The Approaching Primate

By Richard John Kosciejew

Archaebacteria were followed about 3.46 billion years ago by another type of prokaryote known as Cyanobacteria or blue-green algae. These Cyanobacteria gradually introduced oxygen in the atmosphere because of photosynthesis. In shallow tropical waters, Cyanobacteria formed mats that grew into humps called stromatolites. Fossilized stromatolites have been found in rocks in the Pilbara region of western Australia that are more than 3.4 billion years old. As, some rocks found in the Gunflint Chert region of northwest Lake Superior extend over an age of about 2.1 billion years old.

• Language: English
• Publisher: AuthorHouse
• Release date: Dec 11, 2019
• ISBN: 9781728339252

Richard John Kosciejew

Richard john Kosciejew, a German-born Canadian who now takes residence in Toronto Ontario. Richard, received his public school training at the Alexander Muir Public School, then attended the secondary level of education at Central Technical School. As gathering opportunities came, he studied at the Centennial College, he also attended the University of Toronto, and his graduate studies at the University of Western Ontario, situated in London. His academia of study rested upon his analytical prowess and completed ‘The Designing Theory of Transference.’ His other books are ‘Mental Illness’ and ‘The Phenomenon of Transference,’ among others.

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The

APPROACHING PRIMATE

RICHARD JOHN KOSCIEJEW

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Published by AuthorHouse 12/10/2019

ISBN: 978-1-7283-3924-5 (sc)

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Sophisticated dating techniques combined with new fossil discoveries suggest that skeletal remains unearthed in Africa in 1995 come from the earliest known human ancestors to walk upright, according to a report published in the journal Nature on May 7, 1998.

Researchers said the new findings indicated that Bipedalism (walking on two legs - the upright man) emerged 4.07 million to 4.17 million years ago, about 500,000 years earlier than was previously believed. Experts said the new research had important implications for the study of human origins because Bipedalism is widely considered a key, evolutionary adaptation that set the human lineage apart from that of other primates.

The new findings are based on fossils found three years ago in northern Kenya near Lake Turkana. Scientists identified the fossils as belonging to a newly discovered prehuman species, Australopithecus anamensis, a creature with apelike teeth and jaws, long arms, and a small brain.

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The primate has now come and gone, into the

neighbouring space and time, where he alone can steer?

Life originated during the Precambrian. The earliest fossil evidence of life consists of Prokaryotes, one-celled organisms that lacked a nucleus and reproduced by dividing, a process known as asexual reproduction. Asexual division meant that a prokaryote’s genetic heritage that had been productively unaltered. The first Prokaryotes were bacteria known as archaebacteria. Scientists believe they came into existence perhaps as early as 3.8 billion years ago, but of an unequivocal practicality of some 3.5 billion years ago, and where anaerobic-that is, they did not require oxygen to produce energy. Free oxygen barely existed in the atmosphere of the early Earth.

Archaebacteria were followed about 3.46 billion years ago by another type of prokaryote known as Cyanobacteria or blue-green algae. These Cyanobacteria gradually introduced oxygen in the atmosphere because of photosynthesis. In shallow tropical waters, Cyanobacteria formed mats that grew into humps called stromatolites. Fossilized stromatolites have been found in rocks in the Pilbara region of western Australia that are more than 3.4 billion years old. As, some rocks found in the Gunflint Chert region of northwest Lake Superior extend over an age of about 2.1 billion years old.

For billions of years, life existed only in the simple form of Prokaryotes. Prokaryotes were referentially followed by an advanced eucaryote, organisms that have a nucleus in their cells and that reproduces by combining or sharing their heredity makeup rather than by simply dividing. Sexual reproduction marked a milestone in life on Earth because it created the possibility of hereditary variation and enabled organisms to adapt more easily to a changing environment. The latest part of Precambrian time some 560 million to 545 million years ago saw the appearance of an intriguing group of fossil organisms known as the Ediacaran fauna, these were first discovered in the northern Flinders Range region of Australia in the mid-1940s and subsequent findings in many locations throughout the world, these strange fossils might be the precursors of many fossil groups that were to explode in Earth’s oceans in the Paleozoic Era.

At the begging of the Paleozoic Era about 543 million years ago, an enormous expansion in the diversity and complexity of life occurred. This event took place in the Cambrian Period and is called the Cambrian explosion. Nothing like it has happened since. Most of all set-groups of animals known today made their initial arrival during the Cambrian explosion. Most of the different ‘body plans’ are found in animals today-that is, the way and animal’s body is designed, with heads, legs, rear ends, claws, tentacles, or antennae-also originated during this period.

Fishes first appeared during the Paleozoic Era, and multicellular plants began growing on the land. Other land animals, such as scorpions, insects, and amphibians, also originated during this time. Just as new forms of life were being created, however, other forms of life were going out of existence. Natural selection meant that some species could flourish, while others failed. In fact, mass extinctions of animal and plant species were commonplace.

Most of the early complex life forms of the Cambrian explosion lived in the sea. The creation of warm, shallow seas, along with the buildup of oxygen in the atmosphere, may have aided this explosion of life forms. The shallow seas were created by the breakup of the supercontinent Rodinia. During the Ordovician, Silurian, and Devonian periods, which followed the Cambrian Period and lasted from 490 million to 354 million years ago, some continental pieces that had broken off Rodinia collided. These collisions resulted in larger continental masses in equatorial regions and in the Northern Hemisphere. The collisions built many numbers of mountain ranges, including parts of the Appalachian Mountains in North America and the Caledonian Mountains of northern Europe.

Toward the close of the Paleozoic Era, two large continental masses, Gondwanaland to the south and Laurasia to the north, faced each other across the equator. They are slow but eventful collision during the Permian Period of the Paleozoic Era, which lasted from 290 million to 248 million years ago, assembled the supercontinent Pangaea and resulted within several grandest mountains in the history of Earth. These mountains included other parts of the Appalachians and the Ural Mountains of Asia. At the close of the Paleozoic Era, Pangaea represented more than 90 percent of all the continental landmasses. Pangaea straddled the equator with a huge mouthlike opening that faced east. This opening was the Tethys Ocean, which closed as India moved northward creating the Himalayas. The last remnants of the Tethys Ocean can be seen in today’s Mediterranean Sea.

