.
The leaves and flowers are easy to eat, while the bark needs to be removed from the tree.
Some foods are more difficult than others. For example, bees need to extract honey from their hives using sticks as tools.
This is Pongo abelii (a young orangutan) in his mother’s hand, Chester Zoo April 2018.
According to studies done in the past, watching their mother while she eats is how immature orangutans acquire complex foraging skills.
Sometimes they will try to grab food from their mother’s hands, or beg for it.
However, it is a mystery how the learning process turned out to be so “one-sided”, as the mother wasn’t actively teaching her children.
Dr Caroline Schuppli said that it was puzzling why mothers seemed passive in these feeding interactions.
“Mothers spend so much time with their children and have such close relationships, but never seem to actively participate in skill acquisition for their kids.”
For this study, Dr Schuppli teamed up with researchers from the University of Zurich in Switzerland, the Universitas Nasional in Indonesia, and the Max Planck Institute for Evolutionary Anthropology in Germany to gather data on the mother’s role in offspring skill development.
They analysed data on 1,300 instances of begging, or ‘food solicitation’ – the infant asking for or trying to obtain food from the mother – by 27 immature Sumatran orangutans that were collected over 12 years at the Suaq Balimbing research area in Sumatra, Indonesia.
They scored each occasion by asking the mother if she would allow the child to eat the food. Then they analysed the score with data on the age and properties of the food.
The results showed that mothers of orangutans do communicate with their children during food, which facilitates learning.
Mothers of orangutans adjust the ‘tolerance’ they give to children who request food. This is based on how old their offspring are and how complicated it is to prepare.
‘Tolerance’ from the mother is defined as letting the offspring take the food item, while ‘intolerance’ is refusing to let the offspring take the food or showing low-level aggression towards the offspring.
According to the researchers, orangutan mother’s have high tolerance levels when their offspring learn food recognition and processing skills.
Furthermore, their tolerance is the greatest for difficult items and it lasts longest.
For items that require tool use, for example, the mothers show the highest tolerance levels and stay tolerant throughout the offspring’s dependency period.
Leaves that are only to be picked, and not ingested whole by their children show a lower tolerance level and they stop sharing the leaves with them once they have reached an age.
Dr Schuppli stated that “our findings indicate that orangutan mother are active participants in the skill-learning of their children.” They do it in a reactive and not proactive manner.
It was interesting to note that there were few instances of food sharing. It is important that the orangutan adult immatures take responsibility for their learning.
“This is very different than humans. Active teaching plays an important part and role models take a more proactive approach.
“It’s also different than chimpanzees where mothers appear to be more proactive.
Tools are necessary for orangutans to reach the most challenging foods. These tools include sticks, which can be transformed into brushes, in order to extract honey from beehives.
Damien Neadle, a researcher at Birmingham City University who was not involved with the study, thinks the orangutan mother’s change in behaviour might provide an evolutionary advantage.
‘They only reproduce again once their current offspring has gained a large degree of independence – so, the faster this happens, the more offspring can be reared,’ he wrote for The Conversation.
“Mothers who show more compassion and kindness to their children, may be able to reproduce faster.
It’s not yet clear whether these behaviour adjustments observed by mother orangutan orangutan orangutans can be considered functional teaching.
“These findings provide us with a unique insight into what factors lead to evolution in teaching,” said Dr Schuppli.
“Teaching is a rare activity in the animal kingdom. However, it does occur in multiple species.
“Our study showed that the orangutans are capable of teaching in a variety of ways.
Scientific Reports has published the results of this study.