According to the theory of evolution, artificial selection is the process of deliberate or accidental alteration of species through human activities. It allows for the manifestation of  favorable  traits and suppression of  unfavorable  traits. A specific individual is chosen for his or her desirable traits and then inbred with another which has similar traits the product is one with a higher potential of the traits desired. This process is repeated until the desired traits are fully manifested. Scientist Charles Darwin observed that many domesticated animals and plants have favorable traits that were expanded by deliberately, allowing the reproduction of those who had the desirable traits and inhibiting the development of those that did not posses the traits (Lewis et al. 200916). Human preferences have had an effect on evolution, leading to the production of diverse species.
Human activities, to a great extent, contribute to the creation of undesirable environmental pressures like change of habitat which lead to artificial selection. Same as other species, human culture (beliefs, religion, and way of life) is shaped by forces of artificial selection, such as diseases, climatic changes, population, and even droughts (Diamond 1997142). Humans acclimatize hereditarily to constant cultural changes such as fashion and foods. Biologists view culture as a way of humans shielding themselves from the impacts of artificial selection (Lewis et al. 200946). By means of artificial selection, evolution story is being studied in laboratories by formation of new generations of specific laboratory organisms.

The Neothilic Revolution
Domestication of plants and animals began during the Neothilic revolution, a transition era from hunters and gatherers to farmers and stock breeders.  The transition saw to it that people moved from being nomadic and they settled down  (Angeloni 20097). In his work, Guns Germs and Steel, Diamond (1997143) posits that, after the second ice age, water became scarce and people who were used to hunting and gathering had to find alternate methods of obtaining foods. The climatic changes forced people to traverse longer distances in search of food as aridity spread. Over the years, they unknowingly adjusted their lifestyles according to the environmental changes (Lewis et al. 200965). They unconsciously camped near water sources, and they would bring wild seeds back to their settlement areas and plant them. Their knowledge of plants and animals expanded with time. They altered the genetic makeup of plants, mostly grasses, to produce wheat, barley, rice, and other cereal crops. Crops that possessed undesirable tastes were discarded and those that were up to their requirements were eventually domesticated. As their life changed from being nomadic to agriculturists, they found it more convenient to make animals part of their lifestyle they therefore domesticated them as well (Diamond 1997147).

A domesticate is a modified form of a plant or animal. Most studies show that humans have been able to transform different organisms, a factor that has led to the extinction of others in a relatively short time.

Through environmental changes humans were forced to settle down and they increased in population thus domestication.
The early sedentary man considered the animal diet, mating habits, disposition, size, and lifespan as essential factors in domestication of animals (Angeloni 20097). They preferred milk-producing animals like the cows and goats as they gave a renewable source of proteins. The ability of the animal was utilized in such works as plowing where oxen were used, while the donkeys were employed as a mode of transport.  Docile animals like sheep were easily domesticated by capturing and taming their leaders. Early archaeologists argued that some animals like the cattle were domesticated because of religious sentiments (Angeloni 20097).

Over time, humans have transformed numerous plant and animal species to suit their needs (Lewis et al. 20098). One theory that explains the evolution of agriculture is the oasis theory (Lewis et al. 20092 4).  According to researchers, as climate changed, it got drier, causing humans and plants to concentrate around the few oasis that were available. This interaction favored the humans as they eventually took control of the animals (domestication). Other theories suggest it was an accident of nature, co-evolution hypothesis, a symbiotic liaison between humans and animals or plants (Lewis et al. 20095). They evolved to suit each others needs.

Varieties of domesticated animals and plants normally vary from one another. In this respect, domestic dogs ranging from the Chihuahuas to the Danes trace their ancestry from the great gray wolf. The Chihuahuas were preferred because of their small size as they eat less, but the great Danes are much larger in size and are therefore more ferocious. The neothilic people found out that wolf puppies could be tamed and used for hunting. The strains they developed later were used for herding ( Lewis et al. 200912). Another example of domestication is the wild mustard which, over time, has evolved to a variety of vegetables. Starting with the cauliflower which evolved from making the flowers of the mustard sterile, followed by the broccoli, a repression of the flower development, then came the cabbage which was the result of restraint of the internode length. This was then followed by the kale which resulted from the enlargement of the cabbage leaves. An improvement of the kales  lateral meristems resulted in the Kohlrabi (Diamond 1997121 147).
The three main outcome of domestications were
Increased energy returns from consumption of the preferred foods.
Domestication saw to it that time involved in production of foods was reduced. For the animals, their increased small sizes reduced their aggressiveness.

