DECONSTRUCTING THE WORLD
DECONSTRUCTING THE SELF
The Human Mind
The Human Being
THE HUMAN BODY
Our bodies are real, so what they are is what we are, and our bodies are what they are because of numerous changes undergone by our ancestors in order to survive and reproduce over eons of history. These changes are evident in how our bodies are constructed, they are evident in our genetics, and they are confirmed by the fossil record.
We are all the same type of creature. We call ourselves human. According to Carl Linnaeus, we are Homo sapiens (“wise man”). Although animalia vertebrate mammalia primates hominidae homo sapiens sapiens would be more precise, it is still only a quarter of the story. Our full title is terrestrial life-form eukaryote animal metazoan bilateral eucoelomate deuterostome chordate craniate vertebrate gnathostome choanate tetrapod amniote synapsid therapsid cynodont mammal therian eutherian primate anthropoid hominoid hominid hominine sapiens sapiens.
We can trace our ancestry back because we share certain characteristics with some creatures and not with others. The creatures we share a common characteristic with are related to us. These shared characteristics can be traced back through time to see how our bodies evolved to get us to how we are right now, all 28 of them (based on From the Beginning: The Story of Human Evolution by David Peters).
In this vast universe, we are located in the system of Sol, which is in the Orion spiral arm of the Milky Way galaxy (about two-thirds the way from the center). Our system has a single star, Sol, which is an average-sized orange sun about halfway through its ten billion year lifespan. We live on the third of ten satellites.
Sol III is a small, earthen planet with a large moon, but it is most notable for its thriving biosphere which gives the planet its name, Terra (thus terrestrial). Its gentle gravity, protective magnetosphere, mild temperatures, oceans of liquid water, many large continents, and close proximity to sunlight make it an ideal spot, but life would not be possible without the large amounts of organic material also found here.
The organic matter is made of complex carbon compounds such as amino acids and proteins, but they are not alive. Life might be made from organic material, but it is something much more. Life is unlike ordinary matter, as it is more than just its constituent parts, and it is more than just a chemical reaction. All terrestrial life-forms are separated from ordinary matter by four common characteristics: autopoiesis, reproduction, evolution and sentience.
All living things are in a constant state of flux. They are always rebuilding themselves, or autopoiesis (self-creation). They take particular nutrients from their surroundings and use them to replace various parts of their cells. They also remove the waste. The flux of autopoiesis is observed as metabolism.
All living things also have the ability to reproduce, thus creating more living things. Reproduction may produce similar creatures, but they are not exact copies. The complex organic material allows for uniqenesses and mutations can occur. Mutability adds to life’s adaptability to the changing conditions of any planet, thus they are able to continue to metabolize, reproduce and spread to new territories, which leads to the evolution of form and function (as all living things are evolving).
Autopoiesis, reproduction and evolution can be traced directly to the replicating proteins which life evolved from, but sentience is what sets life apart, and makes it more than just matter. All living things are sentient, which means they react to their environment (instead of just being acted upon). They have a will of their own. They respond to stimuli. They remember. In other words, they act as an independent singularity.
The base life-form is bacteria. They are all the same species as well as the same kingdom, which makes them extremely hardy single-celled organisms. They must have come from a planet in the long gone Nemesis system (which pre-dates our current solar system). The extra-terrestrial bacteria came in meteors and quickly adapted to the young planet. All further terrestrial life-forms would follow the same themes. From them we get the four initial conditions of life (autopoiesis, reproduction, evolution and sentience), as well as our basic cell structure with its protective oily lipid membrane shell, cytoplasmic innards, ribosomes and the DNA chromosome strand.
Bacteria are prokaryotes, which means they do not have a nucleus to house the cell’s DNA. Eukaryotes evolved from the synthesis of various different kinds of bacteria into a new symbiotic super-cell 10 times the size of a single bacterium. In other words, many bacteria got together for mutual cooperation and became more than the individual parts. The one-time bacteria now became organelles (tiny organs) within the super-cell, such as respiratory mitochondria, new digestion and waste control organelles, a protective outer wall, as well as a nucleus which houses the DNA.
