18. Primates have bigger brains than other mammals.
Of course, we’ve already discussed some of the other physical differences among primates themselves, but between primates and other mammals, there are some significant differences as well. One of the most critical differences in their brains. Primates have larger-than-average brains proportionally to the rest of the body, and larger-than-average skulls protect their gray matter. Their brain size allows them to process information effectively and utilize their thumbs, tails, and binocular vision. What’s that? Binocular vision? Oh, sure. All living primates have forward-facing eyes, which gives us a wide field of binocular vision. In comparison, species with laterally facing eyes allow them monocular vision. A large binocular visual field enhances depth perception at relatively close ranges (take that, sharks!).
You may be thinking that a big brain is not everything, and if so, you are exactly right. Elephants have enormous brains that weigh about 11 pounds, the largest of any land creature. However, taken as a ratio against their entire body mass, their brains are pretty small. Sperm whales have brains that weigh a whopping 18 pounds, and orcas have brains that weigh between 13 and 15 pounds. Measuring the accurate intelligence of these creatures is difficult because they live underwater, often in the frigid Arctic and Antarctic regions. Nevertheless, what matters is not so much the size of the brain as to how the animal or person actually uses it. Moreover, primates have proven that they can use their large brains to a pretty significant extent.
17. Mother chimpanzees often develop lifelong relationships with their offspring.
Like humans, mother chimpanzees spend significant amounts of time and resources raising their offspring into healthy adults. Primatologists have documented strong relationships between mothers and their adult son chimpanzees. Nevertheless, only recently they discovered that these relationships were considered the norm rather than a heartwarming aberration. With chimpanzees, the females find a new group to mate into when they have reached maturity. Thus, it makes sense that mothers and sons stay close. In fact, some mother and son bonds are more like best friend relationships! That’s not all, however. Though chimps can be seen as friendly and lighthearted, they can also band together when support is needed.
Much like humans, primates tend to give birth to one infant at a time rather than the large litter common to other species. This allows mothers to focus on their one infant the way human mothers do. They provide round-the-clock care for an entire year. The mothers also nurse their offspring for up to five years! In one chimpanzee’s case of a stillborn pregnancy, her community offered her their hands to hold and sat around her for comfort. This physical display of grief proves chimps, at least in captivity, can console each other. They provide affection through intense emotional times.
16. Wild chimps use medicinal plants to treat themselves for illness and injury.
You might scoff at the idea of herbal medicine, but don’t completely write it off just yet! Chimpanzees in the wild practice herbal medicine, and the plant leaves they rely on have been found to contain powerful antibiotics and even anti-tumor agents! When chimps are ill, they seek out leaves with potent bacteria-killing substances. The Aspilia bushes the chimps seek out have a red oil called thiarubrine-A. Thiarubrine-A is a powerful antibiotic that can kill disease-causing bacteria in concentrations of less than one part per million! When a chimp eats the leaves, the chemical contents of these leaves are released into their digestive tract. If that’s not interesting enough, there’s more.
There are four species of Aspilia, but chimps only eat the leaves of three species. Scientists speculated that African peoples might already know the plant’s usefulness, so researchers visited researchers in East Africa. They found records that indicated that Africans did see the plant’s value and only used the same three species that the chimps did! It turns out the plant that chimps eat when they all actually hold promise for humans, as it contains a powerful antibiotic that kills fungi, bacteria, and nematodes. Perhaps chimps and other primates can continue showing us what plants we should be using to develop new and more effective medications.
Sexual dimorphism is the difference in physiological makeup between sexes of the same species. It includes differences in size, coloration, or body structure between the male and females of a species. For example, the male elk grow antlers while the female elk does not. Male birds of paradise are noted for their elaborate plumage and complex mating dances, usually to attract the females, while the females are far less ornate. We see sexual dimorphism in humans, as females tend to be shorter, have more fat tissue (thanks to female hormones), and have wider hips. Males tend to have more facial and body hair, higher muscle mass (thanks to male hormones), and deeper voices. Furthermore, if you have ever noticed that your male dog or male cat behaves differently than their female counterparts, you are not imagining anything.
Male primates are much bigger, more dangerous, and more aggressive than females. Some primate species even have differently colored fur, craniofacial structure, skeletal dimensions, and more prominent teeth. Lowland gorillas show the greatest dimorphism, with a male to female body weight ratio of 2.37. Orangutans also reveal a relatively high dimorphism ratio: 2.23. The sexual dimorphism extends to gender roles, as some groups of monkeys and other primates are led by alpha males who fight their way to the top. They can even have harems with multiple “mistresses.” At the same time, mothers caring for infants are so busy fulfilling the maternal duties that they have little opportunity to improve their social rank.