By increasing their farming area, the availability of foods increased and herding  was also introduced.
Domestication led to agricultural revolution which was a product of the spread of domesticated plants and animals and the emergence of complex communities. Hunters and gatherers who bordered the sedentary farmers had to either adopt the new ways of life or flee in search of more virgin land for their nomadic way of life. Varieties of crops that evolved from early artificial selections made agriculture a more profitable engagement this, and the urge for people to own property ensured agriculture developed (Angeloni 20097).

As agriculture took hold, the farmers got surpluses of foods which necessitated storage. However, the people were unable to store their produce as they were always on the move due to their nomadic lifestyle, but those with sedentary lifestyle were able to store food (Diamond 199739 43 77). They eventually built granaries which allowed for villages to develop and store seeds for longer periods (Diamond 19979).  These increments in food production eventually led to explosion in population and formed communities. They were able to specialize their work, an idea that brought about advancement of tools. Life became easier for the people, and they were able to manage their food supply systems. As climates changed, people were able to produce crops at concentrated water sources. These encouraged larger communities and obliged them settle in specific territories (Diamond 199729 46).

The communities reproduced faster as their permanency made it easier to bring up children. However, this expansion of huge societies required a method of governance. Food surpluses and animal products were used to feed the leaders as they concentrated more on leadership than food production. Settlement allowed people to acquire more personal possession attached to their land of settlement. From their possession, they were able to save for bad times or trade off their surpluses for what they did not produce with other societies. The establishment of food security and trade allowed communities to enlarge (Diamond 199767 138 141).

In Diamonds  (1997426) view,  societies developed differently on different areas courtesy of different climatic changes.  He further concludes that improved technology and centralized forms of government could only develop in dense sedentary communities who were capable of storing food surpluses.

Intense labor was needed to ensure consistence supply of food and at first, farming did not promise the people security from hunger. This caused some smaller communities of hunters and gatherers, migratory cultivators, and fishermen to hold on to their known way of life. Farmers and the nomads coexisted peacefully. Even after sedentary farming became their culture, those of the nomads held on. An example is the America nomadic culture which persisted due to lack of transport and minimal herds of animals (Barry et al. 2009334).
Domestication also led to the rise of the pastoral culture which by far has been a great competitor of sedentary farming. It was mostly preferred because it could thrive in semi and arid areas like central Asia and south of the Sahara desert. These areas were not capable of supporting large populations and tended to produce hardy people who could defend themselves from the wild and also attack the sedentary farmers for food. The specialized occupation brought about civilization which led to the rise of diverse culture, which included religions, arts, and advancement in science and technology. Today, as technology unifies people and the world becomes a global village, homogenized cultures are emerging and early cultures are slowly being eradicated (Lewis et al. 2009334).

Development of Infections
There were complex societies who eventually contracted diseases which spread faster than during times when the people led a nomadic life. These diseases might have been contracted from the animals they domesticated. As they modified the animals to suit their needs, they created germs which in turn they contracted through produce like milk and meat. Some of the diseases that were contracted then were small pox, measles, and others (Barry et al. 2009332).
Most of these infections either killed the humans or eventually gave them immunity. Recent biological studies have shown that these diseases evolved from similar strains found in the domesticated animals. Artificial selection which eventually led to domestication ensured crowded residence due to population and also closer contact of humans and animals. These two factors made it easy for human to contract infections from their animals (Diamond 19979).
The infections that were contracted were eventually used as a mode of capture by the early man most exposed to them. Gradually, the people acquired immunity from the diseases
they had contacted from as early as childhood. Genetic resistance to certain infections eventually
evolved in exposed populations as each generation became more resistant than the previous one, but unexposed communities did not have any form of resistance. Expanding sedentary farmers used such infections as a form of conquest as they expanded their agriculture beyond bounders. They exposed the infections to indigenous people who had no form of resistance, eventually killing them and taking over their pasture lands to utilize them as farmlands (Diamond 199711). Technology has, however, helped scientists to manufacture vaccines for example, they created a vaccine to fight against small pox and eventually eradicated it
Civilization is where societies achieve relatively advanced development and organization often characterized by agricultural advancement, trade, and specialized occupations (Angeloni 200976). The early man became more skilled in farming varieties of crops including protein rich legumes like beans peas, fruits, and others. The exertion used in such activities contributed to the slow phasing of their nomadic activities. As their outside activities were reduced, their crops also reduced their yield. This people involved themselves in selecting only the best seeds and also mixed varying strains so as to improve the yield and disease resistance (Angeloni 200938). They invented herbalism (use of plants and plant extracts for treatment and prevention of diseases). History suggests herbalism originated from the Middle East and was mostly used for trade as it was very profitable. Currently, however, herbalism is used in the formulation of conventional medications, food supplements such as Vitamin c, and many others (Angeloni 200938).