The Paleozoic Ere spread an end with a major extinction event, when perhaps as many as 90 percent of all plant and animal species died out. The reason is not known for sure, but many scientists believe that huge volcanic outpourings of lavas in central Siberia, coupled with an asteroid impact, resulting among the fragmented contributive factors.

The Mesozoic Era, sprang into formation and are approximately 248 million years ago, is often characterized as the Age of Reptiles because reptiles were the dominant life forms during this era. Reptiles dominated not only on land, as dinosaurs, but also in the sea, as the plesiosaurs and ichthyosaurs, and in the air, as pterosaurs, which were flying reptiles.

The Mesozoic Era is divided into three geological periods: the Triassic, which lasted from 248 million to 206 million years ago - the Jurassic, from 206 million to 144 million years ago; and the Cretaceous, from 144 million to 65 million years ago. The dinosaurs emerged during the Triassic Period and was one of the most successful animals in Earth’s history, lasting for about 180 million years before going extinct at the end of the Cretaceous Period. The first mammals and the first flowering plants also appeared during the Mesozoic Era. Before flowering plants emerged, plants with seed-bearing cones known as conifers were the dominant form of plants. Flowering plants soon replaced conifers as the dominant form of vegetation during the Mesozoic Era.

Mesozoic was an eventful era geologically with many changes to Earth’s surface. Pangaea continued to exist for another 50 million years during the early Mesozoic Era. By the early Jurassic Period, Pangaea began to break up. What is now South America begun splitting from what is now Africa, and in the process the South Atlantic Ocean formed? As the landmass that became North America drifted away from Pangaea and moved westward, a long Subduction zone extended along North America’s western margin. This Subduction zone and the accompanying arc of volcanoes extended from what is now Alaska to the southern tip of South America. Abounding of this focus, called the American Cordillera, exists today as the eastern margin of the Pacific Ring of Fire.

During the Cretaceous Period, heat continued to be released from the margins of the drifting continents, and as they slowly sank, vast inland seas formed in much of the continental interiors. The fossilized remains of fishes and marine mollusks called ammonites can be found today in the middle of the North American continent because these areas were once underwater. Large continental masses broke off the northern part of southern Gondwanaland during this period and began to narrow the Tethys Ocean. The largest of these continental masses, present-day India, moved northward toward its collision with southern Asia. As both the North Atlantic Ocean and South Atlantic Ocean continued to open, North and South America became isolated continents for the first time in 450 million years. Their westward journey resulted in mountains along their western margins, including the Andes of South America.

Birds are members of a group of animals called vertebrates, which possess a spinal column or backbone. Other vertebrates are fish, amphibians, reptiles, and mammals. Many characteristics and behaviours of birds are distinct from all other animals, yet they have noticeable similarities.

Despite uncertainties about bird evolution, scientists do know that many types of birds lived during the Cretaceous Period, which dates to about 138 million to 65 million years ago. Among these birds was Ichthyornis Victor, which resembled a gull and had vertebrae similar to those of a fish, and Hesperonis regalis, which was nearly wingless and had vertebrae like those of today’s birds. Most birds of the Cretaceous Period are thought to have died out in the mass extinctions causing the death of many species-that took place at the end of the Cretaceous Period.

The remains of prehistoric plants and animals buried and preserved in sedimentary rock or trapped in amber or other deposits of ancient organic matter, provided a record of the history of life on Earth. Scientists who subject in the field of fossil records are called paleontologists, for which having learnt those extinguishing natural archeological remains, are perpetuated and ongoing of phenomenons. In fact, the hundreds of millions of species that have lived on Earth over the past 3.8 billion years, more than 99 percent are already extinct. Some of this happens as the natural result of competition between species and is known as natural selection. According to natural selection, living things must compete for food and space. They must evade the ravages of predators and disease while dealing with unpredictable shifts in their environment. Those species incapable of adapting are faced with imminent extinction. This constant rate of extinction, sometimes called background extinction, is like a slowly ticking clock. First one species, then another becomes extinct, and new species appear almost at random as geological time goes by. Normal rates of background extinction are usually about five families of organisms lost per million years.

More recently, paleontologists have discovered that not all extinction is slow and gradual. At various times in the fossil record, many different, unrelated species became extinct at nearly the same time. The cause of these large-scale extinctions is always dramatic environmental change that produces conditions too severe for organisms to endure. Environmental changes of this caliber result from extreme climatic change, such as the global cooling observed during the ice ages, or from catastrophic events, such as meteorite impacts or widespread volcanic activity. Whatever their causes, these events dramatically alter the composition of life on Earth, as entire groups of organisms disappear and entirely new groups rise to take their place.

In its most general sense, the term mass extinction refers to any episode of multiple loss of species. Nonetheless, the term is generally reserved for truly global extinction events-events in which extensive species loss occurs in all ecosystems on land and in the sea, affecting every part of the Earth’s surface. Scientists recognize five such mass extinctions in the past 500 million years. The first occurred around 438 million years ago in the Ordovician Period. At this time, more than 85 percent of the species on Earth became extinct. The second took place 367 million years ago, near the end of the Devonian Period, when 82 percent of all species were lost. The third and greatest mass extinction to date occurred 245 million years ago at the end of the Permian Period. In this mass extinction, as many as 96 percent of all species on Earth were lost. The devastation was so great that paleontologists use this event to mark the end of the ancient, or Paleozoic Era, and the beginning of the middle, or Mesozoic Era, when many new groups of animals evolved.

The domestication of animals is the mutual relationship between animals and the humans who have influence on their care and reproduction. Charles Darwin recognized a small number of traits that made domesticated species different from their wild ancestors. He was also the first to recognize the difference between conscious selective breeding in which humans directly select for desirable traits, and unconscious selection where traits evolve as a byproduct of natural selection or from selection on other traits. There is a genetic difference between domestic and wild populations. There is also such a difference between the domestication traits that researchers believe to have been essential at the early stages of domestication, and the improvement traits that have appeared since the split between wild and domestic populations. Domestication traits are generally fixed within all domesticates, and were selected during the initial episode of domestication of that animal or plant, whereas improvement traits are present only in a proportion of domesticates, though they may be fixed in individual breeds or regional populations.

