23.4a – The New World Monkeys

Out with the old, in with the new. (Common squirrel monkey photo by Geoff Gallice)

A whole new world! A dazzling place you’ve never been! Or so goes the song, but if you’ve ever been to the Americas, North or South, you actually have been there.

Here at last we come to the sorts of animals we imagine when we think of primates — the monkeys. And let me tell you, there are a lot of different monkeys out there. Most of the warm places in the world are crammed full of them. But one type of monkey is not quite like another. Scientists who work on these sorts of things have divided monkeys into two major groups — the old world monkeys, those that evolved in Africa and Asia; and the new world monkeys, those that evolved in central and South America.

The two groups split apart about 40 million years ago, but the curious thing is how that came to happen. After all, 40 million years ago there was no known connection between South America and Africa or Asia. We know that monkeys originally developed in the old world, so how did they come to be in the new?

The obvious thought is that they crossed the land bridge that once existed between Russia and Alaska, the same way humans eventually did, but we don’t think that’s what happened. There is absolutely zero fossil evidence to suggest that monkeys ever moved through North America or Siberia. And besides, North and South America were not yet connected, and wouldn’t be for tens of millions of years, so if monkeys had come through North America they would have been forced to stay there for a long time. As far as we know, that’s not what happened.

But there’s another way they could have made the journey. We have no way to know for certain, but the idea is that those ancient monkey pioneers that made the trip to South America to become a new type of monkey actually came from Africa, and crossed the Atlantic Ocean.

Now the Atlantic Ocean is very big, so I understand if you’re skeptical. It’s not as though the monkeys of 40 million years ago could build boats. But remember that South America and Africa are moving apart from one another, which means that the Atlantic was quite a bit smaller back then. It was still, however, a very formidable stretch of ocean, on the order of a thousand miles wide, if not wider.

The current theory goes that there existed at that time a number of islands between Africa and South America, stretching across that growing ocean. This is certainly possible, and the ocean levels of the world were a bit lower back then as well, so there may have been islands. The monkeys may have more or less accidentally crossed them over the course of many thousands of years, populations swept westward on floating debris and material with the currents (which were also different then than they are today).

So it came to be that monkeys, those adaptable, adorable, terrible creatures, set foot on a brave new world and took to the great jungles of South and central America. But what makes a new world monkey special, besides its geographic location?

Is it the fabulous whiskers? (Emperor tamarin photo by Brocken Inaglory)

New world monkeys are typically a little smaller than their old world counterparts, but the nose is where it’s at. Just as we split wet-nosed primates apart form dry-nosed primates, monkeys too are divided by what’s around their nostrils. New world monkeys have flatter, more narrow noses than the old world variety, and their nostrils face to the side instead of down or straight ahead. The new world monkeys also have prehensile, grasping tails, while the old world monkeys are stuck with tails that can’t grasp a thing. To balance this out, most new world monkeys do not have opposable thumbs, either, while the old world monkeys — and by common evolutionary ancestry, us — all have that useful trait.

There are five families in the new world monkey group, and we will examine each of them in their turn. Among them we will find monkeys that swing, monkeys that howl, and the smallest monkey in the world. The new world monkeys are unconscionably addicted to trees, and they show it in some of their names. We’ll have squirrel monkeys, owl monkeys, spider monkeys, and more. But enough with the introduction. It’s time to monkey around.


23.3a – The Tarsier

Eyes on the prize. (Philippine Tarsier photo by Kok Leng Yeo)

If you break the primate tree into its two most basic divisions, all of the primates we’ve looked at so far — the lemurs, the loris, and the galago — belong to one group, and all of the primates still to come belong to the other. That former group, with the lemurs and such, is called strepsirrhine, and they are the wet-nosed primates. All of the others are in a group called haplorhine, and they are the dry-nosed primates.

There are a few other differences between them besides the dampness of their noses. The lemur group, as with most mammals, can make its own Vitamin C within its body, for example, which means they have no need to include citrus fruit or some other source in their diet; but the dry-nosed primates, which includes humans, lack this ability. To make up for it, the dry-nosed primates have much larger brains in proportion to their bodies.

