After the KT impact, which marks the beginning of the Cenozoic era, and the end of the age of dinosaurs, -marsupials had already been overrun by placental mammals everywhere but Australia, which had been separated from the rest of the supercontinent since the mid-Mesozoic. This allowed Australian marsupials to diversify into myriad groups, most of which are now extinct. Among these were a sort of carnivorous kangaroo, and a marsupial "lion", the true nature of which we'll probably never know. Elsewhere in the world, eutherian mammals also diverged into numerous sub-groups, all of whom of course initially looked very similar to each other early on. Before they really began to "grow apart", most of them resembled rats or shrews or opossums. Some of them changed relatively little, and eventually lead to the order, Carnivora. Others developed much thicker keratin on their claws, to the point that they had to walk on the claw itself rather than on their toes. These lead to the ungulates, which are a very diverse group, especially since it includes whales as hooved carnivores! Both of these orders are considered part one superorder, Laurasiatheria, one of four major initial divisions of placental mammals. The common bond between the hooved animals and the carnivores are the basal condylarths and the subsequent mesonychids. Both of these transitional genera are now completely extinct. But we still have some hooved animals like pigs and hippos that will eat meat on occasion, and we even have a few Asian deer which still have their fangs.
The aardvark, a "hooved" Afrotherian relative of the elephant.
In their most basal forms, ungulates weren't very different from elephant shrews and aardvarks, who's thickened claws classify as hooves. These animals are also karyotypes of the basal form of another separate major division of hooved animals, the Afrotherians, another diverse group which include hyrax, moles, tapirs, elephants and manatees, with the latter two being surprisingly closely-related!
The next major group is Xenartha, a South American group which include sloths, anteaters, and armadillos. And the last of these superorders are Euarchontoglires, which begin with a kind of rat-shrew, which radiated into rodents and rabbits on one side, and on the other, to several sorts of tree shrews and shrew-like things which apparently lead to the first primates. Recent discoveries in molecular biology reveal that rodents are more closely-related to "primitive" primates that previously thought.
One half of Euarchontoglires is the subset, Archonta.
The sequence at left illustrates how the orbital process can evolve in a single genera, in this case, resulting in meerkats with fully-enclosed eye sockets. This proves that such structural developments do occur in nature. The animals in this sequence are Carnivores, but something similar happened with euarchontoglires as well, resulting in archontids.
Like rodents, bats also were morphologically-identified as also related to early primates. Although the degree of that relationship is uncertain, they are certainly much closer to primates than another line of animals. Molecular evidence puts them as genealogically distant as flying lemurs, which are considered to be a sort of karyotype of the bat-primate common ancestor. All of these are part of Archonta, a grandorder identified by their retention of "primitive" (shrew-like) features such as pentadactyl digits, in addition to new modifications in the face, particularly related to the more binocular position of the eyes, which are now completely surrounded by bone joining the zygomatic arch and auditory bulla. These traits are consistent among all bats and primates, but not with any other group. If you'll notice from the earlier list of skulls, a dog's orbits are not completely surrounded by bone, which leaves their eyes vulnerable to side impacts. Giant fruit bats [megachiroptera] are so similar to protosimians that they were even thought to be primates once upon a time, and were thought to have evolved separately within primates rather than from smaller insect-eating bats [microchiroptera]. However molecular evidence reveals that all bats stem from within the same clade.
As you can see, apart from the oversized "hands", the skeleton of a bat is not significantly different from that of "lesser" primates, such as the flying lemur pictured above, both as a skeleton and in the flesh. How's this for evidence of the evolution of bats?
One subset of Archonta is Primata, (primates) hind-leg dominant Archontids with opposable thumbs
Tree shrews are
a sort of "living fossil"
and a karytype
of the earliest ancestors
of both rodents
True primates are their own distinct order and are recognized according to a suite of primitive characteristics of the skull, teeth, and limbs, including a shortened rostrum and more forwardly directed orbits associated with stereoscopic vision; relatively large braincase; opposable thumbs on five-fingered limbs, with an unfused and highly mobile radius and ulna in the forelimb and tibia and fibula in the hindlimb. These probably arose as adaptations for life in the trees or are primitive traits that were retained for the same reason. Several species have left the trees for life on the ground; nevertheless, we retain many of these features. All primates can all walk, stand, or hop on their hind legs, and the hind legs are dominant for locomotion for all of them. They also share a skeletal feature with bats that is otherwise unique; a complete clavicle, or "collar-bone".
