What is Evolution?

Evolution is considered an intrinsic part of the Semantic Web. The ontology evolution is defined as a process of adaptation of ontology, which is a branch of metaphysics related to nature and abstract entities. In biology, the term evolution is explained as the change of characters of a group of animals over a few generations and confides in the phenomenon of selection chosen by nature. This theory is mainly based on the concept that all species are related to each other and consistently change over time.

Some important concepts before Darwinian evolution

Empedocles theory

Greek Philosopher Empedocles is best known for his belief in the existence of matter. Presocratic philosophy or early philosophy had a huge influence on evolution. According to him, the matter is composed of four elements. These are fire, air, water, and earth. He put a vessel in the water with a hole in the bottom as well as in the above. He observed the vessel filled up with water. Then he put his finger on the top hole, the water stop entering the bottom part. After removing the finger, the water again started to fill. He deduced that the air prevented the water before it entered. Empedocles firstly discovered air as a separate constituent, then explain that it mingles with elements to compose matter.

Theory of essentialism

According to Aristotle, the nature of a living being is constituted of a particular goal-oriented disposition to generate an organism typical of its kind. It is a matter of essentialism. He assembles the “Philo” or love and life to explain the evolutionary theory.

Gayon’s contribution to the evolution

Jean Gayon describes how the ‘Darwinian Evolution’ becomes well established and natural selection plays a major role in it. He mentioned the changing concept of heredity affects evolution very strongly.

Concept of Lamarckism

Jean Baptiste Pierre Antoine de Monet, chevalier de Lamarck proposed four propositions for a single biological theory in the year 1744-1829. These propositions are-

Change occurs through use and disuse

The organs that are utilized by the organism usually develop and the factors of less desirable are lost in the succeeding generations. For example, the tails of tadpoles diminish at the adult stage of life because of the disuse.

Organisms are driven to greater complexity

Biological organisms start to adapt to their environmental situations and become complex from the simpler forms. Lamarck assumed the generation of life to be spontaneous.

Inheritance of acquired characters

An individual acquires a particular characteristic during his lifetime. These features pass to generation after generation. Lamarck explained it through the example of blacksmith. A blacksmith develops strong-arm muscle due to his work. Any child of a blacksmith will naturally develop strong-arm muscles.

Effect of environment and new needs

The surrounding affects an organism very deeply. When it forms a change in itself, organisms living in it face changes in them as well. It gives rise to new needs, which in turn creates new features and changes the habits of the organisms. A French naturalist, "Étienne Geoffroy Saint-Hilaire" was colleague of Lamarck. He also established the principle of "unity of composition." He too expanded and defended Lamarck's conception on evolutionary theories.

Contribution of neo-Lamarckism

In the field of biology, the theory of inheritance highlights the modification and extension of Lamarckism. This theory emphasizes the genetic changes that are mainly related and influenced by the contribution of environmental factors. Lamarckism focuses on internal vital force and acceptance or rejection of organs. Whereas neo-Lamarckism gives no importance to these attributes. Neo Lamarckism also focuses on those modifications transferred to the next generation by influencing the germ cells only. This is a modified version of Lamarck's theory for suitable modern knowledge.

Concept of Catastrophism

In the field of biology, catastrophism explains unexpected violent changes. There is an argument that evolved due to the weakness of Lamarck's theory. French scientist George Cuvier along with other scientists criticized the idea of earning certain features as an inheritance. Cuvier proposed the theory of catastrophism. The mass extinction is justified by this theory. The catastrophic events are responsible for causing a large mass of extinction. It was formed on the catastrophes like significant floods and some immediate physical changes to the Earth like meteorite impacts, pandemic disease, ocean acidification, and a few more. These events caused the destruction of the organisms living in those places and some of them are replaced with others. Newly established ones are mainly migratory.

Concept of uniformitarianism against catastrophism

Charles Lyell examined and concluded that catastrophism theory was not exactly correct. It was believable that there was more commonly a summation of progressive and retrogressive changes over long periods of geologic time. Lyell mainly fixated the Earth to be very old. It has consistently undergone mechanisms like earthquakes, soil erosion, volcanoes, decomposition of dead plants and animals, and glacial movements throughout time. All these events change the shape and framework of the land. James Hutton originally developed this theory, and it led towards the Darwinian concept.

