Human prehistory is the period between the use of the first stone tools c. 3.3 million years ago by hominins and the invention of writing systems. The earliest writing systems appeared c. 5,300 years ago, but it took thousands of years for writing to be adopted, it was not used in some human cultures until the 19th century or until the present. The end of prehistory therefore came at different dates in different places, the term is less used in discussing societies where prehistory ended recently. Sumer in Mesopotamia, the Indus valley civilization, ancient Egypt were the first civilizations to develop their own scripts and to keep historical records. Neighboring civilizations were the first to follow. Most other civilizations reached the end of prehistory during the Iron Age; the three-age system of division of prehistory into the Stone Age, followed by the Bronze Age and Iron Age, remains in use for much of Eurasia and North Africa, but is not used in those parts of the world where the working of hard metals arrived abruptly with contact with Eurasian cultures, such as the Americas, Oceania and much of Sub-Saharan Africa.
These areas with some exceptions in Pre-Columbian civilizations in the Americas, did not develop complex writing systems before the arrival of Eurasians, their prehistory reaches into recent periods. The period when a culture is written about by others, but has not developed its own writing is known as the protohistory of the culture. By definition, there are no written records from human prehistory, so dating of prehistoric materials is crucial. Clear techniques for dating were not well-developed until the 19th century; this article is concerned with human prehistory, the time since behaviorally and anatomically modern humans first appeared until the beginning of recorded history. Earlier periods are called "prehistoric". Beginning The term "prehistory" can refer to the vast span of time since the beginning of the Universe or the Earth, but more it refers to the period since life appeared on Earth, or more to the time since human-like beings appeared. End The date marking the end of prehistory is defined as the advent of the contemporary written historical record.
The date varies from region to region depending on the date when relevant records become a useful academic resource. For example, in Egypt it is accepted that prehistory ended around 3200 BCE, whereas in New Guinea the end of the prehistoric era is set much more at around 1900 common era. In Europe the well-documented classical cultures of Ancient Greece and Ancient Rome had neighbouring cultures, including the Celts and to a lesser extent the Etruscans, with little or no writing, historians must decide how much weight to give to the highly prejudiced accounts of these "prehistoric" cultures in Greek and Roman literature. Time periods In dividing up human prehistory in Eurasia, historians use the three-age system, whereas scholars of pre-human time periods use the well-defined geologic record and its internationally defined stratum base within the geologic time scale; the three-age system is the periodization of human prehistory into three consecutive time periods, named for their respective predominant tool-making technologies: Stone Age Bronze Age Iron Age The notion of "prehistory" began to surface during the Enlightenment in the work of antiquarians who used the word'primitive' to describe societies that existed before written records.
The first use of the word prehistory in English, occurred in the Foreign Quarterly Review in 1836. The use of the geologic time scale for pre-human time periods, of the three-age system for human prehistory, is a system that emerged during the late nineteenth century in the work of British and Scandinavian archeologists and anthropologists; the main source for prehistory is archaeology, but some scholars are beginning to make more use of evidence from the natural and social sciences. This view has been articulated by advocates of deep history; the primary researchers into human prehistory are archaeologists and physical anthropologists who use excavation and geographic surveys, other scientific analysis to reveal and interpret the nature and behavior of pre-literate and non-literate peoples. Human population geneticists and historical linguists are providing valuable insight for these questions. Cultural anthropologists help provide context for societal interactions, by which objects of human origin pass among people, allowing an analysis of any article that arises in a human prehistoric context.
