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How is Artificial Selection Different from Natural Selection?

Natural and artificial selection forms the basis of evolution on this planet. This article explains the basic difference between the two.
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Examples of natural and artificial selection
Did You Know?
Around 70,000 BC, a mysterious illness almost wiped the human population off the Earth. Only a couple of thousands survived. Although we are the dominant species today, once, we were an endangered species!
The subject of evolution is vast, in content and in span. Natural selection plays a crucial role in evolution. The term was coined by the father of evolution, Charles Darwin. He imagined a future where the population grows exponentially, and the increase in resources is linear and steady. By these assumptions, he theorized that all species cannot survive peacefully. There will be strain on the resources and the weak will feel the pinch of adaptation and survival. The fit will survive and thrive. This was termed as 'survival of the fittest.

After Darwin theorized natural selection, he differentiated it with artificial selection or selective breeding. Selective breeding is much more widely seen nowadays, if you observe carefully. For example, take a look at the purebred dogs around you. Long before humans domesticated them, the wild dog was very generic looking, and had characteristics very similar to its cousin species―the wolves. Humans befriended wild dogs, and some groups found a characteristic interesting. This could have been a soft, furry coat; or a more docile dog; or an increase in size. This led to the various species of dogs we see today.

Thus, selective breeding is human induced, and hence, is not natural. It is not forced by nature or by the surroundings. In natural selection, when a stressful situation is induced, the best organisms equipped to adapt, survive. Their close counterparts who may not be so good at adapting, go extinct.

Artificial Selection vs. Natural Selection

Cases of Natural Selection

Case 1: Brown and Green Beetles

It has been observed that green-colored beetles are more likely to be eaten by birds than the brown ones.
This may be due to the fact that, on the ground and on the bark, the brown beetles have a better camouflage, or may be the birds just love the taste of green beetles.
Due to this, not many green beetles get to live to their full lifespan.
On the other hand, the brown beetles thrive. This will keep on happening until brown beetles form the majority of the population, until they are the only existing species of beetles.

This type of natural selection also happened to our ancestors―the Neanderthals. They were closely related to Homo Sapiens, but had significantly larger brains after attaining adulthood. They were physically stronger too. How would such a species become extinct then? Many hypotheses were proposed, and one of them was that, the female Neanderthals failed to produce a fertile offspring. This led to a dilution of their species, until their extinction.

Case 2: Silent Crickets

silent crickets

On the island of Kauai, near Hawaii, crickets, like the rest of their brethren around the globe are chirpy. This is done to attract a mate.
It became a problem when a species of a fly, which acoustically locates the crickets, started disturbing their conjugal calls.
The species of the fly, known as Ormia Ochracea, acoustically pinpoints the cricket's location, and then sprays it with its eggs.
These eggs then hatch and the maggots that come out bore into the cricket's body, out of which they will hatch, fully grown, killing the cricket.

Silent booty calls. That's what the crickets adapted to. Suddenly, and suddenly is the word, this adaptation turned into evolution, in a span of 4 - 5 years. They started growing special wings that made no noise when rubbed against each other, and the flies were not able to audio-locate them. Thus, the crickets survived, although they got to hump a lot less than earlier.

Case 3: MRSA

This word gives the chills to any doctor practicing in a big hospital.
MRSA or Methycillin Resistant Staphylococcus Aureus, is a strain of staph bacteria that is increasingly showing resistance to penicillin and cephalosporins.
This significantly brings up the time required to rid a patient of the disease.

The way it evolves, is the same.

The patient will go to the doctor, complaining about a sore throat. The doctor prescribes a 5-day course of antibiotics.
The patient feels better in 3 days, and stops taking the medications.
The bacteria, however, has not been completely eliminated, and some of it learns to survive in an antibiotic surrounding. This adaptation gives rise to resistant strains.
Now, the doctor requires a more potent class of antibiotics to kill them.

You can take a guess at what the bacteria will do after it encounters the stronger antibiotics.

In contrast to natural selection, artificial breeding is much simpler.

Cases of Artificial Selection

Case 1: Case of Corn

The first corn plants had one cob per plant. The cobs on these plants had, at the most, 4 - 5 kernels, covered in a outer covering of husk.
The teosintes plant, still found in South America, is similar to them.
The Native Americans then started selective breeding (artificially germinated and inbred and crossbred) to get the corn we eat today.

