At first, our ancestors were bacteria. Then - fish. Then - fishes with legs. Then - "lizards". Then - "mice". Then - "proteins". Then it started. How did our ancestors evolve from the ancient fish? Let's tell.
Picaia lived 530 million years ago in the ocean in what is now Canada. The dimensions of her body were frankly not impressive - from 1.5 to six centimeters, an average of four centimeters. The body of the "relative" was elongated, compressed from the sides, the head was small, indistinct - with two tentacles, similar to the horns of a snail. They probably played the role of organs of touch.
The appendages branched behind the head, which are interpreted by scientists as a very strange formation - external gills. But the main thing is that a dense longitudinal cord, called the "dorsal organ", stretched along the back of the pikaya. A chord was located under it, and the heavy itself was a kind of substitute for the latter.
Since only a tiny fraction of all extinct animals remain in the fossil form, the discovery of the direct ancestor of man (like any other living creature) tends catastrophically to zero. Scientists find only very close relatives of the "transitional form", which by default is considered a distant ancestor. So the pikaya is only a pretender to the role of great-grandmother, a creature that is probably extremely similar to her.
And the pikaya also had a neural tube - the rudiments of the nervous system, but a different species had real gills and eyes - Haikouichthys ercaicunensis, which inhabited the territory of present-day China 530-535 million years ago. However, there are suggestions that the first photoreceptors - the rudiments of future eyes - arose in the Precambrian era, in Ediacaran creatures.
However, what does all this little thing have to do with a person? Almost as straight as our spine. The fact is that the chord performed approximately the same function in our ancestors - support for the body. Well, I would have performed further, why did you need a solid spine? Chordates turned out to be successful players in the evolutionary race: they did not need to shed their shells as the ancestors of arthropods (and therefore become extremely vulnerable during molting), and they were probably a little more agile when meeting a predator than a “soft creature”.
They had one thing to do - to progress and grow larger. Consequently, to acquire a new metabolism, in which calcium and phosphorus play an important role. One problem is that things are in short supply, so it would be nice not only to consume them, but also to store them. And the chordates were stocking up. Calcium and phosphorus began to form in their bodies something like the first teeth (with their help, by the way, you can grab someone by the fleshy part yourself) and cartilage, with which their chord began to grow. This is how the cartilaginous spine appeared, followed by the bony spine.
Where did the chord go? Not gone, but gone: we also have a chord. We are, just like the pikaya in the Cambrian ocean, splashing in the mother's womb. Alas! In this idyllic time, we have to put an end to the past forever - our chord, like that of the sea forefathers, gradually atrophies, and a spine is formed around it. However, there is no need to feel nostalgic.
Something of the chord remains. You will feel it if you hurt your back. You are attacked by an internal pikaya - the remnants of the chord, a jelly-like substance that will come out of the spinal disc and, causing terrible pain, will begin to take revenge. You can't be so negligent about one of the oldest parts of our body - the spine.
Arandaspis, coelacanth and tiktaalik: inside out skeleton and fins
Arandaspis is a cross between pikaya and fish.These creatures reached 35 centimeters in length (but on average - 12-14 centimeters) and are considered the oldest vertebrates, which already had a mineralized skeleton. Their remains have been found in Australia, South America and the Arabian Peninsula and date back to 470-480 million years. Arandaspids resembled a little more fish than their worm-like ancestors, but of all the fins they had only one - the caudal.
But on their heads they wore a "kokoshnik" - a carapace, consisting of many scales and turning into the back. Under the head, from the side of the belly, there was also a small and thin carapace shield, but the tail remained mobile - in order to escape from malicious predators. For example, from the nautiloids, some species of which, together with their shells, reached 9.5 meters in length.
The arandaspids had ten pairs of gill sacs, which opened outward with holes located between small polygonal plates. And also small plates flaunted on the lower side of the mouth. This is how the ancestors of the teeth looked. But the arandaspis did not have the jaws themselves. Their mouth was arranged like that of modern river lampreys (also, by the way, very primitive creatures from those times): a round hole that sucks in everything from the bottom.
This under-hollow already had normally formed eyes and nostrils between them. The exoskeleton of the arandaspis was well developed, but the endoskeleton (what was inside) either was not there at all, or it was extremely poorly developed. Thus, these creatures, like canned food, had only an outer protective shell, and inside were soft, like insects and shells.
It happened on a hot summer day on December 22, 1938, off the South African coast of the Indian Ocean. The Irwin & Johnson fishermen retrieved a sea monster from their nets. It weighed 57.5 kilograms, reached 1.5 meters in length, shone blue, bent and snapped its jaws viciously. It was a fish and not a fish at the same time. She possessed large and very strong scales and … legs. More precisely, their rudiments. In total - seven pieces, including on the back and in the head area. There were fins at the end of the "legs". In general, the monster turned out to be truly wonderful.
An employee of the East London Museum (South Africa), Marjorie Cortenay-Latimer, who arrived at the scene, somehow persuaded the driver to load the creature into a taxi (in the African heat, the fish began to die out) and take it to the museum. It only remained to figure out what to do with this "cthulhu" and how to store it. With such a question, the woman came to the chairman of the museum, Bruce-Bays, but he only grinned: "You all think ugly ducklings are swans." However, he allowed to make a stuffed animal. And Cortenet-Latimer, meanwhile, sent a letter to a friend of ichthyologist James Smith, and he immediately suspected something was wrong (as it turned out later, he was not mistaken): there was an animal in the picture that became extinct 70 million years ago!