Amphibians aren't much smarter than some fish. But reptiles are generally much smarter than amphibians, and both birds and mammals are significantly smarter than any cold-blooded reptile. Bird's brains are still technically reptilian brains, but their smaller brains also work more efficiently than mammalian brains do. Some birds have done quite well with what little they've got, and can even compete with some primates because they have the equivalent of cerebral turbo-chargers and high-performance injection systems. Mammal brains are rather like the engines in American performance cars. We tend to use cubic inches to compensate for the lack of precision engineering. More cubic inches does usually mean more power, even if its not fine-tuned. And within anthropoids, the brain-size to body-mass ratio really takes off, which is one reason all primates excel at complex social behaviour.
One subset of Primata is Haplorhini, "dry-nosed" pimates.
Primata (primates) are divided into two main groups, simians and prosimians. Lemurs and lorises are prosimians, (sub-order, Strepsirhini), meaning that they maintain very "primitive" features, and are a karyotype of the most basal of the primate order. In fact, they're often used to fill in the missing details we can't get from fossil forms. Like rodents, bats, and even carnivores, prosimians have wet noses, muzzles, moveable ears, and even whiskers, and their fingernails are still claws. They're barely primates at all in fact. Some of them even have six mammae, just like a raccoon or some other "lesser" animal might have. But some lemurs, oddly enough, have only two nipples, and they're located over the pectoral muscles where we have them, but where most other mammals don't. This kind of variance within any single lesser taxon is unusual, and could imply that prosimians really do represent the basal origin of more advanced primate sub-groups. Tarsiers (at left) were originally thought to be prosimians, but are now known to be haplorhines. Consequently, they've been reclassified into a sister clade alongside anthropoids.
"Haplorhines are considered to be less primitive than the strepsirrhine "wet-nosed" primates (whose Greek name means "curved nose"), the other suborder of primates. Their upper lip is not directly connected to their nose or gum, allowing a large range of facial expressions. Their brain to body ratio is significantly greater than the strepsirrhines, and their primary sense is vision. Most species are diurnal (the exceptions being the tarsiers and the night monkeys) and have trichromatic color vision. Their hands and feet are more generally adapted, with specialization only for locomotion, such as the hooked hands common to gibbons and orangutans, or the human bipedal feet." -Wikipedia
Among terrestrial mammals, primates are a consistently ingenious order. Even the average lemur is at least the equal of the most brilliant dog. Elephants are quite intelligent also, but still not quite as much as any of the great apes, and nowhere near human intellect. Our nearest competitors in cognizance are the whales, and they are smarter even than most primates. But they're still not quite as bright as the smartest of all primates, ourselves. And this may be due in part to the fact that in their environment, extreme intellect can't really be selected for other than in areas of ultrasonic communication where whales do excel. Elephants are pretty good at this too. Cetaceans (whales and dolphins) have no hands, and no way to make tools or fire with even if they had hands. When they did have "hands", they weren't yet bright enough to use them before they became hooved, or even before they were flippers. So they never had a chance to develop the same kind of cognitive capacity that we have, even though they too were dealt the card for greatly-oversized brains. To me, personally, having all this intellectual potential, but having a body that would never be able to use it, is another indication of undirected development such as does not imply any intelligence or foresight in any designer.
Primates aren't only bound by morphology, physiology, and genetics. There is a pharmacological bond there too, which is why anthropoids and rodents, (our next closest kin) have always been so important to medical research. To better explain this, let me point out that there is a North American spider who's bite is only mildly irritating to humans, but can be lethal to dogs. Similarly, there is an Australian spider who's bite hasn't much effect against any large vertebrates except primates. Dogs, pigs, and even rats and rabbits seem virtually immune to the venom of this one small tarantula. But primates, all primates from lemurs and monkeys on up, will die from it, and die quickly. Now, if you knew only this about the male Australian funnelweb spider, wouldn't you already know that a human bitten by one would be a matter of dire emergency? Wouldn't you realize that humans were part of that high risk group?