Most plants synthesize substances such as phenols, tannins, and aromatic substances which are widely utilized in the maintenance of human health. Some of the herbal medicines being used to date include Aspirin, digitalis, and opium. The early man discovered how to use animal manure to enrich their farms and increase their yield. Today, through artificial selection, technology is being applied to modify manure and give fertilizers. Animal products like the skins and wool were used to make materials for shelter and clothing they also crafted crude boats from them. Other products like horns, hooves and bones were carved for utensils, needles and even weapons, which with time were replaced by steel and guns.

As a large majority of people engaged themselves in food production, a minority engaged themselves in more specialized activities. They included art work, building an advanced warfare, and a centralized form of government capable of controlling all the sophisticate tools being created  (Diamond 1997147).

The Fertile Crescent of the Middle East was where archaeologists deem civilization began. This area had considerable geographical differences, which allowed for different plant species for experimentation. They developed irrigation especially in Mesopotamia, where cities were enclosed with brick walls. Most of their homes were made from reeds, but they later started using bricks to make more permanent structures.
Lewis and associates (2009) argue that civilization brought about less organized communities with complex patterns of exchange and ownership of properties. Since people in civilized places did not farm, they had to trade their goods for food. Trade by use of gold, copper bronze, and steel was introduced, forming economies. They also began to use money as a means of transaction. The Sumerians developed the first form of writing which is considered by archaeologists as the cradle of civilization (Lewis et al. 2009).

In his book, Diamond (1997147) attempts to explain the reason behind the differences in the civilization between continents. He argues that factors like fragmentation of the European community ensured that they advanced in technology while other areas like China remained unified and these did not foster technological growth. There was competition in Europe as states sought different ways to support them and to protect them from invasion. This led to capitalism and advancement in technology and science. He continues to outline that political fragmentation can have more negative than positive consequences, for example World War I and World War II (Diamond 1997147).

The civilized world has been dotted with religious conversions, genocides, and even invasions. By the introduction of agriculture and writing to the primitive societies, trade and formal forms of leadership easily spread. More civilized societies used the advantage of arms and advanced technology to force religion and different cultures on primitive illiterate communities. Childe, as cited by Diamond (1997), describes how civilized societies used the excuse of religion to justify their invasions, and they either succeeded to impose their culture on others or assimilate others cultures into their own for instance, Korea, Japan and Vietnam assimilated the culture of China (Diamond 1997148). Thus, civilization enabled the people to  spread their culture. Nevertheless, civilization can also fall. Diamond (1997148) gives five reasons that can lead to the fall of civilization, namely  deforestation which leads to soil erosion, climatic changes which is not reliable for food production, long distance trade for resources leaving cities with no one to develop them, and increasing levels of internal and external violence.

Long distance trade ultimately led to globalization which has both negative and positive outcomes. In today s world, globalization has led to a rise in sources and types of education systems, diversified career choices, and a massive increment in technological innovations which are supposed to make life easier. An example given by Diamond (1997) is the success Microsoft which made it easy for everyone in the world to communicate and keep track of information and data. Another example is that of the Kuwait bank which managed to fax key documents to Bahrain while the country was being invaded by Iraq. These documents enabled them to continue operating across the border without being affected by restriction being imposed on Kuwait by Iraq. However, research has shown that culture and values are faced with crisis. Barry sees technological innovations as having reduced the time people use to communicate across cultural bounders.
In conclusion, artificial selection has both positive and negative effects whether in medicine, plants, or animals. In artificial selection, humans predetermine which features are favored by what time. Not all artificially selected organisms are well suited to their environment of origin, which necessitates human interventions to help sustain their existence. This has led to great technological inventions like herbicide, pesticides, and enriched fertilizers for crop plants, vaccines for animals susceptible to infections, and artificial inseminations for those which have lost fertility due to artificial selection.
However, in more ways, artificial selection has endangered biodiversity by destroying original wild varieties and by getting rid of competitor varieties. It has also led to the emergence of unfit breeds which have adverse health effects. Examples of an unfit breed are the Pug dogs which have difficulty in breathing and the Boxers which suffer from epilepsy.
The manufacture of artificial fertilizers has also proved to be lethal as runoffs from farmlands end up in the oceans and seas, poisoning the waters and endangering aquatic live. On the other hand, these fertilizers have ensured a steady supply of fortified foods which can be grown in the field over an over without depletion of nutrients.
Nevertheless, artificial selection has also led to the evolution of medicine it offers hope for most who suffer from genetic problems like cystic fibrosis which can be treated by artificially selecting stem cells that will alter the condition. It is also applied in modifying bacteria genetically for production of medicine. Therapeutic viruses are also being manufactured in laboratories and made to reproduce faster. Thus, artificial selection is sure to benefit medicine in future though advanced researches should be done to ensure it safeness and effectiveness.


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