Introduction

Primates are one of the most diversified mammalian orders on the planet. 

Primate species include:

• Lemurs (over 70 species in six families)
• Lorises (three or more species in one subgroup)
• Tarsiers (six or more varieties in one family)
• New World monkeys (roughly 100 species in five families)
• Old World monkeys (more than 100 species in one household)
• Apes
• Humans (about 20 species in two families)

More than 60 million years ago, primates first appeared. Over such a long time, many distinct varieties of primates have evolved, and many of them are now extinct. Others have survived, and there are now more than 350 species of primates surviving on the planet. Almost all primates dwell in Africa, Madagascar, Asia, Central America, and South America’s tropical and subtropical regions. Before discussing the study material notes on the characteristics of primates anthropology, let’s discuss their evolution!

Evolution of Primates

Proto-primates are the first primate-like mammals that evolved. In size and appearance, they were comparable to squirrels and tree shrews. The fossil evidence that exists (mainly from North Africa) is relatively sparse. Until additional fossil evidence becomes available, these proto-primates will remain primarily unknown. Plesiadapis is the oldest known primate-like mammal with a relatively extensive fossil record (although some researchers do not agree that Plesiadapis was a proto-primate). This primate’s fossils have been dated to around 55 million years ago. The teeth and skeleton of Plesiadapiforms were similar to those of real primates. During the Cenozoic, they were found in North America and Europe, but they had become extinct by the end of the Eocene.

In the Eocene Epoch, the first real primates were discovered in North America, Europe, Asia, and Africa. These primitive primates resembled modern prosimians like lemurs. These early primates continued to evolve, with larger brains and eyes and smaller muzzles being the norm. Many early prosimian species perished before the end of the Eocene Epoch, owing to either colder temperatures or competition from the earliest monkeys.

List Four Characteristics of Primates

Because they all came from tree-dwellers, all monkey species have tree-climbing adaptations. Primates (including humans) are unique among animals in that they are the only mammals with the following combination of characteristics of primates:

• A brain that is relatively vast and complicated
• Eyes that are forward-facing and have overlapping fields of view, allowing for depth perception
• Eye sockets surrounded by a ring or cup of bone that supports and protects the eyes
• Fingers that curl around items with long fingers grasped
• Large toes and/or opposable thumbs (able to touch the other digits on the same hand or foot)
• Some fingers and toes have flat nails rather than claws
• Sensitive pads under the tips of the fingers and toes that contain Meissner’s Corpuscles, which are particular touch receptors
• A well-proportioned collarbone (clavicle)
• Minimum two nipples on the chest (but sometimes more). In females, these supply milk to the young
• Testicles and penis that are permanently dangling from the body (in males)
• A long childhood that lasts well past weaning

Prosimians and anthropoids are the two groups that make up the Order Primates. Prosimians include African bush babies and pottos, Madagascar’s lemurs, and Southeast Asia’s lorises. Tarsiers, which are also found in Southeast Asia, have certain prosimian-like and anthropoid-like characteristics. Monkeys, apes, and humans are anthropoids. Prosimians, in general, are nocturnal (as opposed to diurnal anthropoids, except the nocturnal Aotus, owl monkey) and have a smaller brain/body ratio than anthropoids.

Key points

• All primates are descendants from tree-dwellers, with adaptations such as a rotating shoulder joint, separated big toes and thumb for grabbing, and stereoscopic vision that allows them to climb trees
• Other primate features include having only one offspring each pregnancy, flattened claws, and a bigger brain/body ratio than other animals, as well as a tendency to hold the body upright
• True primates, the ancestors of prosimians, first appeared in the fossil record around 55 million years ago and looked similar to lemurs
• Anthropoids, the ancestors of both Old World and New World monkeys, first appeared in the Oligocene epoch, some 35 million years ago
• Around 25 million years ago, ape-like anthropoids appeared in the Miocene epoch
• Apes are classified into two groups: lesser apes (gibbons and siamangs) and great apes (gibbons and siamangs) (Pongo: orangutans, Gorilla: gorillas, Pan: chimpanzees, and Homo: humans)

Conclusion

Primates are a diverse group of between 190 and 350 surviving species, depending on taxonomic frameworks, and have a variety of distinguishing characteristics that make them stand out from other mammals. Primate species include lemurs, lorises, tarsiers, monkeys, and apes. They vary in height, weight, characteristics, etc. The pygmy mouse lemur weighs 2 ounces, and the wild gorilla weighs 440 pounds. Humans and the other primates in the group share many characteristics. Simply refer to the study material notes on Characteristics of Primates for more information.