Most primates seek out the protection and social interaction of an extended community, including male and female-dominated clans, monogamous pairs, and even nuclear families, not at all dissimilar to human societies. It is not all fun and games; primate communities also face bullying, murder, and straight-up murdering newborn babies! Dominant golden lion tamarin males lead groups of up to 20 members. The leader is responsible for protecting the group and the territory they live in and preventing possible attacks from predators. He is also responsible for reproducing with females, the lucky fellow! Woolly spider monkeys are native to Brazil’s jungles and are incredibly peaceful. They share close social bonds with their species and tend to be non-hierarchical. Their resources are shared equally, and they live a reasonably egalitarian life!
That is not quite so much with macaque monkeys. Disneynature did a documentary about macaque monkeys entitled Monkey Kingdom, and it featured an outcast monkey, Maya, who lives at the bottom of her group’s social order. She is frequently tormented by other monkeys who see her as less worthy than them, and she cannot speak up for fear of being cast out of the group and left to die. There is no question that primates have complex social lives that look strikingly similar to those of humans. Whether they are egalitarian or socially striated is probably based on the particular species, and both group structures reflect human societies.
As humans, we use tools so constantly that we hardly even stop to think about what we are doing. Tools refer to more than the hammer, screwdriver, and wrenches that we tend to call “tools,” or even the power drills and chain saws that are labeled as “power tools.” Tools are anything we use to make our lives easier and can refer to walking canes, eyeglasses, even gadgets like computers and phones. Tools go so far back in our history as humans that you might say that one of the distinctive features of what makes us human is our use of tools.
The term “tool” can encompass almost anything in the animal kingdom, but primates seem to use tools more than any other animal type. They use sticks, stones, and leaves for a multitude of tasks like cleaning their ears or scraping their nails. Of course, using tools isn’t limited to primates; for example, birds have been observed using branches to pry insects from trees. Muriqui monkeys are often seen making bridges with their bodies to help their babies cross trees. Chimpanzees are the most intelligent of all primates, as they can imitate human gestures and even learn sign language.
12. Primates develop at a slower rate than other mammals.
As we’ve mentioned, primates have larger brains than other animals. Though that can indicate their advanced intelligence, they also require additional time to catch up to their extra-big brain. Newborn primates cannot survive with the help of one or both of their parents and even the extended community, which makes it all the more necessary to have a bond with their society. And they are not alone; we as humans have relatively large brains compared to body mass, and we take a very long time to develop. Consider that many animals leave their mothers at birth, yet we have an 18-year period called “childhood” in which parents are expected to care for their still-developing young. Moreover, the brain is not fully developed until a person is in their twenties.
Given the relationship between humans and primates, one should not be surprised that primates also develop slowly. They have long childhoods in which they are cared for by their mothers, who nurse them for as long as the first five years of life! While animals who have large litters or lay dozens (if not hundreds) of eggs cannot care for all of their young, primates usually have just one infant at a time and dedicate their lives to caring for them. Instead of the rapid development many other animals experience, primates have close relationships with their mothers and strong social bonds.
You may be all too familiar with the idea of a chimpanzee eating a banana, and there is no question that chimpanzees, alongside other primates, eat a lot of fruit. Researchers who train monkeys generally give them fruit as a reward (similarly to how dog owners give treats as a reward for following commands). Most primates, however, are not strict vegetarians; they are omnivorous, feasting on whatever fruits, leaves, insects, small lizards, and even small mammals they can catch. Tarsiers are the only entirely carnivorous primates, while some lemurs, howler monkeys, and marmosets are complete vegetarians.
Unfortunately, some primates can find themselves as prey instead of predators. Lions, cougars, and jaguars often like to snack on our dear primates! Primates who live outside their groups are the most prone to becoming dinner to a larger animal, while those who remain inside their groups — even when they are at the bottom rung of the social ladder — have the best chance of staying alive. With many different members looking out for each other, they can spot a predator before an attack can be made. Some groups even have watchers who stand watch for predators while the others take a nap, enjoy a meal, or play with each other.
If you think back to your childhood, some of your favorite memories probably enjoy you playing, maybe on the playground, in a swimming pool, or with your favorite toy from the toy box. Furthermore, be honest with yourself, do you still enjoy playing? You probably play a board game with your kids or a round of cards with some friends. Primates enjoy playing; in fact, they are one of the most playful kinds of animals that scientists are aware of. Moreover, the purpose of play in primates seems to be very similar to that in humans: to help children learn social behaviors and other skills necessary for a meaningful and productive adulthood. In other words, the more we play, the stronger our brains become!
