Orangutans Behave Very Similarly to Humans in Terms of Socialization and Sleeping, Claims New Study
In a new study, researchers discuss two possible priorities in an orangutan's life: sleep and friends. After following multiple orangutans over 17 years, a team of experts gained better-than-ever insights into their sleeping patterns, according to Popular Science. The insights revealed that orangutans resorted to power naps if they missed out on their required sleep at night. In most cases, the loss of sleep happened because the orangutans prioritized socialization. Another noteworthy finding revealed that the sleep routine and behavior displayed by the orangutans were very similar to that of humans. The insights about the investigation were published in the journal Current Biology.
Following the Orangutans
The study is based on observations collected by a group of experts following 53 adult orangutans at Suaq Balimbing Monitoring Station in Indonesia from 2007 to 2023. Three people were assigned to each orangutan in the assessment to ensure a thorough database. The team took note of all their daily activities from early morning wake-up to evening bedtime. Researchers noted that each orangutan made their 'bed' before sleeping. They did not just lie down anywhere; they had specific set locations, which they maintained every evening. This preparation involved arranging twigs and foliage together to build a nest.
The team also observed a unique behavior in this particular set of orangutans. These orangutans also made special 'beds' for their daytime naps, something that has not been observed in other populations of these animals. For other groups, researchers have observed them lazing around on bare branches for their naps. Their observed sleeping patterns and behavior could be unique to the Suaq population, as reported by BBC Wildlife Magazine. This population is known for their use of tools and social ability. They may require more rest than others to maintain these cognitive pursuits. It could mean that the other orangutans may not exhibit these sleeping patterns.
Sleep schedule
Researchers believe that these orangutans stay in their 'night nests' for 13 hours. Mothers share nests with their children, implying that they sleep together, while adult orangutans rest alone in their nests. These nests were high in the trees, so the experts couldn't go into them to observe the orangutans, as that would have alerted them. From their vantage point, the team could hear sounds of movement and rustling. After a while, though, everything typically became quiet, which the team considered to be a good indicator of sleep. In the morning, the opposite happened; things went from quiet to rustling, which could imply that the orangutans woke up. According to a study published in 2013, the orangutans spend 75% of their quiet time sleeping. If they are 'resting' in the nest for 13 hours, then they might be sleeping for around 10 hours.
The team also noted instances when the orangutans did not 'rest' for 13 hours. Their observations revealed that it usually occurred due to traveling for long distances during the day, cold weather, and socialization with other orangutans. The last reason was very striking to experts, as it highlighted a similarity with humans. Just like humans, if these orangutans invested time in their peers, their sleep duration was affected. "We thought it was really interesting that just being near other orangutans when building a night nest was linked to shorter sleep periods," Alison Ashbury, a scientist at the Max Planck Institute of Animal Behavior (MPI-AB) and the University of Konstanz, explained. "Imagine you stay up late hanging out with your friends, or your roommate is snoring so loudly in the morning that you get up early. I think it's a bit like that."
The interactions were meaningful because orangutans are semi-solitary animals. They interact with others of their kind but don't function in herds. These apes do not need to coordinate their sleep according to others' schedules. Despite that, these Suaq orangutans reduce their sleeping hours for socialization. This shows that even if it is not necessary, these apes can prioritize social bonds.
Compensation with Morning Naps
Every time an orangutan had less sleep, they took naps in the morning. These naps took place in 'day nests,' made in around two minutes by the orangutans. Though they were less elaborate than the night nests, the day ones also seemed to give them a sense of comfort. In this case, the researchers were also able to observe the orangutans. Caroline Schuppli, a study co-author and an evolutionary biologist and research group leader at the Max Planck Institute of Animal Behavior in Konstanz, claims that the orangutan's body gets relaxed, and their eyes are closed during these 'naps.' All of these made the team believe that the orangutans were truly sleeping.
Researchers were even able to establish a relationship between naps and sleep. They claimed that for every hour of sleep these apes lost at night, five to ten minutes were added to their naptime. In the 455 days experts followed the orangutans, at least one took a nap on 41% of the days. These naptimes, on average, were 76 minutes. The assessment shows the benefit of monitoring activities, like sleep in natural environments rather than labs. "Studying sleep in the wild, in the natural social and ecological conditions under which it evolved, is important to broadening our understanding of the evolutionary origins and the ultimate functions of sleep," explained Meg Crofoot, co-author of the study. "If we're going to answer this question, we need to bring sleep research out of the lab and into the field. Studies such as this one contribute to that effort."