It is proposed that there were three major pathways that most animals being naturalized follow into domestication: (1) commensals, adapted to a human niche (e.g., dogs, cats, fowl, possibly pigs); (2) as to a thing hunted or killed by another for food, but has some influence by which of vulnerability that something as that for being undesirable. The vulnerability of animals sought for food (e.g., sheep, goats, cattle, water buffalo, yak, pig, reindeer, llama, alpaca, and turkey) and (3) targeted animals for draft and nonfood resources (e.g., horse, the donkey, camel). The dog was the first to be domesticated, and was established across Eurasia before the end of the Late Pleistocene era, well before cultivation and before the domestication of other animals. Unlike other domestic species which were primarily selected for productionrelated traits, dogs were initially selected for their behaviors. The archaeological and genetic data suggest that longterm bidirectional gene flow between wild and domestic stocks – including donkeys, horses, New and Old World camelids, goats, sheep, and pigs – was common. One study has concluded that human selection for domestic traits likely counteracted the homogenizing effect of gene flow from wild boars into pigs and created domestication islands in the genome. The same process may also apply to other domesticated animals

Our closest living relative are three surviving species of great apes, the gorilla, the common chimpanzee, And the pygmy chimpanzee (also known as bonobo0). Their confinement to Africa, along with abundant fossil evidence, strongly suggests that they also played the earliest stages of human evolution out in Africa, human history, as something separate from the history of animals, occurring about seven million years ago (estimates range from five to nine million years ago). Around that time, a population of African apes broke off into several populations, of which one preceded to evolve into modern gorillas, a second into the two modern chimps, and the third into humans. The gorilla line apparently split slightly before the split between the chimp and the human lines.

The primate, is the order of mammals that includes humans, apes, which are the closest living relatives to humans, monkeys, and some less familiar mammals, such as tarsiers, lorises, and lemurs. Humans and other primates share a common evolutionary descent. Consequently, primates have always fascinated scientists because their physical features, social organization, behavioural patterns, and fossil remains provide clues about our earliest human ancestors.

Primates evolved from tree-dwelling ancestors. Although some species, such as humans, have since taken to the ground, all primates’ share features that are related to their tree-climbing ancestry. These include arms and legs that can move more freely than those of most other mammals, flexible fingers and toes, forward-facing eyes that can judge distances accurately - a vital aid when moving about high above the ground - and large brains.

Primates live in a wide range of habitats but are restricted by their need for warmth. Most primates live in tropical jungles or dry forests, but some live in dry grasslands, and others have settled in cold, mountainous regions of China and Japan. The world’s most northerly primate, the Japanese macaque, has learned to bathe in hot springs to survive through the winter snows. In parts of the tropics, monkeys can be seen within a few miles of busy city centres, but despite this adaptability, most of the world’s primates retain a close dependence on trees. Apart from humans, baboons are the only primates that have fully made the transition to life out in the open, and even they instinctively climb to safety if danger threatens.

Some primates, especially the smaller species, are active only at night, or nocturnal, while others are diurnal, active during the day. Most primate species - particularly monkeys - are highly sociable animals, sometimes living in troops of more than 100 members. Smaller primates, especially nocturnal ones, tend to be solitary and secretive.

Primates range in size from quite small to quite large. The world’s largest species, the lowland gorilla at 200 kg. (400 lb.) is more than 6,000 times the weight of the smallest primate, the pygmy mouse lemur from Madagascar - measuring only 20 cm. (8 in.) from nose to tail, and weighing about 30 G. (1 oz.), this tiny animal was first identified about two centuries ago, but was later assumed to be extinct until its rediscovery in 1993.

There are about 235 species of primates. Scientists use more than one way to classify primates, and one system divides the order into two overall groups, or suborders: the prosimians and the anthropoids.

The prosimians, or primitive primates, make up the smaller of these two groups, with about 60 species, and include lemurs, Pontos, galagos, lorises, and, in some classification systems, tarsiers. Lemurs are only found on the islands of Madagascar and Comoros, where they have flourished in isolation for millions of years. Pontos and galagos are found in Africa, while lorises and tarsiers are found in southeast Asia. Typical prosimians are small to medium-sized mammals with long whiskers, pointed muzzles, and well-developed senses of smell and hearing. Most prosimians are nocturnal, although in Madagascar some larger lemurs are active by day.

In the past, tree shrews were often classified as primates, but their place in mammal classification has been the subject of much debate. Today, based on reproductive patterns and on new fossil evidence, most zoologists classify them in an order of their own, the Scandentia.

The remainder of the world’s primates makes up the anthropoid, or humanlike suborder, which contains about 175 species. This group consists of humans, apes, and monkeys. Most anthropoids, apart from baboons, have flat faces and a poor sense of smell. With a few exceptions, anthropoids are usually active during the day, and they find their food mainly by sight.

Apes’ are inhabitants of Africa and Asia only, they have no tails, and their arms are longer than their legs. Monkeys from Central and South America, known as New World monkeys, have broad noses and nostrils that open sideways. They are called platyrrhine, which in meaning is broad-nosed. Monkeys from Africa and Asia, known as Old World monkeys, have narrow noses and nostrils that face downward - a characteristic also seen in apes and humans. Old World Monkeys are called catarrhine, meaning downward-nosed.

During evolution, primates have kept several physical features that most other mammals have lost. One of these is the clavicle, or collarbone. In primates, the clavicle forms an important part of the shoulder joint. It helps to stabilize the shoulder, permitting a primate to support its weight by hanging from its arms alone - something that few other mammals can do. Some primates, particularly gibbons and the siamang, use this ability to move through the trees from one branch to another by swinging from arm to arm. This type of locomotion is called the brachiation.

During evolution, many mammals have gradually lost limb bones as they have adapted to different ways of life: horses, for example, have lost all but a single toe on each foot. Nearly all primates, by contrast, have retained a full set of five fingers and toes, and usually these digits have become increasingly flexible as time has gone through. In the aye-aye, a prosimian from Madagascar, the third finger on each hand is long and thin with a special claw at the end. Aye-ayes use these bony fingers to extract insect grubs from bark.