What does play look like for primates? Not all that different from what it looks like in children. Instead of swinging from the jungle gym, monkeys use their tails to play by hanging from the trees. They also like to turn their favorite adults into playsets (remember when your parents or grandparents used to give you “the claw”?), and some even play with their food! Researchers have taught monkeys and other primates to play games, though there is little chance that you would enjoy playing with them. Watching monkeys and other primates play can be truly amusing and may even make you want to get out to the playground yourself, no matter how old you are.
Did you ever play with a barrel of monkeys as a kid? The plastic “barrel” contained dozens of monkeys that could be linked together into a chain. The famous toymakers probably got the idea from the fact that a group of monkeys is called — wait for it — a barrel, though it can also be known as a troop. A barrel of monkeys can consist of a few dozen to over a hundred family members who look out for each other. Many other groups of primates, including gorillas, are also known as troops. A group of apes has a name that is quite fitting for the high intelligence level of the species, a shrewdness.
There is a popular misconception that a group of baboons is called a congress, but this assertion is false. The idea that members of congress are like baboons may be amusing to some, but baboons and the researchers who study them may take offense! These Old World monkeys are brilliant and live in groups that are known as troops. Because they are opportunistic eaters who taste fruits, vegetables, and meat, they often become pests to farmers in places where they thrive, especially in Africa. Some fans of The Lion King believe that the sagacious Rafiki is a baboon, and he is referred to as such in the movie, but baboons do not have tails, and Rafiki does. He is most likely a mandril monkey.
When we think about human intelligence, we are really thinking about something beyond the instinctual drive to behave in a certain way in given circumstances, such as searching for food when we are hungry. We are thinking about more complex behaviors, such as using language to communicate or using tools to accomplish a task. When we think about “smart” people, we think about people who are proficient in not just one area but many, someone who aces all subjects in school rather than someone who can only do math. And here’s the funny thing about human intelligence: it is not all that human. Many animals possess traits belonging to what we think of as human intelligence, and none more so than monkeys.
You may have noticed in your own life that what you eat does affect how much energy you have and, well, how you act in different situations. If you are hungry (and especially if you are hangry!), you may find that you are irritable and easily upset. Suppose you have been eating healthy food full of vitamins and minerals, especially if you are eating more plants than meat. You may find that you have more energy to get through your day. If you have been drinking soda and eating sweets, you will probably find that you are sluggish and unmotivated. Moreover, you should not be surprised, as diet plays a massive role in how well our bodies work from one day to the next.
Most primates live in jungles, where they can nimbly climb up trees and, for many, swing through the branches. That is not the case with Gelada monkeys, who only live in a mountainous area of Ethiopia. The region is primarily rocks and has very little plant life. These monkeys have developed unique adaptations, such as short and stubby hands, perfect for traversing their rocky terrain. Their rear ends also have fatty pads to sit comfortably on the rock rather than the soft jungle floor. Geladas graze for grasses and are the last surviving grazing primates, which used to be much more predominant, particularly in Africa.
Geladas form the largest troops of possibly any other primates, with the most populous numbering well over 1000. They are organized much like human society, with the basic building block of the family. Families of geladas generally consist of one or two males, up to 10 females, and their offspring. These families converge in multiple social layers to form the famously large troops. Unlike other species, gelada troops can grow to such a large number because they feet on abundant grasses and do not have to compete in a scarce environment. Sadly, their population has declined significantly in recent years due to human activity such as agricultural development. It is devastating the grasslands on which they rely.
You may generally think of societies, including animal ones, as being patriarchal, meaning that a male is the group leader. And many societies are, but mouse lemurs are one exception. The females lead their groups. Mouse lemurs are the smallest of all primates, measuring an average of just 27 centimeters from head to tail or less than one foot. Like all other lemurs, their natural environment is limited to the African island of Madagascar. They live in all kinds of forests in Madagascar. That includes arid to tropical humid to even forests that have been tampered with by humans. In fact, mouse lemurs have been found on old plantations.
These critters look like large mice, with large eyes, short and spiky ears, and brownish-gray fur. Yet you are unlikely to see one, even if you do trek out to Madagascar. Why? Because they are nocturnal, meaning they only go out at night. And keep in mind that getting out into the jungle after dark just may be the last decision that you ever make! Mouse lemurs are omnivores who enjoy energy-rich insects and small animals, alongside their diet of fruits, leaves, and other plant life. They frequently live in sympatry with other species. It means that they occupy the same space and frequently encounter the other. However, it is generally without the hostility common to predator and prey.