Eukaryotes could no longer simply just split to reproduce like bacteria. The DNA of the new super-cell was too complex, so eukaryotes created sex organs. Another bi-product of the complex DNA was adaptive radiation as many different types of eukaryotes evolved and their DNA was different from one-another (different enough not to be able to reproduce), thus began the origin of species. Eukaryotes also introduced death, as species with a programmed death survived better through natural selection. Protists were the first successful eukaryotes, but animals, plants and fungi are also eukaryotes.
Early single-celled animals were not too much different from protists in their make-up, but they differed in behavior, as animals devour other creatures to survive. They appeared at a time when chlorophyll-using bacteria and protists needed to find balance in their environment or face total extinction. The entire planet had frozen-over due to their absorption of the greenhouse gasses which keep the planet warm. Animals breathe in their oxygen and release carbon dioxide (a greenhouse gas which the photosynthesizers also need to breathe), thus creating a thriving symbiosis which has lasted for the last 600 million years. Animals introduced sperm, eggs and birth. Animals are very aggressive, which is rewarded by greater survivability.
Most-likely, animals began as single-celled organisms (blastulas), but they soon disappeared as multi-cellular animals replaced them. Protists developed multi-cellularity first, but the aggressive nature of animals accelerated the process as the animal arms race has turned these multi-cellular organisms into monsters. Our ancestors evolved from a tiny multi-cellular crawling hydra-like creature with a single orifice for digestion underneath itself with a very rudimentary nervous system in the late Pre-Cambrian.
Bilateral simply means two-sided. The most primitive bilateral animal is the simple flatworm which slithers along the ocean floor in its own mucus. Their movement is guided by a rudimentary head which contains primitive nerves, sensory hairs and a statocyst (which gives them balance similar to our inner ear). Their mouth/anus is underneath them, and their tails contain their sex organs. Bilateralism probably evolved from their locomotion. It also may be easier for the DNA to hold more information if it just doubles one side into a mirror image (but it is never exactly the same, like all things in this fractal universe).
Most of the major animal groups are more advanced than the flatworm. Whereas the flatworm is a crawling stomach, later animals developed a third inner layer between the stomach and the skin, which would allow for more complex and specialized organs to arise such as more advanced sex organs, kidneys and a rudimentary brain hooked up to sense organs like a pair of primitive eyes and a more advanced nervous system.
As animals became more complex, they began to need healthier habits, so it was a huge step in animal evolution when the mouth and the anus were split. There are two types of these double opening creatures, but they can only be seen as different in the development of their embryos. The embryos of the protostomes develop the mouth first and then the anus, in the embryos of the dueterostomes it is the anus which develops first and then the mouth.
Both have the mouth in front and the anus in the rear. Also, they both developed muscles, intestines, a circulatory system and gender (as males carry the sperm and females carry the eggs unlike flatworms which have both). The protostomes would branch off to become ribbon worms, mollusks and arthropods. Deuterostomes would branch off to become round worms, acorn worms, brachiopods, starfish and chordates.
The first creatures with a spinal cord (as the name implies) were small swimming worms, much like today’s lancelet, which burrow in the sand during the day and then emerge in the safety of the night to swim. They use the notochord for support of the muscles needed for swimming. The early chordates were bottom-dwellers and low on the Cambrian food chain, but the spinal cord gave them a faster reaction time for better survival. They also developed gills.
By the end of the Cambrian, some of the early chordates had been successful enough to stay swimming. They were the first fish, and as their name implies, they have developed heads (or craniums). The head was protected by a soft cartilage skull which holds the familiar three-part brain, as well as two lateral eyes (with well-developed lenses), the pineal third-eye on the top of the head, two semi-circular canals for balance and two nostrils for smell. They also had the first red blood pumped by a heart, a rudimentary sense of touch, and a better developed digestion system with stomach, liver, pancreas and spleen added to the intestines and kidneys. These early fish were feeding on cyanobacteria and algae which they sucked up through their jawless mouths.
