A new study suggests that like humans, chimpanzees are also very particular about their bed. Chimpanzees unlike humans are known to create their bed every day starting from scratch just before their bedtime. The exclusive chimpanzees beds are called nests and it require bending, breaking stems of tree, and piling leaves in an interwoven pattern, on this structure. But researchers noticed that chimpanzees do not make their nest on any random tree, rather choose branches of Ugandan ironwood trees for the purpose. These trees provided them with sturdy and stable nest to sleep.
David Samson an anthropologist at the University of Nevada, Las Vegas and leading the study said that this research also supports the theory that spending quality-sleeping time might be the reason for the evolution of humans from primates.
Researchers always knew that chimps are choosey, but they did not know about the parameters based on which a chimpanzee chooses a tree for creating its one-time use beds. To understand this, researchers analyzed the characteristics as stiffness and strength of seven species of trees found in the Toro Semliki Wildlife Reserve in western Uganda and was most commonly employed by chimps as their one night nesting site. They also analyzed the surface area and density of the leaves and the overall structure of each species of tree.
For the study, the researchers studied some 1,844 chimpanzees nests. Out of these studied nests, they found that 73.6 percent of the nests were created using Ugandan Ironwood which was a strong tree. Interestingly, these trees are not very common and make up only 9.6 percent of all the tree in the area.
Sturdy and Stable Nests
Researchers explain that chimps prefer spending their night sleeping in their nests that are created in the canopy of trees, to avoid their potential nighttime hunters like lions and leopards. Therefore, these nests need to be sturdy and stable without any risk of chimps falling off the bed during the night. And out of the seven species of tree studied in the research, Ironwood was the sturdiest and making them the best material for making beds. It is also believed that the Ironwood leaves, protected the chimps from pathogens apart from predators and acts as temperature regulators.
The researchers also noticed that the Ironwood branches had gaps between shoots, making them easy for the chimps to interweave them together and create a mattress like structure. These properties of Ironwood make them a preferred choice for chimps. The findings from the study suggest that the ease of making a nest and safety are two factors that the chimps decision of making nest are based on.
Sleep and Evolution
Samson is also curious to know if high quality sleep had any role to play in the evolution of humans. Only chimps are known to create beds for sleeping from specific tress, while all other primates still sleep on branches. Other studies have shown a relation between longer sleeping hours and improved brain functioning. After all chimps are closest relatives and just like humans, quality sleep is also equally important for chimps and which require a good bed. No wonder chimpanzees spend so much time and effort in creating a comfortable bed every single night.