The divide between these two groups took place approximately 63 million years ago. The first type of animal to separate from the rest of the dry-nosed primates — at least among those that survive today — were the tarsiers. In fact, they are such an old type of dry-nosed primate that even today some scientists debate which of the two groups they belong to.

But what is a tarsier? There are about ten species of tarsier, give or take a few we haven’t fully settled on yet, and they are small, strange-looking primates that look either very cute or nightmarishly alien, depending on your frame of mind.

The reason for this is their enormous eyes. I don’t want you to think I’m being hyperbolic when I say “enormous”. In absolute terms, certainly, a small monkey can only have eyes that are so big, but the tarsier stretches the bounds of relativity. Each of its eyes — not both together, but each separate — is as big as the animal’s brain. These are the largest eyes relative to body size in the entire mammal world. They look like tiny, big-eyed gremlins.

But you can’t judge a book by its cover, I can hear you saying. Just because it looks a little strange doesn’t mean it’s anything to be afraid of, right? It’s basically a tiny monkey, isn’t it? And tiny monkeys are cute and curious and wonderful, aren’t they?

… aren’t they? (Philippine Tarsier photo by Serafin “Jun” Ramos, Jr)

The first thing to remember about a tarsier is that no, it is not a monkey at all. It is an early, primitive form of the type of primate that eventually produced monkeys. One of the key differences, besides the outward appearance, is that the tarsiers are the only one hundred percent carnivorous primates alive in the world today. They don’t seek out fruit or vegetable matter. They eat nothing but the crunchy, squirming flesh of other living beings, including snakes, bats, birds, and lots of insects. Which I suppose means we’re back to them being essentially gremlins.

But in truth they are shy creatures, and certainly not dangerous. They’re nocturnal and live in and around the jungle islands of southeast Asia, such as the Philippines, Indonesia, and Borneo. Many of them are threatened or endangered due to habitat loss, human hunting, and predation by feral cats.

Sometimes they are kept as pets by well-meaning humans. Keeping a wild animal as a pet is almost never a good idea, but with the tarsier it’s an even worse plan. The tarsier is one of the rare animals that does significantly worse in captivity than it does living in the wild. In the wild, with an abundant food supply and a thick jungle in which to move around, a tarsier can expect to live for 24 years. In captivity, they last only 12 years at most, and can die as young as two years old. In human terms, this is the equivalent of taking a person who can expect to live to the age of 72 and placing him in an environment where he may fade away and die by the age of 6. That’s a poor thing to do to an animal, no matter how cute they look.

Some tarsiers are even known to commit suicide in captivity. They don’t actually kill themselves on purpose, but the stress of lights, unfamiliar noises, and human handling can seriously frighten a shy tarsier, and they will sometimes react to this stress by smacking their own heads against objects in their enclosure. Since they have fairly thin skulls, this can cause death.

Fortunately it’s illegal to sell or trade many types of tarsiers. Conservation efforts in some countries seek to establish safe refuges for the animals, but their future remains uncertain.

Tarsier distribution

Tarsier distribution

23.2b – The Galago

One in the hand is worth two in the bush. (Brown greater galago photo by buecherfresser)

Something in the dark jungle is crying, and it sounds an awful lot like a human baby.

If you’ve never heard of a galago (pronounced guh-LAY-go), don’t despair. Most people don’t know these animals by their official name, but some people have heard the more common term — bushbabies.

Along with lemurs and lorisids, galagos are one of the few remaining primitive primates in the world today. Primitive in this sense means that they are an older type of primate that developed before more modern forms, such as monkeys and apes. But while the lemurs have constrained themselves to Madagascar, and while the lorisids are slow and dropping in number, the galagos are living strong in Africa.

Also known as nagapies, which means “little night monkeys”, galagos are found all over central and southern Africa. There are about twenty different species, all of them nocturnal. It’s believed that the galagos evolved to be nocturnal so that they did not have to compete directly with the faster, more modern monkeys, who do their business in daylight.

But the galagos are no slouches, no slow-moving lorisids. They are quick on their feet and have long tails to give them balance as they jump through the trees. They have strong night vision, good hearing, and are so nimble they can catch flying insects out of the air. Their cries are said to resemble those of a human baby, an unnerving prospect in the jungle at night.