By the late Ordovician, the jawless fish had developed a large bone skull, and the notochord turned into segmented bony vertebra to protect the spinal cord, thus the name. The bones were more than just protective as they also stored calcium and phosphate which are needed for autopoiesis. The armor also extended to scales which protect the fish as well as allow for locomotion. The disadvantages are that the armor slowed it down and that oxygen could no longer be absorbed through the skin (so better gills were developed). These armored jawless fish were quite successful during the Silurian and Devonian.
In the late Silurian, small spiny sharks (no relation to modern sharks) appeared. Their cranium was split into a large skull and a lower jaw which turned their mouth into a weapon with an upper and lower row of enameled teeth. They also developed paired fins for guidance and simple lungs (fish use the stored air for ballast). The hunted had turned into a hunter.
Due to their new diet, they developed a higher metabolism which made them better hunters with a quicker reaction time. The new diet also meant that they needed a better digestive system for the larger and more varied types of food, so their throat and stomach had become stronger, and their intestines became the long twisted pathway we have today. Gnathostomes even developed the bladder for urine storage until it is safe to expel excess from the body. The jawed fish exploded during the early Devonian, conquering the seas.
Most jawed fish breathe through their mouth, so their nostrils are only for smelling. They have two nostrils on each side of their face (four total), one is an entrance and the other is an exit. Choanates have only one nostril on each side with the other end going into the mouth so the opening can also be used for breathing (the old nostril exit has turned into the tear duct in later tetrapods). The first creatures to have the choana (or nasal) passages were the lobed-finned fish which first appeared in the fresh water rivers and lakes of the mid Devonian.
Choanates are known as lobed-finned fish because they have four large bony fins which not only made them more powerful swimmers, but they could also be used to crawl in shallow water as well as on land. They developed larger stronger bone structures, especially in the four limbs, the ribcage and the new hip bone, so they could go after prey on land and return to the safety of the water, as well as find new living places across land bridges. Their dorsal fins shifted to the rear and would eventually disappear as they became more adept at land travel.
The lobed-finned fish were able to adapt to the problems of living in murky fresh water by developing their lungs for more than just ballast. Choanate lungs had to become stronger because fresh water is less salty than ocean water and buoyancy became more difficult, also fresh water holds less oxygen, so some choanates began to absorb the oxygen in their lungs to supplement the oxygen they received from the water, thus becoming the first air-breathing vertebrates. There are still lungfish living today.
The lobed-finned fish also developed strong jaw muscles so their head could snap down on prey similar to how crocodiles bite (as opposed to fish which bite with their jaws). Since the fish could not get far off the ground, an over-bite was more deadly. Their teeth became stronger, and they evolved a strong bony tongue to scrape the bits of food off their teeth. They grew to enormous sizes, and dominated the fresh waters of the Devonian and Carboniferous (and would eventually explode on to land as tetrapods).
As the name implies, these creatures have four limbs (two in front and two in the rear). Although the femur, fibula and tibia, ankle bones, and the five digits of the four limbs came from the lobed-fin fish, they had changed from a fin to legs and feet. They had evolved into amphibians, and all land-based tetrapods are related to them.
The first amphibians appeared in the late Devonian and became the dominant land creature by the mid Carboniferous. They had the familiar four limbs with five digits each, as well as developing shoulder and pelvis bones, interconnecting vertebra, and a long tail needed for moving across land. They also had an eardrum for hearing sound waves in the air, but as with all amphibians, they still had to start life in ponds and develop in water, but that would soon change as they became more reptile-like.
