Primates families evolved from tiny terrestrial animals that adapted to dwell in tropical forest trees 85–55 million years ago. Lemurs, tarsiers, monkeys, apes, and humans are members of the order Primates in the class Mammalia. They range from 1 ounce for a mouse lemur to 441 pounds for a mountain gorilla. Transitional primate-like creatures arose near the end of the Mesozoic Era, 65.5 million years ago. The world was substantially different back then, and the continents were in various places with different forms. North America remained linked to Europe but not to South America. India was not yet a part of Asia, but it was moving in that direction at a startlingly fast rate of about 8 inches yearly. Australia was close to Antarctica. The majority of landmasses had mild tropical or subtropical climates. Non-human primates are mostly found in tropical or subtropical parts of South America, Africa, and Asia.
Characteristics of Primates
Because all ape species came from tree-dwellers, they all have adaptations for climbing trees. In addition, primates’ arboreal ancestry has resulted in hands and feet suited for climbing and swinging through trees. Among these adaptations include, but are not limited to:
- A rotating shoulder joint.
- A big toe far from the other toes and thumbs, widely separated from the fingers except in humans, allowing for branch grabbing.
- Stereoscopic vision consists of two overlapping fields of vision from the eyes and provides the perception of depth and distance.
- Bigger brains than most other animals.
- Claws changed into flattened nails.
- Just one child per pregnancy.
- A tendency to keep the body upright.
Types of Primate Families
The Order of Primates is divided into two Sub-Orders, namely, Strepsirrhini, also known as Prosimians and Haplorrhini. They are further divided into Infraorder, Superfamilies and Families. The two sub-orders of primates families are:
This sub-order of primates, having wet noses, has a rather old evolutionary ancestry. They all have fox-like snouts and long tails and live in woodlands. They also have a smaller brain, larger olfactory lobes for smell, a vomeronasal organ for pheromone detection, and a uterus with a placenta. In addition, their eyes have a reflective coating to help with night vision, and their eye sockets have a bone ring around the eye. This sub-order is further divided into Infraorder, Superfamilies and Families:
Lemuriformes are further divided into two superfamilies:
- Cheirogaleidae: This family of five diminutive or mouse lemurs can only be found in Madagascar in the Indian Ocean. The hairy-eared dwarf lemur is one example.
- Daubentoniidae: This family contains only one species, the aye-aye, which lives in Madagascar’s jungles.
- Lemuridae: This is the biggest family of lemurs, with roughly ten species found solely in Madagascar and the surrounding Comoro Islands. The black lemur and the ring-tailed lemur are two examples.
- Megaladapidae/Lepilemuridae: This family of two sportive lemur species can only be found in Madagascar. The grey-backed sportive lemur is one example.
- Indridae: This is another family of Madagascar prosimians that includes four species known as woolly lemurs. The indri is one example.
- Lorisidae: This prosimian family of 12 species is found in forests throughout South Asia, Southeast Asia, and Africa. India’s thin loris and the potto of tropical Africa are two examples.
- Galagidae: They are also known as galagos, bushbabies, or nagapies, which means “night monkeys” in Afrikaans. Bushbabies are tiny nocturnal primates prevalent in continental and sub-Saharan Africa that belong to the Galagidae family.
Haplorhini, sometimes known as “dry-nosed” primates, is a suborder of primates that includes tarsiers, the Old World monkeys, New World monkeys, marmosets, and apes. The numerous monkeys are tiny, arboreal, and have tails, but the apes are bigger, smarter, and do not have a tail. Except for some, most haplorhine primates are arboreal and live in the woods. Because the haplorhine top lip is not directly attached to their nose or gum, they can make various facial expressions. Vision is their primary sense. Most creatures have only one offspring. Despite having equal gestation lengths, haplorhine infants are significantly bigger than strepsirrhine newborns. But they have a longer time of dependency on their mother. The higher intricacy of their behaviour and natural history is attributed to this disparity in size and dependency. This sub-order is also subdivided further into Infraorder, Superfamilies, and Families:
- Tarsiidae: This family contains three species of little prosimians that live in the woods of Southeast Asia’s islands. The Philippine tarsier is one such example.
Simiiformes is divided into two parvorders:
- Callitrichidae: This family contains around 33 species of little marmoset monkeys found in the tropical forests of South America and Panama. The golden-headed lion tamarin and the pygmy marmoset are two examples from Brazil.
- Atelidae: The Atelidae are a family of 29 New World monkey species that have been identified. The howler, spider, woolly, and woolly spider monkeys are all members of the atelid family, which contains the biggest New World monkey, the woolly spider monkey. They may be found across Central and South America’s wooded areas, from Mexico to northern Argentina.
- Pitheciidae: It is a family of 49 New World monkeys identified. The titis, saki monkeys, and uakaris are all the same family members. They are generally herbivorous, consuming largely fruits and seeds. However, some species may consume insects as well. Finding most species is possible in Brazil’s Amazon area and others from Colombia in the north to Bolivia in the south.
