Our new weekly series, “primate of the hump-day” is an effort to take the ho-hum out of your Wednesday and bring you some fascinating facts about a particular primate species. The very first POHD is the Ring-tailed Lemur (Lemur catta), a zany little primate of the prosimian variety that naturally ranges exclusively on the island of Madagascar.

Ring-tailed Lemur Profile

Age Live to be about 15 years old in the wild and 20 years in captivity. However, the maximum recorded lifespan of a lemur is 37 years in a captive setting.

Body Type Males and females both weigh about 6 pounds and are around 16 inches long from head to rump. Add the long, ringed 24″ tail, for a total of 40″ from head to tail tip…about the size of a small kitty cat!

Sex Females usually begin reproducing at about 1.5 years of age, and males generally are not able to secure mates until about three years of age.

Relationship Status Polygamous: females mate with one or more males, and males mate with multiple females. Mating only occurs once per year.

Kiddos After a pregnancy lasting about four months, females have one or two babies at a time, once per year.  Babies are carried on the mother’s belly, migrating to her back to ride “jockey style” after about 3-4 weeks. Mamas kick the kiddos out of the nest (i.e. wean them) when the youngsters are about five months old.

Political Views Female-dominated society: males and females have separate dominance structures, but the lowest-ranking adult female outranks the highest ranking adult male.

Family Life Prefer to dwell in groups of approximately 20 individuals, formed of a few breeding males, many breeding females, and the prior year’s offspring. Upon maturity, males have to “buck up,” leaving their home groups to join new groups made up of unrelated females. Females usually stay in their group of birth, but female-female evictions from the group do occur from time to time. Ring-tails are even known to kick their own mothers out of a group on occasion!!!

Home Town Range throughout the southern third of Madagascar. Prefer spiny bush and dry deciduous forest, but can live in a variety of habitats, including extreme conditions high in the mountains, in dry areas with little water, or in human populated areas. Ring-tails are well represented in many zoos and also free-range (live on their own outside of cages) at several research facilities in North Carolina, Georgia, and Florida.

Oogivore type Mainly a frugivore/folivore, enjoying fruits from tamarind trees and leaves from a variety of plants. Captive ring-tails love bananas, grapes, and figs!

Interests Stink-fighting for male dominance rights, sunning “Buddha-style,” and leaping distances up to 25 feet!!!

Get your very own Ring-tailed Lemur Product at the Primarily Primate Shoppe!

Dubbed by Rolling Stones as one of the greatest songs of all time, “the locomotion” has been making people dance for decades, but it takes on an entirely different meaning in the world of primatology. We use the term locomotion to describe the way a primate usually travels or moves about in its habitat.  All animals spend the most time traveling by what feels comfortable to them. You wouldn’t want to go for a three mile hike on hands and knees, and neither would a dog follow beside you the entire time upright on two legs. The body postures that we take during travel are dictated by our bone structures and musculature. Human leg muscles work most efficiently when we are using them to walk upright, thanks to our hip, knee, and toe alignments. Other nonhuman primates tend to move in a somewhat upright posture as well, especially compared to most other mammals. However, there is quite a bit of variability among primate groups, which allows for us all to show off some real locomoting style!

Bipedalism: what humans are most familiar with since this is how we get around. The word is taken from the Latin words bi meaning “two” and -ped meaning “feet.”  Bipedal primates have certain features in common including:

• S-shaped backbones
• Short and wide pelvises
• Short arms and long legs
• Short fingers and toes
• Big toe projects forward and cannot bend to touch all our other toes (non-opposable)
• Foramen magnum (opening at the base of the skull where the spinal cord joins the brain) is centrally located on the skull

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Quadrupedalism: form of locomotion used by many primates that tend to travel long distances on the ground or across tree branches. The word comes from quad meaning “four” and –ped meaning “feet.”  Examples include patas monkeys, baboons, and macaques. Quadrupedal primates have the following physical features in common:

• Curved backbones
• Long and narrow pelvises
• Arms and legs about equal length
• Big toe can bend and grasp, much like your thumb does
• Short fingers and toes
• Foramen magnum located towards the back of the skull

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Quadrumanous climbing/Knuckle Walking: form of locomotion seen in larger primates that spend much of their time in trees but also move about on the ground. Quadrumanous comes from quad meaning “four” and –man meaning “hand.” This term describes primates that use all four limbs as hands, such as the heavy bodied orangutans which use the muscles of both hands and feet to slowly climb through trees. Knuckle-walking describes the way gorillas, chimpanzees, and bonobos walk on the ground, placing much of their body weight onto their middle finger bones, or knuckles. (FYI: Orangutans make their hands into fists when walking on the ground!) Traits of living large-bodied apes include:

