Evolution, a theory or fact?

Evolution is the process by which the traits of a species are changed over time because of their Genetic variations and the process of natural selection. According to the theory of evolution, all the species were originally the same and evolved with the advent of time.
Evolution is a theory or fact, it can be explained after a thorough discussion about the theory of evolution. Change in genotype is expressed in the form of change in the phenotype of individuals.

How can evolution be explained?

From the start of life on earth, until now, there have been a lot of changes in the environment of earth. These changes could have been withstood by those who have survived until now.

There was a theory proposed by Jean Baptiste Antoine de Lamarck according to which, the giraffe didn’t have a long neck in the very remote past. The environment changed and trees grew taller than before.
Now there was a matter of survival for the specie of Giraffe living in that region of the earth. So, they started to stretch their necks to reach the trees. By the advent of time, they evolved with a change in the length of necks.

This theory was rejected with the advancement in the field of genetics. Because, the changes that are acquired by the environment, can not be transferred to offspring as there is no change in the genetic makeup. However, Lamarck gave the naturalists and scientists a point to ponder. Later on, Charles Darwin proposed the theory of evolution that was a revolutionary idea in the field of science.

Summary
Changes are necessary to survive, those who are stubborn to changes, die earlier as compared to the ones who are flexible. This is a one-line summary of evolution.

Evolution, a fact or theory?

According to some scientists, who have thoroughly studied the ancestors to decedents sequence and gradual changes in each generation, believe that evolution is a fact. While others think that there is no “proof” of evolutionary mechanism, hence it is considered as theory.

What is the difference between Facts and theory?

  • Fact is a thing that occurs in the real world.

  • Fact is verified and proved by various experiments. It is firmly supported by the data obtained from the experiments. In recent times, facts related to evolution are supported by genetic data more precisely by DNA.

  • For example, DNA studies of fossils have confirmed that there is a link between remote ancestors and today’s descendants.

  • A theory is formed from hypothesis and then passes through rigorous experimentation to falsify it, if it survives the experiments, it is changed into law.

  • For example, Darwin’s theory of natural selection.

Summary
Observable changes in specie are a fact while the processes by which the changes have been developed, is a theory. The theory is a “guesswork” or opinion that has not been confirmed and established by experimental pieces of evidence.

Who is Charles Darwin?

Charles Robert Darwin (1809-1882) an English naturalist, proposed the theories of evolution and natural selection which is considered as the foundation of modern studies about evolution.

For the first time, when he proposed these theories inferring that all the present species have been evolved from a single ancestor and animals and human beings share the common ancestry, the religious societies were greatly shocked.
However, this revolutionary idea was highly appreciated and widely accepted by professional researchers and scientists.

What is the theory of natural selection?

  • Different individuals within the same species exhibit some variations regarding their physical characters. This variation is due to the difference in the genetic makeup of these individuals.

  • Environment is a continuously changing factor, so, the individuals that can cope with these changes due to the courtesy of their genetic makeup, are the survivors.

  • Individuals having different qualities that are best suited to the environment, for example, those regarding earning food, keeping themselves safe from predators, and having resistance against diseases have greater chances to survive and reproduce.

  • On the other side, poorly adapted individuals have fewer chances to survive and produce offspring and hence no transfer of genes to the next generation, ultimately becoming an extinct species.

  • There is an example to better understand the theory of natural selection.

Peppered moth is a species of night-flying moth that had a light-colored wing during the early 1800s.

After 1848, dark-colored peppered moths were collected from Manchester city. They acquired that black color to camouflage themselves in a dark environment where all the trees and plants have become dark due to pigmentation in the environment.
This color change was developed because of pollution during the Industrial revolution. There was a lot of melanin in the industrial smoke of factories that caused gene mutation in the DNA of light-colored moths.
These dark-colored moths then produced offspring with the same black colored wings. Later on, after the reduction of pollution, the same light color was dominated again.

Summary
Nature picks up the ones who are dear to it. It is not the strongest of the species that survive, nor the most intelligent, but the one most responsive to change.

What are the types of evolution?

There are three types of evolution given as follows:

1. Divergent evolution

Divergent evolution simply means:

  • “An accumulation of different characteristics in the groups having same ancestors that result in the formation of a new specie"

  • It mostly occurs because of the changes in biotic (e.g. changes in predation pressure) or abiotic factors (e.g. air, water, heat, or certain other).

  • Species living in that modified environment, try to adapt to the changes, and hence some of their characteristics are changed. These species when reproduce, give rise to the offspring having new characteristics and hence a new specie comes into existence.

  • Although divergent evolution results in the organisms having the structures that are apparently and functionally different, yet there is an anatomical similarity with their common ancestors.

For example:

  • There is an anatomical similarity between the forelimbs of human, dog, bird, and whale although they perform different functions.
  • This shows that they share a common ancestor and have evolved into different species with the advent of time.

2. Convergent Evolution

Convergent evolution is a type of evolution in which the species having different ancestors, start to exhibit similar characteristics maybe because of sharing the same environment or bearing the same kind of environmental pressure.

