Sunday, February 28, 2016

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…

Sunday, November 1, 2015

A Tail’s Tale

Humans and great apes seem to be the only creatures deprived of a tail. Yet, our coccyx is what scientists call a “vestigial” organ. It doesn’t serve any purpose but it is there. As Darwin writes in his Origin of Species: “Rudimentary organs may be compared with the letters in a word, still retained in the spelling, but become useless in the pronunciation, but which serve as a clue for its derivation.” In short, the fact we don’t have a tail doesn’t exclude the possibility that one of our distant ancestors had one. So, what is a tail for?

For some, it is a built-in fly swatter – like cows in the field; for others a navigation tool like fish; for many a means to keep their balance and for others a way to communicate. When you come home, I am sure your dog greets you by jumping around with vigorous tail wagging – that is, if you are lucky enough to have one. Scientists at the University of Bari, Italy, have been studying tail wagging and its meaning for quite some time. The results of their research show that the direction of the tail indicates different emotional states in dogs. For instance, if the tail wags more to the left, emotions tend to be negative; whereas wagging to the right is a sure sign of happiness. The direction the tail goes is a by-product of the asymmetry of the brain and dogs probably do not intentionally communicate their emotional state to others. However experiments showed that when dogs watched videos of other dogs wagging their tails to the left, they exhibited signs of anxiety; they were more relaxed when watching other dogs wag their tails to the right. A domestic cat holding its tail high up can be trusted. It is a friendly and contented cat. Stay clear if the tail is bushy though, that means the cat is bristling with anger.

Now that we know a little bit more about cats and dogs, let’s talk about wild animals. Equidae, like zebras, use their tails to keep away biting insects and, much like dogs, the position and movement of the tail is a good indicator of the animal’s emotional state and condition. Side to side or up and down wagging is a sign of irritation. A threatening zebra will lower its head, pull its ears back, bare its teeth and lash its tail around. One can also read the mood of a panther by its tail. A flicked and twitched tail indicates annoyance, anticipation or anger. As for tigers, they usually keep their tails in a low position, unless they’re curious about something, then they hold it high up.

For birds, the tail is an aerodynamic tool serving pretty much the same function as the rudders of a boat. It helps them steer while flying and provides stability when they take off and land. It also helps them keep their balance when they’re perched. However, nature can be fickle and some birds have a tail so cumbersome, one can wonder what purpose it really serves. Take the male peacock for instance – why does it have such a long, colorful tail? The theory is that it conveys a clear message to females that the individual is healthy. A peacock uses its tail in an elaborate dance to court females and hope to get lucky! Peacocks are not the only ones to attract mates with their exuberant tails, the long-tailed widowbird, Cape sugarbird, quetzal, long-tailed sylph are but a few other examples.

Not all tails are equal. Prehensile tails are by far the coolest! Arboreal mammals, like kinkajous, spider monkeys, capuchin monkeys and also pangolins, anteaters and some rodents have prehensile tails. Those provide safety and come in handy when you have to find your food and evolve in an environment full of unevenly spaced branches. Skeletal structural differences can be found in mammals with and without prehensile tails. Mammals with a prehensile tail have more vertebrae. Those are more robust and allow for increased strength and flexibility of the distal end of the tail. Prehensile tails are so strong they can support the entire weight of the animal it belongs to. Both spider monkeys and capuchin monkeys have prehensile tails – but these differ in more than one way. Spider monkey tails are long, thin and bare underneath with dermatoglyphs (i.e. ridges in the skin like our own fingers). This area of their tail is highly enervated and therefore tactile. As a matter of fact, it pretty much acts as an extra limb or hand. When touching something with the bare part of their tails, spider monkeys gather information about its texture, scent and consistency. Capuchin monkey tails, in contrast, are shorter, fully covered with hair and deprived of tactile receptors. The tail of spider monkeys represent about 7% of their total body weight, slightly less for capuchins – about 5%. While spider monkeys use their tails for suspensory locomotion and for feeding, capuchin monkeys use it mostly as a weight-bearing tool when feeding in the canopy.

Black and white (or red) Ruffed lemurs, who spend their lives up in the canopy, use their tails for balance during locomotion. They can leap great distances between trees, but the use of her tail as a balance mechanism can be easily observed when they walk on all fours along branches or (suspended fire hoses when in captivity). They hold her tails low, slightly curved to the right or the left to keep moving straight along the path. As opposed to black and white ruffed lemurs, ringtail lemurs spend a lot of time foraging on the ground and hold their tails high up in the air. So do coatis. This helps them keep track of each member of the group while foraging or traveling.

