The Primate Species: Our Closest Relatives

March 18, 2020
Because only a relatively small number of primates live inside protected areas, populations outside protected areas are declining rapidly.

The primate species is an order of mammals which includes humans. It’s also a category with a wide variety of species and sizes. For instance, the lightweight lemur mouse weighing 30 grams compared to the massive gorilla at more than 400 pounds. 

This group of animals is characterized, among other things, by possessing five fingers on their hands and feet. They also have clavicles, binocular vision and eye sockets surrounded by bone. The vast majority of species have nails instead of claws, opposable thumbs, and color vision.

Unfortunately, it’s also a very threatened and endangered group. Experts say that as much as 60% of primates could disappear in 25 years, all of them because of one single species of primate: the human species.

“Wet-nosed” primates

Strepsyrines, whose name means ‘curved nose’, are our most distant cousins in the evolutionary scale. They have wet noses as their sense of smell is still one of their most important physical senses.

A long-nosed monkey.
Source: Charlesjsharp

More than 100 species of lemur belong to this group and are located on the island of Madagascar. These animals have very particular vocalizations and a very surprising olfactory communication system. Among them is the famous and characteristic ringed-tail lemur (lemur catta).

We can also find loris and lesser bushbabies among the strepsirrhines, many of which are nocturnal primates. The different species of loris are endangered due to illegal trafficking in order to be sold as pets.

“Dry-nosed” primates

The rest of the primate species are known as “haplorhines” (Greek for ‘simple nose’). These primates developed an upper lip that replaces the rhinarium and isn’t connected to the nose or gum. Thus, this allows the appearance of recognizable faces and a large range of facial expressions in many of them.

Within this group are the tarsiers, a sub-group of primates with large eyes, elongated feet, and small bodies. In addition, their habitat lies in Indonesia, where people consider them to be diabolic animals.

Besides the tarsiers, the haplorhine group also contains the “simians”. Scientists divide simians into the old world monkeys and new world monkeys.

New World Monkeys

All the primates in this group live in Central and South America. In this group of monkeys, we’ll find those that possess prehensile tails. This is to say, they developed muscles in their tails that allow them to use them as a fifth limb (climbing, grabbing).

This prehensile tail not only allows these primates to hang from trees, but they can also pick up objects and scratch themselves. Moreover, their tails possess a great number of nerves, so we could consider them as a real extra limb. An example of this ability is the capuchin monkey.

This group of primates feeds mostly on fruits, and they have a flattened snout with lateral nostrils. These primates live up in the trees. Thus, deforestation greatly affects their habitats by destroying them.

We can also find marmosets in this group, which are some of the smallest primates. The pygmy marmoset weighs little more than 100 grams (4 oz). The group also includes howler monkeys, night monkeys, and spider monkeys.

The term prehensile means “able to grasp” (from the Latin prehendere, to take hold of, to grasp).

Old World Monkeys

Old world monkeys are simian that inhabit the African and Asian continents. The human species is within this group. Moreover, they’re also called catarrhini or catarrhine monkeys, which means ‘downward nose’. In addition, they don’t have prehensile tails and usually possess calluses on their buttocks.

The human species is among the hominids, which we’ll cover next. Most of the catarrhines belong to a large group called Cercopithecidae and have among their ranks baboons, macaques, vervet monkeys, and colobus.

The largest primate of them all is the baboon, which can weigh up to 110 pounds. However, there are also small species such as the talapoins, which can barely weigh around 2 pounds.

Hominids

We’ve arrived at the group of tailless primates, where we find our own species next to the gibbons. This is a very particular primate species that move by brachiation. This means they can swing between branches thanks to their long arms.

A shot of a walking chimpanzee.
Source: Carlos Octavio Uranga

The rest of the hominids are the so-called “great apes”. We share this group with gorillas, chimpanzees, bonobos and orangutans.

Most of them have their homes in Africa and, in fact, gorillas, chimpanzees and bonobos can share habitat. However, the chances of this happening are increasingly remote. Bonobos and chimpanzees are very similar physically but have radically different cultures and social behaviors.

The hominid group is famous for possessing the highest cognitive abilities among primates. Many members of the species within the hominids have been able to communicate with humans through sign language and perform burial-like behaviors or rituals.

The primate species: Currently endangered

Unfortunately, experts have also claimed this is an endangered animal group. As we mentioned before, 60% of primates could disappear in 25 years. The consequent increase in rarity raises the price of primate meat, making it more worthwhile for poachers to risk encroaching into protected areas to hunt.

Their main threat is one of the species among their own family: the human species.