Amniotes get their name from the amnion membrane which protects the embryo in the egg from drying out on dry land. Amniotes are fully land-based tetrapods (from egg to adult). Only reptiles and their mammal and bird kin are amniotes. The first reptiles appeared in the late Carboniferous. By the Permian, reptiles were the well-established rulers of the land.
Without water, fertilization has to be done internally (within the body of the female), and then the eggs are expelled into nests for warmth and protection. Inside the egg, the embryo gets nourished by the yolk sac suspended in the amnion fluid (which replicates the ponds of their amphibian ancestors), and surrounded by the amnion membrane as well as a protective shell. The hatchlings emerge from the egg fully developed and even show a navel where the yolk sac was attached.
Without the buoyancy of the water, true reptiles had become more slender, and their skulls had shrunk becoming more box-like. Their eyes became larger, the nostrils had moved to the very tip of their snout, and hearing was solely done by the inner ear bones which had developed from the long gone gills. The head was now connected to the body by a well-developed neck, the shoulders and pelvis were much stronger, the ribs were used to aid breathing, and the whole creature was surrounded by a water-tight keratin-scale skin.
The early reptiles were anapsids which means they had no opening in their skull behind their eyes (or temple). By the early Permian, reptiles had split into four groups based on their temples (which is important for the jaw muscles). The anapsids are survived by their turtle and tortoise relatives. Diapsids have two temples on each side, and they would become lepidosaurs (lizards and snakes) and archosaurs (crocodiles, pterosaurs, dinosaurs and birds). The synapsids have one temple on each side, and they would eventually evolve into mammals. The marine euryapsids’ two temples grew together into one on each side, so ichthyosaurs and plesiosaurs are a closer relation to the diapsids than the synapsids.
The two temples of the diapsids deliver a vicious bite, but the one temple of the synapsids allowed for a larger brain. To make up for the short comings of their bite, the synapsids began to develop specialized teeth. These early synapsids are known as the mammal-like reptiles. At first, they were lizard-like pelycosaurs, and some had huge sails on their backs for temperature regulation (like dimetrodon, which dominated the early Permian).
In the mid Permian, a new kind of mammal-like reptile appeared. The therapsids (like most mammals) remained on all fours, but they were elevated off the ground with powerful legs, stronger backbones, more equalized digits and shorter tails. Their teeth became more specialized with incisors, molars and canines (some were as large as sabers). Therapsids also developed huge temple openings for a stronger bite, and they lived away from the tropic which indicates they were beginning to become endothermic (warm-blooded).
Cynodonts appeared in the late Permian and managed to survive the catastrophe known as the Permian Extinction. Their skulls were becoming more mammal-like with the thinning of the cheek bone and the widening of the molars for chewing food. The therapsids could use their incisors to rip off small chunks of meat for faster digestion, but chewing breaks the food down even faster, which indicates the higher metabolism of an endothermic creature.
Another clue to warm-bloodedness is the development of the secondary palate (or roof of the mouth) so the creature could breath and eat at the same time (reptiles and amphibians have a low metabolism and this is not a problem). Since they were no longer swallowing their prey whole, they no longer needed their palate teeth, so the number of teeth was more mammal-like.
Being pushed to the dark and cold fringes, the Triassic cynodonts evolved nasal scrolls which warmed the air before it got to the lungs and reabsorbed the warmth as it exited the nose (similar to modern mammals). Also for warmth, they developed hair from scales, since hair is made from the same keratin material. By the Jurassic, cynodonts were most-likely covered in fur with the exception of their short thin tails. They also must have used their warmth to care for their eggs and hatchlings, thus developing a rudimentary parental care.
Cynodonts developed more mammal-like bones which become fully grown at maturity, unlike reptiles which continue to grow all their lives. This difference is also evident in their teeth, as cynodonts only have two sets of teeth unlike reptiles who continue to grow teeth their whole lives. This trait may have come from tooth specialization. To protect their teeth, the cynodonts developed a hard enamel coating. Cynodonts had the mammal double ball-socket neck joint to protect the spinal cord unlike reptiles and birds (who can spin their heads in any direction), so mammals must rely on their bodies to move their heads. They also developed holes in the pelvis for stronger leg muscles, as well as heel bones to anchor the Achilles tendon.