So you see, there is much to tell about tails!

Sunday, August 2, 2015

Should Great Apes Be Granted Similar Legal Status as Humans?

How we treat great apes (and other animals for that matter) is a question that has been gaining momentum the last few years.
Organizations like The Non-Human Rights Project argue that a legal status, other than that of "property" should be granted to great apes in particular.

I could not agree more.  Animals are not objects and should not be considered as such by the law, no matter which country they live in.
We do know that animals (from mice to apes) have feelings and experience empathy ** (see references below) - so how can we justify trading them as mere junk?

The question is even more pertinent when it comes to the ethical treatment of great apes in facilities using them for the greater good - (think medical research).  Progress has been made and it seems that we (humans) are now moving towards a consensus that medical research should move away from animal testing where other solutions apply.  However, some argue that computer simulation, in vitro testing cannot viably replace animal testing - here's an interesting article on the subject from "Speaking Of Research".

Yesterday, non human rights were debated again in the press and the battle is far from being over if some continue to think that keeping things as they are is the right thing to do.  See "Sanity In the Court: Judge Denies Claims that Chimps are Persons".  However, per the article, an Argentinean judge granted habeas corpus to an orangutan at the end of last year.  To quote the article in Scientific American: "In Argentina, at least, Sandra now has the right to life, liberty and freedom from harm." It also mentions that in New Zealand, a river was granted rights as well "Agreement Entitles Whanganui River to Legal Identity"
This means there is hope for those who think that advanced species (and natural resources*** essential to our lives) should be granted some rights - even if they cannot plead their own case in our language.

**  The Scientist "Mice Show Evidence of Empathy"
** Frans De Waal interview about The Feelings of Animals

** Frans De Waal talks about empathy

*** The idea that natural resources should have rights first was formulated in the 1970s by Professor Christopher D. Stone when the book "The Lorax" came out.  You can check out this document "Should Trees Have Standing?" for more details.

Sunday, September 28, 2014

Gorilla News!

Gorillas are endangered and your children may never see one alive.  This is why the event that just took place in London is so encouraging.  Who would have thought a bunch of runners could raise funds and awareness for gorillas when the world is going through so many trials and there are so many things to worry about.  Yet, these runners were able to raise the not so shabby sum of one hundred thousand pounds!

Read the full article in the Irish Independent here.


More gorilla news…

Kiki a seven year old epileptic gorilla was transferred from her home in Germany to the Antwerp zoo where she will find some much needed quiet and rest.  She is being integrated slowly into her new group.

For more information read the full article in Flanders Today.


Some hope for Bua Noi (Little Lotus) a female gorilla who has been exhibited in a high rise zoo in Bangkok since 1987.  It is now a well known fact that great apes (but really all primates) are social animals who do not do well in small cages and isolation.  Activists are requesting Bua Noi be transferred to a facility offering a better environment and it seems they are being heard.
Let's hope this works out and let's follow-up on the story.

More on BBC news.


Let's watch some happy baby gorillas now.

Friday, July 4, 2014

Chimpanzee Gestures Interpreted

While for many years researchers focused on teaching great apes how to learn our language, through sign or symbols, Dr Catherine Hobaiter from the University of St Andrews in Scotland just published an article in the journal Current Biology. She expands on her research into chimpanzee communication and says that wild chimpanzees are able to communicate very specific messages to one another using specific gestures.
For instance, offering a particular part of the body to another chimpanzee is a request to be groomed; whereas tearing strips from a leaf indicates a chimpanzee is showing sexual interest in another individual.
The study findings are based on the analysis of numerous videos made while the research team was following chimps in Uganda.
While we are not quite ready yet to understand the subtleties of chimpanzee gestures and partake in comprehensive conversations with our next of kin, it is great news.

You can consult the BBC article for more details.

Along the same line, an article "Pantomine in Great Apes", published by Anne E. Russon (Professor of Psychology, Glendon College, York University, Toronto) and Kristin Andrews (York University, Toronto) outlines that wild orangutans can communicate using gestures as well.
Orangutans solicite grooming by initiating grooming with another individual; they pretend to be unable to do something when they need help and like chimpanzees, they teach other individuals how to do something through demonstration.