- Aotidae: Night monkeys, sometimes known as owl monkeys, are the lone member of the Aotidae family of 11 New World monkey species. Finding them is possible in primary and secondary forests, tropical rainforests, and cloud forests up to 7,900 feet in Panama and most of South America. Night monkeys have wide eyes, letting them see better at night. Their ears are usually covered, earning them the name Aotus, which means “earless.”
- Cebidae: This family contains roughly 37 New World monkey species characterised by their prehensile or grabbing tails and nostrils separated by a somewhat broad partition. The two examples are the Northern South American dusky titi monkey and the Central American squirrel monkey of Costa Rica and Panama.
This parvorder has two further superfamilies:
- Cercopithecidae: This family contains around 60 Old World monkey species from Africa and Asia, distinguished by non-prehensile tails, tightly located nostrils, and typically exposed skin on the buttocks. Examples include Central African black colobus, South Asian rhesus macaque, West African mandrill, and Borneo proboscis monkey.
- Hylobatidae: This group of six gibbon ape species lack a tail, are very arboreal and agile, and produce loud, complex vocalisations known as “songs”. The two examples are the black gibbon of Southeast Asia and the siamang of Malaysia and Sumatra.
- Hominidae: This family contains five species of great apes, which are quite big and strong, do not have a tail, and are the most cognitive and socially sophisticated primates. The gorilla of Central Africa, the pygmy chimp of Congo, the chimp of Central Africa, the orangutan of Borneo and Sumatra, and humans or Homo sapiens with a global distribution are all members of this group. Except for humans, all Hominidae live solely in tropical jungles.
Evolution of Primate Families
Primates are a relatively new species. Most animal species thrived and died out long before the first monkeys, and their prosimian forebears appeared. So while the world is around 4.54 billion years old and the earliest life goes back at least 3.5 billion years, primates did not exist until approximately 50-55 million years ago. That happened 10 to 15 million years after the dinosaurs became extinct.
Beginning of the First Primates
During the end of the Mesozoic Era, mammals were beginning to supplant giant reptiles as the dominating large terrestrial creatures. However, the majority of the mammal species were tiny, ranging in size from a mouse to a medium-sized domesticated dog. The extensive grasslands that would eventually grow and the big grass-eating placental animals such as cattle and wildebeest were lacking. Rodents and seed-eating birds were also conspicuously absent. Moreover, the massive expansion of blooming plants had not yet occurred. On the other hand, forests of broad-leaved trees were sprouting up throughout much of the globe.
Evolution of Proto-Primates or Primate-Like Mammals
Proto-primates are the first primate-like mammals. In size and appearance, they were comparable to squirrels and tree shrews. The limited fossil evidence from Asia, Europe, North Africa, and, notably, Western North America shows that they suited an arboreal lifestyle in warm, damp climes. They most likely had pretty strong eyesight and hands and feet specialised for tree climbing. Unfortunately, largely from North Africa, the current fossil material is incomplete. Until additional fossil evidence becomes available, these proto-primates will remain mostly unknown. The fossil record of Plesiadap, a primate-like animal, is rather extensive. The date of this primate’s fossils is roughly 55 million years. Plesiadapiforms were proto-primates of the primate families with teeth and skeletons similar to those of real primates. They were discovered in North America and Europe throughout the Cenozoic period and were extinct by the end of the Eocene.
Evolution of Early Strepsirrhini/Prosimians
The Eocene Epoch began 55.8-33.9 million years ago, coinciding with the appearance of early versions of the placental animal orders that exist today. During the same period, animals with larger bodies and brains appeared in the fossil record. In addition, the Eocene Epoch saw the discovery of the first true primates in North America, Europe, Asia, and Africa. These early primates resembled modern prosimians like lemurs. They were still squirrel-like in size and appearance, but they appeared to have hands and feet that were increasingly effective at handling items and climbing trees. In addition, their eye location shows that they were also developing more efficient stereoscopic vision. Evolutionary changes in these early primates persisted, with bigger brains and eyes and smaller muzzles becoming the norm. Unfortunately, many early prosimian species became extinct by the end of the Eocene Epoch, either due to reduced temperatures or competition from the earliest monkeys.
Evolution of Early Monkeys of the Primate Families
During the Oligocene Epoch, anthropoid monkeys developed from prosimians. Evidence suggests monkeys were present in the New World (South America) and the Old World 40 million years ago (Africa and Asia). Because of having large nostrils, the naming of New World monkeys as Platyrrhini is appropriate. Likewise, the naming of Old World monkeys is correct, as Catarrhini. South America and Africa had moved apart when the platyrrhines appeared. By traversing on drifting logs and land bridges, monkeys which originated in the Old World moved to the New World. Because of this reproductive isolation, New World and Old World monkeys evolved separately over millions of years. In addition, the New World monkeys are exclusively arboreal, whereas the Old World monkeys are both arboreal and ground-dwelling.
Evolution of Apes of the Primate Families
Apes developed from catarrhines in Africa some 25 million years ago, midway through the Cenozoic. Proconsul was one of the first monkey-to-ape transitional primates. Apes are typically bigger than monkeys and do not have a tail. Although all apes can move through trees, several species spend most of their time on the ground. Apes are more intellectual than monkeys, and their brains are bigger than their physical size. There are two groups of apes. Firstly, the family Hylobatidae, which includes gibbons and siamangs, comprises smaller apes. Secondly, Pan (chimps and bonobos), Gorilla, Pongo, and Homo (humans) are among the big apes group. The highly arboreal gibbons are smaller than the giant apes and have longer arms for swinging through trees.
