Definition of Evolution, Theory of Evolution, Principles & Process

Evolution is a change in the body structure of living things that takes place slowly over a very long time. Evolution comes from the Latin word Evolvo which means stretching. An understanding of the concept of evolution can arise both naturally and logically from an understanding of genetics.

This concept emerged not from history but was put forward based on the results of research and observations of the similarities and differences in the structure and function of various parts of the world, including the results of research and observations of Charles Darwin. inspired by Charles Lyell with his book Principles of Geology and Thomas Malthus with his book The Principles of Population. Check out more about the discussion of evolution below, Readers.


What is Evolution?

Evolution in the study of biology means changes in the heritable traits of a population of organisms from one generation to the next. These changes are caused by a combination of three main processes: variation, reproduction, and selection.

The traits that form the basis of this evolution are carried by genes that are passed on to the offspring of a living thing and become varied within a population. When organisms reproduce, their offspring will have new characteristics.

New properties can be obtained from changes in genes due to mutations or gene transfer between populations and between species. In sexually reproducing species, new gene combinations are also produced by genetic recombination, which can increase variation between organisms.

Evolution occurs when these inherited differences become more common or rare within a population. Changes that occur in chromosomes and genes are the basic material of evolution, isolation usually causes the emergence of new species and natural selection by the existence of reproductive differences and mutations.

We can see this in the evolution that has occurred in humans from time to time which is discussed in the book The Britannica Education Series: Evolution which is packaged with various illustrations so that learning is fun.

Evolution also suggests that all kinds of living things actually come from the lowest creatures. In accordance with the circulation of the times and geological-astronomical changes, there have been gradual changes in living things until now. Based on evolutionary thinking, humans are classified as animals. Animals themselves experience the lowest level of development and form like creatures, ranging from viruses, bacteria, protozoa, worms, fish to mammals.

Evolution is still ongoing. Even faster the process than in ancient times. Evolution as a gradual and gradual change is divided into several types, namely geological evolution, astronomical evolution, biological evolution and cultural evolution.

Judging from the part that has changed, evolution can be divided into cosmic evolution and organic evolution. Besides that, there are other terms known as geological evolution, too:

  • Cosmic Evolution : Is a continuous change that occurs in the universe (evolution universe).
  • Organic Evolution : Changes that occur in living things or biotic components from generation to generation both morphologically and physiologically. This is also known as biological evolution.
  • Geological Evolution : Known as the changes that occur on the earth’s surface due to weathering from time to time.
  • Biological Evolution : Gradual changes that occur in living things on earth according to changing times.
  • Inorganic Evolution : Planets, stars, world topography, chemical makeup of the earth, chemical elements and atomic particles can change gradually which is known as Inorganic Evolution. All types of animals and plants that exist today are derived from other organisms that occur simply, for example, gradual modification and accumulation in the current generation is called Organic Evolution. The main trend of the study of plant and animal evolution shows the occurrence of adaptation to environmental conditions which in fact often involve increased specialization and complexity of the structure and function of living things.

Definition of Evolution According to Experts

Reported by the Encyclopaedia Britannica (2015), all human cultures have developed their own explanations about the origin of the world and of humans and other living things. Many figures who contributed thoughts on the theory of evolution. Such as Aristotle, Plato, Jean Baptise de Lamarck, Charles Robert Darwin, Alfred Russel Wallace, and August Weisman. Check out the various theories of evolution in Ernst Mayr’s book below.

A number of classical Greek philosophers believed in the evolution of life. The following is an explanation of the theories of the characters:

  • Plato (427-347 BC) Plato stated that he believed in the world, namely an ideal and eternal world and an imperfect virtual (imaginary) world. Both worlds can be understood using the human senses. It is said that evolution will change the world whose organisms are already ideal and perfectly adapted to the environment.