Mammals are named for the mammary glands which allow the females to produce milk for their young, but what really sets them apart is the construction or their ears. Living at night during the dinosaur dominated Jurassic, they developed a great sense of hearing by using the final gill bones from the reptilian jaw for hearing (which also gives mammals a new kind of jaw hinge). The nocturnal mammals also needed a greater sense of smell, so the nasal openings merged (although not the two nostrils). Even their sense of touch was heightened. Only their sight became diminished (as most mammals do not see color well). Their enlarged brains were dominated by the smell and hearing needed by a nocturnal hunter.
All mammals are warm-blooded, which means they maintain their own body temperature independent of the outside world. This was necessary for a night dwelling creature which could not rely on the Sun for warmth. Mammals also have a colon (or large intestine), as well as no neck, waist or tail ribs. Their limbs are also directly underneath them instead of out to the side, which gives them a unique form of locomotion (their backs do not sway back and forth while they move).
The first mammals were egg-laying monotremes like the platypus and echidnas of today. The mammary glands evolved from sweat glands, as monotremes have no teats or nipples (they sweat the milk). The milk flows from a line of glands along the abdomen down to a rudimentary pouch where the hatchlings lap up what they can. All mammals have some form of parental care for their young, which the mammary glands reflect.
Therians are mammals which give birth to live young. They split in the late Jurassic into the marsupials (which give birth to premature young who must develop in a pouch) and placental mammals (which give birth to fully developed young). They both share several traits including external cartilage earflaps, whiskers used as feelers in the dark, a split between the anus and urethra openings, and the development of teats in the females and the scrotum sack in males (as sperm needs cool conditions to develop).
Eutherians (or true mammals) develop as embryos and as fetuses inside their mother’s uterus. The young are born live and are nourished from their mother’s teats. They have distinct shoulder sockets and palate ridges on the roof of their mouths, as well as a single vagina and uterus in females. Marsupials and true mammals were nothing but nocturnal insectivores and scavengers until the extinction of the dinosaurs around 65 million years ago (then both evolved into many similar forms on separated continents).
The first primates were creatures which somewhat resemble the tree shrews of today. They were nocturnal insectivores which were good climbers and leapers. They had five digit hands which were well equipped for grasping. They also had good hand-eye coordination which let them climb brushes and trees, as well as feed hand to mouth.
Around 55 million years ago, the first prosimians appeared. There are two types of prosimians: adapids (which are survived by lemurs and lorises) and omomyids (which are survived by the tarsiers). The adapids were mostly in Eurasia and the omomyids were mostly in North America (Africa had both). Prosimians had become much more primate-like with large eyes angled forward for stereoscopic vision and a bony eye socket completely enclosing the eye. Eyesight had become the dominant sense as their snout began to shrink back into their faces. As omnivores, all primates eat fruit, nectar, nuts and insects (all of which require good color vision).
Prosimians thrived in many various environments (as they do today). They grew to larger sizes, grew stronger limbs and developed opposable thumbs on hands and feet for better grasping. They also began to live in large social groups, as well as communicating through various types of vocalizations and facial expressions. Prosimians have longer pregnancies, their young cling to their mothers for several months during a prolonged childhood and they have a longer lifespan.
Around 35 million years ago, the first anthropoids (or monkeys) appeared in Africa. At first, they were a combination of prosimian, monkey and ape. They were living during the day and sleeping at night. Their faces were getting much more flat as they relied more on their eyes for navigation through the tree branches which provided both food and safety. They also developed a bony plate behind their fully stereoscopic eyes. Monkeys also have a special retina, which can see fine details needed for an arboreal life (especially when a missed branch could lead to death).