And not just extinct, but considered an early transitional form from fish to amphibians - the coelacanth, which belongs to the lobe-finned fish. And a vivid example of such a "transition" - limbs, or rather, their rudiments. It is these fin-tipped processes that will become our hands and feet in the future. With the help of such fin-legs, the descendants of coelacanths will get out of the water in order to master the inhospitable land.
The fish was named coelacanth, after Miss Latimer. The second copy was caught only in 1952, and in 2006 it was filmed. Today these fish are found quite often. They live at a depth of about 100 meters off the coast of Mozambique and South Africa. Interestingly, the movement of fins in coelacanths occurs in the same order as in most terrestrial vertebrates: first, a pair of pectoral and abdominal fins move in an opposed order (sometimes left, then right), and then the right pectoral and left ventral fins. By the way, do you know why we move our hands when we walk? Our brain and body are thus trying to "carry out" a four-legged gait.
But this story took place in 2004 on the northernmost island of Canada - Ellesmere.The fossilized remains of a flat-headed creature with eyes on the crown and limbs with fins were discovered by American paleontologists Edward Deschler, Neil Shubin and Farish Jenkins. Expressing their respect to the local aksakals, they asked the council of local elders to come up with a name for the "flat-faced". And they came up with: tiktaalik, which in translation from the Eskimo means "large freshwater fish."
You look at it from one side - and the truth is a fish like a fish (it has gills and scales), and from the other - no, no, an amphibian (here are the ribs, here are the movable neck, and here are the lungs). This is because tiktaalik is a transitional link between them. The link lived 375 million years ago and was one of the first creatures to climb onto land. The emergence of tiktaalik on the world scientific scene was carried out under the spotlight. And overshadowed the later discoveries of similar creatures. Panderichthys rhombolepis or Elpistostege watsoni, for example, lived even earlier than him.
Just 385-375 million years ago, the Devonian fish burst through: they rushed to unknown shores. The muse of distant wanderings attracted our ancestors, but even more - a bunch of goodies like scorpions and the first insects crawling in pristine forests. "On land!" they called. "On land!" - echoed them by decomposers - bacteria and fungi, which, although they destroyed the dead remnants of forests, were still in short supply in those wild times.
Therefore, trees, which, among other things, had a poorly developed root system in those days, fell into shallow freshwater seas and rotted badly. The fish were getting cramped. And it's stuffy. Therefore, they probably have lungs. But where did the gills go? Nowhere. The fact is that in the hottest epoch in the history of the Earth - all in the same Devonian period - shallow bodies of water probably dried up regularly (add to this the fact that warm water does not dissolve oxygen well).
Therefore, the fish were forced to "invent" lungs, which replaced their gills when the water went into the sand (although there is a version that the lungs arose on the basis of the gills). By the way, the neck, apparently, appeared at the same time: so that the unfortunate ancestors, squelching in the drying mud, could reach up and gasp for air. Both the lungs and the cervical spine were in the tiktaalik.
In less than ten million years, ichthyostegaliae, the first amphibians, from which reptiles will later arise, and from them, very later, mammals, will slap across the Devonian swamps. But more on that later, but for now we return to our limbs - arms and legs. Yes, the master plan of our limbs was already developed then - in the days of tiktaalik and the first amphibians. What did he look like?
Much the same as in vertebrates today: the limbs begin with one large bone (today we call these bones the humerus and femur). Behind them are more graceful paired ones (in some animals, now fused) - ray, ulnar and tibia, tibia. And only then - small bones of the wrist or ankle and bones of the fingers. In typical fish, the skeleton looks different: at the base of their fins - from four bones or more.
And also as a memory, our reptile Eve (tiktaalik and others like him) left us the number of fingers. So we can wave her back to the past - with all fives. And frogs too, although they have only four toes on their front paws - the fifth has simply been reduced over millions of years (that's another thing: the snakes have completely lost their limbs). But it could have been different. This text could be typed not by ten, but, for example, 16 fingers (which would probably be much more convenient), like Acanthoostega gunnari, which had eight of them on each front paw.
But fate decreed otherwise - we all descended from a five-fingered relative. Anthropologist Stanislav Drobyshevsky considers this to be a coincidence, not a tricky adaptive decision. "Who knows, if we were the great-grandchildren of an eight-fingered acanthostega, maybe skillful hands would have appeared earlier?" - he reflects in his book “The Reaching Link. Monkeys and everything, everything, everything."
Do you want to see more ancestors, looking in the mirror in the morning? Please.Put your hands down, relax, turn your palms back. Your ulna and radius will be located crosswise, although it would seem more logical if they were parallel, as on the legs. It's just that a beast-like reptile (the ancestor of a mammal) has appeared in front of you.
At the very moment when she "turned" her hands forward to make her gait more confident. After all, the first terrestrial tetrapods literally crawled vraskoryachku - on paws spread out to the side. So the ulna and radius bones did not intersect at that time, and the hands stuck out to the side - approximately like in today's reptiles. By turning the hands, the ancestors of mammals could no longer swap the bones in the forearms - they had to cross them.