In addition to their night vision, galagos use urine, of all things, to help them scramble through the trees in the darkness. A galago that moves through the trees will mark its path with urine on the branches, and other galagos can smell this so acutely that they can jump right onto the branch even if they can’t see it. Imagine a world where humans marked important things, such as doorways, their vehicles, and favorite restaurants, with urine so they could find them again. On second thought, please don’t imagine that.

“That’s a nice couch. But I’ll tell you what. I’ve been drinking water all day, and I know how to make that couch even nicer.” (Senegal bushbaby photo by OpenCage)

A galago is also a fantastic jumper. It has very strong, elastic legs, and scientists figure that a galago is, proportionally, at least six times better at jumping than a frog. These animals are tiny, but they can jump six feet straight in the air. Don’t give one guff; it could jump straight for your nose.

The social life of a galago revolves around the females. Females control family groups consisting of themselves, their offspring, and sometimes other female relatives, maintaining a specific territory. Males are forced to leave these groups when they grow up. The strongest males form their own territories that overlap female territories, but they are not allowed to live with the females. Weaker males form bachelor groups and hang out, possibly playing Call of Duty and calling each other “bro”.

23.2a – The Slow Loris

Slow and nervous — a toxic combination. (Sunda slow loris photo by David Haring)

In the leafy, tropical forests of southeast Asia, you may happen upon a slow loris — but you would probably never know it.

The slow loris is part of a group known as the lorisids. The ten species of lorisids live in southeast Asia and central Africa, and they include the slender loris, the potto, and the angwantibo. In general they are mid- to small-sized primates with large eyes and very short tails, if they have any tail at all.

But the slow loris is the most interesting of the lot, for one very obvious reason. It is the only type of primate in the world that is venomous.

This trait is extremely rare among mammals. The slow loris does not produce toxins directly in its mouth, but has a rather ingenious system in place. It produces a compound from a gland on its arm, and when it licks this gland, the compound mixes with its saliva to form a toxin inside the mouth. That sounds somewhat foolish and dangerous, but the toxin doesn’t harm the loris — it only harms things the loris bites.

But a slow loris is not an aggressive creature; its bite is used only in self-defense. The animal also licks the toxin into the fur of its young, so that predators will be less likely to look upon a slow loris as a tasty snack.

These precautions are important because of how the slow loris moves — as you might have guessed from the name, it moves very slowly. If you are fortunate enough to spot a slow loris in the jungle, chances are very good that it will be creeping along at a snail’s pace, or not moving at all. It has strong hands that can clamp onto a branch so tightly that it takes a serious effort to make them let go, so they have no problem just hanging around and not moving at all, sloth-like.

But what we didn’t understand about this is that the slow loris is only slow when we’re watching it. This is an interesting effect in science — the notion that a thing might change simply because it is being observed, which in turn means that any conclusions we draw from our observations may be false.

The thing is, the slow loris, and indeed all of the lorisids, move slowly when they feel there might be danger nearby, and in their eyes anything that moves is a potential danger. In their dense, leafy homes, moving slowly helps them blend in and avoid being spotted and eaten.

But put a loris in an environment where it feels safe, such as darkness, and it will move about normally, yet it wasn’t until we had the proper technology that we understood that. So we named it the slow loris, and the name has stuck. However, there is still one difference between a loris’s normal movement and what you would expect from a primate — the slow loris does not jump. At all. It has no future in basketball.

Slow loris species are either vulnerable or endangered, for two reasons. One is a reason that threatens many species in southeast Asia, namely habitat destruction from deforestation to clear land for human use or consumption. The second reason is the wildlife trade. Slow lorises are popular as exotic pets, but this is very bad for the species. In order for a slow loris to become a human pet, its teeth are usually removed so that it cannot inflict its toxic bite (which is painful but not fatal to humans). Many of these animals eventually die from infection or malnutrition after having their teeth removed.

A baby slow loris has its teeth removed with nail clippers before it becomes a pet. Yes, it’s just as bad as it looks. (Photo by International Animal Rescue)

People like slow lorises so much because they are docile, agreeable pets, but you must remember — the slow loris acts slow and docile only when it is feeling threatened. The cuter it looks, the more it fears for its life. Life as a pet is not good for a slow loris, but people all over the world own them. Since 2007 it has been completely illegal in every country in the world to import a slow loris, but exotic pet traders still find ways to smuggle them into other countries and sell them, often to people who don’t know that they are illegal.