Anthropoids have unique faces and exaggerated individual personalities. They show their emotions on their face for all in the tribe to see by using color (blushing or paling) and various expressions which are universally known throughout the species. They lost most of their facial fur and whiskers to enhance these expressions. Anthropoid brains also started to get larger as they evolved to accommodate the increase in the information coming from vision and social interaction.
All anthropoids have 32 teeth (just like we do), and they are more adapted to eating vegetation with maybe a smattering of meat here and there. The males have enlarged canines which indicate that they were living in large male dominated groups where the males fought for the right to reproduce. The large canines can also be used for protection from predators. The Old World monkeys (which we evolved from) lost their claws for the more useful nails, as well as developing padded buttocks for sitting.
Hominoids (or apes) first appeared in Africa around 20 million years ago, and they are more than just tailless monkeys. Apes are larger than monkeys and their arms are extremely well developed for foraging by climbing under the branch instead of over it (or brachiation). They did so by developing the joints of their wrists, shoulders, arms and hips to get more flexible so they could get more vertical (and not needing a tail). Apes also have five cusp molars like humans do (as opposed to monkeys which have four), large brains in a rounder skull with almost no snout, the buttocks pads replaced with muscular buttocks and they have an appendix.
There are two types of apes today. The tree-dwelling apes are survived by the Asian gibbon, siamang and orangutan. The ground-dwelling apes, like the gorilla and the chimpanzee, live in Africa. Humans did not evolve from chimps, but we share a common ancestor (which makes them our closest living relative). Hominoids have highly developed social and communication skills and are capable of learning complex tasks such as tool use and social manipulation.
Hominids are ground-dwelling apes which have developed bipedal locomotion (they walk on two legs). Hominids split from hominoids around eight million years ago in Africa. There are many reasons for them to turn bipedal, as it is more efficient than the ape way of walking on their knuckles, costs less calories, is faster, as well as frees the hands for carrying food, young and weapons. It also gives us our knocked-knees (our knees fold in, not bowed out like apes), a unique pelvis, arched feet and we lost the thumb on our feet.
No other mammal has the same locomotion. No other animal is an upright biped (as dinosaurs, birds and kangaroos have tails to balance themselves). It is difficult to balance upright, and our hip-bone makes giving birth dangerous, but the benefits must have out-weighed the costs, because there have been many different types of hominids found in the fossil record from orrorin and ardipithecus to the many different varieties of fully bipedal australopithecines and hominines.
Hominids also have smaller canines, which suggest that pair-bonding had replaced the old ape-style of dominance. The ape trait of female-heats and male-ruts was replaced by females being fertile all year long (introducing sex-for-pleasure, which caused the enlarging of the sex organs, and the elimination of the penis bone). All of which stemmed male aggression, thus increasing the cooperation within the tribe.
Around 2.75 million years ago, a new genus of hominids appeared. The hominines were similar to the australopithecines, but differ in having smaller molars and larger brains. The oldest known hominines are Homo rudolfensis and Homo habilis. Their brains were only slightly larger than the australopithecines, and it is difficult to tell if they were the first hominines or another type of australopithecus, but the hominines seem to be the first stone tool-crafters, as somebody was making their own flint cutting-devises at this time and leaving their shavings (as well as cuts in fossilized bones).
Their small molars, tool crafting and growing brains size suggest that the early hominines were eating meat. Chimps eat meat to supplement their diets (and it is assumed that so did the australopithecines), but hominine brain growth suggests that they had increased the amount substantially (which coincides geologically with the Savanna fully replacing the East African rainforest as a result of the formation of the Rift Valley). The new mountains wiped out their jungle and replaced it with grassland. They had to survive on the plains or die, and life on the Savannah was radically different from the safe confines of the jungle.