  • Aristotle (384-322 BC) Aristotle adhered to the theory of natural scales. Quoted from the website of the Ministry of Education and Culture (Kemendikbud), the theory presented by Aristotle discussed that all life forms are arranged according to a scale or ladder whose complexity increases upwards. According to him, every form of living being has a ladder with the rungs of each being at different levels.
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  • Jean Baptiste de Lamarck (1744-1829)In Lamarck’s theory of evolution there are two main ideas, namely: Having two ideas about evolution. The first idea relates to the parts of the body that are and are not used by living things. Through this idea, he assumed that the parts of the body that living things constantly use in dealing with certain environments will become bigger and stronger than the parts of the body that are rarely used. Meanwhile, limbs that are rarely used will experience a setback. Lamarck’s second idea relates to the inheritance of traits or characteristics acquired by living things in adapting to their environment. Inheritance of these traits or characteristics that modify the organism it acquires during its lifetime. For example, giraffes are called short-necked, but because its neck is constantly stretching out to get leaves on tall trees, the giraffe’s neck starts to get long. This long neck is passed on to all descendants.


  • Charles Robert Darwin (1809-1882)Darwin considered that evolution occurs through a process of natural selection. Living things that are able to adapt to nature can survive. While living things that cannot adapt to nature will not survive or die. Darwin is the pioneer of modern theory. The theory of evolution is what he observed while sailing on the Beagle to the Galapagos Islands. Through in-depth observations and studies, Darwin finally put forward his theory of evolution through a book entitled On The Origin of Species by Means of Natural Selection. The book was published on November 24, 1859. There are two theories in Darwin’s book, namely the species that are alive today came from species that lived in the past.


  • Alfred Russel Wallace (1823-1913) Russel Wallace’s theory of evolution is developing a theory of natural selection put forward by Charles Darwin. Russel Wallace’s thoughts were obtained from the results of expeditions in Malaysia, then Borneo (Kalimantan), Sulawesi and Maluku. The results show that the fauna in West Indonesia is different from East Indonesia. Wallace and Darwin, argue that the giraffe crew has a variety of necks, there are long and short. As a result, natural selection favored giraffes with long necks. Because it can reach high leaves, it can survive. For giraffes with short necks they can’t. Giraffes who have long necks are passed on to their offspring.


  • August Weismann – On August Weismann’s theory that changes in body cells due to environmental influences are not passed on to their offspring. Evolution involves the inheritance of genes through sex cells. This means that evolution is related to the symptoms of natural selection on genetic factors. Weismann proved his theory by using mice. Where to mate two mice whose tails are cut off. Furthermore, the adult rats cut their tails and mated with each other. The result is tailed rat children. He carried out the experiment for up to 21 generations of mice and the results were the same.


Principles of Evolution

Evolution is driven by two main mechanisms, namely natural selection and genetic drift. Natural selection is a process that causes inherited traits that are useful for the survival and reproduction of organisms to become more common in a population and conversely, traits that are detrimental to them become less.

This happens because individuals with favorable traits are more likely to reproduce, so that more individuals in the next generation inherit these beneficial traits. Over many generations, adaptation occurs through the combination of these small, continuous and random changes in traits with natural selection.

Meanwhile, genetic drift is an independent process that results in random changes in the frequency of a trait in a population. Within humans there are instincts that are at the bottom of us which can be explored through various approaches discussed in Mortido’s book Fear, Greed and Vigilance, An Evolution of Civilization, Revised Edition.

Genetic drift results from the probability of whether a trait will be inherited when an individual survives and reproduces. Although the changes produced by drift and natural selection are small, these changes will accumulate and cause substantial changes in organisms. This process culminates in producing a new species.

