After his graduation from Cambridge University in 1831, Charles Darwin developed deep enthusiasm in biology and consequently embarked on a mission to investigate the origin of species (Quammen, 2006). Several years later, after conducting extensive research, he came up with the theory of evolution which mainly suggests that organisms evolved from simple forms to their present complex forms. He proposed several theories that sought to explain how the process of evolution took place. The process of natural selection is one of them. This theory suggests that nature selects a variety of species that are suitable for survival and reproduction in a particular environment (Darwin, 1896). In other words, nature acts as a sieve: it separates organisms that can survive in a given environment from those that cannot. Darwin described this process as “survival of the fittest”. Another process, artificial selection, also explains how organisms survive and reproduce in a given environment. This process contrasts with the process of natural selection in the sense that it is driven intentionally by human beings hence the term artificial.
Farmers and breeders had been using the idea of selection to cause desirable changes in plants and animals long before Darwin. As a matter of fact, artificial selection was a common practice among the Romans as a means of producing desired crops and animals (Hancock, 2004). Charles Darwin used the term to illustrate his proposal of natural selection. In artificial selection, organisms are bred based on certain traits. Much of practices of artificial selection took place during the era of plant and animal domestication. In the modern society, wide variety of new traits of plants and animals has been produced through artificial selection by using genetic technology.
Through artificial selection, a wide variety of plants have been developed from one ancestor. A good example is broccoli. Broccoli belongs to the Brassicca oleracea family. The term mostly refers to the heading and sprouting forms belonging to the Brassicca oleracea L. Italica group. There are various types of broccoli which have developed from the initial type that was initially derived from the ancestor. These include the following: purple sprouting broccoli, purple cape broccoli, white sprouting broccoli, purple Sicilian broccoli, and black broccoli. Purple sprouting broccoli is branched. The purple cape broccoli has single purple heads. Purple silicon broccoli on the other hand has single head which is pale purple. In horticulture, it is known as purple cauliflower. It is mostly grown in South West Italy. Black broccoli is more distinct from the rest in that it has dark green spears and sickle-shaped leaves. In addition to this, it is annual. It traces its origin to Rome. These are some of the variations among the broccoli group. This variation may be attributed to artificial selection since people still continue to control breeding of various domesticated crops in a bid to ensure that crops with desirable characteristics survive.
Broccoli is said to have been developed from wild cabbage through artificial selection. Broccoli is an Italian term which means brachium. Brachium means an arm of a branch. There were a variety of cabbage plants. Other vegetables developed from the same plant include cabbage, kohlrabi, kale and cauliflower. Farmers are said to have examined the variations in the wild cabbage plants and then crossed them and artificially selected their traits (Kallo & Bergh, 1993). In the end, they obtained these plants. The selection process depended on the need and taste of every farmer. The selection process took place as follows: Some farmers wanted to have wild cabbage with denser leaves. After careful selection and crossing of different varieties of the wild cabbage, they obtained the common cabbage. Others opted for arrested development of flowers of the wild cabbage plant and eventually developed broccoli. Another group of farmers preferred the wild cabbage with sterile flowers. Consequently, they crossed different varieties of the wild cabbage and eventually produced cauliflower. Kohlrabi on the other hand was developed by farmers who preferred swollen part of cabbage. Finally, kale was developed by farmers who wanted large leaves of the wild cabbage. It is therefore argued that the wild cabbage, otherwise known as wild mustard, is the ancestor of broccoli (Kallo & Bergh, 1993).
The various types of broccoli may also have been produced from the original ancestor through different methods of selective breeding. For instance, purple and white sprouting broccoli, and purple cape broccoli are believed to have been produced in the UK. Evidence point out that selective breeding might have been practiced by the then inhabitants of UK and France hence gave rise to this crop. Despite the fact that history point out that much activity in controlling the breeding of broccoli occurred several years ago, fresh evidence show that there has been little effort to transform the plant. This is attributed to recent lack of interest by growers in these crops.
Cabbages and kales were first domesticated one thousand years ago (Hancock, 2004). Broccoli and cauliflower on the other hand are said to have emerged within the last five hundred years (Hancock, 2004). Perhaps this explains why they are more similar to one another than to other plants that are also descendants of wild cabbage. From a wild cabbage with flowers, relatively large lives, and a long stalk, broccoli has evolved. In the modern society, advancement in technology has made selective breeding more effective. Genetic innovations have made it possible to transfer genes from one organism to another. Consequently, much progress has been made in eliminating undesirable traits among plants and animals.
We have seen that artificial selection that led to the development of broccoli was based on certain desired traits, which varied from one farmer to another. Traits related to structure include such qualities as the size of leaves of the plant, length of the stem of the plant, presence of flowers, and many other traits. Other important traits farmers took into consideration were taste and texture of the plant. Artificial selection ensures that only organisms with desired qualities are allowed to breed. This may be disadvantageous in several ways. First, it should be noted that a characteristic considered undesirable may be useful after all. For instance, a plant may be considered undesirable because of its bitter leaves. However, the bitter leaves may exhibit curative benefits. If such plants are prevented from reproducing, the benefits they would offer in future may not be realized. This is one of the disadvantages of artificial breeding. Other disadvantages of artificial breeding are discussed below.
Artificial breeding can lead to loss of variety. This may create an ecosystem comprised of only plants or animals susceptible to a similar disease. Under such circumstances, any occurrence of an epidemic would be risky to the ecosystem. In other world, an ecosystem is insecure if its inhabitants posses similar weaknesses. Variety is very essential for the wellbeing of an ecosystem. For instance, presence of a variety of traits among any given species can lead to development of a better and more useful trait. In addition, continuity in variations can help ensure that there will be enough variety from which researchers can carry out their studies.
Artificial breeding has led to production of genetically engineered plants. The genetically modified plants undergo processes that may lead to alteration of their various natural contents that are of value to human consumption. Maximum benefit is therefore not derived from such plants. In addition, claims have been made that genetically modified crops pose adverse health effects to individuals who happen to consume them. Many have argued that they are either mutagenic or teratogenic.
Finally, artificial breeding can lead to transfer of resistant pathogens from one plant to another. This may in turn give rise to new pathogens. To make matters worse, all organisms given rise to by selective breeding may end up hosting these pathogens. In the long run, the whole set of the organisms may become extinct.
.Artificial selection has been employed widely to promote the continuity of plants and animals with desirable traits. Despite certain benefits derived from it, there are equally many challenges associated with it. In a nut shell, artificial selection is not beneficial. In my view, it is not necessary since man can promote the breeding of organisms with desirable traits while also not interfering with reproduction of those with undesirable traits. Organisms should be allowed to reproduce and only nature should select.
References
Darwin, C. (1896). The origin of species by means of natural selection, or, The preservation of favored races in the struggle for life. New York: D. Appleton.Bottom of Form
Hancock, J. F. (2004). Plant evolution and the origin of crop species. Wallingford, Oxon, UK: CABI Pub.
Kalloo, G., & Bergh, B. O. (1993). Genetic improvement of vegetable crops. Oxford: Pergamon Press.Bottom of Form
Quammen, D. (2006). The reluctant Mr. Darwin: An intimate portrait of Charles Darwin and the making of his theory of evolution. New York: Atlas Books/Norton.