Life on the Savanna is violent; and flesh is the currency of life. The early hominines must have been scavengers since they were small and had no natural weapons. They were preyed upon by many types of big cats, hyenas and dogs; and a carcass would attract these animals, so they had to get what they could as fast as possible by using simple stone tools to cut flesh and quickly escape to safety. Apes use tools, and hominids most-definitely did (even throwing sticks and rocks for protection), but hominines were the first to fashion their own stone tools (thus beginning the Stone Age). They developed a taste for meat, and later began to hunt in bands.
Hominine brains began to grow geometrically, as Homo erectus appears about two million years ago with an average brain size of 900 cubic centimeters (compared to habilis at 650 and australopithecines from 450 to 530 cubic centimeters). Erectus brains would grow to 1200 cc, and during that time they would become the true “King of the Jungle.”
In the 600 million years of the animal arms race, no creature had used its brain as its main weapon until the hominines. Their tools would get more sophisticated, as they became efficient hunters, mastered fire and built huts. By one million years ago, erectus was the only hominid left, and they were spread-out from Africa and Europe to Indonesia (Java Man) and China (Peking Man).
They were beginning to look like humans too with long legs, shorter arms and large heads. Our loss of fur most-likely began with the early hominines as sexual selection favored less hair. Also, their outer eyes probably turned white at this time so one hunter could see where the other hunters where looking at from a distance (which is why we instinctively look where others are staring).
Around 400,000 years ago Homo erectus began to radiate into different types of new hominines known collectively as the neanderloids. They are named after the famous neanderthals of Europe, but they appeared all over the eastern hemisphere. The remains of our earliest human ancestors (Homo sapiens) are found in East Africa from about 160,000 years ago, South Africa from about 120,000 years ago, and Canaan from about 90,000 years ago.
The greatest change from earlier hominines is in the shape of our skull with the forehead over the face, as the brow ridges over the eyes have almost disappeared, and the bulge at the rear of the skull is gone as well. Erectus and neanderloids have a bulge in the back of their skulls, which is where eye-sight is interpreted by the brain. It seems that their language was more visual than vocal. Early hominines most-likely used sign language accented by vocalizations, as their language center overlapped the visual part of the brain. Our language is vocal accented by gestures, so the language center moved to overlap the hearing part of the brain which is over our ears, thus pushing the brain forward and giving us our domed skull and minimal bow-bridges. Our vocalized language also caused our vocal cords to drop down our throats making us the only creatures which can choke to death on its food.
The human head is also different from other hominines in the jaw (humans do not have a protruding chin), our unique eye brows and our full lips. We also have a protruding nose which seems to have evolved for swimming. The openings of the nose are below the tip, small and close together, this design aides in keeping water pressure at an equal with the air pressure inside the nostrils, therefore preventing air from escaping the nose and water penetrating it. Since most primates avoid the water, it would seem that our ancestors must have went through a marine harvesting phase which would explain our proficiency at swimming, our dainty skeletons (as compared to the hardy erectus and neanderloids), our use of seafood and shells, as well as our fine motor skills (needed for sewing nets).
Sometime around 75,000 years ago, the Sumatra super-volcano erupted and almost wiped-out our species, but afterwards humans emerged as we are today (Homo sapiens sapiens). By 35,000 years ago, their numbers had recovered enough that they had spread throughout the eastern hemisphere and made all other hominines extinct (similar to erectus one million years earlier), but they did not stop there, as humans moved to Australia and the Americas (even the South Pacific). It is obvious when humans arrived into an area because they left litter to find thousands of years later, such as arrowheads and spearheads combining wood and stone technology.
Homo sapiens sapiens is more noted for cultural evolution than for physical evolution. Cave paintings, figurines, jewelry, clothing and music are hallmarks of human activity. They were also using weapons and tools made from antler and bone. Evidence shows that dogs were domesticated and the first pottery was made around 15,000 years ago. Agriculture and herding began around the Fertile Crescent (now Israel, Syria and Iraq) around 12,000 years ago, which led to the first civilizations (Sumer and Egypt over 5,000 years ago), and the beginning of writing and history.
Next Chapter: The Human Mind