ARTIFICIAL SELECTION: TYPES, EXAMPLES, ADVANTAGES - BIOLOGY - 2025

The artificial selection or selective breeding is a form of selection in humans consciously choose the traits of living beings who want to be transmitted to their offspring, rather than let the species evolve and change gradually without human interference, as in natural selection.

Humans have used selective breeding long before Darwin wrote the postulates of natural selection and the discovery of the bases of genetic inheritance.

Artificial selection of current corn (right), from teosinte (left)

During artificial selection, a species is selectively bred in each generation, allowing only those organisms that exhibit desired characteristics to reproduce.

Farmers have chosen vegetables with characteristics they consider beneficial, for example larger size, and have made them reproduce. As generations go by, these characteristics develop more and more.

Although the producers did not know anything about the genes, they knew that the beneficial traits they selected could be inherited in the next generations. For example, having selected certain traits in their crops, they probably noticed that the offspring became more and more productive with each generation.

Scientists have studied these traits and spent a lot of time calculating how heritable they can be. The more these traits are expressed in the offspring, the more hereditary they are said to be.

Hunting is also a form of artificial selection, where the characteristics desired by humans are reduced or eliminated from the population gene pool, thus allowing the less desired characteristics (and genes) to pass to the next generation, as they will have increased their mating probabilities compared to samples that have been hunted.

How has artificial selection contributed to the evolution of the human being?

The ability of human beings to understand the phenomena of nature has allowed them to use its products for their own benefit. The degree of intelligence achieved by the human species has been very important for the generation and development of strategies that improved their quality of life and increased the chances of survival.

One of the great achievements of humanity has been the selective breeding of animals and plants that have been fundamental for the development and expansion of human populations.

By actively selecting the best characteristics of animals and plants, humans were able to feed themselves better, better withstand adverse environmental conditions, colonize more environments, and spread throughout almost the entire world.

It is important not to forget that evolution works through reproduction. No matter how much the human manipulates the environment, if these changes do not have an effect on the frequency of alleles in the population over time, that is, the changes are not heritable, then it is not a factor that affects the evolution.

Types of artificial selection

Any action that the human performs on another living being that is different from what would occur naturally, is considered artificial selection and this can be in several ways:

Positive artificial selection

It occurs when the characteristics that you want to maintain or enhance in the species are selected. This selection is often made to increase production. For example: larger plants, meatier fruits, mammals that produce more milk, etc.

Negative artificial selection

In some cases, some features may not be considered good or desirable. For example: a bitter taste in a fruit, aggressive behavior in a canid. In fact, domestication is considered a form of artificial selection.

Differences between natural and artificial selection

Unlike artificial selection, in which humans favor specific traits in some species, in natural selection it is the environment that acts.

In natural selection, the environment favors the most adapted organisms and with certain adaptive traits that increase the ability to survive or reproduce.

However, in some cases artificial selection may be unintentional. For example, the domestication of crops by early humans is thought to be largely unintentional.

Examples of artificial selection

Corn

Many plants and animals have been artificially selected for thousands of years for the benefit of man. For example, the modern sweet corn eaten today is quite different from its predecessor, a plant called teosinte.

Both plants are grains, but teosinte looks much more like grass than modern corn, which has large, juicy grains.

Mustard

Wild mustard has also been extensively selected and bred to maintain certain traits. Broccoli, cauliflower, kale, and cabbage are related to the wild mustard plant.

For example, broccoli is obtained by the floral suppression of wild mustard and kale from the enlargement of its leaf. Which means that wild mustard plants with larger leaves were selected and eventually developed into a plant that now has very large and tasty leaves.

Dogs

Animals have also been selected in many domestic settings. More than 30,000 years ago, humans began to tame wolves. Today, these domesticated animals are what are known as dogs.

Domestication is the act of separating a small group of organisms (wolves, in this case) from the main population, and selecting the desired characters through breeding.

For thousands of years, the domestication of wolves resulted in the loss of some of the most aggressive traits, such as instinctive and defensive behavior in the presence of humans (howling, showing teeth, attacking or fleeing), as well as size and the shape of your teeth.

Currently, humans select a variety of traits in dogs based on personal preferences and companionship. Thus, a Great Dane is nothing like a Chihuahua.

This is because in both dog breeds, the specific traits that led to their differences were selected by humans, and the animals that had these traits were bred so that the traits would continue to descend in family lineages.

The cows, pigs and chickens that are eaten today also have traits that have been artificially selected. Larger animals that grow quickly and produce more meat are desirable because they are more profitable for producers.

Advantages and disadvantages of artificial selection

Advantage

We understood the chemical and biological mechanisms to influence the functioning of our cells, our brain, our own behavior and even the natural destiny of other species, playing with their reproductive suitability for our own benefit.

The degree of intelligence that man has reached as a species, has allowed him to modify the species of their natural environment for his benefit.

Food production

For example, the production of food in abundance or the discovery of cures for many diseases, which has reduced mortality and considerably increased their quality of life with each discovery.

Improves survival and well-being

In the past, human beings had a much shorter life expectancy as they were more prone to succumbing to disease. This limitation in the survival and adaptation of humans has been overcome thanks to their intelligence, their ability to think and discover new ways to increase their well-being and reduce discomfort.

In reality, neither the shape of the brain, nor the neurotransmitters, nor the intelligence evolved as a result of the human being's own will. The above serves to illustrate that evolution has no definite purpose, it just happens.

For example, in birds birds arose due to evolution, not because birds wanted to be able to move to other places by flying.

Disadvantages

The characteristics that represent some benefit for the survival and reproduction of a species are selected in a natural way. Thus, the brightly colored feathers of certain birds increase the chances of mating, an elongated neck like that of giraffes facilitates the consumption of leaves that are higher up and the larger udders contain more milk for the young.

However, when traits that used to be beneficial are exaggerated, the balance that existed naturally is lost. Thus, birds that are excessively showy are more likely to be seen and captured by their predators, the too long neck becomes a limiting factor for the giraffe that needs to drink water and the cow can develop mastitis.

Affects original features

Taking into account the negative effects that could arise from exaggerating certain characteristics, certain disadvantages that artificial selection brings with it are revealed, since they would somehow affect the original features selected by nature in evolutionary time.

One of the great challenges that humanity faces is to use its intelligence and reasoning capacity to make decisions with the highest ethics possible, since for thousands of years great control has been exerted over the other species that live on this planet and, since certain points of view, these modifications could be considered an excess on the part of humans.

Reduce genetic variability

Selective breeding tends to eliminate genetic variability in the population. This means that there are fewer traits that compete with the desirable trait, but it can also concentrate mutations that can be problematic for the individual, such as hip dysplasia in dogs.

Creation of dangerous organisms

Artificial selection can create organisms that are dangerous to the population. For example, killer bees, also known as Africanized honey bees, were bred to produce more honey, but they have killed a couple of people due to the unforeseen more aggressive characteristic these insects possess.

For these reasons, it is important not only scientific knowledge, but also the responsibility to carry out artificial selection taking into account the consequences of such actions.

In the end, evolution is a natural process that exerts its function on all species, including the human being, and if this is not able to conserve its environment, it will logically perish.

References

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