Evolution of Genus Homo
Human is a term applicable to all individuals of the genus Homo. It comprises not just current Homo sapiens — the only existing Homo species — but also humans from various extinct Homo species, including Homo heidelbergensis. At different points throughout history, many species of Homo coexisted at the same time and in the same region. It is also plausible that many early Homo species developed into Homo sapiens at various times and locations. A protracted era of climatic instability began at the vital moment in time when the earliest Homo species were emerging. Throughout the development of the genus Homo, the human brain grew in size. The rise was slow at first, but it got quite fast around 800 thousand years ago. Homo’s technical sophistication increased in tandem with the development of the brain. Let us now see the various genus Homo:
The earliest known species of Homo originated in East Africa between 2.5 and 2.8 million years ago, around the same time that the final known australopithecines departed from the fossil record. Assumption has been made that an australopithecine species was Homo’s direct predecessor in East Africa. The discovery of a fossil skull, an early transitional human fossil, has made in 1960 in Tanzania’s Olduvai Gorge. Individuals of Homo habilis were typically bipedal and short and lightweight in build. Homo habilis also had smaller molar teeth, jaws, and faces and were smarter. Homo habilis fossils indicate that they inhabited East Africa until around 1.4 million years ago. They appear to have become extinct after that. H. erectus, another species of Homo, had already emerged at that time.
Homo erectus appeared in the fossil record for the first time around 1.9 million years ago in East Africa. For around half a million years, Homo erectus and Homo habilis coexisted. Its direct ancestor is unknown. Both Homo erectus and Homo habilis might have descended from older australopithecines, or Homo erectus could have descended from Homo habilis. Homo erectus existed until at least 800,000 years ago, and in certain areas, including East Asia, much more recently. Homo erectus was a successful species of the primate families. It persisted for around 1.5 million years, significantly longer than our species, Homo sapiens. H. erectus were the first humans to depart Africa 1.8 million years ago. Homo erectus spread as far as Georgia in Eurasia, India, China, and Indonesia. H. erectus also discovered how to regulate and use fire.
Homo heidelbergensis is the name given to more modern-looking Homo individuals that lived less than 800,000 years ago. The name of this Homo species was after the city of Heidelberg, Germany. This is where the first fossil of this extinct species was found in 1907. Discovery of many fossils of this species were in parts of the Old World, including England in Europe. Homo heidelbergensis appears to have possessed Homo erectus and Homo sapiens characteristics. Their physical size was only slightly less than that of contemporary humans, and their brain size was at least 90% that of today’s Homo sapiens. On the other hand, their heads would have seemed different from ours. They possessed a sloping forehead and thick brow ridges like Homo erectus. H. heidelbergensis was also the ancestor of the now-extinct Homo neanderthalensis, also known as Neanderthals.
Homo neanderthalensis existed in Europe and Asia between 400,000 and 28,000 years ago. There are some distinct anatomical distinctions between contemporary humans and Neanderthal groups. Many of these are related to the Neanderthal populations’ improved adaption to cold conditions. Neanderthals also had much bigger brains. This aspect would appear to imply the intellectual superiority of Neanderthal communities. The increased size of the occipital lobe indicates that Neanderthals had superior visual acuity to modern people and better eyesight in the low-light circumstances encountered in Glacial Europe. Physically, Neanderthal populations appear to have been superior. With greater numbers, social and technical improvements were simpler to implement in human groups, which may have all led to modern Homo sapiens displacing Neanderthals.
A variety of species, known as archaic Homo sapiens, appear to have developed from H. Erectus some 500,000 years ago. The brain size of these ancient H. sapiens was close to that of contemporary humans, averaging 1,200–1,400 cubic centimetres. They were different from contemporary humans by their broadheads, strong brow ridge, and receding chin. Some of these creatures coexisted with modern humans until 30,000–10,000 years ago. The origins of Homo sapiens are debatable. H.erectus travelled out of Africa and into Asia and Europe in the first major wave of migration around 1.5 million years ago, as previously reported. Modern humans have evolved in Africa from H. Erectus and moved out of Africa around 100,000 years ago in a second big migratory wave. Then, in the second wave, H. Erectus species replaced H. Erectus species that had moved into Asia and Europe in the first wave.
Because primate families descend from tree-dwellers, all monkey species adapt to climbing trees; however, not all species are arboreal. Other traits of primates include bigger brains than other animals, claws changed into flattened nails, just one offspring per pregnancy, stereoscopic vision, and a tendency to maintain the body upright. During the Oligocene Epoch, monkeys evolved from prosimians. During the Miocene Epoch, apes originated from catarrhines in Africa. Apes are classified as smaller apes or bigger apes. By the early Miocene Epoch, apes had developed from monkeys and supplanted them in various habitats. The evolutionary path leading to hominins became distinct in the late Miocene. Our immediate ancestors were part of this hominini line.