Natural Selection


According to Darwin, the primary mechanism for evolution is natural selection. It is a logical and elegant system, which explains how a population can ‘undergo modification’ to fit in its immediate environment. He proposed this concept of natural selection after several observations. According to him, traits are heritable, differential reproduction exists, and there is variation in characteristics. Also, organisms may undergo random mutation and natural selection to avoid various barriers in their survival. Such modification includes horizontal gene transfer that carriers specific genes/traits which promote survival. Based on the principle of natural selection, organisms mutate to become resistant to drugs and other things.

The woman in Nevada died from a near-ultimate superbug which is categorized into a group of antibiotic-resistant bacteria known as Carbapenem-resistant Enterobacteriaceae (CRE). Despite drug resistance, the bacteria possessed a dangerous mutation called NDM-1. The NDM-1 mutation promotes drug resistance whereby half of the affected victims die. The same case applies to multi-drug resistant tuberculosis (MDR-TB). The bacterium undergoes what is known as Vertical Gene Transfer (vertical evolution). The bacteria’s offspring become resistant because they possess the traits of resistance which would last for long. To solve this problem of drug resistance, rapid molecular tests need to be established to detect resistant strains. An example of such tests is the Xpert MTB/RIF diagnostic test. Early treatment and drug adherence are mainstay preventive measures.


The article entitled “Why Sex” provides information concerning sexual selection. It presents sexual selection using the peacock’s tail. A sexual assortment is a “special case” of natural selection. An organism obtains, by any means necessary, the ability to copulate with a mate. Animals have various ways of displaying the concept of ‘sexual selection,’ which refers to “struggle for mates.” For example, the peacocks maintain elaborate tails to search for their mates. Darwin developed the radical idea of female’s power to choose their mates. People use their secondary sexual characteristics as a mechanism to attract their opposite sex. Also, females engage in singing and dancing which attract male partners. Individuals tend to see gorgeous things in others, which contribute to sexual selection. The feminine and masculine behaviors play a crucial role in reproduction.


The engine that drives evolution is known as natural selection. Additionally, the organism which best fit to survive in specific circumstances has a significant chance of passing their genes to their offspring. Concerning the basic tenet of biology, living organisms pass their genes from one generation to another. However, human beings share traits, which are passed from the parents to offspring. The inherited traits vary among the offspring. This explains why a member in a family may have a condition that can be passed to a single child and the rest not having it. This is based on Mendel’s version of inheritance. Sex chromosomesare essential in determining the sex of the baby. According to Darwin’s theory of evolution by natural selection, “phenotypic variation exists among individuals and the variation is heritable.”

Moreover, human reproduction involves a combination of male and female, partner each producing 23 chromosomes. During fertilization, the father’s deoxyribonucleic acid (DNA) unites with those of the mother, thus, completing the count of 46 chromosomes of the offspring. In this way, the ancestor’s traits are passed down to the offspring. Hence, the DNA is the code of life in human beings because it carries the information blueprint.

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