Evolution has affected the thumbs and big toes of primates. In most mammals, these digits bend in the same plane as the other fingers and toes. However, in many primates, the thumbs or big toes are opposable, meaning that they are set apart in a way that permits them to meet the other digits at the tips to form a circle. This enables primates to grip branches, and equally importantly, pick up and handle small objects. Instead of having claws, most primates have flat nails that cover soft, sensitive fingertips—another adaptation that helps primates to manipulate objects with great dexterity.

Tails are absent in humans and apes, but in most monkeys and prosimians, the tail plays a special role in maintaining balance during movement through the treetops. Many New World monkeys have prehensile tails, which can be wrapped around branches, gripping them like an extra hand or foot.

Primate skulls show several distinctive features. One of these is the position of the eyes, which in most species is on the front of the skull looking forward, rather than on the side of the skull looking to the side as in many other mammals. The two forward-facing eyes have overlapping fields of view, which give primates stereoscopic vision. Stereoscopic vision permits accurate perception of distance, which is helpful for handling food or swinging from branch to branch high above the ground. Another distinctive feature of primate skulls, in anthropoids particularly, is the large domed cranium that protects the brain. The inside surface of this dome clearly shows the outline of an unusually large brain - one of the most remarkable characteristics of this group. The shapes of anthropoid brains are different from other mammals: The portion of which the distributive contribution whereby the brain is enwrapped to the visual modalities is especially large, while the compensable portion of attribution to smell is comparatively small.

The primate order includes a handful of species that live entirely on meat (carnivores) and a few that are strict vegetarians (herbivores), but it is composed chiefly of animals that have varied diets (omnivores). The carnivorous primates are the four species of tarsiers, which live in Southeast Asia. Using their long back legs, these pocket-sized nocturnal hunters leap on their prey, pinning it down with their hands and then killing it with their needle-sharp teeth. Tarsiers primarily eat insects but will also eat lizards, bats, and snakes.

Other prosimians, such as galagos and mouse lemurs, also hunt for insects, but they supplement their diet with different kinds of food, including lizards, bird eggs, fruit, and plant sap. This opportunistic approach to feeding is seen in most of monkeys and in chimpanzees. Several species of monkeys, and chimpanzees, but not the other apes, have been known to attack and eat other monkeys. Baboons, the most adept hunters on the ground, often eat meat and sometimes manage to kill small antelope.

Most apes and monkeys eat a range of plant-based foods, but a few specialize in eating leaves. South American howler monkeys and African colobus monkeys eat the leaves of many different trees, but the proboscis monkey on the island of Borneo is more selective, surviving largely on the leaves of mangroves. These leaf-eating monkeys have modified digestive systems, similar to cows, which enable them to break down food that few other monkeys can digest. Other apes and monkeys eat mostly fruit, while some marmosets and lemurs depend on tree gum and sap.

Compared with many other mammals, primates have few young, and their offspring take a long time to develop. The gestational period, the time between conception and birth, is remarkably long compared with other mammals of similar size. A tarsier, for example, gives birth to a single young after a gestational period of nearly six months. By contrast, a similarly sized rodent will often give birth to six or more young after the gestational period lasting just three weeks. Most primates usually give birth to a single baby, although some species, such as dwarf lemurs, usually have twins or triplets.

Once the young are born, the period of parental feeding and protection can be even more drawn out. In small prosimians the young are often weaned after about five weeks, but in apes they are often fed on their mother’s milk for three or four years, and they may continue to rely on her protection for six or more years. This long childhood - which reaches its extreme in humans - is a crucial feature of a primate’s life because it enables complex patterns of behaviour to be passed on by learning.

Some primates have fixed breeding seasons, but many can breed anytime of the year. In many species, females signal that they are in estrus - receptive and ready to mate - by releasing special scents. In other species, females develop conspicuous swelling around their genitals to signal their readiness for mating. Such swelling is especially noticeable in chimpanzees. While most copulation occurs when the females are receptive, in some species, such as humans and pygmy chimpanzees, copulation frequently occurs even if the female is not in estrus.

Primates display a wide range of mating behaviours. Solitary primates, such as aye-ayes and orangutans, have simple reproductive behaviour. Within the imperitives of propetry that each male controls, his imperative territorial rights are in assess of several females live, each with their own territory. The male mates with any females within his territory that are receptive. Other species, such as gibbons, form small family groups consisting of a monogamous pair and they’re young. Gorillas form harems, in which one adult male life with several adult females and they’re young. Among social primates, breeding can be complicated by the presence of many adults. Males may cooperate in defending their troop’s territory, but they often fight each other for the chance to mate. In some species, only the dominant male mates with the females in the group. Chimpanzee females mate promiscuously with several adult males, although they usually pair up with one high-ranking male during the final few days of estrus, spending all of their time together and mating together exclusively.

Primates have the most highly developed brains in the animal kingdom, rivalled only by those of dolphins, whales, and possibly elephants. Anthropoid primates in particular are intelligent and inquisitive animals that are quick to learn new patterns of behaviour. This resourcefulness enables them to exploit a wide range of foods and may help them to escape attacks by predators.

Many zoologists believe that primates’ large brains initially evolved in response to their tree-dwelling habits and their way of feeding. Anthropoid primates, which have the largest brains, live in a visual world, relying on sight to move about and to find and manipulate food. Unlike smell or hearing, vision generates a large amount of complex sensory information that has to be processed and stored. In primate brains, these operations are carried out by part of the brain called the cerebral cortex, which evolved into such a large structure that the rest of the brain is hidden beneath it. Some unrelated mammals, such as squirrels, also live in trees, but they have less-developed eyesight and much smaller brains.

During the Stone Age, Earth experienced the most recent in a succession of ice ages, in which glaciers and sea ice covered a large portion of Earth’s surface. The most recent ice age period lasted from 1.6 million to 10,000 years ago, a period of glacial and warmer interglacial stages known as the Pleistocene Epoch. The Holocene Epoch began at the end of the ice age 10,000 years ago and continued to the present time.