In general, a biology textbook is, in fact, a history book. Stories of life on Earth. Take at least embryos. Everyone knows that the embryos of all vertebrates are similar - one comparative picture tells about millions of years of evolution. But let's get down to the details. With limbs and lungs - it is understandable, but why does a terrestrial animal need gills? After all, we also had them when our height did not exceed eight to ten millimeters. However, these are not really gills, but gill arches. In fish, they calmly turn into a respiratory organ, and in vertebrates, they go through a thorny path to become jaws and many other parts of the head, neck and upper body. How does this happen?
The transformation of the branchial arches is entangled like quantum states. The first terrestrial vertebrates passed this way for a long and difficult time. But the result was worth it: with the help of the jaws, the animals learned to bite through the strong shells of especially stubborn arthropods, with the help of the hearing organs - to hear the one who wants to eat them, turn their heads, and some even frown and smile.
From the upper half of the first arch, the upper jaw was formed, from the middle part - the auditory bones, malleus and incus, - from the lower half of the arch - the lower jaw. The upper half of the second arch gave us the smallest bone of our body - the stapes, and at the same time the styloid process of the temporal bone, the lower half - the upper part of the hyoid bone. For its lower part, one must thank the third branchial arch. For the cartilage of the larynx - the fourth and fifth.
And that's not counting a bunch of other body elements - the tongue, tonsils, thymus, Eustachian tube, and so on. By the way, about the latter. The Eustachian tube is the only branchial cleft that has not overgrown in our country (the tympanic membrane, which blocks the way to the ear, does not count - it is too thin), playing the role of a pressure equalizer in the middle ear and bringing it into line with the outer one. You can learn more about the structure of the bones of the human facial skull here.
Gilonomus and cynodont: lizard and beast
Gilonomus is a tiny lizard 20 centimeters long (including its tail), the remains of which were first discovered back in the middle of the 19th century by the Canadian geologist John Dawson. This lizard (more precisely, a creature very similar to it) is considered the oldest known reptile - it lived 312-315 million years ago. Catches up with her in the race for the right to be called the first reptile Paleothyris acadiana - the same small "lizard" that lived from 304 to 312 million years ago.
But how were these ugly creatures so different? Its independence from water. How did they do it? They have grown an amnion - an individual "pool" for the embryo. After all, it is known that amphibians lay eggs in water, so they have no right to move far from the latter. Eggs need moisture, otherwise they will simply dry out. You can, of course, carry eggs in your own back, as does the terrible dream of all trypophobes - the Surinamese pipa - but this is inconvenient and unaesthetic. Better to invent live birth, but in those days it was too difficult. Therefore, we had to find an evolutionary compromise - to learn how to lay eggs.
But why such excesses? For food. In the Carboniferous, plants conquered land more and more, which means that insects also conquered it more and more. Often gigantic.The atmosphere in those days was different from the modern one and was extremely saturated with oxygen, which is why all kinds of chitinous creatures grew by leaps and bounds. Take, for example, the giant dragonfly mega-neura, whose wingspan reached 65 centimeters, or the one and a half meter centipede arthropleura.
All this yummy fluttered and crawled happily in the middle of the Cambrian forests, and there were many competitors in the water - how can you not rush in search of adventure on an unknown, but so alluring land! This is how amniotes appeared - creatures from which dinosaurs (including birds), reptiles and mammals will descend in the future. And a group of amphibians will remain forever tied to water.
Now we have before us an amazing creature - either an animal or a lizard. In fact, both. Cynodonts is a group of creatures that still laid eggs, like reptiles (modern animals like prochidnas and platypuses, by the way, continue to do this, therefore they are considered primitive mammals), but were already covered with wool, like animals. And they already, finally, could boast of at least some impressive size: some types of cynodonts grew up to two meters in length and were distinguished by a massive physique.
And they also had differentiated, that is, different from each other, teeth. The latter were divided into classes, like ours: the front, as a rule, were smaller than the back, there were canines and chewing or cutting teeth. However, the heterodont dental system appeared even before the cynodonts - in the first animal-like reptiles. Thanks to the appearance of bite and classes of teeth, they have also already learned to chew, and not just tear apart prey, as, for example, modern crocodiles, which have remained reptiles, do.
But why chew food thoroughly at all? If this is not done, food enters the stomach in huge chunks and is absorbed much more slowly, therefore the animals themselves are forced to remain slightly "inhibited" (which cannot be said about the ability of crocodiles to quickly grab food, of course). In addition, the lack of chewing leads to the fact that part of the food itself is inevitably lost. With the help of the heterodontic system and the bite, the animals coped with this problem with dignity, increasing the digestibility of food resources, and were able to speed up their metabolism.
The one with the larger one moves faster, which means that he can more quickly overtake the prey or, conversely, escape from the predator. But it was still necessary to preserve the heat produced by the body. The late cynodonts coped with this task, having acquired wool, which in millions of years will become our hair. Reptile scales became the basis of wool (like feathers in birds). However, these disbeliefs ran not very well yet, since their hind limbs remained primitive - like those of reptiles - and, as it were, pressed to the ground.
But the reptiles themselves progressed: some dinosaurs, for example, stood on two legs and began to develop a very decent speed, and shamelessly increase in size. Our ancestors were left with the fate of a gray mouse - in the literal sense: they became smaller, more inconspicuous, hid in holes and ate what they had to. However, cynodonts were not yet mammals.