Supernaturally specially-created monkey-looking things wouldn't necessarily have to belong to all of the above groups at the same time in every case, the way only related descendants should always be. But as a human, with a clavicle, opposable thumb, hindlimb-dominant locomotion, and all your other similarities and shared susceptibilities with other anthropoids, you must accept that you are not only a primate, but that you are also (by definition) a member of every one of these other parent clades as well.
When defining primates, you can't just point at a capuchin, and say "that is a monkey", because that won't say anything about maquaques, marmosets, or baboons. Neither could you describe them all by using character traits that are only true of some of them. So what you have to do is to define them by the characters that are common to all of them. Any group with more specific characters would then become a subset of the whole.
For example, primates can be defined as any gill-less, organic RNA/DNA protein-based, metabolic, metazoic, nucleic, diploid, bilaterally-symmetrical, endothermic, digestive, tryploblast, opisthokont, deuterostome coelemate with a spinal chord and 12 cranial nerves connecting to a limbic system in an enlarged cerebrial cortex inside a jawed-skull with a relatively large braincase, with specialized teeth including canines and premolars, forward-oriented fully-enclosed optical orbits, and a single temporal fenestra, -attached to a vertebrate tetrapoidal skeleton with a sacral pelvis and wrist & ankle bones; and having lungs, tear ducts, body-wide hair follicles, lactal mammaries, and keratinized nails on all five digits on all four extremities, in addition to an embryonic development in amniotic fluid, leading to a placental birth. But its a lot easier to tally all these characters into a clade, and define them as "any member of the order of Primates." And as a clade, this definition would of course also include any evident descendants of the parent group, which is why humans are primates.
One subset of Haplorhini is Anthropoidea, (monkeys)
Anthropoidea: (monkeys) a subset of Haplorhines, are more advanced simians adding a few more details to the definitions above. For one thing, they have only two actual breasts, pectoral mammae which are unlike those of any other mammal. And unlike lemurs, most monkeys have completely lost the ability to move their ears. Only a few individuals remain who can even wiggle them anymore. Monkeys also lack the specialized sensory whiskers and the wet nose that lemurs and so many "lesser" animals have. Among the other obvious external differences are that male monkeys' genetalia are naked and pendulous in that they're not thethered to their abdomens anymore, as they are on most other eutherians. They have a well-developed caecum, and a tendancy toward bipedalism. Like most bats, but unlike lemurs, monkeys usually have a flatter face, and all monkeys have completely forward-facing binocular eyes and trichromatic vision, meaning that monkeys can see in color where lemurs, and most other "lesser" mammals can't.
A few humans have a mutation for tetrachromatic vision meaning that these individuals can even see into the ultraviolet spectrum! But most human's vision is no more advanced than any other simian. All monkeys have other internal distinctions from prosimians too. They all have a well-developed caecum, which is a sort of distension in the digestive tract that is mildly advantageous. But they have detrimental mutations too. All anthropoids have lost the ability to synthesize either vitamin D3 or vitamin C, and need to supplement both of these in their diet or they'll succumb to a condition of malnutrition commonly known as scurvy.
The clade, 'Anthropoidea' is also now known as 'Simiiformes'. Everything in that clade is a monkey, or a descendant of a monkey. And since there is no way to determine when the descendants of monkeys aren't monkeys anymore, then all their descendants should still be monkeys. Because again, monkeys can be defined by all of these characters, or they can be defined by a collective tally of them as "members of the clade, "Anthropoidea" (or Simiiformes). Either way, humans may be really big smart monkeys. But we are still monkeys in the same way that lions are cats, the way that ducks are birds. .
One subset of Anthropoidea is Catarrhini, (Old World monkeys)
Strict bipedality is extremely rare in most Catarrhine species, but certain individuals have adopted that trait, sometimes for medical reasons, (as with the maquaque at left) and sometimes just as a matter of preference -as in the famous case of Oliver the humanzee.
There are no defining characteristics common to all Catarrhines that don't also apply to humans. For example, Old World monkeys are one of the very few animals intelligent enough to recognize a reflection of themselves in a mirror. Some Old World monkeys have even been filmed stealing mirrors which they then use to examine their own teeth. .