Early hominids made stone artifacts either by smashing rocks between a hammer and anvil (known as the bipolar technique) to produce usable pieces or by acceding to a greater extent the controlled process termed flaking, in which stone chips were fractured away from a larger rock by striking it with a hammer of stone or other hard material. Subsequently, throughout the last 10,000 years, additional techniques of producing stone artifacts were to include pecking, grinding, sawing, and boring, in so that it turns into other traditional standards. The most excellent rock for flaking lean of a hard, fine-grained, or amorphous (having no crystal structure) rocks, including lava, obsidian, ignimbrites, flint, chert, quartz, silicified limestone, quartzite, and indurated shale. Ground stone tools could be made on a wider range of raw material types, including coarser grained rock such as granite.

Flaking produces several different types of stone artifacts, which archaeologists look forward to at prehistoric sites. The parent pieces of rock from which chips have been detached are called cores, and the chips removed from cores are called flakes. A flake that has had yet smaller flakes removed from one or more edges to become sharper or form the contours of the known of a retouched piece. The stone used to knock flakes from cores is called a hammerstone or a precursor. Other flaking artifacts include fragments and chunks, most of which are broken cores and flakes.

The terms culture and industries both refer to a system of technology (Toolmaking technique, for example) shared by different Stone Age sites of the same broad time. Experts now prefer to use the term industry instead of culture to refer to these shared Stone Age systems.

Archaeologists have divided the Stone Age into different stages, each characterized by different types of tools or tool-manufacturing techniques. The stages also imply broad time frames and are perceived as stages of human cultural development. The most widely used designations for the successive stages are Palaeolithic (Old Stone Age), Mesolithic (Middle Stone Age), and Neolithic (New Stone Age). British naturalist Sir John Lubbock in 1865 defined the Palaeolithic stage as the period in which stone tools were chipped or flaked. He defined the Neolithic as the stage in which ground and polished stone axes became prevalent. These two stages also were associated with different economic and subsistence strategies: Palaeolithic peoples were hunters-gatherers while Neolithic peoples were farmers. Archaeologists subsequently identified a separate stage of stone tool working in Eurasia and Africa between the Palaeolithic and the Neolithic, called the Mesolithic. This period is characterized by the creation of microliths, small, geometric-shaped stone artifacts attached to wood, antler, or bone to form tools such as arrows, spears, or scythes. Microliths began appearing between 15,000 and 10,000 years ago at the end of the Pleistocene Ice Age.

The Palaeolithic/Mesolithic/Neolithic division system was first applied only to sites in Europe, but is now widely used (with some modification) to refer to prehistoric human development in much of Asia, Africa, and Australasia. Different terminology is often used to describe the cultural-historical chronology of the Americas, which humans did not reach until some point between 20,000 and 12,000 years ago. However, there is a general similarity, the transitional form of flaked stone tools are associated with prehistoric hunters-gatherers to both flaked and ground stone tools associated with the rise of early farming communities. The period in the Americas up to the end of the Pleistocene Ice Age about 10,000 years ago, when most humans were hunters-gatherers, is convened as Paleo-Indian and the subsequent, post-glacial period is known as Archaic.

Archaeologists subdivide the Palaeolithic into the Lower Palaeolithic (the earliest phase), Middle Palaeolithic, and Upper Palaeolithic (the later phase), based upon the presence or absence of certain classes of stone artifacts.

The Lower Palaeolithic dates from approximately 2.5 million years ago until about 200,000 years ago and include the earliest record of human Toolmaking and documentation as much of the evolutionary history of the genus Homo from its origins in Africa to its spread into Eurasia. Two successive Toolmaking industries characterize the Lower Palaeolithic: the Oldowan and the Acheulean.

Increased brainpower has had important effects on the way primates live. It has helped them to move about and find food and enabled them to develop special skills. One of the most remarkable of these is Toolmaking, seen in chimpanzees and, to a far greater extent, in humans. Toolmaking, as opposed to simple tool use, involves a preconceived image of what the finished tool should look like - something that is only possible with an advanced brain.

The intelligence of primates is also evident in their social behaviour. For species that live in groups, daily life involves countless interactions with relatives, allies, and rivals. Mutual cleaning and grooming of the fur, which removes parasites, helps to reinforce relationships, while threats

- sometimes followed by combat - maintain the hierarchy of dominance that permeates typical primate troops.

Primates use a variety of methods to communicate. In solitary prosimians, when animals are not within sight of each other, communication is often accomplished by using scents. Such animals use urine, faeces, or special scent glands to mark territory or to show a readiness to mate. In social anthropoids, visual and vocal signals are much more important. Most monkeys and apes speak with a complex array of facial expressions, some of which are similar to the facial expressions used by humans.

Primates also talk with a repertoire of sounds. These range from the soft clicks and grunts of the colobus to the songs of the gibbon and the roaring of the howler monkey, which can sometimes be heard more than 3 km. (2 mi.) away. Far-carrying calls are used in courtship, both to keep group members from getting separated and to mark and maintain feeding territories. Some primate utterances convey more precise messages, often denoting specific kinds of danger. In the wild, researchers have observed that chimpanzees run through as much as 34 different calls, and evidence suggests that they can pass on information-such as the location of food-using this form of communication.

Comparatively, little in effect is known about the origins of primates compared with many other groups of mammals, because primates have left relatively few fossil remains. The chief reason for the scarcity of fossils is that forests, the primary home for most early primates, do not create good conditions for fossilization. Instead of being buried by sediment, the bodies of early primates were more likely to have been eaten by scavengers and their bones dispersed.

The earliest fossils of primates discovered dates from the end of the Cretaceous Period, about 65 million years ago. These early fossils include specimens of a species called Notharctus, which resembles today’s lemurs and had a long pointed snout. The ancestors of another prosimian group, the tarsiers, are known from fossils that date from the early Eocene Epoch, about 50 million years ago. In 1996 researchers in China recovered fossil bones of a primitive primate no bigger than a human thumb. The animal, named Eosimias, existed in as much as 45 million years ago. Many scientists believe that Eosimias is an example of a transitional animal in the evolution of prosimians to anthropoids.

The origin of anthropoids has been difficult to pin down. A single anthropoid fossil has been found that may come from the Eocene Epoch, but conclusive fossil evidence of anthropoids does not appear until the Oligocene Epoch, which had its beginnings in around 38 million years ago. These early anthropoids belonged to a lineage that led to the catarrhine primates - the Old World monkeys, apes, and humans. The platyrrhine primates, which include all New World monkeys, are presumed to have diverged from the Old World monkeys during the Eocene Epoch. They evolved in isolation on what was then the island continent of South America. Genetic analysis shows that New World monkeys clearly have the same ancestry with the catarrhines, which means that they must have reached the island continent from the Old World. Exactly how they did this is unclear. One possibility is that they floated across from Africa on logs or rafts of vegetation, journeying across an Atlantic Ocean that was much narrower than it is today.