The improbability of pre-Darwinian concepts

It has evolved on a critical observation for better, broad-minded, imbalanced, system-oriented views. These are supposed to clear the processes that emerged in the pre-Darwinian era or before the Darwinian evolution occurred. Most scientists acclaimed an evolutionary linkage that has always been located between chemistry and biology. The result of the scenarios is reviewed as per its strength and weaknesses. The differences are observed first in metabolism, then in replicators, and lastly in the combination of metabolism-replicators. There were unclear explanations of heredity and chirality found.

Contribution of Carolus Linnaeus to evolution

He is best known for the discovery of classification systems in taxonomy. It is a universal naming system for living things. In the beginning, Linnaeus assumed species were permanent and unchangeable. After further studies, he admitted that speciation exists and evolution is possible. Due to experiments, Linnaeus's belief in evolution became stronger.

Darwin's Theory of Evolution

According to Charles Darwin, the reason for evolution is strongly influenced by organic changes. It mainly results from natural selection. It is regulated by three principles:

1. Variation- It is a liberalizing factor present in all forms of life.
2. Heredity is the force of conservation that sends a similar organic form to one generation from the one.
3. Struggle for Existence – It focuses on the variations in the physique that are proved to be advantageous in a particular environment. Along with that, it alters the species on a basis of a selective reproduction rate.

What is natural selection?

Natural selection is a type of event, through which inheritable traits make it more likely for an organism to survive long. The survivability is long enough to reproduce and become more common over consecutive generations of a population. The key mechanism of evolution is known as the synonym of natural selection itself. For example, Galápagos finches display the best result of natural selection. Among this bird, which ends up in an arid environment, its beak suits better for eating cactus. Similarly, some finches display beaks that are more suitable for drinking nectar from the flowers. Darwin proposed this theory because of the limited resources in nature and a wide variety of living beings have been developed over time with the existence of a single common ancestor.

Weaknesses in Darwin's theory

The biological organisms are not explained in genetic terms in the natural selection theory. It does not account for a genetic basis of variations. Genetic inheritance was not much known at Darwin's time. His belief was mainly focused on natural selection.

Brief concept on neo-Darwinism

It is the modern version of the thesis of evolution that is automatically generated by nature. This concept incorporates the genetic aspect with the rest of the previous assumptions and it gives importance that animals evolve throughout the by the genetic alteration. The possible genetic variation concept is assisted by Mendelian genetics along with the modern synthesis of natural selection. The major driving force of this theory is the involvement of genetic variations. Genetic mutation, recombination, reproductive isolations are the reasons for this situation.

Context and Application

The evolutionary species concept is mainly a major part of biological history. It is applicable in some parts of biology-

• Evolution
• Zoology
• Taxonomy

This concept is also covered in some areas of Geology.

Practice Problems

1. What is the full name of Lamarck?
   1. Jean Baptiste Pierre Antoine de Monet, chevalier de Lamarck
   2. Jean de Monet Lamarck
   3. John Baptiste Lamarck
   4. Carl Lamarck

Correct Answer: a. The full name of Lamarck is Jean Baptiste Pierre Antoine de Monet, chevalier de Lamarck.

2. Who had invented catastrophism?
   1. Lamarck
   2. Erasmus Darwin
   3. John Ray
   4. George Cuvier

Correct Answer: d. George Cuvier. He first proposed the concept of catastrophism.

3. What is not included in neo Darwinism?
   1. Genetic variation
   2. Natural Selection
   3. Biodiversity in nature
   4. Genetic recombination

Correct Answer: c. Biodiversity in nature. neo Darwinism mainly combines Darwin’s theory of evolution with Mendel’s theory of genetics.

4. What is heredity?
   1. transmission of characters from parents to their children
   2. Transfer of genetic material to the next generation
   3. Genetic similarity between the parent and the offspring.
   4. All the above.

Correct Answer: d. All the above. Heredity mainly focuses on the transmission of a unique set of characters from the parents to the offspring. Information travels to the next generation in the form of unique codes of genetic material.  

5. Which cells help to transfer the modification to the next generation?
   1. Somatic cells
   2. Germ cells
   3. Nerve cells
   4. Bone marrow cells

Correct Answer: b. Germ cells. These cells produce gametes and undergo two types of cell divisions. They act as the linkage between the generations.

Common Mistakes

Students often confuse Lamarckism as the only pre-Darwinian concept. Along with Lamarck, several other researchers like Charles Lyell, George Cuvier, Carolus Linnaeus also provide huge contributions to the pre-Darwinian time. All these theories ultimately lead to the Darwinian theory.

Related Concepts

There are some topics found in the field of biology, which is quite similar to it. These topics are-

• Speciation
• Post-Darwinism
• Biological Nomenclature