4. There are only about 1000 mountain gorillas left in the wild.
There are two types of gorillas, eastern and western, depending on which part of Africa they live. Mountain gorillas are a subspecies of eastern gorillas, and they are very endangered due to human activity destroying their natural habitats. Today, there are only about 1000 left in the wild, with a few living in captivity. Animals bred in captivity cannot be released into the wild because they have not developed the necessary skills to survive. For example, if they are used to humans feeding them, they have not developed the ability to forage for food and may starve very quickly if taken to the wild. They also would not have the protection of shrewdness because they did not grow up in one. Likewise, they do not have the social skills necessary to join one.
Like other primates, gorillas are extremely social and depend on their troops for protection. They even curl up together at night, with infants cuddling close to their mothers. Their shrewdnesses are small, only about ten each, so they frequently join other troops in adulthood to prevent inbreeding. What may surprise people is that human DNA is 98% similar to gorilla DNA, meaning that we are so closely related that we can actually spread our diseases to gorillas. They do not have the same immunity to those diseases as we do, so a simple cold could make a gorilla extremely ill.
Apes are large primates with no tail and generally have flat faces without a prominent snout. As you might guess, great apes are the largest kind of apes and include gorillas and orangutans. Gorillas can grow to over five feet tall and weigh nearly 500 pounds, and orangutans are not far behind. They are the largest primate that lives in the trees, and they can get to around 4.5 feet tall and weigh as much as 200 pounds. Their massively long arms can stretch as much as seven feet across! Their bodies are built so that they can stretch across long distances and eat with their feet.
Like other primates, orangutans are incredibly social and live in groups known as shrewdness. They have very long birth intervals of about seven to nine years due to how long mothers care for their young. Baby orangutans learn everything from their moms, including what foods to eat and how to swing from the trees. Until they reach those critical learning milestones, they ride around on mom’s back and eat what she feeds them. Males become fully mature around age 35 when they develop distinctive fatty flaps on their faces. They have been known to live upwards of 50 years in the wild, but they are severely endangered and face the genuine risk of extinction.
2. Primates have been around since the time of the dinosaurs.
Dinosaurs ruled the earth up until about 65 million years ago, until an event known as the KT impact, an asteroid collision that most likely happened around Mexico’s Yucatan Peninsula, caused them to become extinct. However, dinosaurs were far from the only animals that roamed the planet, and some tiny mammals lived during their reign. About the KT impact, a new kind of mammal evolved that scientists consider the first identifiable primate-like creature. It was known as Purgatorious, was about the size of a mouse, and maybe the ancestor of the primates that evolved during the later Cenozoic Era.
Genetic sequencing is something that biologists do to try to understand the genetic makeup of individuals are species. Researchers have used genetic sequencing to determine that the earliest primate may have actually lived 20 million years before Purgatorious. However, fossil evidence of this proto-primate has yet to be uncovered. Two similar creatures evolved around 10 million after Purgatorious that scientists identify as the first true primates. The first is known as Archicebus and lived in Asia, and the second was known as Plesiadapis and lived in North America and Europe. Archicebus and Plesiadapis were much more anatomically similar to today’s primates.
Madagascar is an island in the Indian Ocean off the coast of Africa. It is the fourth-largest island in the world and the only native habitat for lemurs. Lemurs are primates that look like monkeys. However, because their native habitat is an island, they evolved entirely independently of their genetic cousins. Humans arrived on Madagascar a mere 2000 years ago. At that point, there were enormous lemurs the size of gorillas. The larger lemurs went extinct due to human activity. Nevertheless, many kinds of smaller lemurs dominate the island they call home. Still, they are one of the world’s most endangered species. Lemurs face the imminent risk of extinction within the next few years.
There is a puzzling question as to how lemurs evolved on Madagascar, as it split off from the mainland of Africa about 160 million years ago. That was far before even the ancestors of Purgatorious had come into existence. So just how did they end up there? Scientists have a theory, of course. A few primates caught a ride on some driftwood, possibly fitted together like a raft. Lemurs traveled the 200-mile voyage to Madagascar within a matter of days. Because they had no predators, their numbers increased very rapidly. Lemurs developed unique adaptations that allowed them to survive and thrive. On the island of Madagascar, they proliferated and evolved into the lemurs that populate every terrestrial ecosystem on the island today.