We have always known that orangutan infants are very dependent on their mothers in their early years. But it turns out that orangutan mothers are also changing their own behaviors to help their children learn and become independent as quickly as possible.
Primate culture has fascinated many of us who study animal behavior since we learned back in the 1990s how chimpanzee behavior varies in Africa. This discovery gave rise to the possibility that apes could have their own “culture”, something that was once considered to be the definition of humanity. Since then, we have tried to draw comparisons between the learning methods used by our offspring and those used by monkeys.
So-called proactive teaching, in which a student is deliberately taught by a parent – usually by demonstration – is less common in humans than we might think, outside of formal education. Instead, we learn by copying our parents’ actions to allow us to replicate this behavior in our own lives.
In contrast, great apes – orangutans, gorillas, chimpanzees, and bonobos – learn by using an exciting mix of individual learning through play and non-copying social learning, such as improvement – when an object (or place) becomes more interesting to one monkey. because they’ve seen another monkey use it.
A helping hand from mom
Orangutans have an interesting social life. Unlike the rest of the great apes, they live semi-lonely lives, and are dependent on their mothers for the first eight years of their lives. Through support, mothers can help them acquire the skills needed to survive and thrive in their canopy habitat in the forests of Borneo and Sumatra, Indonesia.
For example, they must learn to move between the trees in the same way that their mothers do. Orangutans seem to learn adult-type movements around the age of seven. This happens after several years of help from the mother, who is adapted to the infant’s developmental level, as well as a good portion of individual exploration through play.
Orangutans have a complex and varied diet, and the food sources they depend on seem to follow almost no pattern. But through trial and error and a little help from mom, young orangutans learn to utilize the forest for food. They also routinely use tools to access high-reward fruits, such as neesia, and these skills are not developed overnight.
Why infants beg for food
So if we are to find formal evidence in monkeys for human-like teaching – by demonstration and copying – then orangutans are probably the monkeys to be seen. That was the logic behind a recent study on infant learning through “encouragement” – this is when a young, inexperienced monkey begs or asks for food from their mother to help them learn what and how to eat.
Researchers wanted to investigate the effect of various factors, including the age of the offspring and the complexity of food on an orangutan mother’s behavior towards her young offspring. The complexity of the food was measured by the number of steps it took to process the food before it could be ingested – from simply picking and eating leaves to complicated tool use on the neesia fruit. The researchers followed 27 immature orangutans on Sumatra for more than 4,000 hours over a four-year period and recorded the conditions around the 1,390 invocation experiments they observed.
Despite infants’ best efforts, the researchers found that mother orangutans were less likely to share food with them in the first year or so of their lives when they got used to it, meaning the success of getting food was low. .
But after the infant began consuming solid foods, their attempts became far more successful with a sharp increase in the number of times their mother agreed to share food. As the infants got older, their requests for food began to become less successful again. After the offspring reached the age of five, the rate of maternal care took a bit of a dive, most extremely in the case of more complex foods such as the neesia fruit or meat from small invertebrates.
As their offspring got older, Sumatran orangutan mothers seemed to become less willing to help them eat. The researchers suggest that this may be due to the mother changing her behavior to provide the correct level of guidance required for the infant to become independent as quickly as possible.
They compare this to scaffolding in humans, where parents will initially give a child plenty of support in the early stages of learning a skill, but then this support is gradually withdrawn until the infant operates independently. But scientists do not assume that what they observed in orangutans is conscious in the same way as human teaching.
The change in behavior of the orangutan mother may provide an evolutionary benefit. They only reproduce when their current offspring have achieved a large degree of independence – so the faster this happens, the more offspring can be bred. Those mothers who are more tolerant and helpful, with offspring that potentially gain independence earlier, can reproduce more.
The authors do not suggest that this is a conscious choice on the part of the mothers, as it cannot be known from the study. And since we do not know if it is conscious, we can not say that it is evidence of human-like teaching. However, this is an interesting development in research on social learning and culture in orangutans, as it suggests that mothers play a more active role in developing the feeding skills of their immature offspring than previously thought.
Instead of trying to apply our human labels to other species, we should simply learn to understand and celebrate the different kind of culture that we observe in our closest living relatives. It is for this reason, and many others besides, that we must all do everything in our power to preserve these amazing animals.