Mammals appeared in the Triassic (although there is an assumption that this happened already in the Permian period) and their main difference was the feeding of young with milk. Originally mammary glands arose from sweat, so the first mammals did not have nipples, and they probably just "sweated" milk, like modern platypuses and echidnas, whose young simply lick it off the mother's belly. And in mammals, the ribs that protected the abdomen disappeared (only the chest ribs remained, like ours). This is understandable: with such a "shell" it is difficult to be agile, bend and dive into holes from predators.
The features of our vision originate from about the same time.The fact is that dinosaurs were daytime predators, so mammals had no choice but to become nocturnal: to escape from evil lizards and not compete with them. But at night, colorful vision is unnecessary, so since then most mammals see combinations of only two colors.
This vision is called dichromatic. True, in primates, including humans, in the process of evolution, vision has become more complicated, becoming trichromatic: we see combinations of three colors (probably, this happened also because our ancestors needed to determine the ripeness of fruits). But where do we go to the existing dinosaurs - birds! Their vision has remained tetrachromatic, and their world is much more picturesque than ours. But mammals have another trump card - the sense of smell. By the way, it was from the olfactory lobes of the brain that the large hemispheres subsequently developed, which are responsible for our intelligence.
Juramaya and Purgatorius: Mouse Eve and Squirrel with a Secret
This rat-like genus of creatures revealed to the world the first placental mammals that lived from 167.7 to 150.8 million years ago. By the way, Yuramaya is translated from Latin - "Jurassic mother". True, she looks a little like the canonical Eve: small, nondescript, mustachioed and with a tail. All in all, a rat-rat, but with a lot of potential.
This is the first known mammal to have grown a placenta (by the way, other living creatures had and still have analogues of it, for example, the worm-like onychophores that appeared at the end of the Precambrian, some species of sharks and even plants). But the mammalian placenta is the most complexly arranged, it allows you to grow a full-fledged fetus (and not the same as, say, in marsupials), however, it complicates childbirth with abundant blood loss to the mother. But what can you not do for the sake of the bright future of the descendants!
This creature also resembles either a mouse or a squirrel, nevertheless, it is considered the first known primate. By the way, the word “primacy” itself means “the first, the highest”. However, not quite a primate yet - the animal belongs to primatoforms, creatures whose features are very similar to primates. This tiny "squirrel" 10-15 cm in length and with a brain weight of 1 gram is our most ancient common ancestor with all primates. The ancestor's name was Purgatorius and he lived 66-56 million years ago.
And no wonder. By this time, flowering plants had already appeared on Earth, which gave the world nectar, juicy fruits, fragrant flowers, and, therefore, flocks of insects. All this delicious and buzzing menu had to be eaten by someone. This someone became the primatomorphs. For this, they even learned not only to actively climb trees, but also to jump. Primatomorphs turned out to be real lively ones, and not only in terms of agility - they learned to survive well: their size was small and it was easy for them to hide among the branches and thick grass (which had also appeared by that time).
They ate, as we found out, in fact, everyone (this feature has been preserved with us to this day), so they were unpretentious in their menu and could cope with difficulties in a crisis situation. Not like the proud dinosaur giants, which by that time were just actively dying out. By the way, if this had not happened, it is unlikely that primatomorphs, like most mammals, would have a chance for development, especially the one that Homo sapience reached.
Omnivorousness also contributed to the development of intelligence - puragtorius and creatures like them constantly had to remember when fruits ripen, when insects are more active, and when not. As for jumping ability, proteins are also known to be capable of this. Only they jump differently. Squirrels and other rodents move from tree to tree, descending to the ground or gently jumping over closely spaced branches.
The Purgatorius were much more desperate - they jumped far greater distances and probably didn't need to descend to the ground like modern primates. Such dashing jumps developed the vestibular apparatus of our ancestors, which stimulated the development of neural connections in the brain.And yes, eye contact. In squirrels, they are located on the sides, as in purgatorius.
But in order to actively jump in trees and look into the distance, it is better to have eyes not on the sides of the head, but in front. So our eyes began to approach each other. But the potential of these little nimble creatures was not exhausted by this. Another acquisition of those times was the grasping brush, because only with its help you can tenaciously hold on to branches (not only for adults, but also for cubs, which, in turn, hold onto the mother's fur while jumping). For 2 million years after the death of the dinosaurs, primatomorphs became the most successful group of mammals on the planet. They did not have serious enemies until large birds of prey appeared.
Millions of years after the primatomorphs, the "design" of the eyes has undergone a change. A squirrel or horse does not really need to rotate its eyes in different directions - the view of such animals sometimes covers almost 360 degrees around it, because their eyes are located on the sides. Primates, on the other hand, in order to assess what was happening and rotate their eyes in all directions, had to reduce the corneas, which made the sclera or simply protein visible. More precisely, it can only be called a protein in humans: chimpanzees and gorillas, for example, also have a sclera, it's just much darker than ours, so it often feels like the entire space of the eye is occupied by the pupil and iris.
The same effect can be observed in most mammals that have acquired binocular vision - the ability to simultaneously and clearly see an image of an object with both eyes. For example, predators have become such animals, because it is important for them not so much to notice what is happening around as to estimate the distance to the prey. The sclera of a domestic cat are also light, but not white, like ours, but yellow, blue or green.
