Pillow
History

Though the exact origin is unknown, use of pillows evolved in animals well into prehistory, the earliest examples including reptiles and mammals resting their heads on themselves, and one another, to support the head and neck. Animals, including humans, evolved use of inanimate objects in their nests out of wood and stone as pillows. Since domestication, many animals have also learned to make use of human-made pillows and cushions, as well as to rest on members of their own and other species, for this purpose.

Sometime between 5 and 23 million years ago tree-dwelling great apes began building sleeping platforms, including wooden pillows, to improve their sleep. According to studies on chimpanzees that sleep up to eight to nine hours a night using specifically selected ironwood pillows, sturdy pillows enabled great apes to escape being hunted by night predators and not fall out of the trees while asleep. It is likely that this was necessitated by the evolution of large, energy-consuming brains. Though it may also have led to longer periods of REM sleep, that in turn increased their cognitive capacity.
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