Artificial Selection - Good or Bad?

(Choosing the Fittest)

Based on the encyclopaedia term definition for artificial selection (or selective breeding) describes intentional breeding for certain traits, or combination of traits. The term was utilized by Charles Darwin in contrast to natural selection, in which the differential reproduction of organisms with certain traits is attributed to improved survival or reproductive ability (“Darwinian fitness”). As opposed to artificial selection, which humans favour specific traits, in natural selection the environment acts as a sieve through which only certain variations can pass. Humans have carried out artificial selection (or selective breeding) for thousands of years. In one sense, the history of farming is the history of artificial selection.

We humans have been artificial selecting animals and plants for thousands of years ago. Animals and plants were first domesticated in the eastern Mediterranean; in the area known as the Fertile Crescent. And the first animal to be domesticated was the dog, from wild wolves around 13,000 years ago. In all parts of the world our ancestors realised they could breed animals and crops that in some way produced a greater yield of food. Equally by breeding from animals that displayed particular behavioural traits, early farmers were able to make use of abilities such as herding or hunting by dogs.

Being able to predict what the next generation to an animal or food plant would be like, turned the early farmers into genetics, long before genes were thought of. And knowing these facts when can’t disregard bugling questions behind artificial selections – is it good or bad?

I believe artificial selection is not bad at all; these vast changes in occupation from hunting and gathering to cultivating food crops and raising livestock had important consequences for human cultural evolution. Agriculture permitted the establishment of permanent villages and ultimately cities, city-states, and empires. Increasing agricultural productivity freed a significant portion of the population from the demands of growing food and allowed them to take up scientific, technological, religious, and artistic endeavours. These facts prove that artificial selection is not bad at all, rather helpful to us indeed.

Artificial selection has resulted in plants that are more disease-resistant, cows that produce more milk, and racehorses that run faster. One must wonder what will come next, which would lead us to this question – under what circumstances should humans be artificially selecting plants or animals, if any?

Humans can only be artificially selecting plants or animals for the following acceptable circumstances:

Animals with leaner meat

Animals that produces more milk

High-yielding and stand ability of crops (e.g. corn)

Plants with large amount of nutrients or nutritious plants

Resistant to high level of salinity (e.g. wheat, in which high level of salt are applied to the soil to kill almost all of the affected wheat plants, but almost certainly a few plants will survive. These survivors can then be used to breed a line of salt-tolerant plants)

Screening (the breeder’s term for selecting certain individuals from a large population of specimens) is now possible in the test tube where it is referred to as in vitro selection. Individual cells from plants may be subjected to certain chemical toxins. Those are able to grow despite the presence of a toxin are mutants that are naturally resistant. Using this method, corn with 10 to 100 times more resistance to certain herbicides has been developed.

Evolution of Corn

For example, corn breeding, a plant breeder trying to increase yields might pollinate a number of high- yielding corn plants with the pollen of other high-yielding ones in the hope that the offspring will produce even more corn. Alternatively, if the breeder wants corn that has a high yield and will tolerate drought (a commonly desired pair of traits), he might try pollinating drought-tolerant corn with pollen from high-yielding corn.

Other methods like enhancing reproduction.

Although artificial selection is mainly an advantage, but because of sweeping and comparatively rapid cultural changes, another slower one is taking place – we are beginning to direct the evolution of increasing numbers of plants and animal species. Like one circumstance which is disturbing is the artificial selection for “Perfect Pet.” This can also be a down side to artificial selection. And because this process essentially removes variation in a population, selectively bred organisms can be especially susceptible to diseases or changes in the environment that would not be a problem for a natural population. Inbreeding — the mating of closely related individuals — is also a problem. In dogs, this has resulted in breeds that have health issues ranging from decreased life span to hip dysplasia. Therefore, artificial selection is indeed a good thing; we just have to be aware of the circumstances and consequences to our decisions in selecting plants or animals.

Video Source:

http://www.youtube.com/watch?v=-K6ja_ZJkKk&feature=related

Picture Source:

http://evolution.berkeley.edu/evolibrary/images/news/corn.gif

http://www.windows.ucar.edu/earth/geology/images/dogs_sm.jpg

http://www.apartmenttherapy.com/uimages/kitchen/2008_03_21-GMFoods.jpg

Sources:

http://www.wisegeek.com/what-is-artificial-selection.htm

http://www.learner.org/courses/essential/life/session5/closer1.html

http://faculty.ed.uiuc.edu/g-cziko/wm/14.html