• Curved backbones
• Long and narrow pelvises
• Long arms and short legs
• Big toe that functions for grasping
• Long fingers and toes
• Modifications to the bones of the wrist, hands, and fingers that enable a locking mechanism that can support knuckle walking
• Foramen magnum located towards the back of the skull

Photo By: Jochen Ackermann*

Vertical clinging and leaping: locomotion used by many lemurs and small-bodied primates such as tarsiers that frequently jump from branch to branch. Traits of clingers and leapers include:

• Curved backbones
• Long and narrow pelvises
• Short arms, long legs
• Opposable big toes
• Long fingers and toes
• Sometimes with modified nails that resemble claws for clinging onto trees
• Foramen magnum located towards the back of the skull

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Brachiation: style of moving used by primates such as gibbons, siamangs, and spider monkeys. These guys are true aerial acrobats and capable of flying through trees hand-over-hand at break-neck speed. (Watch the video below for brachiators in action!) Physical features of primate brachiators include:

• Curved backbones
• Long and narrow pelvises
• Long arms, short legs
• Opposable big toes
• Long curved fingers, reduced thumbs
• Foramen magnum located towards the back of the skull

So, although primates may be capable of performing all of these styles of movement, there’s only one type that is used the most, and that’s the one that you use to do the locomotion with me!

As a spanking new grad student, I showed up for my first class, “Primate Ecology” uber-excited and ready to learn all I could about the fascinating world of primates. Pen in hand, I was armed and ready to furiously copy down pages of notes as I had done before in my undergrad courses. But then, without so much as a greeting to the class, my adviser waltzed into the room, dumped a box of jaw fragments on the table, and said “You have the remainder of the class to detail all you can about these primates. You may leave your papers on the podium, and I will see you tomorrow.” Several of my peers quickly jumped up, eager for the challenge, while I seriously considered high-tailing it out the door. I had never studied human anatomy, let alone primate dentition! What was I doing here, and how in the world was I to come up with anything to write?

I decided to stay and muddle my way through that first day. I wrote about variables such as how large or small I thought the primate was, and whether any of the teeth were obviously missing. Little did I know that so much more can be learned from primate jaw fragments or that the next two years of primate classes would generally involve some form of huddling over a dissecting microscope, carefully analyzing details of tiny little primate teeth. And if I was taught anything during my time volunteering as a primate dentist’s apprentice, I definitely learned how to tell what kind of “oogivore” you are.

• Frugivore: predominantly eats fruit: back teeth tend to be broad with round cusps, two incisors in the front are wide and somewhat spoon-shaped
• Folivore: munches on leaves and vegetables: back teeth tend to be large with high cusps to shred tough leaf material, two front teeth are narrow
• Graminivore: likes seeds/nuts and grains: back teeth are tall and strong, incisors are variable
• Gummivore: scrapes up gums, saps, and other tree fluids: all teeth are small and somewhat pointy, front teeth stick out straight for scraping bark
• Carnivore: devours meat: back teeth are adapted for shredding meat (not grinding), canines and incisors are long and sharp
• Insectivore: chomps insects: all teeth are small and very sharp for crushing exoskeletons of insects
• Omnivore: sophisticated palate and likes to eat a little bit of everything: teeth are variable in size and appearance

And what good are these little parcels of dentary knowledge? Put quite simply, animal teeth reflect the type of foods that predominates the diet. In turn, the type of diet tells us a lot about where the individual might have been living and even how his social system may have been set up.

Though the dietary descriptions based on tooth shape make sense, perhaps even seeming self-explanatory, it has taken extensive research to construct these types of generalizations. And just why are the teeth of primates and other animals so well-studied? The answer is rooted (no pun intended) in paleontology, more specifically in fossil preservation. Some of the most consistently well-preserved mammal fossils are the lower jawbones (mandibles), which are very hard bones.

Have you ever read the Biblical story of how Samson puts the mandible of a donkey to use? Judges 15:16 reads, “Then Samson said, “With the jawbone of a donkey, I’ve piled them in heaps! With the jawbone of a donkey, I’ve killed a thousand men!”