Why Do Apes Point? (Janni Pedersen, Iowa State University), Par Segerdahi (Uppsala University) and William M. Fields (Great Ape Trust of Iowa), argue that bonobos deliberately use pointing gestures.

Although not related to primates, here are two interesting articles addressing how dogs and elephants understand human gestures and sometimes can use that knowledge to their advantage.

The Scientist : Catch My Drift?

National Geographic: African Elephants Understand Human Gestures

Wednesday, February 12, 2014

A great start for 2014 in the primate world!

I have been so busy, I have neglected my blog but I have decided 2014 would be a little more prolific.  So, to begin with, I browsed through all the news related to primates since the beginning of January and there are already quite a few exciting highlights.

The Cincinnati zoo celebrated the first birthday of Gladys, the baby gorilla raised by surrogates.  It's like Tarzan, but in reverse - human surrogates helped raise a baby primate - not an easy task but definitely worthy.
In this video you can see Gladys and her gorilla friends eating a very special birthday cake and hear about the great conservation work the zoo is doing.

Bonobos are extremely rare and only found in one specific region of the Congo.  Needless to say they are extremely endangered.  Only a handful of zoos in the US have the privilege to exhibit bonobos and  the same Cincinnati zoo introduces to the world a young bonobo female (the 8th bonobo birth in that facility).   See the baby in the video below.

Then… out of nowhere comes the great news that a "chimpanzee mega-culture"has been discovered in the central Uele region of Northern DRC.  A group of thousands of individuals sharing the same "customs" and behaviors. Knowing the chimpanzee populations have been declining drastically over the years, this was totally unexpected.  For more information, read this article in the Huffington Post.

Wounda, a female chimpanzee overcame illness and is released on the island of Tchindzoulou. Watch the story of Wounda now.  So very touching.

What would you do if one of your animals escaped?  Well, a zoo in Japan holds drills every two years to keep its staff on the alert.  See for yourself…

Come back soon for more news on primates.

Sunday, October 27, 2013

Say "Cheese" Before I Snap!

Did you ever curse at your dentist for saying you don't floss enough?  Well, you think twice because apparently, some primates do it without the prompt of a professional.  So, whether you agree or disagree that flossing is a necessity to preserve your pearly whites, there might be some benefit to it after all.

A Japanese macaque female, named Chompe, resident at Kyoto University Primate Research Institute, was seen pulling a hair tight between her hands and running it through her teeth to remove food remnants.  According to Jean-Baptiste Leca, the lead author of a report published in the January 2013 issue of the journal Primates, flossing may have been an "accidental bi-product of grooming".
Apparently, this wise female came up with three different techniques of flossing - 1) by moving her mouth to run hers or another monkey's hair through her teeth; 2) by gently moving her head backwards to run hers or another monkey's hair through her teeth; 3) by pulling a strand of her own hair and running it through her teeth with her hands (much like we do).
For more details on this interesting phenomenon, I recommend you check out an article on Discovery entitled "Tidy Monkey Flosses Teeth".

Let's look at the differences between human and non-human primate teeth.  The most obvious difference is that humans do not have large canines.  Baring our teeth to impress a competitor would be a most unusual behavior for our kind.  Note that the presence of large canines prevents side to side jaw movements.  Another important difference.  Female primates usually have smaller canines - especially for apes.  Human teeth are smaller and less specialized than those of non-human primates - we really are not furry enough to necessitate the use of a tooth comb like our lemur friends.  Human molars have five points on the grinding surface, while ape molars only have four - a very useful trait for paleontologists to identify their finds.  In humans, permanent canines grow before permanent second molar, it is the reverse in apes.  The arch of the mouth is different in humans and non-human primates.  Humans seem to have fast growing enamel, whereas apes seem to have slow growing enamel.  Thin enamel generally characterizes fructivores; humans have thick enamel more adapted to plant and meat eating.  There is more micro wear in thick enameled teeth and a diet higher in sugary food is more likely to cause decay.

Mind your diet and keep flossing.

Recommended readings: Primate Dentition - An Introduction To The Teeth of Non-Human Primates. - Daris Swinder.

Dental Microwear in Live, Wild-Trapped Alouatta palliata From Costa Rica - Duke Univsersity

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