Of all primate groups, the apes are the direct ancestors of humans that bring on the most provocative of studies. One distinguishing query that finds of its vexation is that of two groups diverging. Based on the comparisons of genes and the structure of body parts, scientists think that the line leading to the orangutan was diverged from the one leading to humans about 12 million years ago. The ancestral line leading to chimpanzees did not diverge until more recently, probably between five and seven million years ago. This evidence strongly suggests that chimpanzees are our closest living relatives.

The word primate means the first. When it was originally coined more than two centuries ago, it conveyed the widely held idea that primates were superior to all other mammals. This notion has since been discarded, but nonhuman primates still generate great interest because of their humanlike characteristics.

In scientific research, much of this interest has focussed on primate behaviour and its correspondence with human behaviour. Attempts have been made to train chimpanzees and orangutans to mimic human speech, but differences in anatomy make it very difficult for apes to produce recognizable words. A more revealing series of experiments has involved training chimpanzees, and later gorillas, to understand words and to respond using American Sign Language. In the late 1960s, a chimp named Washoe learned more than 130 signs. In the 1970s and 1980s, a gorilla named Koko learned to use more than 500 signs and to recognize an additional 500 signs. One outcome of these long-running experiments was that the chimps or gorillas occasionally produced new combinations of signs, suggesting that the animals were not simply repeating tricks that they had learned. More recently, chimps have been trained to talk with humans by using coloured shapes or computer keyboards. They too have shown an ability to associate abstract symbols with objects and ideas - the underlying basis of language.

Apes and monkeys also play an important role in the field of medical research. Because their body systems work very much like our own, new vaccines and new forms of surgery are sometimes tried on apes and monkeys before they are approved for use on humans. Species that are most often used in this way include chimpanzees, baboons, and rhesus monkeys. This kind of animal experimentation has undoubtedly contributed to human welfare, but the medical use of primates is an increasingly controversial area, particularly when it involves animals captured in the wild.

According to figures published by the World Conservation Union (IUCN), more than 110 species of primates - nearly half the world’s total - are currently under threat of extinction. This makes the primates among the most vulnerable animals on earth.

The species most under threats are those affected by deforestation. This has been particularly severe in Madagascar, the only home of the lemurs, and it is also taking place at a rapid rate in Southeast Asia, threatening gibbons and orangutans. The almost total destruction of Brazil’s Atlantic rainforest has proved catastrophic for several species, including the lion tamarins, which are found only in this habitat. Primates are also threatened by collection for the pet trade and by hunting. Illegal hunting is the chief threat facing the mountain gorilla, a rare African subspecies that lives in the politically volatile border region straddling Uganda, Rwanda, and the Democratic Republic of the Congo.

In the face of these threats, urgent action is currently underway to protect many of these endangered species. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) currently forbids the export of many primates, although not all countries have chosen to follow this law. More direct methods of species preservation include habitat protection and captive breeding programs. Sometimes - for example, the lion tamarin—these programs have met with considerable success. However, without the preservation of extensive and suitable natural habitats, many primate species are destined for extinction.

Humans as primates, have themselves of a physical and genetic similarities showing that the modern human species, Homo sapiens, has a one and the same close relationship to another group of primate species, the apes. Humans and the so-called great apes (large apes) of Africa - chimpanzees (including bonobos, or so-called pygmy chimpanzees) and gorillas - have the same ancestor that lived sometime between eight million and six million years ago. The earliest humans evolved in Africa, and much of human evolution occurred on that continent. The fossils of early humans who lived between six million and two million years ago come entirely from Africa.

Humans and great apes of Africa have the same ancestor that lived between eight million and five million years ago. Most scientists distinguish among 12 to 19 different species of early humans. Scientists do not all agree, however, about how the species are related or which ones simply died out. Many early human species - probably most of them - left no descendants. Scientists also debate over how to identify and classify particular species of early humans, and about what factors influenced the evolution and extinction of each species.

The tree of Human Evolution Fossil evidences that the first humans evolved from primates or ape ancestors, in at least six million years ago, and many of the species of humans followed, but only some left descendants on the branch leading to The Homo sapiens. In this slide show, white skulls represent species that lived during the period shown; gray skulls represent extinct human species.

Early humans first migrated out of Africa into Asia probably between two million and 1.7 million years ago. They entered Europe much later, generally within the past one million years. Species of modern humans populated many parts of the world much later. For instance, people first came to Australia probably within the past 60,000 years, and to the Americas within the past 35,000 years. The beginnings of agriculture and the rise of the first civilizations occurred within the past 10,000 years.

The scientific study of human evolution is called Paleoanthropology. Paleoanthropology is a subfield of anthropology, the study of human culture, society, and biology. Paleoanthropologists search for the roots of human physical traits and behaviour. They seek to discover how evolution has shaped the potentials, tendencies, and limitations of all people. For many people, Paleoanthropology is an exciting scientific field because it illuminates the origins of the defining traits of the human species, and the fundamental connections between humans and other living organisms on Earth. Scientists have abundant evidence of human evolution from fossils, artifacts, and genetic studies. However, some people find the concept of human evolution troubling because it can seem to conflict with religious and other traditional beliefs about how people, other living things, and the world developed. Yet many people have come to reconcile such beliefs with the scientific evidence.

Modern and Early Humans have undergone major anatomical changes during evolution. This illustration depicts Australopithecus afarensis, the earliest of the three species, the Homo erectus, an intermediate species, whereby the Homo sapiens, a modern human, and Homo’s ergaster. The modern humans are much taller than A. afarensis and have flatter faces and a considerable brawny brain. Modern humans have a larger brain than H. erectus and almost flat face beneath the front of the braincase.