Mandibles are thick, strong bones, and they are often all that remains of a fossilized organism after the more delicate bones of the body are destroyed over time. Thousands of scientists have spent countless hours studying the intricacies of teeth and jaw bones, using the teeth of living specimens to make predictions about fossilized organisms. In addition to dietary type, other variables, such as species identification, age, health, and body size, can be garnered from looking at dentition. Just a couple of teeth embedded in a mandible are enough to tell a scientist that she is looking at the remains of a juvenile spider monkey approximately five pounds in weight that liked to feed predominantly on fruit. Not too shabby!

So, get out a mirror and check out your chompers. What type of oogivore are you?

In a former posting covering female dominance, I referred to the particular structure of ring-tailed lemur society in which all adult females are dominant over all adult males.  In order to be allowed to hang around and gain the benefits of group living, male lemurs submit to females when it comes to access to food, water, and sleeping sites.  It might be easy to look at these males as being wimpy since they pretty much avoid challenging female authority over them. However, I have witnessed extreme counts of unmitigated violence among adult males during the breeding season that has resulted in severe injuries and even their death. (Cute and cuddly? Of course. Capable of inflicting serious bodily harm? Most definitely!) Male ring-tails exhibit all sorts of fighting styles, usually beginning with a “stink fight” whereby they rub their tails with scent and fling it at each other, but potentially escalating to acrobatic grappling and vicious biting. If a male doesn’t fight fiercely for breeding rights during the mating season, he may not have any offspring the following year. So, while males spend most  of their lives in a submissive state towards others in the group, there are definitely times when aggression heightens and their combative side is revealed. Males can quickly become anything but wimpy in regards to staking their claim on breeding females. I like to think of lemurs as the Knights of the Primate Kingdom who keep their manhood by practicing a devout code of chivalry: respect female group members but possess adept strength and skill to fight when the need arises.  And you’d best believe, no mama can resist a tough guy with a sensitive side.

Who’s the boss here? Mama Lemur, of course! Ring-tailed lemurs have the distinction in the animal kingdom of being one of the few species of mammals that display true female dominance. When a female wants to sit in a particular crook of a tree currently occupied by a male tenant, a mere guttural grunt on her part causes the male to jump up and move out of the way.

Simple seating preferences can cause a male to hop to attention, but feeding time is even more relegated. When encountering a new feeding site, adult males sit on the outer edges of the group while females and youngsters rush in and feast on all the good stuff. After a time (the amount of which is determined by female tolerance of said males), the males will eventually work their way into the group to feed. I have seen many instances where males often do not even get to feed until the females have moved off from the site! Females rarely have to use extreme forms of aggression to maintain their position as top boss. Instead, young males seem to learn the pecking order as they undergo puberty, a time during which all the females in the group continually remind them of their place by chasing them away from food, biting them, and clucking angrily when they get out of line.

This type of female authority over males is actually unusual as far as mammals go. In most mammalian species, males tend to be larger and physically stronger than females. Females do not often challenge male authority since physical confrontation would result in significant male advantage and potential bodily damage to the female or her babies. Disparity in strength between the sexes has to do with the way the mammalian body uses its energy supplies. Most energy in the female body goes to the task of raising babies…getting pregnant, supplying nourishment to the developing fetus, undergoing the physical birth, and spending months nourishing a growing infant, only to begin the process again after weaning the infant(s). Energy in the adult male body, on the other hand, goes towards anything that helps the male to find a mate. In many animals, this means males grow large and strong so that they can fight amongst each other for access to cute females! The simple advantage of physical power usually leads to males having priority over females when it comes to food and water sources and resting and sleeping sites.

However, growing big is costly! Just as bodybuilders cannot reach their large size without eating thousands of calories of protein a day, any male animal has to be able to get enough calories, vitamins, and minerals on a regular basis to grow large bodies. Are you surprised to know that in most animals with female dominance (including lemurs), males and females  are similar in body size, with males only slightly larger (if at all) than females?!? How can this be explained? There are several theories, one of the most well-known being that when food is extremely limited, male and female body sizes tend to be more equalized, simply because there isn’t enough available energy around for males to “get pumped.” Most available food in the territory goes to female’s energy requirements for raising babies, and it makes sense that natural selection would favor a situation where a female gets first dibs on the quality food since survival of the species is dependent on her ability to raise offspring.

Several other lemur species also have female dominated societies, and various primate species such as bonobos, squirrel monkeys, patas monkeys, gibbons, bush babies, lorises, sifakas, indrids, and owl monkeys have systems where females can be the boss or at least have equal opportunity to compete with males for resources. What about humans, you may ask? Stay tuned for future posting on the power of the female in human societies.