For example:

  • There is a similarity in nature of the flight/wings of insects, birds, pterosaurs, and bats although all of them belong to different species and their ancestors did not have such analogous structures.

  • Wings of birds, bats, insects, and pterosaurs perform a similar function and have similarities in their structure, but each of them has evolved independently.

3. Parallel Evolution

  • Parallel evolution is generally observed in the species that are irrelevant to each other and not even live in the same conditions or habitats.

  • In this type of evolution, similar characteristics in two different species evolve independently of each other.

  • Mostly, parallel evolution is present in the species that have close lineages and where different species respond to the changes in the same way, resulting in the development of the same traits.

For example:

An important example of parallel evolution is the similarity between marsupial mammals (pouched mammals that carry their newborns in a pouch, e.g. kangaroo) of Australia and the placental mammals (mammals having placenta for the exchange of nutrients and waste materials between mother and fetus in the womb) everywhere in the world.

Summary
There are different types of evolution including convergent evolution, divergent evolution, and parallel evolution.

What are the different parts of Darwin’s theory of evolution?

Darwin’s theory of evolution also known as “Darwinism” is further divided into 5 parts. These 5 parts were devised by Ernst Mayr by the thorough study of Darwin’s world-famous publication about evolution “On the origin of species”.

These parts can be explained as:

1. Evolution as such

According to this, species can change over time.

2. Common descent

This part of evolution theory states that all the species have evolved from some common ancestor. For example, the forelimbs of humans, birds, animals, and whales have anatomical similarities which show that they somehow have a common ancestor.

3. Population speciation

This part of Darwin’s theory explains that changes in the species of the same population occur when the hereditary characteristics are more inclined towards that population.

According to Darwin’s point of view, the long neck of giraffes is not the result of evolution, instead, some were randomly born with long necks and then this specific trait was inherited by the next generations and finally dominated in the population.

4. Gradualism

According to gradualism, small changes are produced after long periods and a specific trait is spread in the population gradually.

For example, selective breeding of animals with desired characteristics is an example of gradualism.

5. Natural selection

  • Natural selection is the most striking part of Darwin’s theory of evolution. According to this part, it’s the competition or struggle for existence that results in the survival or extinction of a species.

  • Those who acquire the desired traits to survive, are selected by nature to live. While others, who fail to adapt and compete with the changed circumstances, become extinct.

  • Circumstances that give rise to competition, involve limited food, limited habitat, predators, disease, mating chances, and harsh climate, etc.

Summary
Different parts of evolution theory consist of evolution as such, common descent, population speciation, gradualism, and natural selection.

What are the pieces of evidence for evolution?

The evolution theory is supported by certain evidence. They involve:

The fossil records

  • Paleontologists (scientists who study the fossils) have been studying the fossils of millions of organisms that have lived in remote past. This thorough study and research support the idea that organisms in the past were much more different than the ones that are present nowadays.

  • After the death of an organism, it is either decomposed by certain microorganisms or destroyed by weathering processes. However, some specific body parts, mostly that contain calcium e.g. shells, bones, or teeth, can not be destroyed. They undergo petrification and preservation within the rocks where they had been present.

  • Radioactivity is the property that helps to determine the age of a specific mineral which leads to the estimation of the age of rocks and the embedded fossils.

  • According to the radiometric dating technique, the earliest fossils exhibit the genetic makeup the same as the microorganism (bacteria or algae).

  • Several fossils are found to be more than 650 million years old. According to genetic studies of these fossils, it is clear that those organisms are much more different than the organisms of present times. Hence, these fossil records highly support the idea of evolution.

Structural similarities:

The internal study suggests that there is a striking similarity in the skeletons of humans, alps, birds, bats, and horses although they all are much different from each other in the ways of morphology and way of life.
For example, forelimbs of all these organisms are the same in spite of the fact that they use them for different purposes.

  • Humans eat, write, work and do other tasks with their forelimbs (hands)

  • Birds use them to fly (wings)

  • Turtles use their forelimbs to swim

  • Horse utilize them to walk or run (front legs)

So, it simply suggests that these skeletal similarities have been inherited from common ancestors and modified later on to cope with the circumstances.

Biogeography

  • Another evidence in support of evolution is the biogeographical studies.

  • For example, Drosophila (fruit fly) has near to 1,500 species around the world. About 1/3rd of all these species are inhabitants of Hawaii. Moreover, Hawaii is the residence of >1000 species of snails and mollusks.

  • This strange fact has an only explanation that lies in evolution.

Molecular biology

  • This branch of biology is the most supporting and convincing point in favor of evolution theory.

  • DNA and proteins that are studied in molecular biology, provide all the information about the ancestors of an organism.

  • Fossils are recovered and genetic data is obtained by a detailed study of these fossils. This genetic data that is confined in the form of DNA provides the data to understand the evolutionary events. All these studies are carried out in the field of molecular biology.