The corn we eat today has exposed kernels and is significantly larger than the earlier varieties, with more cobs per plant too.

Case 2: Sheep, Cows, and Cattle in General

Sheep were very generic with random traits about 300 years ago.
Then, they were introduced to selective breeding, where only the ones with the best characteristics were allowed to mate.
The attractive characteristics could be the quality and quantity of meat, the quality of wool, the size of the sheep.
By the end of such selective breeding, many different varieties of sheep were reared.

The same was applied to cattle too. Bulls used for meat were also selectively bred. This has resulted in their size being doubled.

Cows were also bred on the quantity of milk they produced. The factor for selection was the amount of milk they produced in a day. The Jersey cow is an example of this.

Case 3: Human Selection

human selection

There could not be a more complicated breeding system in this world. Earlier, it just used to be attractive physical characteristics that led to copulation. Now, as the species is becoming more and more aware of personal rights, intelligence, charm, and manners are wanted in addition to physical beauty.

The human population is the dominant species of the planet, and this is due to both natural and artificial selection. Artificial selection took over when we became much more self-aware of what we want from a mate. Some of the old selection traits that attract still remain. They are body odor and facial hair in men, and wide hips and big breasts in women.

You may think that all this love and a part of it is just finding a mate that will give you a progeny with features you like. You are naturally programmed to pass on your genes to the next generation, and the rest of the stuff you like comes from the partner.

All in all, in the vast time of evolution, you are just a gene donor.

The Basic Difference

Take the following example:
  1. A company starts employing.
  2. New employees are selected and start working.
  3. The management has a specific set of criteria or parameters by which it retains the employees.
  4. This could be punctuality, productivity, profitability, etc.
  5. The employees know these parameters and adapt accordingly.
  6. Some will display better productivity, some will be very punctual, and some will satisfy all criteria of a good employee.
  7. A few will not perform by the standards set, and after a few months are let go.
  8. If, in the long run, these set of parameters remain the same and quality is not compromised on, only the best in the industry will work for that company.

In the above example, we take out the management, it is an example of natural selection. But because the management wants better employees, it is artificial selection. It is analogous to a florist cutting off the branches of a rose plant that does not give good quality flowers. It is through pruning he gets the best blossoming plants.

Natural selection depends on the stress provided by nature in the form of limited resources, the food chain, climate, invasion of an aggressive species, etc. Natural selection can take a long time if needed, and can take a short time too.

Artificial selection is due to the stress provided by humans in the form of culling, pruning, breeding, etc. The results of artificial selection are almost immediate, as the desired traits are seen in the next generation itself.

It is a marvelous phenomenon―selection of species. It is happening all around you, and in you too. Darwin said that we are woefully ignorant of these changes, and he was so true. Changes could be happening in your garden and even in your house. The nipples on a male, the organ appendix, and the ear lobe muscles, are all useless organs on the human body. As they have no functions whatsoever, they have been sidelined and are slowly diminishing, as we speak.

Mosquitoes are gaining resistance against the liquid vaporizer mosquito repellents, and it is pressuring the companies to produce even more potent versions. The virus that causes malaria is developing resistance to quinine, the anti-malaria drug.

Some species of bacteria have started eating nylon and metabolizing it to thrive. Some species even survive in containers that hold radioactive waste.

Some mice have even started learning to deal with the classic mousetraps. They can get the cheese without getting trapped. Some of them ignore the traps altogether.

Ever wondered why coniferous trees are dominant in temperate and cold regions?

Ever wondered why palm trees are everywhere in the tropics?

Ever wondered why polar bears are covered in white insulating layer of tiny hollow, miniature pipes (no, it is not fur)?

Ever wondered why giraffes have long necks?

Ever wondered why the trees in the Amazon and Congo cover the whole forest in a dense canopy?

Ever wondered why the steak you eat is so tasty, succulent, and meaty?

Ever wondered why the flowers you buy are so colorful and attractive?

There is so much to see out in nature and everywhere. But children today are stuck to television and computers. May be they are adapting to the indoors. Get out of the house and marvel. Go out and explore to see how the planet is changing. Go out and ask why.

Fun Fact
Because of the advent of smartphones and high-speed Internet, the attention span of the general population is reducing. So, if you actually got here reading every line, you should know that you are very special, because you are going to go extinct―by natural selection. BOOM.
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Published: July 29, 2014
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wonderfull article - maria [September 11, 2014]