Why did our ancestors need such bright sclera, which stood out very much against the background of black irises and pupils (scientists believe that the light iris of the eyes appeared in people by historical standards quite recently, and before that it was dark brown, since our ancestors were dark-skinned and dark-haired)? Probably in order to better understand each other and read the non-verbal gestures of fellow tribesmen. This is useful, for example, for effective hunting, when you need to sit in ambush and show something to your fellows not with sounds and active gestures, but with facial expressions.
It is interesting, however, that in great apes, the sclera, in fact, also exhibit great contrast. It's just that their "proteins" are often, on the contrary, much darker than the iris. That is, there is a significant contrast in them, just their eyes are significantly smaller than in humans. Perhaps this is due to the fact that our ancestors, like us, need to read more communications with each other than gorillas and chimpanzees.
Architsebus and Egyptopithecus: cute relatives
Some people regret that humans descended from monkeys and not from seals. Especially for them, evolution 54-55 million years ago "invented" archicebus - a small animal weighing 20-30 grams, with a body of only about 7 cm, a small cute muzzle and a very long tail - 13 cm. This creature resembles modern tarsiers to the extreme. However, it belongs to the tarsiers, although it is considered the first of the found oldest true primates.
Interestingly, this baby could not only jump on the branches, like modern tarsiers, but also run on four legs, like real modern monkeys. Architsebus is none other than a transitional form between semi-monkeys ("wet-nosed" primates) and monkeys (in modern science, this suborder from the order of primates is called "dry-nosed" primates; monkeys are an outdated, but familiar term to everyone), as such.
The change in the shape of our nose also begins with the tarsus ancestors. Semi-monkeys have a leathery nose with a strong base of cartilage, which is also fused to the upper lip. The monkey's nose literally stands "apart" on the face, just like ours - on the face.Among other things, this was probably facilitated by the reduction of smell - compared to other mammals, primates increasingly focused on sight, rather than scent. And the separation of the nose from the mouth, in turn, contributed to a better development of facial expressions - the muscles of the upper lip were able to move more freely in all directions, which contributed to the further development of the communication skills of primates.
But this creature really looks like a small monkey in the form in which contemporaries are used to representing it. This is Egyptopithecus (its remains were found in Egypt) - an extinct genus of early narrow-nosed monkeys (they are also called the monkeys of the Old World) - the very ones to which modern monkeys and hominoids belong: gorillas, chimpanzees, orangutans and us (and also completely extinct parapithecus monkeys). The main distinguishing feature of the narrow-nosed (except for fat bodies) is a narrow nasal septum, and nostrils facing down (in wide-nosed ones, both the nose is larger and the nostrils are directed forward).
Previously, it was believed that broad-nosed relatives (monkeys of the New World: marmosets, tamarins, capuchins and others) from this moment will go their own way and in the future will populate both America. But later it turned out that Egyptopithecus was probably a relative of both. Although the latter is in question. But the fact that he is the ancestor of the narrow-nosed no doubts.
Egypopithecus lived 28-33 million years ago and weighed much more decently compared to its tarsier relatives - about 6 kg, although it had a "cat" brain size - about 30 grams. Probably, the enlargement of the body went as a strategy of defense against advanced predators, which became more and more after the era of the dinosaurs.
And Egyptopithecus also had a large snout and a long tail, ate plant foods and led a diurnal lifestyle. All these traits are characteristic of the narrow-nosed monkeys. And yes, in Egyptopithecus, obvious sexual dimorphism is already noticeable, when males are quite different from females - they are larger and stronger. But sexual dimorphism is one of the characteristic features of a developed social structure (if we are not talking about such complex communities as in modern people).
Saadanius and the proconsul: goodbye, monkey and orangutan
Narrow-nosed monkeys, as we have already said, are divided into hominoids and monkeys. And Saadanius is the last goodbye to the last. His remains were found on the territory of Saudi Arabia, and in Arabic "saadan" - a monkey. And this monkey was already much larger than a cat - the size of a baboon and weighed 15-20 kg. The creature lived in a moist warm forest 29-28 million years ago. It marks the separation of monkeys from hominoids. It seems that this is the last ancestor that had the traits of both. Separation from monkeys, as scientists assume, will occur soon after the appearance of Saadanius. Subsequent forefathers will finally part with their "monkey" past.
It seems to be the last ancestor that had the traits of both. On the one hand, Saadanius has common features of narrow-nosed monkeys (for example, similar teeth), on the other, its individual features are very difficult to classify in order to understand who is in front of us - a monkey or a hominoid. Although the features of the latter, if desired, can still be found - this is the structure of the ecotympanic, the "drum plate", that is, the bone, which belongs to the hearing aid.
In hominoids, this plate grows to the temporal bone, in other narrow-nosed ones, it is independent. In this regard, scientists have concluded that Saadanius is a creature that preceded the divergence of signs of the primates of the Old World. Paleoanthropologists believe that separation from monkeys took place shortly after the appearance of Saadanius. Subsequent forefathers will finally part with their "monkey" past.
The ways of naming ancient species are inscrutable. So it happened with the proconsul. When his remains were first found in 1909, the common name for circus chimpanzees was Consul.The name "proconsul" means only "before the consul", that is, a creature that lived before the appearance of the chimpanzee. Later, along with new findings, it turned out that proconsuls and related species existed not only before the appearance of chimpanzees, but also other great apes.