Catarrhines are a more specific simian group, recognizable in fossils by the fact that they have only two premolars (cuspids & bicuspids) while New World monkeys (of the order, Platyrrhini) have three. Old World monkeys are actually "newer" in some respects than the 'New World monkeys. New World monkeys actually have more "primtive" features than Old World monkeys do. One of these are the splayed position of the nostrils. Old World monkeys have downward turned nostrils, and most of them have a recognizable nose. None of this group has claws. All of their nails are as flat and harmless as our own. For grasping, they've replaced their claws with sensative fingertips, and each of them bears a uniquely distinctive fingerprint as well, particularly in certain subgroups. In Platyrrhines, the tail is usually long and prehensile. But among Catarrhines, the tail is effectively useless and unimportant since most of these monkeys now live on the ground. Some Catarrhines have weak, wispy tails, some have short stubs for a tail, and many don't have any tail at all.
Like every other group described so far on this site, this one too is divided into two main groups: Modern catarrhine species which are traditionally recognized as "monkeys" are all Cercopithecids. But there is another, much older group called Propliopithecoidea, from which we have found many fossil species dating from 14 million to 34 million years old; Amphipithecus mogaungensis, Aegyptopithecus zeuxis, Morotopithecus, Catopithecus browni, Apidium phiomense, Branisella, and of course Propliopithecus itself, to name but a few. Apart from their possible descendants, the cercopithecids, most Propliopithecids are now extinct except for one other specific subgroup, which we will discuss next.
Now, obviously, if you are scientifically classified as an Old World monkey, and so was your mother, and your grandmother, and all your other ancestors that you know of, then certainly you must have descended from monkeys, right?
One subset of Catarrhini is Hominoidea, (apes)
Hominoids (apes) emerged from within Propliopithecoidea, and are another subset of Old World monkeys, all with uniquely distinctive fingerprints. But there are specific differences between them and all other tailless monkeys so that it is possible to tell an ape from other Catarrhines. Apes have a broader chest, and even less olfactory capacity (ability to scent) than other monkeys, and their dentition shows traits unique to that clade. They all also show a greater tendency toward bipedality, and some species apart from humans are exclusively bipedal, at least on the ground. One commonality they all have, and which they still share with most "lesser" monkeys, are their ears. Nothing else in the animal kingdom has ears like the ones we share with every other ape. Another trait that is distinctly "ape" is that they're all capable of brachiation, (hanging or swinging only from the arms) due to a greatly-increased occipital arc (shoulder rotation) which other monkeys don't have, and can't do, or can't do nearly as well.
Like everything else mentioned so far, Hominoidea is divided into two main sub-groups, the lesser apes, gibbons and siamangs of the family, Hylobatidae, (pictured above) and the "great apes" of the family, Hominidae. Both appear to have branched off from from progenitors like the fossil, Proconsul, a very gibbon-like ape which was also similar to the ancient monkeys like Aegypithecus and Pliopithecus.
One subset of Hominoidea is Hominidae, (Great apes)
Hominidae (the "great" apes) aren't just "large apes". There are more distinguishing features than just their size. For one thing, although all of them, including humans, have the same number of hair follicles all over their bodies, they are described as having more sparse hair than "lesser apes" or non-hominid monkeys. But they also have an unprecedented brain-size-to-body mass of any animal on Earth. Consequently, they also have the most complex socio-emotional relationships of any other "social animal. All apes also share a unique dentition of 2 incisors, 1 canine, 2 premolars, and 3 molars in each quarter of the mouth. In most cases, the canine is reduced, almost useless as a cynodont tooth. And the molars are also unique in all the animal kingdom. Every ape has them, and only apes have them. Each molar comes to five points interrupted by a Y-shaped crevasse. If you want to know what that looks like, go to a mirror and open your mouth real wide.
When you do that, also look at the dome-shape in the roof of your mouth. Therein lies the only significant difference between humans and the other apes that are still alive. That shape, that bit of space above the tongue that the other apes don't have, is what allows us to form the words which they can't speak.
They (we) all make and use tools out of whatever implements they think they can use. Bonobos, who are more closely-related to us than any other living species, engage in every sexual practice and perversity that humans frequently do. They even French kiss! In a sense, they are the lovers, not the fighters. Their sister species, the troglodytes, are the fighters! They are the only species besides our own who engage in the act of war by its truest definition. In all other animal societies, conflicts arise between individuals that remain between those individuals. Other society members may be spectators but will rarely become involved themselves. In chimpanzee society, it is different. A conflict between individuals can escalate to include their supporting factions, and these may join into the fight with fists and clubs or hurled projectiles. In another sense of war, chimpanzees may send out armed parties into more fruitful lands to drive out or kill whatever apes happen to already live there. So even in matters of love and war, (both long considered to be difinitively human) we are still not unique among the other apes.
