Primate Taxonomy | Anthropology Optional for UPSC PDF Download

Introduction

Primates are a diverse group of animals that belong to the taxonomic order within the class Mammalia, which is a part of the phylum Vertebrata in the animal kingdom. Mammals are characterized by having advanced evolutionary traits, and within this class, there are 19 different orders. One of these orders is the primates, which contains various eutherian mammals, including monkeys and apes, as well as other species such as lemurs, lorises, and tarsiers.

Evolution of Class Primata

• Based on the paleontological evidence found in North America and Europe, the primates may have evolved 55 – 60 million years ago in these continents.
• The oldest primate-like mammal or proto primate is known to be plesiadapis. They were found in Europe and North America in the Cenozoic era and are believed to have gone extinct by the end of the Eocene epoch.
• The fossils of primates were found in North America, Asia and Africa, which belongs to Eocene epoch. They resembled present-day lemurs. It has been believed that monkeys arose in the old world (Europe, Asia and Africa) and reached the New World (America) by drifting on logs or with floating islands.
• Due to this, new world monkeys and old world monkeys were reproductively isolated and followed different adaptive radiations over 30 million years
• Evolution of prosimians occurred during the Oligocene epoch. All living species of present-day primates got evolved some 30 million years ago.
• Recent estimates reveal that there are 230 to 270 primate species that exist today.

General Characteristics of primates

All primates have evolved from tree-dwelling ancestors, and as a result, they possess certain adaptive features that enable them to climb trees effectively. These features include:

• Rotating shoulder joints: Primates have strong collarbones (clavicles) and secure ball joints in their shoulders, which allow them to use their arms efficiently for climbing trees. This rotating shoulder joint provides greater mobility and flexibility as they navigate through branches.
• Grasping fingers and toes: Most primates have five fingers and toes (pentadactylism) on each hand and foot. The combination of mobile fingers and toes and an opposable thumb allows primates to grasp objects with ease. Additionally, all primates except humans have prehensile feet, which aid in gripping tree branches. Small World monkeys have a power grip due to the rotation and forceful pressing of their thumb towards their fingers, while monkeys and apes have more dexterity, enabling them to grip objects with precision.
• Stereoscopic vision: Primates possess enhanced visual capabilities compared to other mammals, with 50% of their cerebral cortex involved in processing visual information. Their ability to perceive color and depth through binocular vision results in stereoscopic vision, which allows them to accurately judge distances and navigate through their environment.

Other characteristics of Primates

• The majority of primates are arboreal, meaning they primarily live in trees, with a few notable exceptions such as humans and gorillas. Most primates have an upright upper body posture and occasionally display bipedalism, or walking on two legs. Humans, however, maintain an erect posture and consistently exhibit bipedalism.
• Primates, except for lemurs, generally have smaller noses and corresponding olfactory regions in their brains. They also possess larger brains relative to their body size in comparison to other mammals. The enlarged areas of the brain are responsible for controlling manual dexterity, hand-eye coordination, and stereoscopic vision, which are important for their survival and daily activities.
• Primates typically have longer gestation periods relative to their size when compared to other animals. They are also known for being highly social creatures, with most species being active during the day (diurnal).
• Advanced primates, such as humans, engage in an enjoyable activity called grooming, which helps maintain social bonds and hygiene. Overall, primates exhibit a wide range of unique characteristics and behaviors that set them apart from other mammals.

Classification of Primates

Classification of primates is primarily based on the similarities and dissimilarities of external morphology, although phylogenetic classifications have also been done. Primates consist of two suborders: Strepsirrhini and Haplorrhini.

Strepsirrhini

Strepsirrhini primates, also known as "lower primates" or "prosimians" (meaning "pre-monkey"), were the first suborders of primates to evolve. They are characterized by their moist, large, hairless nose tips and are predominantly found in tropical regions around the world.
This group of primates includes lemurs, lorises, and tarsiers. Lemurs can only be found in Madagascar and the nearby Comoro Islands, with 22 species of arboreal (tree-dwelling) lemurs in existence today, spread across five families.

• Lorises, on the other hand, are primarily found in India and Southeast Asia. These arboreal creatures are omnivorous, feeding on insects, eggs, and baby birds, although they prefer easy prey. They are also nocturnal, meaning they are active during the night.
• Tarsiers are larger rat-sized primates found in Southeast Asia, specifically in the southern Philippines, Borneo, and the Celebes Islands. They possess a unique combination of prosimian and monkey-like traits but have a distinct genetic makeup from both groups. At least seven surviving species of tarsiers rely on their vision and hearing more than their sense of smell. They are known for their ability to produce ultrasounds for communication and can rotate their heads more than 180°. Tarsiers are strictly nocturnal and carnivorous creatures.