Therefore, data about prehistory is provided by a wide variety of natural and social sciences, such as paleontology, archaeology, geology, comparative linguistics, molecular genetics and many others. Human prehistory differs from history not only in terms of its chronology but in the way it deals with the activities of archaeological cultures rather than named nations or individuals. Restricted to material processes and artifacts rather than written records, prehistory is anonymous; because of this, reference terms that prehistorians use, such as Neanderthal or Iron Age are modern labels with definitions sometimes subject to debate. The concept of a "Stone Age" is found useful in the archaeology of most of the world, though in the archaeology of the Americas it is called by different names and begins with a Lithic sta
Spall are flakes of a material that are broken off a larger solid body and can be produced by a variety of mechanisms, including as a result of projectile impact, weathering, cavitation, or excessive rolling pressure. Spalling and spallation both describe the process of surface failure; the terms spall and spallation have been adopted by particle physicists. The neutrons that are ejected from the target are known as spall. Mechanical spalling occurs at high stress contact points, for example, in a ball bearing. Spalling occurs in preference to brinelling where the maximal shear stress occurs not at the surface, but just below, shearing the spall off. One of the simplest forms of mechanical spalling is plate impact, in which two waves of compression are reflected on the free-surfaces of the plates and interact to generate a region of high tensile stress inside one of the plates. Spalling can occur as an effect of cavitation, where fluids are subjected to localized low pressures that cause vapor bubbles to form in pumps, water turbines, vessel propellers, piping under some conditions.
When such bubbles collapse, a localized high pressure can cause spalling on adjacent surfaces. In anti-tank warfare, spalling through mechanical stress is an intended effect of high-explosive squash head anti-tank shells and many other munitions which may not be powerful enough to pierce the armor of a target; the soft warhead, containing or made of plastic explosive, flattens against the armor plating on tanks and other armored fighting vehicles and explodes, creating a shock wave that travels through the armor as a compression wave and is reflected at the free surface as a tensile wave breaking the metal on the inside. The resulting spall is dangerous to crew and equipment, may result in a partial or complete disablement of a vehicle and/or its crew. Many AFVs are equipped with spall liners inside their armor for protection. A kinetic energy penetrator, if it can defeat the armor causes spalling within the target as well, which helps to destroy/disable the vehicle and/or its crew. Spalling is a common mechanism of rock weathering, occurs at the surface of a rock when there are large shear stresses under the surface.
This form of mechanical weathering can be caused by freezing and thawing, thermal expansion and contraction, or salt deposition. Unloading is the release of pressure due to the removal of an overburden; when the pressure is reduced the rapid expansion of the rock causes high surface stress and spalling. Freeze–thaw weathering is caused by moisture freezing inside cracks in rock. Upon freezing its volume expands; as this cycle repeats the outer surface undergoes spalling, resulting in weathering. Some stone and masonry surfaces used. If exposed to severe freezing conditions the surface may flake off due to the expansion of the water; this effect can be seen in terra-cotta surfaces if there is an entrance for water at the edges. Exfoliation is the gradual removing of spall due to the cyclic increase and decrease in the temperature of the surface layers of the rock. Rocks do not conduct heat well, so when they are exposed to extreme heat the outermost layer becomes much hotter than the rock underneath causing differential thermal expansion.
This differential expansion causes sub-surface shear stress, in turn causing spalling. Extreme temperature change, such as forest fires, can cause spalling of rock; this mechanism of weathering causes the outer surface of the rock to fall off in thin fragments, sheets or flakes, hence the name exfoliation or onion skin weathering. Salt spalling is a specific type of weathering which occurs in porous building materials, such as brick, natural stone and concrete. Dissolved salt is carried through the material in water and crystallizes inside the material near the surface as the water evaporates; as the salt crystals expand this builds up shear stresses which break away spall from the surface. Some believe that porous building materials can be protected against salt spalling by treatment with penetrating sealants which are hydrophobic and will penetrate enough to keep water with dissolved salts well away from the surface. Great care and expert advice must be consulted, however, to ensure that any coating is compatible with the substrate in terms of breathability, or other serious problems can be created.
Chimneys show spalling damage before other portions of buildings because they are more exposed to the elements. In corrosion, spalling occurs when a substance sheds tiny particles of corrosion products as the corrosion reaction progresses. Although they are not soluble or permeable, these corrosion products do not adhere to the parent material's surface to form a barrier to further corrosion, as happens in passivation. Spallation happens as the result of a large volume change during the reaction. In the case of actinide metals, the material expands so upon exposure to air that a fine layer of oxide is forcibly expelled from the surface. A oxidised plug of metallic uranium can sometimes resemble an onion subjected to desquamation; the main hazard however arises from the pyrophoric character of actinide metals which can spontaneously ignite when their specif
In archaeology, a celt is a long, prehistoric, stone or bronze tool similar to an adze, a hoe or axe-like tool. The term "celt" came about from what was probably a copyist's error in many medieval manuscript copies of Job 19:24 in the Latin Vulgate Bible, which became enshrined in the authoritative Sixto-Clementine printed edition of 1592. While this is now considered to be the case by most scholars, some are still prepared to consider the existence of a real Latin word. A "celt" was thus wrongly assumed to be a type of ancient chisel. Early eighteenth century antiquarians, such as Lorenz Beger adopted the word for the stone and bronze tools they were finding at prehistoric sites. A shoe-last celt was a polished stone tool used during the early European Neolithic for felling trees and woodworking. Palstave "Celt, a word in common use among British and French archaeologists to describe the hatchets, adzes or chisels of chipped or shaped stone used by primitive man". Encyclopædia Britannica. 1911
In geology and related fields, a stratum is a layer of sedimentary rock or soil, or igneous rock that were formed at the Earth's surface, with internally consistent characteristics that distinguish it from other layers. The "stratum" is the fundamental unit in a stratigraphic column and forms the basis of the study of stratigraphy; each layer is one of a number of parallel layers that lie one upon another, laid down by natural processes. They may extend over hundreds of thousands of square kilometers of the Earth's surface. Strata are seen as bands of different colored or differently structured material exposed in cliffs, road cuts and river banks. Individual bands may vary in thickness from a few millimeters to a kilometer or more. A band may represent a specific mode of deposition: river silt, beach sand, coal swamp, sand dune, lava bed, etc. Geologists categorize them by the material of beds; each distinct layer is assigned to the name of sheet based on a town, mountain, or region where the formation is exposed and available for study.
For example, the Burgess Shale is a thick exposure of dark fossiliferous, shale exposed high in the Canadian Rockies near Burgess Pass. Slight distinctions in material in a formation may be described as "members". Formations are collected into "groups" while groups may be collected into "supergroups". Archaeological horizon Geologic formation Geologic map Geologic unit Law of superposition Bed GeoWhen Database
Irrigation is the application of controlled amounts of water to plants at needed intervals. Irrigation helps to grow agricultural crops, maintain landscapes, revegetate disturbed soils in dry areas and during periods of less than average rainfall. Irrigation has other uses in crop production, including frost protection, suppressing weed growth in grain fields and preventing soil consolidation. In contrast, agriculture that relies only on direct rainfall is referred to as rain-fed or dry land farming. Irrigation systems are used for cooling livestock, dust suppression, disposal of sewage, in mining. Irrigation is studied together with drainage, the removal of surface and sub-surface water from a given area. Irrigation has been a central feature of agriculture for over 5,000 years and is the product of many cultures, it was the basis for economies and societies across the globe, from Asia to the Southwestern United States. Archaeological investigation has found evidence of irrigation in areas lacking sufficient natural rainfall to support crops for rainfed agriculture.
The earliest known use of the technology dates to the 6th millennium BCE in Khuzistan in the south-west of present-day Iran. Irrigation was used as a means of manipulation of water in the alluvial plains of the Indus valley civilization, the application of it is estimated to have begun around 4500 BC and drastically increased the size and prosperity of their agricultural settlements; the Indus Valley Civilization developed sophisticated irrigation and water-storage systems, including artificial reservoirs at Girnar dated to 3000 BCE, an early canal irrigation system from c. 2600 BCE. Large-scale agriculture was practiced, with an extensive network of canals used for the purpose of irrigation. Farmers in the Mesopotamian plain used irrigation from at least the third millennium BCE, they developed perennial irrigation watering crops throughout the growing season by coaxing water through a matrix of small channels formed in the field. Ancient Egyptians practiced basin irrigation using the flooding of the Nile to inundate land plots, surrounded by dykes.
The flood water remained until the fertile sediment had settled before the engineers returned the surplus to the watercourse. There is evidence of the ancient Egyptian pharaoh Amenemhet III in the twelfth dynasty using the natural lake of the Faiyum Oasis as a reservoir to store surpluses of water for use during dry seasons; the lake swelled annually from the flooding of the Nile. The Ancient Nubians developed a form of irrigation by using a waterwheel-like device called a sakia. Irrigation began in Nubia some time between the third and second millennia BCE, it depended upon the flood waters that would flow through the Nile River and other rivers in what is now the Sudan. In sub-Saharan Africa irrigation reached the Niger River region cultures and civilizations by the first or second millennium BCE and was based on wet-season flooding and water harvesting. Evidence of terrace irrigation occurs in pre-Columbian America, early Syria and China. In the Zana Valley of the Andes Mountains in Peru, archaeologists have found remains of three irrigation canals radiocarbon-dated from the 4th millennium BCE, the 3rd millennium BCE and the 9th century CE.
These canals provide the earliest record of irrigation in the New World. Traces of a canal dating from the 5th millennium BCE were found under the 4th-millennium canal. Ancient Persia used irrigation as far back as the 6th millennium BCE to grow barley in areas with insufficient natural rainfall; the Qanats, developed in ancient Persia about 800 BCE, are among the oldest known irrigation methods still in use today. They are now found in the Middle East and North Africa; the system comprises a network of vertical wells and sloping tunnels driven into the sides of cliffs and of steep hills to tap groundwater. The noria, a water wheel with clay pots around the rim powered by the flow of the stream, first came into use at about this time among Roman settlers in North Africa. By 150 BCE the pots were fitted with valves to allow smoother filling as they were forced into the water; the irrigation works of ancient Sri Lanka, the earliest dating from about 300 BCE in the reign of King Pandukabhaya, under continuous development for the next thousand years, were one of the most complex irrigation systems of the ancient world.
In addition to underground canals, the Sinhalese were the first to build artificial reservoirs to store water. These reservoirs and canal systems were used to irrigate paddy fields, which require a lot of water to cultivate. Most of these irrigation systems still exist undamaged up to now, in Anuradhapura and Polonnaruwa, because of the advanced and precise engineering; the system was further extended during the reign of King Parakrama Bahu. The oldest known hydraulic engineers of China were Sunshu Ao of the Spring and Autumn period and Ximen Bao of the Warring States period, both of whom worked on large irrigation projects. In the Sichuan region belonging to the state of Qin of ancient China, the Dujiangyan Irrigation System devised by the Qin Chinese hydrologist and irrigation engineer Li Bing was built in 256 BCE to irrigate a vast area of farmland that today still supplies water. By the 2nd century AD, during the Han Dynasty, the Chinese used chain pumps which lifted water from a lower elevation to a higher one.
These were powered by manual foot-pedal, hydraulic waterwheels, or rotating mechanical wheels pulled by oxen. The water was used for public works, providing water for urban residential quarters and palace gardens, bu
History of technology
The history of technology is the history of the invention of tools and techniques and is one of the categories of the history of humanity. Technology can refer to methods ranging from as simple as stone tools to the complex genetic engineering and information technology that has emerged since the 1980s; the term technology comes from the Greek word techne, meaning art and craft, the word logos, meaning word and speech. It was first used to describe applied arts, but it is now used to described advancements and changes which affect the environment around us. New knowledge has enabled people to create new things, conversely, many scientific endeavors are made possible by technologies which assist humans in traveling to places they could not reach, by scientific instruments by which we study nature in more detail than our natural senses allow. Since much of technology is applied science, technical history is connected to the history of science. Since technology uses resources, technical history is connected to economic history.
From those resources, technology produces other resources, including technological artifacts used in everyday life. Technological change affects and is affected by, a society's cultural traditions, it is a force for economic growth and a means to develop and project economic, military power and wealth. Many sociologists and anthropologists have created social theories dealing with social and cultural evolution. Some, like Lewis H. Morgan, Leslie White, Gerhard Lenski have declared technological progress to be the primary factor driving the development of human civilization. Morgan's concept of three major stages of social evolution can be divided by technological milestones, such as fire. White argued. For White, "the primary function of culture" is to "harness and control energy." White differentiates between five stages of human development: In the first, people use the energy of their own muscles. In the second, they use the energy of domesticated animals. In the third, they use the energy of plants.
In the fourth, they learn to use the energy of natural resources: coal, gas. In the fifth, they harness nuclear energy. White introduced a formula P=E*T, where E is a measure of energy consumed, T is the measure of the efficiency of technical factors using the energy. In his own words, "culture evolves as the amount of energy harnessed per capita per year is increased, or as the efficiency of the instrumental means of putting the energy to work is increased". Nikolai Kardashev extrapolated his theory, creating the Kardashev scale, which categorizes the energy use of advanced civilizations. Lenski's approach focuses on information; the more information and knowledge a given society has, the more advanced. He identifies four stages of human development, based on advances in the history of communication. In the first stage, information is passed by genes. In the second, when humans gain sentience, they can pass information through experience. In the third, the humans start develop logic. In the fourth, they can develop language and writing.
Advancements in communications technology translate into advancements in the economic system and political system, distribution of wealth, social inequality and other spheres of social life. He differentiates societies based on their level of technology and economy: hunter-gatherer, simple agricultural, advanced agricultural, special. In economics, productivity is a measure of technological progress. Productivity increases. Another indicator of technological progress is the development of new products and services, necessary to offset unemployment that would otherwise result as labor inputs are reduced. In developed countries productivity growth has been slowing since the late 1970s. For example, employment in manufacturing in the United States declined from over 30% in the 1940s to just over 10% 70 years later. Similar changes occurred in other developed countries; this stage is referred to as post-industrial. In the late 1970s sociologists and anthropologists like Alvin Toffler, Daniel Bell and John Naisbitt have approached the theories of post-industrial societies, arguing that the current era of industrial society is coming to an end, services and information are becoming more important than industry and goods.
Some extreme visions of the post-industrial society in fiction, are strikingly similar to the visions of near and post-Singularity societies. The following is a summary of the history of technology by time period and geography: During most of the Paleolithic – the bulk of the Stone Age – all humans had a lifestyle which involved limited tools and few permanent settlements; the first major technologies were tied to survival and food preparation. Stone tools and weapons and clothing were technological developments of major importance during this period. Human ancestors have been using stone and other tools since long before the emergence of Homo sapiens 200,000 years ago; the earliest methods of stone tool making, known as the Oldowan "industry", date back to at least 2.3 million years ago, with the earliest direct evidence of tool usage found in Ethiopia within the Great Rift Valley, dating back to 2.5 million years ago. This era of stone tool use is called the Paleolithic
Aşıklı Höyük is a settlement mound located nearly 1 km south of Kızılkaya village on the bank of the Melendiz brook, 25 kilometers southeast of Aksaray, Turkey. Aşıklı Höyük is located in an area covered by the volcanic tuff of central Cappadocia, in Aksaray Province; the archaeological site of Aşıklı Höyük was first settled in the Aceramic Neolithic period, around 9000 B. C, it is situated 1119.5 metres above sea level, a little higher than the region's average of c. 1000 metres. The site itself is about 4 ha smaller than the situated site of Çatalhöyük; the surrounding landscape is formed by erosion of river valleys into tuff deposits. The Melendiz Valley, where the Aşıklı Höyük is located, constitutes a favourable and diverse habitat; the proximity to an obsidian source did become the base of a trade with the material supplying areas as far away as today's Cyprus and Iraq. Aşıklı Höyük was first investigated by Professor Ian A. Todd when he visited the site in the summer of 1964. Todd emphasised the importance of the obsidian in the area, based on over 6000 obsidian pieces collected from the surface layer alone.
The site was classified as a medium sized mound and destroyed by the river situated next to it. On the basis of the lithics and animal bones located in the surface layers the site became known as a contemporary to the Palestine PPNB, reinforced by 14C dates; the first comprehensive excavations took place late: first when the government launched a plan that would result in the rise of the waters of the Mamasın Lake located close to Aşıklı Höyük, Professor Ufuk Esin started the salvage excavations in 1989. Nine excavations have been undertaken up to 2003, uncovering 4200 m2 on the horizontal plain, making it one of the largest scale excavations in the region; the newest dates for Aşıklı Höyük show that the occupational period was from 8200 to 7400 BC, extracted from 3 layers with a total of 13 phases. It is known as one of the earliest Aceramic Neolithic sites on the Anatolian plateau, the prior mentioned extraction of the obsidian source was to be frequented as far back as the Paleolithic nomadic hunter-gatherers.
Due to its date and structural organization Aşıklı Höyük is known to be "a prime example of a first foray into sedentism". After more than 400 rooms had been excavated, the total number of individual found to have been buried within the settlement did not surpass 70. All these burials were under building floors; the dead were placed in pits cut through the floor during the occupation of the building. The buried are people of all ages. There is a variety of skeletal body postures, from burials in a hocker position to extended skeletons facing upwards. Others are lying on one side with the legs bent at the knees; the orientation of the burials varies within the buildings, as does the number of individuals buried inside them. The male population had individuals up to the age of 55–57 years of age, while the majority of females died between the ages of 20 and 25; the skeletal remains of these women show spinal deformities indicating that they had to carry heavy loads. This does not itself prove; the fact that the men seem to have outlived the women might be interpreted as sign that the women were subject to more strenuous physical labour than their male counterparts.
From Natufian Abu Hureyra there are similar osteological signs, such as pathologies in metatarsals, phalanges and shoulder joints, being specific to females resulting from habitual kneeling in the use of saddle querns. The Neolithic evidence show indications of increased physical workload in the osteological material on both genders, where the male skeletons show signs of joint disease and trauma arguably caused by cutting timber and tilling. Children represent 37.8% of the deceased, with 43.7% mortality within a year of birth. The skeletal remains are complete and with articulations intact, indicating that the burials have been primary; the graves contain either double burials. On one occasion two graves were found under the floor of room AB, belonging to an adjacent court with a large domed mudbrick oven paved with blocks of basalt. In one of the graves were the skeletons of a young woman and an elderly man; the young woman had undergone trepanation and survived only a few days after the operation.
All skeletons were buried in the hocker position, a fetal-like positioning were the arms are embracing the lower limbs. From a different grave a woman shows signs of being scalped after her death, according to the cut marks on her skull; as many as 55% of the skeletons show signs of being burned. The burial under the floor AB is accommodated by walls with the interior side were painted in a purplish red colour; the oven in HG indicates that this was indeed "special individuals of an elite class", claiming it can be compared to the "Terrazzo" Building at Çayönü and the "Temple" Building at Nevalı Çori and therefore have been a shrine used for religious ceremonies. Many of the burials contain burial goods consisting of necklaces and bracelets made of beads of various sorts.70 burials in over 400 rooms suggest that some form of selection took place of, buried at the site, implementing that AB indeed could be the residence or resting place of people influential in terms of both economy and political power.
Rooms containing hearths are more to contain burials. It has been argued that the number of burials could be an