Primates - How they differ from other mammals

Primates belong to an order in the Mammalia class. They include lemurs, tarsiers, monkeys, apes, and humans. Over 300 species exist, making primates the third most diverse mammalian order. The word “Primates” comes from Latin primat, meaning highest rank. Carl Linnaeus named them as ‘Primates’ because he regarded them as the top animals.

Evolution and Diversity

Primates first arose about 55–85 million years ago. Their ancestors, Plesiadapiformes, adapted to tree life in tropical forests. Many primate traits evolved for arboreal life, including big brains, flexible hands, and keen vision. The smallest primate is the mouse lemur (Microcebus berthae), weighing about 35 g. The largest primate is the gorilla, weighing over 140 kg.

Special Differences from Other Mammals

1. Brain Size and Structure

Primates have proportionally larger brains than other land mammals.
Their brains have a unique groove called the Calcarine sulcus, which separates visual areas.
Vision is more developed in primates, while most other mammals rely more on smell.

2. Digits and Nails

Unlike other mammals that have claws or hooves, primates usually have flat nails.
Some primates still have claws but often retain a flat nail on the big toe.
All primates are pentadactyl, meaning they have five fingers on each limb.

3. Grasping Ability

Most primates have a grasping foot.
The big toe (hallux) is separate and forms a pincer grip with other toes.
Opposable thumbs are found in Old World monkeys, apes, humans, and some lemurs and lorises.

4. Tactile Sensitivity

Primates possess Meissner’s corpuscles, which are special nerve endings in hands and feet.
These allow high tactile sensitivity, a feature not found in other placental mammals.

5. Tails and Body Development

Most primates have tails, but apes and humans lack tails.
They grow slowly, reach maturity later, and have longer lifespans than mammals of similar size.

6. Sexual Dimorphism

Many species show differences between males and females (sexual dimorphism).

These differences include:

Fat and muscle distribution
Canine tooth size
Pelvic width
Hair patterns
Colouration

Habitat and Diet

Habitat and Distribution

Primates are mainly found in Central and South America, Africa, and southern Asia. Some species also live in southern Mexico (North America) and Japan (northern Asia).

They inhabit a wide range of environments such as:

Tropical forests
Savannas
Temperate forests
Mountains
Deserts
Coastal regions

Locomotion and Lifestyle

Most primates are arboreal and they live in trees.

Some are partially or fully terrestrial, including:

Humans
Gorillas
Baboons

Arboreal primates move by leaping or swinging between branches.

Terrestrial ones use knuckle-walking or bipedalism for movement.

Feeding Habits

Primates are omnivores, eating both plant and animal matter.

Their diet includes:

Animal-based items: insects, crustaceans, spiders, birds’ eggs
From plants (reproductive): fruits, flowers, seeds, nuts, rhizomes, tubers
From plants (vegetative): leaves, stems, grasses, bark, gums

This diverse diet allows primates to adapt to various environments.

Classification of Primates

Primates are grouped into two suborders:

Strepsirrhines (wet-nosed), including lemurs, galagos, and lorisids.
Haplorhines (dry-nosed), including tarsiers, monkeys, apes, and humans.

Threats and Conservation

Endangered Status

More than one-third of primate species are vulnerable or critically endangered.
Almost 60% face extinction risk.
Population decline is seen in 75% of primates.

Regional Endangerment Statistics

Madagascar: 87% of primate species are endangered
Asia: 73%
Africa: 37%
South and Central America: 36%

Critically Endangered Species

Some examples of highly threatened primates include:

Sumatran orangutan
Silky sifaka
White-headed langur
Delacour’s langur
Tonkin snub-nosed monkey
Cross River gorilla

Major Threats

Deforestation due to logging and urban development
Hunting for food, medicine, or pest control
Land clearing for agriculture
Urbanisation and timber extraction
Retaliatory killing of crop-raiding primates

Reproductive Challenge

Primates reproduce slowly, with:

Delayed sexual maturity
Long intervals between births

This leads to slow population recovery after a decline.

Summary

Primates are mammals such as lemurs, tarsiers, monkeys, apes, and humans. They have flat nails, unique thumbs, and strong eyesight. Many live in forests and eat both animal and plant matter. Traits like Meissner’s corpuscles give them great touch. Due to habitat loss and slow reproduction, many species are at risk.

FAQs

Q1. How many species of primates exist?

A. There are more than 300 species of primates known today.

Q2. What are some examples of primates?

A. Common primates include monkeys, apes, lemurs, tarsiers, and humans. Other examples are gorillas, chimpanzees, baboons, and gibbons.

Q3. How are primates classified into suborders?

A. Primates are divided into two suborders based on nose structure and traits. Strepsirrhines have wet noses; Haplorhines have dry noses and complex brains.