The proconsulid family included many now extinct species that lived from 15 to 27 million years ago. Representatives of the genus of proconsuls are considered the last common ancestors, separating humans, chimpanzees, gorillas and orangutans. After that, our paths with the orangutans will part forever.
In the structure of the proconsulids, all sorts of features characteristic of the lower narrow-nosed monkeys are still found: arms and legs approximately equal in length, a short external auditory canal, and others. At the same time, the proconsulids already had an enlarged brain in comparison with the rest of the monkeys, which allows them to be attributed to anthropoid. Although not all scientists agree with this. Meanwhile, these were already rather large animals, weighing from 10 to 40 kg.
And the proconsuls also lost their tail, although this may have happened even before they appeared. But the fact remains: such large animals no longer need a tail. With its help, it will still not be possible to stay on the branches, and communications (which the tail also serves) had already been replaced by more expressive facial expressions by that time.
By the way, on the underside of the tips of the tails of some monkeys there are the same papillary patterns as on our fingers (and the fingers of other monkeys), which once again proves that these patterns are associated with tree climbing: rough fingers provide a better grip on the branch, and later they were useful to our ancestors in order to better hold stones and make tools of labor out of them. Think about your inner proconsul when you shower - the patterns on your fingers will swell and become very rough. What do you think for what? It is correct that the grip on wet branches is even greater.
Nakalipitek: Goodbye Gorilla and Chimpanzee
But, sooner or later, the time has come to say goodbye to the last fellow hominoids - gorillas and chimpanzees. 8 million years ago, the ancestors of gorillas separated from our line, a little earlier - about 10 million years ago - the ancestors of chimpanzees. The key link in this separation was the nakalipithecus, whose appearance is still completely unknown: the finds are too fragmentary. But, most likely, Nakalipitecus moved on four limbs, climbed trees and ate seeds and nuts, as evidenced by a thick layer of enamel on the teeth.
And they found him on the territory of modern Kenya, more precisely, his jaw and teeth. The latter were covered with a thick layer of enamel, from which scientists concluded that the creature ate solid food like seeds and nuts. And scientists also believe that Nakalipithecus was similar to Uranopithecus, who lived 9, 6-8, 7 million years ago in northern Greece.
In the appearance of the latter, they fantasize about the appearance of the first. The Uranopithecus had a large and wide face with rectangular orbits of eyes, rather large body sizes and prominent canines in males (which indicates intraspecific aggression). But Ouranopithecus was not our ancestor, but the existence in Africa about 8 million years ago of Nakalypithecus and the like is another proof in the treasury of the African theory of the origin of man.
Sahelanthropus, orrorin and ardipithecus: who is erectus?
Perhaps the maximum number of copies has been broken about the remains of a Sahelanthropus that lived six to seven million years ago on the territory of the modern Republic of Chad. The main question that divided paleoanthropologists into two irreconcilable camps was whether the Sahelanthropus walked on two legs, or did he still run on four?
There are arguments, both in favor of one, and in favor of the other version. It is possible that the Sahelanthropus did not yet have a priority mode of travel. There is no final clarity as to whether the Sahelanthropus was our great-great-grandfather at all - perhaps he was a relative of gorillas.
But he already had a large brain - about 340-360 cubic centimeters, like in modern chimpanzees, or four times less than in humans.True, there is no final clarity about whether the Sahelanthropus was at all our great-great-grandfather - perhaps he was a relative of gorillas. So, the skull of the creature is elongated, which is more typical for monkeys, but the nape is also quite flattened and not very similar to the nape of a chimpanzee.
In general, the face combines both primitive and more or less advanced features - for example, weak nasal prognathism (forward jaw protrusion) and not very large canines.
At the same time, the teeth of the Sahelanthrope are similar to the teeth of all other anthropoid Miocene epochs, but they differ markedly from the teeth of other ancient hominoids. At the same time, some of the teeth of the Sahelanthropus are not at all similar to the teeth of our ancestors. The thickness of the enamel of the cheek teeth corresponds to intermediate values between chimpanzees and australopithecines. From which it is concluded that perhaps the Sahelanthropus was not our ancestor, but belonged to a closely related lineage to us.
The famous Tumai skull belongs to the Sahelanthropus. By the way, Tumay is the name given to children born before the dry season in the African Dyurab Desert. And in the local dialect it means "hope for life." Phylogenetic analyzes show that the Sahelanthropus belongs to our ancestors, but the fragmentation of the finds does not exclude the possibility that the creature could be representatives of a parallel line of anthropoid species.
When the remains of this creature (more precisely, several), who lived 6 million years ago, were found in Kenya in 2000, the media instantly dubbed him millenium man - "man of the millennium." In the local dialect, the word "orrorin" also sounds pretentious - "the first person". Most scientists consider him already definitely our ancestor, although there are those who doubt it.
The main reason for doubt, as in the case of the Sahelanthropus, is the upright posture of Orrorin. Did he walk on foot? If this is so, then, it seems, out of hand, or rather, out of "legs" very bad. Analysis of the femurs shows that Orrorin could not fully straighten his legs when walking, therefore, if he had bipedality, then his gait was clumsy and waddling.
What did Orrorin look like? It looks like a monkey. Although, for example, he had small teeth in relation to the size of his body. The creature had a rounded head and an elongated neck. Interestingly, some scientists believe that if Orrorin is our direct ancestor, Afar Australopithecines may turn out to be a lateral line. Because Orrorin, who lived 3 million before them, looks more like representatives of the genus Homo than Australopithecines. Thus, the femur of Orrorin is morphologically closer to sapiens than in Australopithecus Lucy. Although there are different opinions on this.
