Chimpanzees like to sleep comfortably the same as humans do, and they deliberately pick sturdy, leafy branches for their wooden beds, a new study has found.
Observing a collective of chimpanzee nests in Uganda's Toro-Semliki Wildlife Reserve, researchers examined the wood used in 1,844 nests, NBC News reported.
"Chimpanzees, like humans, are highly selective when it comes to where they sleep," David Samson of the University of Nevada said in a news release quoted by NBC News. "This suggests that for apes there is something inherently attractive about a comfortable bed--down to what kind of wood you use to make it."
He and Kevin Hunt of Indiana University studied the nests and published their findings in the journal PLOS ONE on Wednesday.
The colleagues discovered that the chimps were especially partial to Ugandan ironwood, which was used for 73.6 percent of the nests they surveyed.
Chimps look for strong wood with plenty of leaves to sleep on. Samson and Hunt theorized in the study that Ugandan ironwood is selected because it protects the chimps from threats and is the least likely wood to break and let them fall. The ironwood is also more densely leafy with the least amount of space between leaves on the branch.
The chimps likely have to hunt for this particular wood since of the seven tree species in the reserve, only about 9.6 percent of the trees are Ugandan ironwood.
"We conclude that chimpanzees are aware of the structural properties of C. alexandri branches and choose it because its properties afford chimpanzees sleeping platforms that are firm, stable and resilient," the authors wrote.
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