Additional characteristics (not necessarily unique to primates) include a first toe with a nail, while other digits bear either nails or claws depending on their phylogeny. The stomach is relatively simple in most forms. There is also a tendency towards reduction of the olfactory region of the brain and another expansion of the cerebrum (especially the cerebral cortex), correlated with an increasing reliance on sight and increasingly complex social behavior. Source: University of Michigan department of Zoology
None of the other great apes can speak because of that little extra space in the mouth which only we possess. But other apes are all capable of complex communication either by their own body language in addition to grunts and squeals with particular meanings, or by learned forms of sign language or symbols taught to them. Koko the gorilla is the most famous of the articulate signing non-human apes. Washoe the chimpanzee and Chantek the orangutan are other famous examples, and of course there are many more around the world who are not so well-known. These beings definitely aren't just mimicking their owners, nor are they "trained" to appear as if they really know what they're saying. This is no stupid pet trick. All of them have been repeatedly proven to possess sufficient cognitive skills and comprehension of the meanings of their words, and they may know more than a thousand of them. And they all use these words to express personal feelings, love and compassion, and all of them grieve for their loved ones who have died. One of them, Michael, Koko's life mate, even remembered his mother being killed on the day he was captured. Upon his death, one of Koko's human visitors told her that Mike was now an angel, to which the grieving gorilla responded "Imagine".
They're not as intelligent as we are because our frontal lobes are larger than any of theirs. But they are definitely intelligent, even sentient beings. Even among the smartest creatures on earth, we are still the smartest by far. But we are not so unique, nor so far above them that we are not still one of them.
In the 1700s, Carolus Linnaeus did an in-depth character analysis of thousands of life forms, and devised the first system of taxonomic classification which is still in popular use today. When he came to humans, he encountered a quandary. Without any knowledge of molecular biology, he concluded that there were several species of humans. He basically divided humanity up by thier continent of residence, and declared them all different subspecies based on thier racial characteristics, which today of course, we know they are not. Some isolated peoples probably could have become more distinct if left isolated long enough. But that's not what happened. Increases in technology and international interrelations have put a stop to that. But one of Linnaeus' human species did turn out to be separate; Homo troglodytes, what we now know as Pan troglodyte, commonly known as the chimpanzee.
The mostly-creationist pre-Darwinian scientific community of the 18th Century reacted harshly to Linnaeus' system, and deliberately restructured taxonomy so that chimpanzees, gorillas, and orangutans would appear to be in their own genus, (Pongo) separate from men, whom they wished to keep completely apart from all other animals as much as possible, even though it was already known that chimpanzees and even gorillas were more like men than either were like orangutans. Linnaeus was a Christian and a creationist himself. But he was also a scientist with first-hand experience of evidence that didn't fit his own system of beliefs. In a letter to his friend and colleague, J. G. Gmelin, Linnaeus expressed his frustration with his peers and their religiously-motivated reclassification.
"I demand of you, and of the whole world, that you show me a generic character ... by which to distinguish between Man and Ape. I myself most assuredly know of none. I wish somebody would indicate one to me. But, if I had called man an ape, or vice versa, I would have fallen under the ban of all ecclesiastics. It may be that as a naturalist I ought to have done so."
--Carolus Linnaeus, February 14, 1747
For more than 200 years, extant non-human "great" apes were collectively considered pongids, and the word, "hominid' had to be devised to explain the fossil "humanoids" we started digging up in the interim. The Pongid classification strained to keep "apes" and humans separate in the presence of all these new discoveries of fossilized "ape-men", and particularly fossilized non-humanoid apes, especially since "lesser apes" made "great apes" a contradiction if their own extinct intermediate ancestors weren't considered apes as well. But just in the last decade, molecular evidence has finally vindicated Linnaeus' case, and cleared up all this confusion by discrediting the old notions of men and apes, by replacing that with men are apes -the same way that lions are cats and ducks are birds. Based on genomic sequencing, Pongidae and Hominidae had to be restructured again, to correct the error which everyone had already known was wrong for centuries.
