What is the difference in the way a baboon and an orangutan sleep? 

Scientists conducted a research study to see if there was a difference in the way large primates sleep.

American scientists, Dr. Samson of Duke University in Durham, North Carolina and Robert Shumaker of Indiana University in Bloomington, chose two primate species to study, and they published their findings in the American Journal of Physical Anthropology in 2015. 

The primate species they chose to study were the baboon and the orangutan. The baboon is a monkey (it has a tail) and the orangutan is an ape (it does not have a tail). 

They video-taped 12 baboons and 5 orangutans sleeping over a period of 1-4 months. The scientists studied their sleeping positions, body movements, sleep patterns, and brain activity by measuring rapid eye movement (REM) sleep (which is light sleep) and non-rapid eye movement (NREM) sleep (which is deep sleep associated with dreaming). 

This is what the scientists learned:

The baboon does not use a sleeping platform and likes to rest sitting down, whereas the orangutan sleeps on a sleeping platform such as a branch of a tree. 

In fact, most monkeys sleep in a sitting position in trees, often upright and sitting on their bottom. They sleep in the ‘guarded’ position, keeping on eye on danger.

Also, all apes (orangutan, gorilla, chimpanzee, and bonobo) build a sleeping or nesting platform in trees. The ape likes to relax, lying down, sleeping on its front or back.

The baboon sleeps lightly for a short time with fragmented sleep, and the orangutan sleeps deeply for a longer time with less fragmented sleep (i.e. more continuously) than the baboon. Therefore, the ape sleeps more efficiently (‘better’) than the monkey. 

This means that the baboon, and most monkeys, don’t sleep very well, but they are quick to wake up, especially when there is a predator or danger nearby. The orangutan, and all apes, sleep securely and comfortably, but are slower to wake up. 

The photographed monkey is the Black Crested Mangabey Monkey. The monkey typically sleeps in a sitting position in a branch of a tree. But not this one. This monkey, at the Paris Zoo, is sleeping on the ground in a lying position, just like apes do. This might be because there are fewer dangers, or no dangers, in its enclosure in the zoo. 

[Location of photographs: Parc Zoologique de Paris in Bois de Vincennes, France, andParis Zoo, France]

Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM