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Domestic Animals and Their Wild Ancestors

Encyclopædia Britannica, first edition, art: wolf [credit: Encyclopædia Britannica, Inc.]

Encyclopædia Britannica, first edition, art: wolfcredit: Encyclopædia Britannica, Inc.

The domestication of wild animals, beginning with the dog, heavily influenced human evolution. These creatures, and the protection, sustenance, clothing, and labor they supplied, were key factors that allowed our nomadic ancestors to form permanent settlements. Though to many urbanites livestock are as distant a part of reality as country music, without them, humans would never have been able to form cities at all. Take a look at the organisms that gave rise to some of our present animal companions.

Gray wolf

gray wolfcredit: © Jeff Lepore/Photo Researchers

The gray wolf (Canis lupus) is thought by most scientists to have given rise to the domestic dog, a key event in the evolution of our species that may have occurred as early as 32,000 years ago and certainly by 14,000 years ago. Some scientists, however, have posited, due to a number of morphological differences between dogs and wolves, that dogs may actually be descended from an extinct wild ancestor that likely resembled contemporary pariah dogs and dingoes. Whatever its origins, the dog was the first animal to be domesticated by early humans.

Domestic dog

Chihuahuacredit: © Photos.com/Jupiterimages

Millenia of puppy love have generated more than 400 breeds of domestic dog (Canis lupus familiaris), ranging from the wolfish, robust Siberian husky to the shrieking, guinea-pig adjacent chihuahua. Research on the origin of dogs, and on their unique, sympatric relationships with humans, is ongoing. Now if someone would only figure out why LOLCats have such an edge over similar canine memes

Bezoar

bezoarcredit: © iStockphoto/Thinkstock

The second species of wild animal to be selectively bred by humans was the bezoar, or wild goat (Capra aegagrus). These spry, wirey ungulates might not seem like the best candidates for domestication at first blush, but their ability to turn sparse vegetation into hides, meat, and milk likely made the effort worth the while to settlers of the Fertile Crescent, who first bred them as early as 11,000 years ago. Generations of lonely goatherds ensued.


HUGGING – DID YOU KNOW…

It is recommended at least eight hugs a day to be happier and enjoy better relationships.

Psychotherapist Virginia Satir said: “We need 4 hugs a day for survival. We need 8 hugs a day for maintenance. We need 12 hugs a day for growth.”

 

This may very well be the “hug threshold” that allows your body to produce ample amounts of oxytocin, which is released in response to physical touch. The neuropeptide oxytocin, released by your pituitary gland, is a naturally occurring hormone in your body with incredibly powerful, health-giving properties.

It is also a key reason why the simple act of hugging is such an incredible way to not only bond with others but also boost your physical, and emotional, health.

How Hugging Makes You Healthier

Hugging increases levels of the “love hormone” oxytocin. This, in turn, may have beneficial effects on your heart health and more. One study found, for instance, that women had lower blood pressure following a brief episode of warm contact with their partner.

A 20-second hug, along with 10 minutes of hand-holding, also reduces the harmful physical effects of stress, including its impact on your blood pressure and heart rate. This makes sense, since hugging is known to lower levels of stress hormones like cortisol. But research suggests there’s even more to it than that. As reported by Mail Online:

The skin contains a network of tiny, egg-shaped pressure centers called Pacinian corpuscles that can sense touch and which are in contact with the brain through the vagus nerve. The vagus nerve winds its way through the body and is connected to a number of organs, including the heart.

It is also connected to oxytocin receptors. One theory is that stimulation of the vagus triggers an increase in oxytocin, which in turn leads to the cascade of health benefits.”

A 10-second hug a day can lead to biochemical and physiological reactions in your body that can significantly improve your health. According to one study, this includes:

Lower risk of heart disease Stress reduction Fight fatigue
Boost your immune system Fight infections Ease depression

Does Cuddle Therapy Work?

There’s no doubt that hugging, caressing, and cuddling feel good. As neurologist Shekar Raman, MD, said in the Huffington Post:

“A hug, pat on the back, and even a friendly handshake are processed by the reward center in the central nervous system, which is why they can have a powerful impact on the human psyche, making us feel happiness and joy… And it doesn’t matter if you’re the toucher or touchee. The more you connect with others — on even the smallest physical level — the happier you’ll be.”

Yet, many people are touch-deprived. One study found that one-third of people receive no hugs on a daily basis while 75 percent said they wanted more hugs. Findings such as these, coupled with the emotional and health benefits of human touch, have led to the emergence of cuddle therapy centers, where people can pay for a lunchtime cuddle.

However, the verdict is still out on whether or not cuddles from strangers have the same impact as those from someone you know and trust. While cuddling with a spouse or partner has been shown to boost satisfaction in relationships, at least one study showed that hugs are only beneficial if trust is involved.

The lead researcher actually cautioned against worldwide “free hugs” campaigns (where strangers offer hugs to others), saying that this may be perceived as threatening and actually increase emotional burden and stress. However, proven benefits have been found from cuddling with a pet, which shows hugs don’t have to only be between humans to be beneficial. Even cuddling with your trusted pet may offer significant benefits to your heart and overall health.

Fun Facts About Hugging

Did you know that, on average, people spend on hour a month hugging? That doesn’t sound like much, but when you consider that the average hug is under 10 seconds long… that’s a lot of hugs!

Happiness Weekly compiled even more fun facts about hugging that highlight just how incredible this act of touch really is. For instance, a full-body hug stimulates your nervous system while decreasing feelings of loneliness, combating fear, increasing self-esteem, defusing tension, and showing appreciation.

And if you had any doubt about the importance of touch, consider that children who aren’t hugged have delays in walking, talking, and reading. A quick hug has a near-immediate impact on health, lowering your heart rate and inducing a calming effect while also leading to a more upbeat mood!

Interestingly, hugging has just as much a benefit for the person doing the hugging as the person being hugged, revealing the reciprocal nature of touch. Touch is even described as a universal language that can communicate distinct emotions with startling accuracy. One study found that touch alone can reveal emotions including anger, fear, disgust, love, gratitude, and sympathy, with accuracy rates of up to 83 percent.

Even More Reasons to Give (or Get) a Hug Today

Hugs are one of the most succinct ways to encourage your body to release oxytocin, and the more oxytocin your pituitary gland releases, the better able you are to handle life’s stressors.

Oxytocin decreases the level of stress hormones (primarily cortisol) your body manufactures and lowers your blood pressure response to anxiety-producing events. Oxytocin quite likely plays a role in why pet owners heal more quickly from illness, why couples live longer than singles, and why support groups work for people with addictions and chronic diseases.

Oxytocin has also been found to reduce the cravings of drug and alcohol addiction, as well as for sweets. It even has a positive influence on inflammation and wound healing. Even beyond this, regular hugs have the added benefit of:

  • Cultivating patience and showing appreciation
  • Activating the Solar Plexus Chakra, which stimulates your thymus gland (this may help balance your production of white blood cells)
  • Stimulating dopamine, the pleasure hormone, and serotonin, for elevated mood
  • Balancing out your nervous system for better parasympathetic balance

Do You Need a Good Hug?

Often making a concerted effort to hug the people close to you is one of the best ways to get more hugs in return. This can include your spouse, children, and other family members along with close friends. But even if you’re not currently in a life situation conducive to getting daily hugs and producing enough of your own oxytocin on a regular basis, the good news is there are some alternatives you can use to help you deal in a healthy way with your emotional response to stress and anxiety.

With the already known and still-to-emerge health and quality of life benefits to be derived from the natural release of oxytocin in your body, your best course of action is to make sure you’re cultivating warm, loving, intimate relationships, no matter what stage of life you’re in. Additionally, if you have a pet, just a few minutes petting your dog or cat can promote the release of your body’s “happiness” hormones, including oxytocin. Since touch anywhere on your body, as well as positive interactions and psychological support, are known to increase oxytocin levels, you might also consider:

  • Holding hands and kissing
  • Giving and receiving a backrub
  • Nurturing others
  • Getting a massage
  • Practicing mind-body therapies like breathing exercises and yoga

courtsey: http://articles.mercola.com/sites/articles/archive/2014/02/06/hugging.aspx

MAIN CAUSES OF WATER POLLUTION

Sewage and Wastewater

Domestic households, industrial and agricultural practices produce wastewater that can cause pollution of many lakes and rivers.

  • Sewage is the term used for wastewater that often contains faeces, urine and laundry waste.
  • There are billions of people on Earth, so treating sewage is a big priority.
  • Sewage disposal is a major problem in developing countries as many people in these areas don’t have access to sanitary conditions and clean water.
  • Untreated sewage water in such areas can contaminate the environment and cause diseases such as diarrhoea.
  • Sewage in developed countries is carried away from the home quickly and hygienically through sewage pipes.
  • Sewage is treated in water treatment plants and the waste is often disposed into the sea.
  • Sewage is mainly biodegradable and most of it is broken down in the environment.
  • In developed countries, sewage often causes problems when people flush chemical and pharmaceutical substances down the toilet. When people are ill, sewage often carries harmful viruses and bacteria into the environment causing health problems.

 

 

 

Marine dumping

Dumping of litter in the sea can cause huge problems. Litter items such as 6-pack ring packaging can get caught in marine animals and may result in death. Different items take different lengths of time to degrade in water:

  • Cardboard – Takes 2 weeks to degrade.
  • Newspaper – Takes 6 weeks to degrade.
  • Photodegradable packaging – Takes 6 weeks to degrade.
  • Foam – Takes 50 years to degrade.
  • Styrofoam – Takes 80 years to degrade.
  • Aluminium – Takes 200 years to degrade.
  • Plastic packaging – Takes 400 years to degrade.
  • Glass – It takes so long to degrade that we don’t know the exact time.

 

 

Industrial water and water pollution

Industry is a huge source of water pollution, it produces pollutants that are extremely harmful to people and the environment.

  • Many industrial facilities use freshwater to carry away waste from the plant and into rivers, lakes and oceans.
  • Pollutants from industrial sources include:
    • Asbestos – This pollutant is a serious health hazard and carcinogenic. Asbestos fibres can be inhaled and cause illnesses such as asbestosis, mesothelioma, lung cancer, intestinal cancer and liver cancer.
    • Lead – This is a metallic element and can cause health and environmental problems. It is a non-biodegradable substance so is hard to clean up once the environment is contaminated. Lead is harmful to the health of many animals, including humans, as it can inhibit the action of bodily enzymes.
    • Mercury – This is a metallic element and can cause health and environmental problems. It is a non-biodegradable substance so is hard to clean up once the environment is contaminated. Mercury is also harmful to animal health as it can cause illness through mercury poisoning.
    • Nitrates – The increased use of fertilisers means that nitrates are more often being washed from the soil and into rivers and lakes. This can cause eutrophication, which can be very problematic to marine environments.
    • Phosphates – The increased use of fertilisers means that phosphates are more often being washed from the soil and into rivers and lakes. This can cause eutrophication, which can be very problematic to marine environments.
    • Sulphur – This is a non-metallic substance that is harmful for marine life.
    • Oils – Oil does not dissolve in water, instead it forms a thick layer on the water surface. This can stop marine plants receiving enough light for photosynthesis. It is also harmful for fish and marine birds.
    • Petrochemicals – This is formed from gas or petrol and can be toxic to marine life.

 

 

Nuclear waste – how it is produced

Nuclear waste is produced from industrial, medical and scientific processes that use radioactive material. Nuclear waste can have detrimental effects on marine habitats. Nuclear waste comes from a number of sources:

  • Operations conducted by nuclear power stations produce radioactive waste. Nuclear-fuel reprocessing plants in northern Europe are the biggest sources of man-made nuclear waste in the surrounding
    Radioactive traces from these plants have been found as far away as Greenland.
  • Mining and refining of uranium and thorium are also causes of marine nuclear waste.
  • Waste is also produced in the nuclear fuel cycle which is used in many industrial, medical and scientific processes.

 

 

Oil pollution

Oceans are polluted by oil on a daily basis from oil spills, routine shipping, run-offs and dumping.

  • Oil spills make up about 12% of the oil that enters the ocean. The rest come from shipping travel, drains and dumping.
  • An oil spill from a tanker is a severe problem because there is such a huge quantity of oil being spilt into one place.
  • Oil spills cause a very localised problem but can be catastrophic to local marine wildlife such as fish, birds and sea otters.
  • Oil cannot dissolve in water and forms a thick sludge in the water. This suffocates fish, gets caught in the feathers of marine birds stopping them from flying and blocks light from photosynthetic aquatic plants.

 

 

 

Underground storage leakages

A tank or piping network that has at least 10 percent of its volume underground is known as an underground storage tank (UST). They often store substances such as petroleum, that are harmful to the surrounding environment should it become contaminated. Many UST’s constructed before 1980 are made from steel pipes that are directly exposed to the environment. Over time the steel corrodes and causes leakages, affecting surrounding soil and groundwater.

 

 

 

Atmospheric

Atmospheric deposition is the pollution of water caused by air pollution.

  • In the atmosphere, water particles mix with carbon dioxide sulphur dioxide and nitrogen oxides, this forms a weak acid.
  • Air pollution means that water vapour absorbs more of these gases and becomes even more acidic.
  • When it rains the water is polluted with these gases, this is called acid rain.
  • When acid rain pollutes marine habitats such as rivers and lakes, aquatic life is harmed.

 

 

Global Warming

An increase in water temperature can result in the death of many aquatic organisms and disrupt many marine habitats. For example, a rise in water temperatures causes coral bleaching of reefs around the world. This is when the coral expels the microorganisms of which it is dependent on. This can result in great damage to coral reefs and subsequently, all the marine life that depends on it.

The rise in the Earth’s water temperature is caused by global warming.

  • Global warming is a process where the average global temperature increases due to the greenhouse effect.
  • The burning of fossil fuel releases greenhouse gasses, such as carbon dioxide, into the atmosphere.
  • This causes heat from the sun to get ‘trapped’ in the Earths atmosphere and consequently the global temperature rises.

 

 

Eutrophication

Eutrophication is when the environment becomes enriched with nutrients. This can be a problem in marine habitats such as lakes as it can cause algal blooms.

  • Fertilisers are often used in farming, sometimes these fertilisers run-off into nearby water causing an increase in nutrient levels.
  • This causes phytoplankton to grow and reproduce more rapidly, resulting in algal blooms.
  • This bloom of algae disrupts normal ecosystem functioning and causes many problems.
  • The algae may use up all the oxygen in the water, leaving none for other marine life. This results in the death of many aquatic organisms such as fish, which need the oxygen in the water to live.
  • The bloom of algae may also block sunlight from photosynthetic marine plants under the water surface.
  • Some algae even produce toxins that are harmful to higher forms of life. This can cause problems along the food chain and affect any animal that feeds on them.

 

 

 

 

What Can You Do?

If you want to help keep our waters clean, there are many things you can do to help. You can prevent water pollution of nearby rivers and lakes as well as groundwater and drinking water by following some simple guidelines in your everyday life.

  • Conserve water by turning off the tap when running water is not necessary. This helps prevent water shortages and reduces the amount of contaminated water that needs treatment.
  • Be careful about what you throw down your sink or toilet. Don’t throw paints, oils or other forms of litter down the drain.
  • Use environmentally household products, such as washing powder, household cleaning agents and toiletries.
  • Take great care not to overuse pesticides and fertilisers. This will prevent runoffs of the material into nearby water sources.
  • By having more plants in your garden you are preventing fertiliser, pesticides and contaminated water from running off into nearby water sources.
  • Don’t throw litter into rivers, lakes or oceans. Help clean up any litter you see on beaches or in rivers and lakes, make sure it is safe to collect the litter and put it in a nearby dustbin.

 

REFERENCE>>>>>>>>>>>>>>Advisory Committee on Protection of the Sea (ACOPS) – www.acops.org

 

START OF TECHNOLOGY

Technology in the ancient world

The beginnings—Stone Age technology (to c. 3000 bce)

The identification of the history of technology with the history of humanlike species does not help in fixing a precise point for its origin, because the estimates of prehistorians and anthropologists concerning the emergence of human species vary so widely. Animals occasionally use natural tools such as sticks or stones, and the creatures that became human doubtless did the same for hundreds of millennia before the first giant step of fashioning their own tools. Even then it was an interminable time before they put such toolmaking on a regular basis, and still more aeons passed as they arrived at the successive stages of standardizing their simple stone choppers and pounders and of manufacturing them—that is, providing sites and assigning specialists to the work. A degree of specialization in toolmaking was achieved by the time of the Neanderthals (70,000 bce); more-advanced tools, requiring assemblage of head and haft, were produced by Cro-Magnons (perhaps as early as 35,000 bce); while the application of mechanical principles was achieved by pottery-making Neolithic (New Stone Age; 6000 bce) and Metal Age peoples (about 3000 bce).

Earliest communities

For all except approximately the past 10,000 years, humans lived almost entirely in small nomadic communities dependent for survival on their skills in gathering food, hunting and fishing, and avoiding predators. It is reasonable to suppose that most of these communities developed in tropical latitudes, especially in Africa, where climatic conditions are most favourable to a creature with such poor bodily protection as humans have. It is also reasonable to suppose that tribes moved out thence into the subtropical regions and eventually into the landmass of Eurasia, although their colonization of this region must have been severely limited by the successive periods of glaciation, which rendered large parts of it inhospitable and even uninhabitable, even though humankind has shown remarkable versatility in adapting to such unfavourable conditions.

The Neolithic Revolution

Toward the end of the last ice age, some 15,000 to 20,000 years ago, a few of the communities that were most favoured by geography and climate began to make the transition from the long period of Paleolithic, or Old Stone Age, savagery to a more settled way of life depending on animal husbandry and agriculture. This period of transition, the Neolithic Period, or New Stone Age, led eventually to a marked rise in population, to a growth in the size of communities, and to the beginnings of town life. It is sometimes referred to as the Neolithic Revolution because the speed of technological innovation increased so greatly and human social and political organization underwent a corresponding increase in complexity. To understand the beginnings of technology, it is thus necessary to survey developments from the Old Stone Age through the New Stone Age down to the emergence of the first urban civilizations about 3000 bce.

Stone

The material that gives its name and a technological unity to these periods of prehistory is stone. Though it may be assumed that primitive humans used other materials such as wood, bone, fur, leaves, and grasses before they mastered the use of stone, apart from bone antlers, presumably used as picks in flint mines and elsewhere, and other fragments of bone implements, none of these has survived. The stone tools of early humans, on the other hand, have survived in surprising abundance, and over the many millennia of prehistory important advances in technique were made in the use of stone. Stones became tools only when they were shaped deliberately for specific purposes, and, for this to be done efficiently, suitable hard and fine-grained stones had to be found and means devised for shaping them and particularly for putting a cutting edge on them. Flint became a very popular stone for this purpose, although fine sandstones and certain volcanic rocks were also widely used. There is much Paleolithic evidence of skill in flaking and polishing stones to make scraping and cutting tools. These early tools were held in the hand, but gradually ways of protecting the hand from sharp edges on the stone, at first by wrapping one end in fur or grass or setting it in a wooden handle, were devised. Much later the technique of fixing the stone head to a haft converted these hand tools into more versatile tools and weapons.

With the widening mastery of the material world in the Neolithic Period, other substances were brought into service, such as clay for pottery and brick, and increasing competence in handling textile raw materials led to the creation of the first woven fabrics to take the place of animal skins. About the same time, curiosity about the behaviour of metallic oxides in the presence of fire promoted one of the most significant technological innovations of all time and marked the succession from the Stone Age to the Metal Age.

Power

The use of fire was another basic technique mastered at some unknown time in the Old Stone Age. The discovery that fire could be tamed and controlled and the further discovery that a fire could be generated by persistent friction between two dry wooden surfaces were momentous. Fire was the most important contribution of prehistory to power technology, although little power was obtained directly from fire except as defense against wild animals. For the most part, prehistoric communities remained completely dependent upon manpower, but, in making the transition to a more settled pattern of life in the New Stone Age, they began to derive some power from animals that had been domesticated. It also seems likely that by the end of prehistoric times the sail had emerged as a means of harnessing the wind for small boats, beginning a long sequence of developments in marine transport.

Tools and weapons

The basic tools of prehistoric peoples were determined by the materials at their disposal. But once they had acquired the techniques of working stone, they were resourceful in devising tools and weapons with points and barbs. Thus, the stone-headed spear, the harpoon, and the arrow all came into widespread use. The spear was given increased impetus by the spear-thrower, a notched pole that gave a sling effect. The bow and arrow were an even more effective combination, the use of which is clearly demonstrated in the earliest “documentary” evidence in the history of technology, the cave paintings of southern France and northern Spain, which depict the bow being used in hunting. The ingenuity of these primitive hunters is also shown in their slings, throwing-sticks (the boomerang of the Australian Aborigines is a remarkable surviving example), blowguns, bird snares, fish and animal traps, and nets. These tools did not evolve uniformly, as each primitive community developed only those instruments that were most suitable for its own specialized purposes, but all were in use by the end of the Stone Age. In addition, the Neolithic Revolution had contributed some important new tools that were not primarily concerned with hunting. These were the first mechanical applications of rotary action in the shape of the potter’s wheel, the bow drill, the pole lathe, and the wheel itself. It is not possible to be sure when these significant devices were invented, but their presence in the early urban civilizations suggests some continuity with the late Neolithic Period. The potter’s wheel, driven by kicks from the operator, and the wheels of early vehicles both gave continuous rotary movement in one direction. The drill and the lathe, on the other hand, were derived from the bow and had the effect of spinning the drill piece or the workpiece first in one direction and then in the other.

Developments in food production brought further refinements in tools. The processes of food production in Paleolithic times were simple, consisting of gathering, hunting, and fishing. If these methods proved inadequate to sustain a community, it moved to better hunting grounds or perished. With the onset of the Neolithic Revolution, new food-producing skills were devised to serve the needs of agriculture and animal husbandry. Digging sticks and the first crude plows, stone sickles, querns that ground grain by friction between two stones and, most complicated of all, irrigation techniques for keeping the ground watered and fertile—all these became well established in the great subtropical river valleys of Egypt and Mesopotamia in the millennia before 3000 bce.

Building techniques

Prehistoric building techniques also underwent significant developments in the Neolithic Revolution. Nothing is known of the building ability of Paleolithic peoples beyond what can be inferred from a few fragments of stone shelters, but in the New Stone Age some impressive structures were erected, primarily tombs and burial mounds and other religious edifices, but also, toward the end of the period, domestic housing in which sun-dried brick was first used. In northern Europe, where the Neolithic transformation began later than around the eastern Mediterranean and lasted longer, huge stone monuments, of which Stonehenge in England is the outstanding example, still bear eloquent testimony to the technical skill, not to mention the imagination and mathematical competence, of the later Stone Age societies.

Manufacturing

Manufacturing industry had its origin in the New Stone Age, with the application of techniques for grinding corn, baking clay, spinning and weaving textiles, and also, it seems likely, for dyeing, fermenting, and distilling. Some evidence for all these processes can be derived from archaeological findings, and some of them at least were developing into specialized crafts by the time the first urban civilizations appeared. In the same way, the early metalworkers were beginning to acquire the techniques of extracting and working the softer metals, gold, silver, copper, and tin, that were to make their successors a select class of craftsmen. All these incipient fields of specialization, moreover, implied developing trade between different communities and regions, and again the archaeological evidence of the transfer of manufactured products in the later Stone Age is impressive. Flint arrowheads of particular types, for example, can be found widely dispersed over Europe, and the implication of a common locus of manufacture for each is strong.

Such transmission suggests improving facilities for transport and communication. Paleolithic people presumably depended entirely on their own feet, and this remained the normal mode of transport throughout the Stone Age. Domestication of the ox, the donkey, and the camel undoubtedly brought some help, although difficulties in harnessing the horse long delayed its effective use. The dugout canoe and the birch-bark canoe demonstrated the potential of water transport, and, again, there is some evidence that the sail had already appeared by the end of the New Stone Age.

It is notable that the developments so far described in human prehistory took place over a long period of time, compared with the 5,000 years of recorded history, and that they took place first in very small areas of the Earth’s surface and involved populations minute by modern criteria. The Neolithic Revolution occurred first in those parts of the world with an unusual combination of qualities: a warm climate, encouraging rapid crop growth, and an annual cycle of flooding that naturally regenerated the fertility of the land. On the Eurasian-African landmass such conditions occur only in Egypt, Mesopotamia, northern India, and some of the great river valleys of China. It was there, then, that men and women of the New Stone Age were stimulated to develop and apply new techniques of agriculture, animal husbandry, irrigation, and manufacture, and it was there that their enterprise was rewarded by increasing productivity, which encouraged the growth of population and triggered a succession of sociopolitical changes that converted the settled Neolithic communities into the first civilizations. Elsewhere the stimulus to technological innovation was lacking or was unrewarded, so that those areas had to await the transmission of technical expertise from the more highly favoured areas. Herein is rooted the separation of the great world civilizations, for while the Egyptian and Mesopotamian civilizations spread their influence westward through the Mediterranean and Europe, those of India and China were limited by geographical barriers to their own hinterlands, which, although vast, were largely isolated from the mainstream of Western technological progress.

The Urban Revolution (c. 3000–500 bce)

The technological change so far described took place very slowly over a long period of time, in response to only the most basic social needs, the search for food and shelter, and with few social resources available for any activity other than the fulfillment of these needs. About 5,000 years ago, however, a momentous cultural transition began to take place in a few well-favoured geographical situations. It generated new needs and resources and was accompanied by a significant increase in technological innovation. It was the beginning of the invention of the city.

Craftsmen and scientists

The accumulated agricultural skill of the New Stone Age had made possible a growth in population, and the larger population in turn created a need for the products of specialized craftsmen in a wide range of commodities. These craftsmen included a number of metalworkers, first those treating metals that could be easily obtained in metallic form and particularly the soft metals, such as gold and copper, which could be fashioned by beating. Then came the discovery of the possibility of extracting certain metals from the ores in which they generally occur. Probably the first such material to be used was the carbonate of copper known as malachite, then already in use as a cosmetic and easily reduced to copper in a strong fire. It is impossible to be precise about the time and place of this discovery, but its consequences were tremendous. It led to the search for other metallic ores, to the development of metallurgy, to the encouragement of trade in order to secure specific metals, and to the further development of specialist skills. It contributed substantially to the emergence of urban societies, as it relied heavily upon trade and manufacturing industries, and thus to the rise of the first civilizations. The Stone Age gave way to the early Metal Age, and a new epoch in the story of humankind had begun.

By fairly general consent, civilization consists of a large society with a common culture, settled communities, and sophisticated institutions, all of which presuppose a mastery of elementary literacy and numeration. Mastery of the civilized arts was a minority pursuit in the early civilizations, in all probability the carefully guarded possession of a priestly caste. The very existence of these skills, however, even in the hands of a small minority of the population, is significant because they made available a facility for recording and transmitting information that greatly enlarged the scope for innovation and speculative thought.

Hitherto, technology had existed without the benefit of science, but, by the time of the first Sumerian astronomers, who plotted the motion of the heavenly bodies with remarkable accuracy and based calculations about the calendar and irrigation systems upon their observations, the possibility of a creative relationship between science and technology had appeared. The first fruits of this relationship appeared in greatly improved abilities to measure land, weigh, and keep time, all practical techniques, essential to any complex society, and inconceivable without literacy and the beginnings of scientific observation. With the emergence of these skills in the 3rd millennium bce, the first civilizations arose in the valleys of the Nile and of the Tigris-Euphrates.

Copper and bronze

The fact that the era of the early civilizations coincides with the technological classification of the Copper and Bronze ages is a clue to the technological basis of these societies. The softness of copper, gold, and silver made it inevitable that they should be the first to be worked, but archaeologists now seem to agree that there was no true “Copper Age,” except perhaps for a short period at the beginning of Egyptian civilization, because the very softness of that metal limited its utility for everything except decoration or coinage. Attention was thus given early to means of hardening copper to make satisfactory tools and weapons. The reduction of mixed metallic ores probably led to the discovery of alloying, whereby copper was fused with other metals to make bronze. Several bronzes were made, including some containing lead, antimony, and arsenic, but by far the most popular and widespread was that of copper and tin in proportions of about 10 to one. This was a hard yellowish metal that could be melted and cast into the shape required. The bronzesmiths took over from the coppersmiths and goldsmiths the technique of heating the metal in a crucible over a strong fire and casting it into simple clay or stone molds to make axheads or spearheads or other solid shapes. For the crafting of hollow vessels or sculpture, they devised the so-called cire perdue technique, in which the shape to be molded is formed in wax and set in clay, the wax then being melted and drained out to leave a cavity into which the molten metal is poured.

Bronze became the most important material of the early civilizations, and elaborate arrangements were made to ensure a continuous supply of it. Metals were scarce in the alluvial river valleys where civilization developed and therefore had to be imported. This need led to complicated trading relationships and mining operations at great distances from the homeland. Tin presented a particularly severe problem, as it was in short supply throughout the Middle East. The Bronze Age civilizations were compelled to search far beyond their own frontiers for sources of the metal, and in the process knowledge of the civilized arts was gradually transmitted westward along the developing Mediterranean trade routes.

Sahure: Egyptian seagoing ship [Credit: Courtesy of the Science Museum, London]In most aspects other than the use of metals, the transition from the technology of the New Stone Age to that of early civilizations was fairly gradual, although there was a general increase in competence as specialized skills became more clearly defined, and in techniques of building there were enormous increases in the scale of enterprises. There were no great innovations in power technology, but important improvements were made in the construction of furnaces and kilns in response to the requirements of the metalworkers and potters and of new artisans such as glassworkers. Also, the sailing ship assumed a definitive shape, progressing from a vessel with a small sail rigged in its bows and suitable only for sailing before the prevailing wind up the Nile River, into the substantial oceangoing ship of the later Egyptian dynasties, with a large rectangular sail rigged amidships. Egyptian and Phoenician ships of this type could sail before the wind and across the wind, but for making headway into the wind they had to resort to manpower. Nevertheless, they accomplished remarkable feats of navigation, sailing the length of the Mediterranean and even passing through the Pillars of Hercules into the Atlantic.

Irrigation

Techniques of food production also showed many improvements over Neolithic methods, including one outstanding innovation in the shape of systematic irrigation. The civilizations of Egypt and Mesopotamia depended heavily upon the two great river systems, the Nile and the Tigris-Euphrates, which both watered the ground with their annual floods and rejuvenated it with the rich alluvium they deposited. The Nile flooded with regularity each summer, and the civilizations building in its valley early learned the technique of basin irrigation, ponding back the floodwater for as long as possible after the river had receded, so that enriched soil could bring forth a harvest before the floods of the following season. In the Tigris-Euphrates valley the irrigation problem was more complex, because the floods were less predictable, more fierce, and came earlier than those of the northward-flowing Nile. They also carried more alluvium, which tended to choke irrigation channels. The task of the Sumerian irrigation engineers was that of channeling water from the rivers during the summer months, impounding it, and distributing it to the fields in small installments. The Sumerian system eventually broke down because it led to an accumulation of salt in the soil, with a consequent loss of fertility. Both systems, however, depended on a high degree of social control, requiring skill in measuring and marking out the land and an intricate legal code to ensure justice in the distribution of precious water. Both systems, moreover, depended on intricate engineering in building dikes and embankments, canals and aqueducts (with lengthy stretches underground to prevent loss by evaporation), and the use of water-raising devices such as the shadoof, a balanced beam with a counterweight on one end and a bucket to lift the water on the other.

Urban manufacturing

Manufacturing industry in the early civilizations concentrated on such products as pottery, wines, oils, and cosmetics, which had begun to circulate along the incipient trade routes before the introduction of metals; these became the commodities traded for the metals. In pottery, the potter’s wheel became widely used for spinning the clay into the desired shape, but the older technique of building pots by hand from rolls of clay remained in use for some purposes. In the production of wines and oils various forms of press were developed, while the development of cooking, brewing, and preservatives justified the assertion that the science of chemistry began in the kitchen. Cosmetics too were an offshoot of culinary art.

Pack animals were still the primary means of land transport, the wheeled vehicle developing slowly to meet the divergent needs of agriculture, trade, and war. In the latter category, the chariot appeared as a weapon, even though its use was limited by the continuing difficulty of harnessing a horse. Military technology brought the development of metal plates for armour.

Building

In building technology the major developments concerned the scale of operations rather than any particular innovation. The late Stone Age communities of Mesopotamia had already built extensively in sun-dried brick. Their successors continued the technique but extended its scale to construct the massive square temples called ziggurats. These had a core and facing of bricks, the facing walls sloping slightly inward and broken by regular pilasters built into the brickwork, the whole structure ascending in two or three stages to a temple on the summit. Sumerians were also the first to build columns with brick made from local clay, which also provided the writing material for the scribes.

In Egypt, clay was scarce but good building stone was plentiful, and builders used it in constructing the pyramids and temples that remain today as outstanding monuments of Egyptian civilization. Stones were pulled on rollers and raised up the successive stages of the structure by ramps and by balanced levers adapted from the water-raising shadoof. The stones were shaped by skilled masons, and they were placed in position under the careful supervision of priest-architects who were clearly competent mathematicians and astronomers, as is evident from the precise astronomical alignments. It seems certain that the heavy labour of construction fell upon armies of slaves, which helps to explain both the achievements and limitations of early civilizations. Slaves were usually one of the fruits of military conquest, which presupposes a period of successful territorial expansion, although their status as a subject race could be perpetuated indefinitely. Slave populations provided a competent and cheap labour force for the major constructional works that have been described. On the other hand, the availability of slave labour discouraged technological innovation, a social fact that goes far toward explaining the comparative stagnation of mechanical invention in the ancient world.

Transmitting knowledge

In the ancient world, technological knowledge was transmitted by traders, who went out in search of tin and other commodities, and by craftsmen in metal, stone, leather, and the other mediums, who passed their skills to others by direct instruction or by providing models that challenged other craftsmen to copy them. This transmission through intermediary contact was occurring between the ancient civilizations and their neighbours to the north and west during the 2nd millennium bce. The pace quickened in the subsequent millennium, distinct new civilizations arising in Crete and Mycenae, in Troy and Carthage. Finally, the introduction of the technique of working iron profoundly changed the capabilities and resources of human societies and ushered in the Classical civilizations of Greece and Rome.

Technological achievements of Greece and Rome (500 bce–500 ce)

The contributions of Greece and Rome in philosophy and religion, political and legal institutions, poetry and drama, and in the realm of scientific speculation stand in spectacular contrast with their relatively limited contributions in technology. Their mechanical innovation was not distinguished, and, even in the realms of military and construction engineering, in which they showed great ingenuity and aesthetic sensibility, their work represented more a consummation of earlier lines of development than a dramatic innovation. This apparent paradox of the Classical period of the ancient world requires explanation, and the history of technology can provide some clues to the solution of the problem.

The mastery of iron

The outstanding technological factor of the Greco-Roman world was the smelting of iron, a technique—derived from unknown metallurgists, probably in Asia Minor, about 1000 bce—that spread far beyond the provincial frontiers of the Roman Empire. The use of the metal had become general in Greece and the Aegean Islands by the dawn of the Classical period about 500 bce, and it appears to have spread quickly westward thereafter. Iron ore, long a familiar material, had defied reduction into metallic form because of the great heat required in the furnace to perform the chemical transformation (about 1,535 °C [2,795 °F] compared with the 1,083 °C [1,981 °F] necessary for the reduction of copper ores). To reach this temperature, furnace construction had to be improved and ways devised to maintain the heat for several hours. Throughout the Classical period these conditions were achieved only on a small scale, in furnaces burning charcoal and using foot bellows to intensify the heat, and even in these furnaces the heat was not sufficient to reduce the ore completely to molten metal. Instead, a small spongy ball of iron—called a bloom—was produced in the bottom of the furnace. This was extracted by breaking open the furnace, and then it was hammered into bars of wrought iron, which could be shaped as required by further heating and hammering. Apart from its greater abundance, iron for most purposes provided a harder and stronger material than the earlier metals, although the impossibility of casting it into molds like bronze was an inconvenience. At an early date some smiths devised the cementation process for reheating bars of iron between layers of charcoal to carburize the surface of the iron and thus to produce a coat of steel. Such case-hardened iron could be further heated, hammered, and tempered to make knife and sword blades of high quality. The very best steel in Roman times was Seric steel, brought into the Western world from India, where it was produced in blocks a few inches in diameter by a crucible process, melting the ingredients in an enclosed vessel to achieve purity and consistency in the chemical combination.

Mechanical contrivances

Though slight, the mechanical achievements of the Greco-Roman centuries were not without significance. The world had one of its great mechanical geniuses in Archimedes, who devised remarkable weapons to protect his native Syracuse from Roman invasion and applied his powerful mind to such basic mechanical contrivances as the screw, the pulley, and the lever. Alexandrian engineers, such as Ctesibius and Hero, invented a wealth of ingenious mechanical contrivances including pumps, wind and hydraulic organs, compressed-air engines, and screw-cutting machines. They also devised toys and automata such as the aeolipile, which may be regarded as the first successful steam turbine. Little practical use was found for these inventions, but the Alexandrian school marks an important transition from very simple mechanisms to the more complex devices that properly deserve to be considered “machines.” In a sense it provided a starting point for modern mechanical practice.

The Romans were responsible, through the application and development of available machines, for an important technological transformation: the widespread introduction of rotary motion. This was exemplified in the use of the treadmill for powering cranes and other heavy lifting operations, the introduction of rotary water-raising devices for irrigation works (a scoop wheel powered by a treadmill), and the development of the waterwheel as a prime mover. The 1st-century-bce Roman engineer Vitruvius gave an account of watermills, and by the end of the Roman era many were in operation.

Agriculture

Iron Age technology was applied to agriculture in the form of the iron (or iron-tipped) plowshare, which opened up the possibility of deeper plowing and of cultivating heavier soils than those normally worked in the Greco-Roman period. The construction of plows improved slowly during these centuries, but the moldboard for turning over the earth did not appear until the 11th century ce, so that the capacity of turning the sod depended more on the wrists of the plowman than on the strength of his draft team; this discouraged tackling heavy ground. The potentialities of the heavy plow were thus not fully exploited in the temperate areas of Europe until after the Roman period. Elsewhere, in the drier climates of North Africa and Spain, the Romans were responsible for extensive irrigation systems, using the Archimedean screw and the noria (an animal- or water-powered scoop wheel) to raise water.

Building

aqueduct [Credit: Courtesy of the Deutsches Museum, Munich]Though many buildings of the Greeks survive as splendid monuments to the civilized communities that built them, as technological monuments they are of little significance. The Greeks adopted a form of column and lintel construction that had been used in Egypt for centuries and was derived from experience of timber construction. In no major sense did Greek building constitute a technological innovation. The Romans copied the Greek style for most ceremonial purposes, but in other respects they were important innovators in building technology. They made extensive use of fired brick and tile as well as stone; they developed a strong cement that would set under water; and they explored the architectural possibilities of the arch, the vault, and the dome. They then applied these techniques in amphitheatres, aqueducts, tunnels, bridges, walls, lighthouses, and roads. Taken together, these constructional works may fairly be regarded as the primary technological achievement of the Romans.

Other fields of technology

In manufacturing, transport, and military technology, the achievements of the Greco-Roman period are not remarkable. The major manufacturing crafts—the making of pottery and glass, weaving, leatherworking, fine-metalworking, and so on—followed the lines of previous societies, albeit with important developments in style. Superbly decorated Athenian pottery, for example, was widely dispersed along the trade routes of the Mediterranean, and the Romans made good quality pottery available throughout their empire through the manufacture and trade of the standardized red ware called terra sigillata, which was produced in large quantities at several sites in Italy and Gaul.

Transport

Transport, again, followed earlier precedents, the sailing ship emerging as a seagoing vessel with a carvel-built hull (that is, with planks meeting edge-to-edge rather than overlapping as in clinker-built designs), and a fully developed keel with stempost and sternpost. The Greek sailing ship was equipped with a square or rectangular sail to receive a following wind and one or more banks of oarsmen to propel the ship when the wind was contrary. The Greeks began to develop a specialized fighting ship, provided with a ram in the prow, and the cargo ship, dispensing with oarsmen and relying entirely upon the wind, was also well established by the early years of Classical Greece. The Romans took over both forms, but without significant innovation. They gave much more attention to inland transport than to the sea, and they constructed a remarkable network of carefully aligned and well-laid roads, often paved over long stretches, throughout the provinces of the empire. Along these strategic highways the legions marched rapidly to the site of any crisis at which their presence was required. The roads also served for the development of trade, but their primary function was always military, as a vital means of keeping a vast empire in subjection.

Military technology

Roman military technology was inventive on occasion, as in the great siege catapults, depending on both torsion and tension power. But the standard equipment of the legionnaire was simple and conservative, consisting of an iron helmet and breastplate, with a short sword and an iron-tipped spear. As most of their opponents were also equipped with iron weapons and sometimes with superior devices, such as the Celtic chariots, the Roman military achievements depended more on organization and discipline than on technological superiority.

The Greco-Roman era was distinguished for the scientific activity of some of its greatest philosophers. In keeping with Greek speculative thought, however, this tended to be strongly conceptual so that it was in mathematics and other abstract studies that the main scientific achievements are to be found. Some of these had some practical significance, as in the study of perspective effects in building construction. Aristotle in many ways expressed the inquiring empiricism that has caused scientists to seek an explanation for their physical environment. In at least one field, that of medicine and its related subjects, Greek inquiry assumed a highly practical form, Hippocrates and Galen laying the foundations of modern medical science. But this was exceptional, and the normal Hellenic attitude was to pursue scientific enquiry in the realm of ideas without much thought of the possible technological consequences.

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