All species of organisms originate through the process of biological evolution. In this process, new species arise from a series of natural changes. In animals that reproduce sexually, including humans, the term species refers to a conjunctive organization into groups whose adult members regularly interbreed, resulting in fertile offsprings that are, offsprings themselves capable of reproducing. Scientists generally categorize a class species of which all are unique, but two-partially scientific names. In this system, modern humans are classified as Homo sapiens.

The mechanism for evolutionary change resides in genes—the basic units of heredity. Genes affect how the body and behaviour of an organism develop during its life. The information contained in genes can change - a process known as mutation. The way particular genes are expressed - how they affect the body or behaviour of an organism - can also change. Over time, genetic change can alter a species’s overall way of life, such as what it eats, how it grows, and where it can live.

Genetic changes can improve the ability of organisms to survive, reproduce, and, in animals, raise offspring. This process is called adaptation. Parents pass adaptive genetic changes to their offspring, and ultimately these changes become common throughout a population - a group of organisms of the same species that share a particular local habitat. Many factors can favour new adaptations, but changes in the environment often play a role. Ancestral human species adapted to new environments as their genes changed, altering their anatomy (physical body structure), physiology (bodily functions, such as digestion), and behaviour. Over long periods, evolution dramatically transformed humans and their ways of life.

Geneticists estimate that the human line began to diverge from that of the African apes between eight million and five million years ago (paleontologists have dated the earliest human fossils to at least six million years ago). This figure comes from comparing differences in the genetic makeup of humans and apes, and then calculating how long it probably took for those differences to develop. Using similar techniques and comparing the genetic variations among human populations around the world, scientists have calculated that all people may share common genetic ancestors that lived sometime between 290,000 and 130,000 years ago.

Humans belong to the scientific order named Primates, a group of more than 230 species of mammals that also includes lemurs, lorises, tarsiers, monkeys, and apes. Modern humans, early humans, and other species of primates all have many similarities plus some important differences. Knowledge of these similarities and differences helps scientists to understand the roots of many human traits, and the significance of each step in human evolution.

The scientific classification of primates reflects evolutionary relationships between individual species and groups of species. Strepsirhini (meaning ‘turned-nosed’) primates - of which the living representatives include lemurs, lorises, and other groups of species all commonly known as prosimians - evolved earliest and are the most primitive forms of primates. The earliest monkeys and apes undergo an evolution from transmissiblel haplorhine (meaning ‘simple-nosed’) primates, of which the most primitive living representative is the tarsier. Humans evolved from ape ancestors.

Tarsiers have traditionally been grouped with prosimians, but many scientists now recognize that tarsiers, monkeys, and apes share some distinct traits, and group the three together. Monkeys, apes, and humans - who share many traits not found in other primates -together make up the suborder Anthropoidea. Apes and humans collectively carry out the superfamily of the Hominoidea, a grouping that emphasizes the close relationship among the species of these two groups.

Paleoanthropologists Donald C. Johanson of the Cleveland Museum of Natural History and Tim D. White of the University of California, Berkeley, announced that in January the discovery of the most ancient Hominid (humanlike) species yet uncovered, which they have named Australopithecus afarensis. The fossils on which they base this claim are about three million to four million years old and were found during the 1970’s at two widely separated localities in East Africa. The majority were collected at Hadar, a remote region of the Afar Depression of Ethiopia, by Johanson; the others were uncovered in northern Tanzania at Laetolil, 30 miles south of Olduvai Gorge, by anthropologist Mary Leakey. The Hadar material consists of bones from at least 35 individuals and includes the best preserved australopithecine skeleton yet found. Nicknamed Lucy by Johanson, this skeleton is about 40 percent complete and is evidently of a female who stood about 3.5-4 feet tall and lived some three million years ago. The Laetolil fossils, closer to four million years old, are astonishingly similar in many ways to the Hadar material. Because of the remarkable completeness and good preservation of both fossil collections, we are afforded a previously unavailable glimpse of early human evolution. Analysis suggests that these creatures had rather small brains, no larger than those of the gorilla, but the leg and pelvic bones clearly indicate that A. afarensis walked on two legs like humans. In these respects the newly described fossils do not differ substantially from previously described australopithecine species, which date from about 1.5 million to 2.5 million years ago. All previously recognized hominids, however, show larger cheek teeth (molars) and smaller front teeth (incisors and canines) than the apes. A. afarensis, in contrast, shows very broad incisors and large, projecting canines, to some degree more like those of an apes. The appearance of such primitive dental characteristics in an australopithecine has profound implications for evolutionary history. The most widely held theory states that the evolutionary lines leading to modern humans and apes diverged some 12 million to 15 million years ago, when apes from which humans are descendent of tree habiting of inhabited out of the trees which began to exploit the resources of open grasslands for food. This change in habitats is thought to have produced the characteristic humanlike denotation, which is more efficient at chewing tough food, such as seeds, roots, and tubers, than is the denotation of the apes. Fossil teeth and jaws of a human type characterize a creature called Ramapithecus, were inhibited to live in a round ten million years ago and is generally considered a human ancestor. However, the primitive, more primordial apes of A. afarensis have now cast doubt on the status of Ramapithecus as an ancestral hominid and made unclear the ultimate reason for the differentiation of human ancestors from the apes.

Researchers in South Africa having discovered what they believe are the oldest and best-preserved skulls and skeletons of one of humanity’s earliest ancestors, according to a report published in the December 9, 1998, publication of The South African Journal of Science. Paleontologists said the fossilized remains would exceedingly be every bit as two million years older than the oldest previously known complete hominid skeletons. The new finding is expected to reveal much about the anatomy and evolution of early humans, and may rank among the most important breakthroughs in Paleoanthropology (the archaeological study of early human evolution).It is one of many key elements from ape to man, said Ronald J. Clarke, some paleoanthropologists at the University of Witwatersrand in Johannesburg, South Africa, who led the team that made the discovery. The skeleton was discovered in the fossil-rich vicinitized near the Sterkfontein Caves, near Krugersdorp in northeastern South Africa. The skeleton is of a small, adult hominid who was about 1.2-m (4-ft) tall and weighed about 32 k. (70 lb.). Clarke’s team dated the bones at 3.2 million to 3.6 million years old.