And in fact, the similarities between organisms suggest that all the species we know came from a common ancestor by this slowly diverging process. Furthermore, there are five principles of evolution, namely:

  • The new species is not the most perfect form that immediately lives, but comes from simple, unspecialized forms.
  • Evolution is not always from simple to complex, in fact there are many examples of “regressive evolution” namely from complex forms to simple forms. For example, the cassowary is descended from a winged bird that can fly and then develops into a cassowary that is wingless and cannot fly.
  • At one time evolution occurs faster than others. New forms appear and old forms disappear.
  • The pace of evolution does not take place the same in every different organism. In general, evolution is rapid at first as new species appear and then slows down as groups form.
  • Evolution occurs within populations, not within individuals, by the processes of mutation, differential reproduction and natural selection.
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Characteristics of the Evolutionary Process

Biologists had made observations of the comparison of dark to brightly colored butterflies in Southern England still in the 1850s. But when they studied collections from England’s smoky industrial Midland region, they found very few butterflies. brightly colored butterfly.

There is no doubt that coloration is genetically controlled, but why are brightly colored butterflies more common in some areas and darker ones more in others? From this event we can note four important things, namely:

  • An event must have a basis, namely “raw material”. Before the frequency of dark colored butterflies increased, there were already some dark colored individuals in this population and this dark coloration was decreasing. So evolutionary events require genetic drift as a raw material. There is a factor of change in evolution.
  • Evolutionary events do not encompass all existing raw materials. A century ago there were many aberrant declines in butterflies. But only one deviation, namely the dark color, is the basis for changes in the population. the other deviations are more or less fixed in frequency. evolution is selective change, with environmental factors (in this case soot and birds of prey) driving this selection. So in evolution there is a guiding factor.
  • Evolutionary events are changes in populations, not changes in one or a few individuals. A century ago in the population of the Biston Betaria butterfly there were only a few dark butterflies. The change that occurred over the next hundred years was a change in the frequency of dark colors in the population.
  • In general, change is not the most important characteristic of evolutionary events. In 1850 all individuals were nearly identical. Now they are still almost the same anyway. Most of the discrepancies that were rare in 1850 are still rare today and only a few new deviations can be discovered. The only thing that changes is the frequency of the color traits. So in evolution there is a factor of stability.


Evolution Theory


Before discussing further about the theory of human evolution, Readers can use the book Theory of Evolution: Origin and Purpose of Humans as a reference to better understand the various explanations below.

Early Human Evolution Theory

Up here, you have started to understand what is meant by the theory of evolution, right? To be clearer, it’s better if you know the theory of ancient human evolution. As previously discussed, Anaximander, a pre-Socratic philosopher who lived around 610–546 BC, has discussed the possibility of how humans evolved from fish.

However, there is no scientific evidence that can prove this opinion, right, Pahamifren. Over time, this theory of human evolution actually focuses more on the assumption that humans developed or evolved on earth from primates that were already extinct, you know. The primates that are often associated with human evolution are ape-like primates. That is why there is a lot of information circulating that humans come from monkeys.

Evidence that primates are related to humans is from their genetics. DNA between humans and primates can reach up to 97% similarity. However, that does not mean that humans are considered to have come from monkeys, yes. These facts can only trace that humans and primates may have a common ancestor.

Charles Darwin’s Theory of Evolution

In fact, information about humans evolving from apes emerged because of Charles Darwin’s theory of human evolution. In the book “The Origin of Species” which put forward the theory of evolution written by Charles Darwin, concluded that all living things came from a common ancestor (common ancestor) and are related to one another. According to Darwin in the book, the process of genetic mutation from the same ancestor resulted in the process of evolution and the emergence of various new species.

Darwin imagined human evolution to be like a tree. The single trunk of a tree and its roots are the ancestors of living things. While the branches and leaves of trees become new species that are born due to a process of genetic mutation. The process of genetic mutation can occur due to natural selection in a long time. From natural selection, Darwin then divided the evolutionary process into microevolution and macroevolution.

Microevolution is the changes that occur in species in small ways. For example, changes in color or size in a population over several generations. While macroevolution is a change due to natural selection that is able to create new species. For example, dinosaurs turned into birds, amphibian mammals into whales, and ape ancestors became humans.