  • Molecular biology provides the data in support of the evidence that all the descendants have been evolved from common ancestors.

Embryology

  • Embryology is the science that studies the development of an organism from the level of fertilization to the birth

  • Embryonic development of all the vertebrates ranging from fish to human beings, exhibit striking similarities, although they become different from each other as the development proceeds from embryo to fetus.

  • Similar species for example humans and alps carry these similarities for a longer time as compared to others. This similar pattern exhibited by embryonic studies supports the theory of evolution.

Summary
Darwin’s theory of evolution can be supported by various evidence, for example, the fossils record, embryology, molecular biology, and biogeography.

Islam and evolution theory

There are a lot of controversies between the Islamic point of view and the theory of evolution. Most religious scholars are strictly against Darwin’s theory of evolution about common ancestors.

As the Quran says in Surah Alaq, Parah # 30, Surah # 96:

اقۡرَاۡ بِاسۡمِ رَبِّكَ الَّذِىۡ خَلَقَ

Read: In the name of thy Lord Who created,

خَلَقَ الۡاِنۡسَانَ مِنۡ عَلَقٍ

Created man from a clot.

According to the Quran, all human beings have been created by a clot of blood. This is clearly against the theory of evolution, according to which, human beings have been evolved from bacteria and share common ancestors with all the reptiles, birds, and mammals.

Muslim scholars have different points of view regarding the theory of evolution.

  1. Few of them think that although the theory of evolution is lying on the base of the hypothesis, Quranic verses clearly show that human beings were created instantly. Although Quranic verses can be interpreted in some other ways.

  2. Others think that verses of the Quran related to the sudden creation of man have no other meanings and can’t be interpreted in any other way. So, although there is supporting evidence in favor of evolution theory, there is an exception regarding the creation of human beings.

  3. Third group of religious scholars believe that science and religion are two entirely different things and so is their language. Quran has been granted to human beings for their guidance and so, there should be no imposition of anyone’s own thoughts while interpreting different meanings of the same verses.

  4. While the last group debates that verses from the Quran provide can infer the theory of evolution.

Hence the conclusion is that there are several ideas and schools of thought regarding Islam and evolution. However, there is no competition between the Quran and the theory of evolution.

Frequently asked questions

1. How do you explain evolution?

  • Evolution is the process by which the traits of a species are changed over time because of their Genetic variations and the process of natural selection.

  • Charles Darwin was the first person who proposed the theory of evolution and theory of natural selection. Species that adapt to the changing circumstances have more chances to survive as compared to those who do not adopt them.

  • Fossils study, embryology, molecular biology and biogeography studies provide clear evidence in the support of evolution theory.

2. What is the difference between placental mammals and marsupial mammals?

Placental mammals:

Those mammals that develop a placenta during the process of fertilization and zygote is implanted inside this placenta are called placental mammals. The placenta acts as a medium to exchange the nutrients and waste materials between the mother and fetus blood. For example human beings.

Marsupial mammals:

They are also called as “pouched” mammals. Marsupials are born before they are ready to face and survive in the outside world. So, they are kept in the pouch of a mother that is outside the body and nourished until they are mature enough to survive outside.

For example; the Australian kangaroo.

3. Who is the father of evolution?

Charles Robert Darwin, an English naturalist is known as the father of evolution. He is known because he proposed the theories of natural selection and theory of evolution.

His theories brought a huge storm in the field of science although the theories have faced a lot of controversies.

4. Does Islam support the theory of evolution?

Although Islam urges the followers to do the research and contemplation yet there are some controversies between the theory of evolution and religious scholars.

Different scholars propose different ideas regarding this theory. Various Fatwas has also been applied over the teaching of evolution theory in the educational institutes. However, there is no single school of thought either in the favor or against the theory of evolution.

Conclusion

  • Evolution is the process that is necessary to survive in the changing circumstances. Species that are flexible enough to modify themselves to adjust in the changing environment, they survive as compared to the robust species who can’t adjust to the changes. However, its a dilemma that either evolution is a theory or fact?
  • Theory of evolution was proposed by Charles Darwin. According to this theory, the species that are the strongest and most responsive to changes are chosen by nature. This is called the theory of natural selection. Fossil records, molecular biology, geographical studies, and embryology studies are evidence for evolution.
References
  1. https://www.britannica.com/science/Lamarckism#:~:text=Lamarckism%2C%20a%20theory%20of%20evolution,be%20transmitted%20to%20their%20offspring.
  2. https://www.sciencedaily.com/terms/convergent_evolution.htm#:~:text=In%20evolutionary%20biology%2C%20convergent%20evolution,similar%20environments%20or%20ecological%20niches.
  3. https://www.britannica.com/animal/placental-mammal
  4. https://biologydictionary.net/divergent-evolution/
  5. https://www.britannica.com/biography/Charles-Darwin
  6. https://www.dummies.com/education/science/different-patterns-of-evolution/

Related articles

What is inheritance and gene expression?

How can you transcribe DNA into mRNA?

Where do transcription and translation occur?