Haplorrhini

• Suborder Anthropoidea consists of primates that are considered to be "higher primates" and are also known as "Anthropoids." There are 145 living species in this suborder, with over 90% being monkeys and the rest being apes and humans. These primates are the most successful on Earth and are classified into two groups based on their nose and specific types of teeth: Platyrrhini (New World Monkeys) and Catarrhini (Old World Monkeys, Apes, and Humans).
• Platyrrhini, or New World Monkeys, have a flat nose with nostrils that point sideways and are separated by a wide septum. They have a dental formula of 2132 or 2133 and are found only in the tropical forests of southern Mexico, Central, and South America. These monkeys are exclusively arboreal and herbivorous, and many have a tail that functions like a third hand. There are two families within this group, Cebidae and Callitricidae, which include 53 species such as squirrel and capuchin monkeys, night and titi monkeys, howler and spider monkeys, uakaris, sakis, marmosets, and tamarins.
• Catarrhini includes Old World monkeys, apes, and humans. These primates have downward-projecting nostrils with a narrow septum separating them. They inhabit regions in South and East Asia, the Middle East, and Africa. This group is comprised of seven species in two families: Cercopithecinae and Colobinae. Cercopithecines include baboons, mangabeys, mandrills, guenons, patas monkeys, and macaques, with macaques being the most successful in spreading worldwide and commonly used in clinical research. Colobines, also known as leaf-eating monkeys, have a sacculated stomach for better digestion of plant materials.
• Apes and humans are both part of the superfamily Hominoidae, which is further divided into two families: Hylobatidae (gibbons) and Hominidae (orangutans, African apes, and humans). Gibbons, or lesser apes, are excellent brachiators (suspensory climbers) and are monogamous. Orangutans are the largest and rarest Asian apes, which walk quadrupedally and face the danger of extinction. African apes include gorillas, the largest apes that possess quadrupedal knuckle walkers, and chimpanzees, which closely resemble humans and are intelligent animals with generally pleasant personalities. Bonobos are close relatives of chimpanzees and are sometimes referred to as pygmy chimpanzees.
• Humans, or Homo sapiens, are the only living species within the Hominidae family. They show sexual dimorphism similar to that of other apes and share the same internal organs, bones, and some blood groups. Humans have an erect posture and bipedalism due to modified pelvic bones and spinal column. Humans and chimpanzees share 96% similarities in DNA base-pair sequences, indicating that the two species had a common ancestor and evolved into separate species 6-7 million years ago.

Conclusion

In conclusion, primates are a diverse and complex group of mammals belonging to the class Mammalia, which consists of 19 different orders. They have evolved over millions of years and have developed unique characteristics, such as rotating shoulder joints, grasping fingers and toes, and stereoscopic vision. Primates are classified into two suborders: Strepsirrhini (prosimians) and Haplorrhini (anthropoids). Strepsirrhini includes lemurs, lorises, and tarsiers, while Haplorrhini consists of both New World and Old World monkeys, apes, and humans. Primates demonstrate a wide range of fascinating behaviors and adaptations that set them apart from other mammals, making them a crucial subject of study for understanding the evolution, biology, and behavior of various species, including our own.

Frequently Asked Questions (FAQs) for Primate Taxonomy

What are the two suborders of primates?

The two suborders of primates are Strepsirrhini and Haplorrhini. Strepsirrhini includes "lower primates" or "prosimians" like lemurs, lorises, and tarsiers. Haplorrhini, also known as "higher primates" or "Anthropoids," includes monkeys, apes, and humans.

What are the main differences between New World monkeys and Old World monkeys?

New World monkeys (Platyrrhini) have a flat nose with nostrils that point sideways and are separated by a wide septum. They are found in the tropical forests of southern Mexico, Central, and South America. Old World monkeys (Catarrhini) have downward-projecting nostrils with a narrow septum separating them and are found in regions in South and East Asia, the Middle East, and Africa.

What are some common characteristics of primates?

Common characteristics of primates include rotating shoulder joints, grasping fingers and toes with an opposable thumb, and stereoscopic vision. Most primates are arboreal (tree-dwelling), have an upright upper body posture, and are highly social creatures.

How are humans related to other primates?

Humans are part of the superfamily Hominoidae, which also includes apes. Humans belong to the Hominidae family and share many similarities with other primates, such as internal organs, bones, and some blood groups. Humans and chimpanzees share 96% similarities in DNA base-pair sequences, indicating that the two species had a common ancestor and evolved into separate species 6-7 million years ago.