To make a long story short, don’t ever buy a slow loris as a pet. Most die in captivity, and live unhappy existences up until they do, but so long as people are willing to pay for them because they are cute, there will be those who circumvent the law to take them from the wild and sell them.

23.1f – The Sportive Lemurs

Loner lemurs. (Sahamalaza sportive lemur photo by R. Hilgartner)

At long last we have scrambled across the entire island nation of Madagascar, we have scoured its corners and learned about the lemurs, that remarkable, cooperative, sometimes strange, often endangered branch of the primate group. Only one family of lemurs remains unaccounted for — the sportive lemurs.

While most of the lemurs we’ve seen so far have been generally kind, sportive lemurs do not like members of their own species and gender. They are nocturnal lemurs, about a foot in length with a tail that goes on for another foot, and they live alone. Males and females have their own territory, and these may overlap, but no male is allowed to overlap his territory with another male, and similarly no female is allowed to overlap her territory with another female. If this happens, whoever was there first will get very angry, rather violent, and there will be a fight.

Like many lemurs, sportive lemurs stick to the trees when they can, but when drawn to the ground they move about in hops, more like a kangaroo than an indriid. Sportive lemurs are on the whole not as active as the other lemurs. They rest and conserve energy during the day, and when they come out at night, though they are very good climbers and jumpers, they keep their activity rate to a reasonable level and don’t make a fuss. A sportive lemur would much rather pass by unnoticed if it can.

Sometimes it’s hard to tell a sportive lemur apart from a woolly lemur, or even a large dwarf lemur. The trick is in the ears. Sportive lemurs tend to have big ears. If you see a lemur with big round ears sticking out from its head, you’ve probably got a sportive lemur situation on your hands. Let the poor fellow pass on into the night in peace.

There is something of a funny trend in recent animal discoveries, and the sportive lemurs give me a chance to touch on it. Once upon a time animals were named almost exclusively for their physical characteristics. If a lemur has white feet, it becomes the white-footed sportive lemur. If it has small teeth, it becomes the small-toothed sportive lemur. That sort of thing. Other times the animal is named for its location in a given area — if it’s found to the north of that type of animal’s range, perhaps it might be named the northern sportive lemur, for example. This is all relatively straightforward.

As you get away from the better-known animals in a group, particularly in a group with a lot of different species, you start to find animals that are named after a person, often the person who discovered it, but sometimes as an homage to someone who did a lot of work with that type of animal. At times this leads to a straightforward name — there is Hubbard’s Sportive Lemur, for example, or Scott’s Sportive Lemur, even Otto’s Sportive Lemur. Other times it leads to names that have a bit more flourish to them — for example, Flaurete’s Sportive Lemur, or Randrianasolo’s Sportive Lemur.

And sometimes, once in a great while, they name a lemur after something that doesn’t even sound like it should belong in the realm of animal names. When a research team discovered a new type of lemur after twelve years of work, they decided to name the lemur after their sponsor, the Association Europeenne pour l’Etude et la Conservation des Lemuriens (The European Association for the Study and Conservation of Lemurs). And thus, AEECL’s sportive lemur was born. You are supposed to pronounce each letter separately, like an acronym. And yes, that is the animal’s official name. I am certain that the AEECL has done fantastic work with lemurs and deserves every accolade they can receive; it’s only that my sense of aesthetics wishes they could have found a better-sounding name for their lemur.

“Wait, my scientific name is Lepilemur aeeclis? You guys have got to be kidding me.” (AEECL’s sportive lemur photo by U. Thalmann)

23.1e – The Indriids

The lemurs of hip-hop. (Diademed Sifaka photo by Tom Junek)

In the mad, mad world of lemurs in Madagascar, we’ve looked at the tiny dwarf lemurs, the bizarre aye-aye, and the typical lemurids, but those aren’t all. There are even more types of lemurs sharing the treetops on this crowded island.

