Do Primates Understand Property?

As is the tradition in many zoos and sanctuaries, we distributed Christmas boxes filled with shredded paper and some treat items to small primates at the place where I have been volunteering for many years .

"What is the point?" - will you ask - "animals, do not know the meaning of Christmas."

True.  They don't, but keepers have a duty to ensure animals in their care are busy. They must provide some enrichment to their lives in captivity and the gift boxes are an opportunity to forage for treat items. Foraging is a natural behavior in the wild. Figuring out how to unwrap and open a box provides primates with an opportunity to use their brains and hands.  It is an exciting moment.  All observe carefully as volunteers place the boxes in their enclosures.  They get excited. They know it is for them.
No sooner is the catch cage open than they each rush and grab a box. They bring it to a corner where their mates will not disturb them and start the grand ceremony of opening their gifts.
One colorful capuchin reaps the wrapping paper apart with the enthusiasm of a 5 year old human child under the Christmas tree. He utters little screams of joy as he finally opens a side of the box - but then seems disappointed that it only contains the usual shredded paper, peanuts and seeds.  He jumps over to the next platform where his friend opened another box. The two exchange places and seem pretty satisfied to get the treats out.
Another capuchin monkey leaps up in the air screaming, while he swiftly lifts a gift box and brings it to his catch cage.  He is a lot more delicate than his friend and carefully opens one side of the box without spilling anything out.  He calmly eats out the treats as his two roommates who already finished up theirs look at him.  The baboon gets slightly irritated because the box is not cooperative- harder to open than he anticipated.

I am rejoiced at their reaction to the gifts. They each individually behaved as if they knew this was a special gift - which made me wonder if primates do have a sense of ownership and property.
In the wild, this manifests around food items.  In captivity, studies have demonstrated that they understand and practice barter - giving different values to different food items (or even tokens representing food items).

I refer you to two interesting articles:
Property in Non-Human Primates - Georgia State University
and
How scientists taught monkeys the concept of money (ZMEScience.com)

And to cheer everyone up, a video from Chimp Haven.

Wishing all a great end of the year and holidays!

Cheek Pouches

Cheek pouches are pockets between the jaw and the cheek used to temporarily store food.  Many rodents, marsupials and monkeys have them.

Apes and New World monkeys do not have cheek pouches.
Old World monkeys have cheek pouches but do not use them with the same frequency.  For instance, baboons in the wild don't seem to use their cheek pouches as much as they do in captivity.

It was long believed that cheek pouches were the result of an adaptation to ground foraging, to store food in high risk situation while on the ground and consume it later high in a tree, however Ciochon and Feagle argue that cercopithecines who live mostly arboreal have the largest cheek pouches. (Primate Evolution and Human Origins).

Unlike those of rodents, primates' cheek pouches secrete large quantities of amylase - which converts starches into sugar.  In her book "Primate Behavioral Ecology",  Karen Strier writes: "this adaptation for digesting unrip fruits, which are often high in starch, gives cercopithecines a competitive advantage over sympatric chimpanzees which tend to wait for fruits to ripen and may account for cercopithecines' high evolutionary success compared to apes (Lambert, 2005)." Cheek pouches also soften the fruit.  Gautier-Hion recorded in 1971 that cercopithecus talapoin used their cheek pouches to hold live prey - such as insects. Lindburg suggested that in addition to providing temporary storage for food monkeys could eat in a safer place away from danger and conspecific individuals, it also allowed the animal to continue feeding while engaging in social activities (like grooming and feeding the young).

In a study conducted in Japan between 1986-1995, scientists collected data related to seed dispersal via cheek pouches and compared the results to seed dispersal via feces.  (Japanese monkeys - Macaca fuscata yakui, on Yakushima Island, Japan - Takakazu Yumoto, Naohiko Noma, Tamaki Maruhashi).  They found that the seeds dispersed via cheek pouches were bigger than those spread through feces and a higher percentage (82%) germinated compared to those spread through feces.  They conclude that cheek pouch seed dispersal plays an important role in the evergreen forest of Yakushima.

More recently a study looked at the correlation between cheek pouch use and the use of a preferred hand.  The scientists wanted to find out if right or left-handedness evolved from the pre-existing laterality of basic brain functions and behavior of if the two evolved simultaneously.  (Do Right-Handed Monkeys Use the Right Cheek Pouch Before The Left?)

In captivity, it seems that primates use their cheek pouches more than in the wild - most likely because in a small environment where escape is not much of an option (apart from climbing up or hiding under a contraption), they feel more pressure to take as much food as they can before a higher ranking individual shows up.  I have seen this scenario many times with baboons - females will fill their cheek pouches as quickly as possible before the dominant male arrives and grabs all the enrichment items he can get his hands on.  What I have never seen is an individual stealing food directly from the cheek pouches ofa lower rank individual or a juvenile.  Yet, this situation occurs.  So cheek pouches are a safe  way to save food, but not always…