The bones are believed to belong to a species of australopithecine, an early hominid that had human and apelike features. However, most of the bones remain embedded in rock within the cave. Paleontologists may be accredited for being as far as possible and study of anatomical skeletons until it is removed, a process that Clarke said could take a year or longer. Clarke made the discovery after unexpectedly finding four hominid foot bones in a box of unsorted fossils at the university in 1994. Another search of boxes in a university storage room in May 1997 revealed more feet and lower leg bones. To Clarke’s astonishment, all of the bones appeared to belong to the same hominid.

Clarke’s initial discovery, announced in 1995, added new evidence to a longstanding debate among anthropologists about the path of early hominid development. Clarke and several of his colleagues argued that the bones of the specimen, dubbed Little Foot, reflected a transition from four-legged tree dwellers to two-legged creatures capable of walking upright. In particular, Clarke said the specimen’s humanlike ankles and grasping, an apelike big toe suggested that the creature was a capable tree climber who could easily walk on two legs. Other anthropologists dismissed the idea, however, asserting that humans evolved from plains-dwelling hominids and did not live in trees.

After finding additional bones in 1997, Clarke believed that the rest of the skeleton might be present in Sterkfontein’s Silberberg Grotto, where the bones had been originally excavated. Within days of searching, his assistants discovered a piece of fossilized bone protruding from the cave wall that perfectly matched one of Clarke’s fossil fragments. Although the excavation is at a preliminary stage, Clarke said the remainder of the skeleton might be present and intact, laying face downward in limestone.

Before Clarke’s find, the most comprehensive australopithecine skeleton was an Australopithecus afarensis specimen known as Lucy, discovered by anthropologist Donald Johanson in Ethiopia in 1974 and dated at 3.2 million years old. Lucy, however, is only about 40 percent complete. The oldest known complete hominid skeleton was a species of The Homo erectus were found in Kenya and dated at 1.5 million years old.

The new discovery is considered extraordinary because the fossil record of early hominids is so fragmentary. Paleontologists have had to piece together knowledge about ancient human species by using bone fragments derived from many individuals, making generalizations about anatomy difficult. Once the bones have been chipped from the grotto rock, scientists will examine the hips and legs to determine whether or not the creature could easily climb trees. In addition, they hope skeletal features will give them clues about the specimen’s sex and how these early hominids lived, including their likely diet and possible foraging behaviours.

Scenists also believe the skeleton’s intact skull could shed light on another key puzzle of early human evolution: the relation between a brain size and upright locomotion. Many experts believe that it was the ability to walk on two legs - rather than brain size or use of tools - that set the human lineage apart from all other primates

Another mystery scientists will explore is whether the fossils represent an example of Australopithecus afarensis (like Lucy), of a southern African hominid species, known as Australopithecus africanus, or possibly a new species together. If the species is unrelated to Lucy and is older, then it could force anthropologists to reconsider their views about hominid evolution in Africa. Because of Lucy’s age, many scientists now believe that A. afarensis is a common ancestor to all succeeding australopithecine species.

Nevertheless, some paleontologists cautioned that the age of the new find had not yet been conclusively established and could be only about two million year’s old. The most accurate forms of dating require the presence of volcanic ash, which contains radioactive elements that decay in a predicable manner. No such material was present in the cave.

To date the skeleton, Clarke and his team finds distinctive animal fossils near the hominid remains. The age of these animal fossils had already been determined at other datable sites. This technique is not foolproof, however, because movements in the rock layers could make fossils from animals that did not coexist appear next to each other, experts said.

Yet, Spanish paleoanthropologists recently described the fossil remains of several human ancestors from the last Ice Age that were found at a cave site in northern Spain. Did their findings identify a distinct human ancestral species, as the Spaniards suggested? The debate over the paths of human evolution continued as new findings about Human ancestors came of Spanish paleoanthropologists, and have added to the complexity of theories about early humans in Europe with their recent description of the fossil remains of several Ice Age human ancestors found in northern Spain. The researchers suggested that these early humans, who lived more than 780,000 years ago, may have been a separate species that preceded both modern humans and the now-extinct early humans known as Neanderthals.

The researchers said that among the fossils were the facial bones of a boy showing both primitive and modern features and identifying these human ancestors as a distinct species. They suggested the name Homo’s antecessor for the proposed new species. Spanish paleoanthropologists José Bermúdez de Castro of the National Museum of Natural Sciences in Madrid, Spain, and his colleagues described the fossils in the May 30, 1997, issues of the Journal Science.

Although anthropologists agreed that the fossil find was very important, most were not ready to accept the ancient humans as representing a new species. Anthropologists pointed out that not only are the dental and facial bones of a boy scant evidence on which to identify a new species, but also there is a chance that some of the boy’s features were in an intermediate stage that would have changed when the boy reached adulthood. The Spanish researchers’ proposed path of human evolution also was controversial, because it pushes groups of early humans off the direct line leading to modern humans, suggesting that there may have been more dead ends in human evolution than previously thought.

The Spanish scientists first reported finding this group of fossils, the oldest remains of prehumans ever found in Europe, in August 1995. Previously the oldest known Europeans were a group of early humans sometimes classified as a separate species, Homo heidelbergensis. The earliest known specimens from this group date from roughly 500,000 years ago. Using a technique known as Paleomagnetic analysis, the Spanish researchers dated the fossil remains found recently in northern Spain to at least 780,000 years ago, in the Pleistocene Epoch.

Paleomagnetic dating is because the direction of the earth’s geomagnetic field has reversed often during the history of the world. The dates of these irregular reversals in geomagnetic polarity have been well documented. Currently the geomagnetic polarity of the earth is facing north, but less than a million years ago it faced south. Internal magnetic traces in the layers of rock that lay the groundwork for nearby fossils shown that the fossils had been buried before the earth’s magnetic field last switched direction, from south to north, 780,000 years ago.

The picture of early human residence in Europe is unclear at best. Anthropologists agree that hominids - a family of bipedal primates that includes modern human beings and all extinct species of early humans - have their origins in Africa. The Spanish anthropologists speculated that the early humans they called Homo antecessor may have first inhabited and evolved in Africa from a primitive human classified by some paleoanthropologists as Homo ergaster and by others as early Homo erectus and that Homo sapiens developed from Homo antecessor in Africa. The researchers further proposed that Homo antecessor migrated to Europe, and that Homo heidelbergensis