There are 19 different species of indriids, and we can roughly divide them into three types — the woolly lemur, the sifaka, and the indri. The basic thing that sets indriids apart from the other lemurs is that they are not very good at moving on the ground. An indriids hind legs are very much longer than their arms, and this means that they cannot move around on all fours, as the lemurids do.

To visualize their dilemma, try it yourself, for humans suffer the same problem. Try to move not on your hands and knees, but on your hands and feet. You will quickly see why indriids don’t really like to move around this way. But unfortunately for the indriids, they aren’t able to walk upright in the manner of humans either. What’s a poor indriid to do?

Well, for the most part they stick to the trees, where they are incredibly agile and can jump great distances with their long, powerful legs. But they don’t hesitate to use the ground when they have to. What they do is stand up tall on their hind legs, stick their arms in the air for balance, and hop.

The sifakas are the best at this, or at least the most interesting to watch. They take great, sideways leaps across the ground in order to cover distance as quickly as possible. I cannot embed videos on this blog, but if you would like to click on the following link it will open a new window in which you can see the sifaka doing its wonderful thing.


The woolly lemurs are much like the sifakas, but the indri is the odd animal in the group — every family has at least one. The indri is one of the largest of all lemurs, measuring up to two and a half feet, not including its tail. The reason it’s not fair to include the tail is that the indri, well, does not really have one.

Every other type of lemur on the entire island has a magnificent tail, sometimes longer than the entire rest of its body. These tails are used for balance and sometimes for stink-fights, as we saw with the lemurids. But the indri has only a tiny knob of a tail, hardly even worthy of the name. Despite this balance handicap it still climbs and jumps around in the trees as well as anything, and still does the side-stepping hop-along movement on the ground.

No tail? No problem. (Indri photo by Erik Patel)

One interesting thing about the indri is that it is entirely monogamous. It is one of those rare species that mates for life; a mating pair will stay together and raise multiple generations of offspring — one at a time — until one of them dies, and will only then move on to seek a new partner.

Indris are very vocal, and different groups will “sing” to one another. Their songs can last several minutes at a time, and when one group is finished singing another group nearby may take up the tune. We aren’t entirely certain why they do it, but it may simply be a means of letting all the other indris know where they are. There doesn’t seem to be any one reason why they do it, however. Indris will sing after some loud noise has disturbed them, will sing to respond to other groups singing or even to other types of lemurs making noise, and sometimes will sing seemingly just because they want to. A group of indris might sing up to seven times a day, and their songs resemble in some ways those of humpback whales.

To hear what an indri’s song sounds like, give this link a gander: https://www.youtube.com/watch?v=4d3vFI5UpIc

In some ways the indri is one of the most advanced lemurs, and the natives of Madagascar treat it as a sacred animal. In local mythology, the indris and humans have close relationships. One myth tells the story of two brothers, long ago. One brother decided to leave the forest and cultivate the land, and he became the first human; the other brother stayed in the forest and the trees, and became the first indri. The myth says that the indris sing as a form of mourning for their long-lost brothers who left the forest.

And if that isn’t wonderful enough, the Malagasy people also believe that the indris worship the sun, much as a human would worship a god. There is a surprising amount of truth to this idea. Every morning when the sun rises, an indri will face it and sit cross-legged, back straight, palms in its lap or facing up, and watch the sun with eyes half-closed, the very image of a human in meditation. It is not believed by scientists that indris have enough social organization to actually be worshiping the sun, of course; it is most likely only a coincidental body posture and a desire to warm up in the morning. But it is wonderful all the same, and these strange, knob-tailed lemurs have a lot of surprisingly human-like features for being so far removed from us in the primate group.

Unfortunately, the indri is also endangered, highly threatened by habitat destruction. They do not survive in captivity, and have never been successfully bred, which means that without adequate protection this wonderful creature, and indeed many of the indriids, may someday soon leave our world forever. It is unfortunate that Madagascar combines at the same time such a rich diversity of species and such a lack of environmental protection, due to the material needs of a poverty-stricken society.