Consequently, the Linnaean taxon, Hominidae has been elevated from a genus to a family in all publications that are both current and still favoring the Linnaean system. Pongidae is now one of several genera within that family, and includes only orangutans and their extinct relatives like Sivapithecus and gigantopithecus. The seven surviving species of gorilla are now their own genus, and are believed by some to have begun with Sahalanthropus tchadensis some six million years ago. Chimpanzees, (bonobos and troglodytes) are another hominid genus called Pan. They're still not human, but they're all humanoid; they're all Hominids.
Just look how human-like these ape babies appear to be -and how beastial their parents are.
Since the days of Darwin and Haeckel's study of embryology, it was known that the offspring of two closely-related species will resemble each other more than the parents do. Its a sort of evolutionary parallel illustrated in one life time that two beings should be so similar in the beginning and diverge so much as time wears on. Phylogenetics has revived these earlier observations in a new field of study called "Evo-Devo", short for "evolutionary development" where ancestral phylogeny appears to be repeated in some illustrative way over a single lifetime.
One subset of Hominidae is Hominini, (also known as humanoids) exclusively bi-pedal great apes.
The taxonomic tribe, Hominini (upright-walking humanoids) are the beings formerly referred to as "hominids", and commonly known as "ape-men". Excluding only Oreopithecus bombolli, (who was also a bi-ped, but not part of human ancestry), this clade includes all other apes known to walk on two legs, and who are believed to be in the human family tree. Their (our) line begins with Ardipithecus ramidus about six million years ago, roughly the same time as the gorilla and chimpanzee lineages also diverged from common forms like Dryopithecus, -and then lead to Australopithecus afarensis, AKA "Lucy", of which some 300 individuals have been found so far. There are also many others known from at least three other associated species, A. africanus, A. anamensis, and A. garhi. And another line referred to Kenyanthropus, which is also believed by many to be directly ancestral to humans. From there, Hominini diverges into two main groups, the gracile Australopithecines, and the robust Australopithecines, also known as Paranthropines; Paranthropus robustus, P. boisei, & P. aethiopicus. Paranthropines lived alongside early humans for many hundreds of thousands of years. But some of the gracile Australopithecines (possibly including Kenyanthropus) actually became the first humans.
There is some debate as to which ones were truly different species, and whether Paranthropines should be called Australopithecines, and even whether other Australopithecines should bare a new monophyletic name. But all of these were certainly bi-pedal apes more closely-related to early humans than to any chimpanzee.
The top row of skulls belong to a modern gorilla, chimpanzee, orangutan, and something else from the fossil record which may be ancestral to both chimpanzees and humans. The bottom row of skulls are hotly-debated but generally all considered to be human. Those trying to deny any evolutionary ancestry for mankind insist that a couple of these be "100% human" and the rest be "100% ape" -even though they can't agree on which ones belong "completely" in which artificially-separated group.
There was once a "missing link" in the evolution of modern humans from familiar ape forms. That gap could be represented by the absence of the 3rd, 4th, & 5th figures in the animation above. And we once had only a scant few fossil fragments of any our anient "hominid" ancestors we knew of by that point. But since Australopithecus afarensis, was finally discovered in 1974, we've found the other links too, and even more than that, such that there are no more gaps apparent in our lineage anymore The fossil record of human evolution is now more fluid than the animation above, and that record includes several nearly complete skeletons.
It would be impossible to find fossilized remains for every individual who ever died, because fossils only occur when conditions are just right. Finding a 100% complete skeleton for any of them would be impossible too, unless it was buried in a casket. Larger animals fossilze easier, and are easier to find. Yet throughout most of the 20th century, only a half-dozen T-Rex had ever been found, and only one of those finds had a skull to go with the body. All the other museum displays had to use a plaster casts of that one skull. But we know that all of them had to have heads, and we know that there had to be more than a dozen of them alive at one time. So whatever we find in the fossil record only ever represents a fraction of whatever that population really was. And we now have the fossil remains of thousands of individuals of no-longer-missing links in the evolution of humans from non-human apes.