Ardipithecus lived 4, 4 million years ago and, probably, were already erect or close to this type of movement. They lived in forests, but already walked on the ground, although they did not lose their ability to deftly climb trees.
So, these creatures still had very long arms, reaching up to the knees, the big toe set far to the side, which retained the grasping ability, as well as curved phalanges of the fingers. Ardipithecus already weighed about 50 kg and had a height of about 1.2 meters. But the brain volume still remained at the level of chimpanzees and even less - 300-350 cubic centimeters.
“The upright walking of Ardipithecus is quite obvious, given the structure of its pelvis (combining, however, ape and human morphology) - wide, but also quite high, elongated,” writes anthropologist Stanislav Drobyshevsky in his article “Ardipitec Ramidus” on the Antropogenesis.ru website.
“However, signs such as the length of the hands reaching to the knees, the curved phalanges of the fingers, the big toe set far to the side and retaining the grasping ability, clearly indicate that these creatures could spend a lot of time in the trees.”
Two types of ardipithecus are described - ramidus and kadabba. Both lived in East Africa.Not all paleoanthropologists attribute the Ardipithecus to a human ancestry, although there are reasons for this - primarily due to the similarities of teeth with the teeth of Australopithecus.
Moreover, the foot of the Ardipithecus contains the so-called accessory fibula, which is present in the human foot and is absent in the foot of other modern hominoids. Therefore, sometimes ardipiettes are referred to as early australopithecines. Their skull is intermediate between the skull of chimpanzees and australopithecus. But the body size is similar to that of a chimpanzee.
But why did our ancestors need to stand on two legs at all? This is another "javelin" question. Previously, it was believed that this was caused by the Miocene cooling, which 3-2.5 million years ago drained the climate, reduced the area of African forests and expanded the area of savannahs. But, as we can see, attempts to get back on their feet began long before that, so climate change was definitely not the only reason for this.
Although it could strengthen this tendency. It became more and more difficult to survive in forests full of aggressive ancestors of modern gorillas and chimpanzees, because these forests were shrinking (this process was gradual), there was not enough food. And since by that time walking on two legs was already quite common - a slow retreat to the savannah did not become a serious stress for our ancestors.
But the savannah was inhabited by predators hiding in the tall grass. By the way, about grass and predators. To make it easier to see any saber-toothed cat sneaking up to small hominids, the latter probably had to get up on two legs more and more often. In addition, experiments show that quadruped movement in warm climates is less energetically beneficial than bipedal movement. And even with a bipedal gait, the body area is reduced, which is very important under the scorching rays of the African sun. Less space means less heating.
By the way, precisely because of the heating, our ancestors probably gradually lost their hair - or rather, it became shorter and thinner. Lush hair remained only on the head - in order, again, to protect the head from the deadly ultraviolet radiation. But the lost hair not only warmed the hominids in the rainforests - the young clung to it. Now there was not much to hold on to (except for the hair; maybe that's why babies are so active in doing this and clench their fists cleaner than armwrestling champions), so mothers had to carry babies in their arms. That only contributed to upright posture and release of hands.
And the latter was used not only as care for the calf, but also in tool activities. At first, it was probably just stones that flew into the heads of the evil predators, and then - and the victims. And 3.4 million years ago, the first tools of labor appear. Why are they needed? With their help, it became easier to butcher prey and scrap meat from bones. And eating meat helped the brain grow. How the very manufacture of tools helped him to grow, and the increasingly complicated communication of our ancestors, which was necessary for effective hunting.
Australopithecus afar: the sky in diamonds
The most famous representative of this species, key for our evolution, is called Lucy - in honor of the Beatles song "Lucy and the sky in diamonds". A perfectly preserved skeleton of Australopithecus afar was found in 1974 in Ethiopia - this song was constantly played in the camp of scientists during excavations.
Lucy is our true Eve, albeit with short legs and hairy, but her own, dear and erect. The steps of Eve, who lived 3, 9-2, 9 million years ago, of course, were not as confident as ours, but she did not descend to four limbs. And her brain also grew a little - up to 400 cubic centimeters. The arms were shorter than those of the Ardipithecus, and the pelvis was already very much like a human. In front of Lucy, the sky in diamonds really opened up - gorgeous perspectives.
Indeed, almost no one doubts that from these creatures we originated (directly or indirectly). Australopithecus walked on two legs, but were covered with hair. Their height did not exceed 1-1.5 meters, their weight was from 30 to, possibly, 55 kilograms.At the same time, their body sizes can vary greatly - probably, depending on sexual dimorphism. Its severity is equal to the values of orangutans and gorillas.
This is clearly more than that of humans and chimpanzees. Some believe that Australopithecines already led a terrestrial lifestyle, others that they lived in trees (because their arms are longer than those of humans), and the structure of the limbs presupposed adaptation to tree climbing. So, Australopithecines walked on slightly bent legs and had curved fingers and toes, hips resembled the thighs of chimpanzees.
Females had a significantly narrower pelvis compared to modern females. Although the pelvis of these creatures is already much more similar to the pelvis of modern people compared to the pelvis of other great apes. They had a low forehead, a flat nose like a monkey, massive jaws with large teeth, and no chin protrusion.