23.1d – The Lemurids

Life in lemur-land. (Ring-tailed lemur photo by Alex Dunkel)

We have met the tiny dwarf lemurs and the mysterious aye-aye, but they are not the only lemurs in the forests of Madagascar — not by a long shot. Even on such a small island, the lemurs have split into so many different species and types that it is a wonder they all get along and have not reduced their diversity through competition, with a smaller number of stronger lemur species coming out on top. Instead, lemurs have each found their own niche and area on the island, and none has dominated the others. However, when it comes to the popular conception of a lemur, the lemurid group is what most people think of.

Lemurids are generally one to two feet long, with the tail an extra length beyond that. They are more capable and willing to move about on the ground than the other lemurs we’ve discussed, even though their back legs are longer than their front legs, giving them a wobbly, hoppy sort of gait when they walk on all fours on land.

They are, as you might expect, much more at home and agile in the trees. With long tails for balance, grasping fingers, and strong vision, they can fly about through the branches and will regularly leap more than ten feet from one tree to the next.

The lemurids are more social than the other lemurs we’ve mentioned as well. They live in groups of up to thirty individual lemurs, and in some species they form long-lasting groups with stable hierarchies, like large families.

The most prominent member of the lemurid group is also the animal that most people think of when they imagine a lemur — it is the ring-tailed lemur. It is perhaps the best-known and most recognized lemur in the world, even though it only lives in one corner of Madagascar. The reason everyone loves the ring-tailed lemur is, of course, for its long, black-and-white striped tail, which is two feet long and is actually longer than the entire rest of its body.

Unlike the dwarf lemurs and the aye-aye, the ring-tailed lemur does its business during the day, not at night. It lives in large groups where the females have social dominance (which is true for most lemurs), and these lemurs love to do things together. They can be found huddling together for warmth or just for fun, and they like to group up to sunbathe, turning their white underbellies to the sky to soak up some rays.

Like a boss. (Photo by Keven Law)

Despite their relatively small brain, ring-tailed lemurs display some measures of intelligence. They are highly vocal and social, and can understand basic arithmetic and tool use. They don’t use tools in the wild, but they quickly pick up the knack when trained and are able to select tools based on how well they will do the job.

Though they are highly vocal and enjoy chattering at one another, ring-tailed lemurs use scents for a lot of their communication. The males in particular are covered with scent glands of various types, and they will not hesitate to stink you up with some sort of scent from almost any part of their body. They use these scents to mark territory, to maintain their group hierarchies, and for mating purposes.

The most wonderful use of scent among ring-tailed lemurs is stink fighting. For this, males will coat their tails with smelly liquid from their glands and will then wave their stinky tails at other males, often ones who are their rivals for mates. Boys will be boys, whatever the species. Males will also wave their smelly tails at females as a means of attraction, but the females usually respond by punching or biting the male, because who on earth really wants a stinky tail in their face?

And as a random closing fact about ring-tailed lemurs, the females have four nipples, but only two of them work. Why? Impossible to say.

Contrasted with the ring-tailed lemur is the common brown lemur, also a lemurid. This particular lemur lives in groups, but does not have hierarchies at all. The females are still dominant, but members can come and go from the groups as they please, and no one is really the boss. When there are disagreements and fights, both parties reconcile their differences afterward and are nice to one another again with no hard feelings.

“Right, mate. I’m sure you didn’t mean it.” (Common brown lemur photo by David Dennis)

Combined with the fact that so many different types of lemurs co-exist without trouble on a small island, sometimes it seems as if lemurs got the whole social thing right, and it’s humans who have somehow messed it up and gone off course.

And there are many other lemurs in the lemurid group as well, all being social, getting along with others, and having a happy time on their island except for the fact that many of them are endangered due to human activity. They range from the endangered but vain red ruffed lemur (you would spend a lot of time grooming yourself as well if you had such a luxurious coat of red hair), to the critically endangered black-and-white ruffed lemur who roar and shriek in groups that form a sort of synchronized chorus, to the small and funny-looking bamboo lemurs.

The greater bamboo lemur is one of the world’s most endangered primates. Once believed extinct, a new population was discovered in 1986, but there are believed to be only between 60 and 160 remaining. There is every chance that they will not survive, because they are not protected in their habitat, more of which is destroyed all the time. This is unrelated to the fact that they are one of the few male-dominant lemur species, but you have to admit, it looks suspicious.