Chimpanzees, our closest genetic relatives with approximately 99% of the same DNA, have always fascinated scientists. From their complex social behaviors to their intricate tool-use abilities, these great apes offer valuable insights into the evolution of human traits. One behavior that stands out is their nest-building routine, a fundamental activity for chimps that serves multiple purposes, from rest to play, grooming, and even ecological exploration. But a new study led by Canadian primatologist Iulia Bădescu from the Université de Montréal (UdeM) and published in the American Journal of Primatology reveals an interesting difference between young female and male chimpanzees when it comes to nest building—females start earlier and build nests more frequently, hinting at greater independence from a younger age.
The concept of nest building in chimpanzees is more than just a nightly routine; it’s an essential survival skill. Much like humans make their beds each day, chimpanzees create nests in the trees, weaving branches into a secure circle and lining it with twigs and leaves to ensure comfort during rest. They usually build their nests at dusk, preparing for a full night’s sleep, but they are also known to construct nests during the day. These daytime nests serve a variety of purposes, including resting, eating, and engaging in play or social grooming.
Chimpanzees have been building nests for millions of years, and it’s crucial for their well-being. Just like humans, the quality of their rest impacts their cognitive functions, memory, and energy levels, making the act of nest building critical for their survival. The more rest they get, the better they are able to engage in daily tasks, remember essential tasks, and process information in their environment.
The New Study
In the study led by Iulia Bădescu, researchers observed the nest-building behavior of 72 wild immature chimpanzees in Kibale National Park, Uganda, a region renowned for its chimpanzee population. The study took place in two phases, 2013–2014 and 2018, with a focus on how factors such as age, sex, and maternal parity (how often a chimp mother has given birth) influenced the likelihood of a chimpanzee building nests during the day. The researchers also looked at the frequency of nest-building activities and the duration of each session.
What the team found was both fascinating and surprising: female chimpanzees started nest building earlier and were more consistent in building nests compared to their male counterparts. These findings align with previous studies suggesting that female chimpanzees generally tend to achieve greater independence from their mothers at a younger age than males. This early independence could be a sign of the different roles females and males play in chimpanzee societies. While males typically stay dependent on their mothers longer, females appear to be more self-reliant earlier on in life, as demonstrated by their early and frequent nest-building behavior.
Age also played a significant role in nest building. The study showed that older infant chimpanzees were more likely to build nests and did so more frequently compared to younger infants. This makes sense from a developmental perspective: nest building requires certain physical abilities and learning that younger infants simply haven’t developed yet. As the infants grow older and gain strength and coordination, they begin to build nests more effectively and frequently.
The researchers found that once infants reached a certain developmental threshold—around four years of age—nest building became more functional, serving primarily as a place to sleep and rest, whereas younger infants were more likely to use their nests for play and exploration. Despite these differences in the types of nests built, the study noted that once infants started building nests, the overall rates and durations were similar across sexes and ages. This suggests that while there may be early differences in the frequency of nest building, once chimpanzees begin practicing, there is little variation in how they approach the task.
The Role of Sex in Nest Building
The most striking result of the study was the gender gap in nest building. Female infants were found to build nests more often than their male counterparts, confirming previous research that indicated females reach certain developmental milestones earlier than males. This has important implications for understanding not only chimpanzee behavior but also the development of independence in other primate species, including humans.
The fact that females build nests earlier could point to a variety of underlying factors related to sexual dimorphism, or the differences between males and females in a species. Female chimpanzees may be more inclined to build nests early on because it’s part of their broader socialization process, which prepares them for roles in their communities that involve nurturing and independence. On the other hand, males may take longer to become self-reliant as they stay closer to their mothers longer, which could be tied to their role in social dynamics and mating strategies later in life.
The development of nest-building skills is also a form of tool use, according to the study. Just like chimps use stones to crack nuts or sticks to fish for ants, nest building requires them to manipulate their environment in a practical and useful way. The young chimps must figure out how to select the right materials, break branches, and assemble them into a stable structure. This ability to use their environment effectively for a specific purpose is another example of the sophisticated tool-making behaviors observed in chimpanzees.
Evolutionary Implications
One of the reasons this study is so important is that it sheds light on the developmental processes shared by humans and chimpanzees, our closest evolutionary relatives. Humans, like chimpanzees, learn skills related to their environment from a very young age, and nest building in chimps offers a window into how early skills are acquired. The act of building a nest is not just about creating a resting place; it’s about interacting with and manipulating the environment in a purposeful way. By studying how chimpanzees learn to build nests from such a young age, researchers can gain insight into the broader cognitive and social development of primates, including humans.
“Humans, too, sleep in beds,” said Iulia Bădescu, highlighting the evolutionary significance of nest building. “Studying how chimps learn to build nests from a very young age helps us better understand how all hominids, including us, develop and learn new skills.”
The study also offers broader insights into how early life experiences shape the future roles and behaviors of animals within their communities. For chimpanzees, learning to build nests is a foundational skill that influences their socialization and independence. By comparing the different developmental trajectories of male and female chimpanzees, scientists can learn more about how sex and age influence the acquisition of crucial life skills.
More information: Julie Gooderick et al. Developmental and Sex-Based Variation in Nest Building Among Wild Immature Chimpanzees, American Journal of Primatology (2025). onlinelibrary.wiley.com/doi/10.1002/ajp.70011