Australopithecus collected plant food and probably already knew how to make the simplest tools of wood and stone, but not for hunting, but in order to separate the meat from the bones of animals killed by predators. That is, the Australopithecines probably ate carrion and ate up after others. But they lived, most likely, in families in which there was one main male and several females.
Skillful and upright man: the first tools and muse of distant wanderings
The genus Homo, that is, "People" begin to be distinguished from about 2, 4-1, 85 million years ago. Homo habilis or Homo habilis lived a little later - 2, 3-1, 5 million years ago. It was he who became the first to regularly use tools of labor (and became the founder of the so-called Olduvai culture), and it is with him that the rapid growth of the brain begins. His body is already much more like a human than that of Australopithecus, but his face is not very much. Although the size of the jaws and teeth has already become smaller, and the brain - more: 600-700 cubic centimeters.
Eating meat contributed to the reduction of teeth and jaws: it is more nutritious than plants (which means that there is enough saturation for a long time), and you need to chew it less. And also the reduction of the jaws "made room" for the growing brain. And the growing brain, at one time, made the jaws shrink.
In appearance, the habilis still somewhat resembled australopithecines, but the pelvis was already different and provided a more perfect bipedal gait. And, besides, the birth of children with a larger head, and, therefore, more "skillful". The occipital lobe of the brain, judging by the endocranes (internal imprints of the skulls), decreases, and the more progressive lobes increase: frontal, parietal, temporal.
The structure of the skull is already different - it is expanded in the infraorbital and parieto-occipital regions. The brush combines both progressive features and adaptations to tree climbing. A power grip is formed, which contributes to the development of weapon skills.
But the face is still quite archaic and has large supraorbital ridges, a flat nose and protruding jaws. But the head becomes more rounded. The bulge inside the thin-walled skull suggests that they had Broca's center - the one that is responsible for speech. However, the structure of the larynx shows that the habilis could not yet pronounce as many sounds as we pronounce. Nevertheless, they probably already had the beginnings of speech.
For the first time, people left Africa a little earlier than Homo erectus or Homo erectus appeared (who lived from 800 thousand to 1.45 million years ago). It was then, probably for the first time, that they tried to use fire. But erectus actively continued these endeavors. And outwardly, they were already noticeably similar to us, and their brain volume reached a record 850-1200 cubic centimeters. In our country, these figures range from 1250 to 1600 cubic centimeters.
And erectus also had more pronounced sexual dimorphism than us, which continued to smooth out in the process of evolution. Homo erectus are the ancestors of a more advanced culture than the Olduvai, Acheulean: they already lived in caves, used wooden spears and sometimes cooked food on fire.
The erectuses were still quite low - 1, 2-1, 5 meters in height.Their thigh bones were similar to ours, so they moved confidently on two legs. And their body was already very similar to ours, perhaps with a more developed hairline. But the facial features were still quite archaic - the skull had thick walls, a low forehead, protruding brow ridges and a sloping chin. Sexual dimorphism was also greater than modern values.
Homo erectus were engaged in gathering, feeding on roots, berries and other gifts of the plant world. But from time to time they went hunting, that is, carrion was probably no longer the main meat diet. Remains of rhinos, elephants, giraffes and hippos were found near their fireplaces. That is, they were probably capable of hunting very large prey.
Unsurprisingly, they were constantly exposed to danger. This circumstance probably forced them to unite into large family groups, which in Soviet historical literature were called the “primitive herd” or the primitive community. These communities lived in small “settlements”. And, as studies show, these settlements were permanent. They already had something like dwellings in which a certain group of people lived permanently.
The Heidelberg man: at the finish line
These people were already very similar to us, and also to the Neanderthals, who are not our direct ancestors, but "cousins". The Heidelberg people of Africa (not the Heidelbergs of Europe, who are the ancestors of the Neanderthals) lived from 800 to 400 thousand years ago. Some scientists believe that they already knew how to build primitive huts, and the average volume of their brains hovered around 1,200 cubic centimeters. Before the appearance of Homo sapiens sapiens, there was very little left - a moment by historical standards. And he appeared. According to various estimates, this happened from 200 to 45 thousand years ago.
At the same time, the Heidelberg people had a rounded back of the head, but an archaic low skull with thick walls and very massive jaws with large teeth. But they were already tall, almost exactly like us. Or just like we are in the pre-industrial era. Male representatives reached 175 centimeters in height, female - 150 centimeters. The former weighed about 62 kilograms, the latter 51.
The structure of the ear shows that they had approximately the same hearing sensitivity as modern people, therefore they could distinguish many different sounds. It is also shown that they were right-handed. They knew how to make high-quality tools of labor (their culture is called Acheulean, sometimes even with signs of transition to Mousterian), but traces of any kind of art were not found in them.
It is believed that the Heidelberg people have already lost the air sacs that are involved in the vocalization of other humanoid representatives. This loss probably contributed to the development of speech. Moreover, it is shown that the speech abilities of these people were quite close to ours. But whose relatives the Heidelberg people remain is still not entirely clear.
Those who lived in Europe are traditionally referred to as the ancestors of the Neanderthals. But not everyone adheres to this opinion, sometimes putting forward versions that the Heidelberg people could be the ancestors of only Neanderthals, while our ancestor could be some other species.