Traditionally, evolutionary scientists always said that men did not evolve from apes, and apes did not evolve from monkeys. What they meant was that Homo sapiens sapiens did not evolve from any 'modern' ape species, like chimpanzees, and that the ancestors of both men and chimps did not evolve from any species of Cercopithecid monkey living or extinct. And that is correct. But then we had to re-evaluate exactly what an ape was, and what a monkey was, given volumes of evidence from the fossil record. It turns out that the ancestor of humans and robust australopiths, as well as the ancestors or australopiths and chimpanzees, chimpanzees and gorillas, etc. -was an ape by definition, albeit not any kind of knuckle-walking one such as one might expect. Because the ancestor of both lesser apes and great apes would logically have to be an ape of some sort itself. Also any common ancestor of both cercopithecid monkeys and the entire ape collective would logically have to be an Old World monkey too. A lot of evolutionary scientists still today insist that the word, "monkey" cannot include apes, and the reason they say this is because they think all the Old World monkeys, apart from apes, are in the Cercopithecid family. But they're forgetting Propliopithecoidea, an ancient lineage which are universally agreed to be Old World "monkeys" and believed to have begat both modern subsets. Not only that, but obviously the common ancestor of both Old World monkeys and New World monkeys would logically have to be a monkey too, and that lineage is a paraphyletic grouping of Parapithecids, which again are universally accepted by primatologists as "monkeys".
So in fact humans did evolve from apes, and are still apes now. And apes did evolve from monkeys, and are still monkeys now.
Everything about these early hominines is transitional from the relative sizes of their brains to the location of their brain stem, which is at the bottom of the balanced skull, forcing it to move bipedally. But so are the knees and pelvic region definitely bipedal, and adapted from an originally quadrupedal structure, which is one explanation for why so many people develop lower back problems.
One subset of Homini is Homo, (humans) bi-pedal apes with enormous brains
While it may be a bit difficult to determine exactly who is or isn't "truly" human, the genus, Homo (humans) began with either Homo habilis or Homo rudolfensis, both of which are very similar to each other, and both retain several features from Australopiths that aren't still present in later humans. Were they still around, there would be little doubt we would be capable ot interbreeding with them. Both of these latter "species" were definitely human, even if not "fully" human in some people's opinions. If you saw them sitting on a pew in your church, you would consider them "ape-men". But if you saw in them in their own world, you would have seen them as nothing less than men. Very simple primitives, certainly, but unquestionably human none the less.
Homo habilis and Homo rudolfensis were tool makers beyond the capacity of any non-human ape, extinct or extant. The next significant stage beyond them was Homo erectus, who was the first human species known to make and use fire. They also had the capacity for speech. And their brains, through small for the average modern man, were still often well within in the range of modern humans. They could be as smart as some of us are today, even though their sloping foreheads and jutting brows may still give the initial impression of a "dumb" ape.
One subset of Homo is our species, Homo sapiens sapiens, modern man
This clearly "ape" skull belongs to the mother [species] of all neandertals, hobbits, and modern men. So far, we've found fossils for more than a couple hundred individuals from this one species alone. This sloping forehead and jutting brow are no freak individual occurrence, but appear common to the lot of them for at least several tens of thousands of years. This is very definitely an ape, and certainly a member of every last clade this site described which lead up to apes, but with a brain much too big not to be human too.
The only reason anyone objects to evolution is for religious reasons, and the only religious reason is
to defend a literal interpretation of dogma which cannot be literally interpreted and still be considered 'truth'.
There is no evidence from any source anywhere to indicate any separate origin of humans apart from all other life-forms. Instead, literally everything we know about anything at all from any relevant field of scientific study ever all overwhelmingly demands that this creature called man is a really big monkey and a brilliant ape
who shares common ancestors with every other living thing on Earth.
That's why man belongs to every clade in this list.
I mean, is there any other explanation for all of this?
"Humans differ from both common chimps and bonobos in about 1.6% of DNA, and share 98.4%. Gorillas differ somewhat more, by about 2.3%, from us and from both of the chimps. Humans differ from orangutans by 3.6% of DNA, and from gibbons and siamangs by 5%."
--Diamond, Jared. "The Third Chimpanzee," in The Great Ape Project.
New York : St. Martin's Press, 1993. Pp. 94-95. (as quoted by Primates.com)
Homo erectus had a range of brain sizes where the largest of their brains overlapped that of what would be considered small brains in modern humans. But they greatly improved the tools and technology of their forefathers, and were the first race harness fire. They were the first humans with the anatomical ability to articulate an entirely verbal language.