Evidences For Evolution



Evolution is the most interesting area in the field of Biology. It is the combined effect of many internal and external factors surrounding the organisms. Some scientists have argued that evolution is a result of environmental forces and a few argued it is a result of a genetic tendency within the organisms. Evolution is the overall influence of both internal and external factors on the living organisms. It is a gradual process as a result of a series of genetic, environmental and other influences among the biotic and abiotic factors. Many scientific, historical, philosophical evidences have explained the basis for evolution. Some of the specific areas that support the evolution are from physiology and biochemistry,  comparative anatomy of organisms, palaeontology, embryological evidence,  colouration and the evidence from mathematical modelling. This article will further explain the well-known evidence for evolution.


Table Of Content

1. Introduction

2. Genetics and evolution

3. Biochemical organization of organisms  

4. Fossils as the biological evidence

5. The comparative anatomy and morphology           as evidence of evolution

6. Analogous features and evolution

7. Embryology as a source of evolution


Genetics and evolution

Genetics and heredity are one of the strongest supporting factors of evolution because genes have a direct influence on the transmission of inherited traits from parents to the children. The transmission of inherited characters is a continuous process for many generations. During the process of inheritance, there is a substantial difference between the 2 farther generations than the nearest generation. However, a parent and child cannot be completely similar in all aspects such as intelligence, skin colour and the colour of eyes etc.   Although parents and children look alike, we can still find some differences between the 2 and this is because of the external influences that had an influence on the transmission of traits. Hence, it is concluded that genes played their role in the variation between the 2 generations. As the gap between the generations increase, the similarity keeps decreasing.


Biochemical organization of organisms  

From the biochemical viewpoint, the process of translation of all the genetic formation and protein synthesis takes the same course irrespective of the species such as bacteria, viral organisms,  human beings, and animals. This has proved the fact that there is a common chemical composition in the genetic elements of various species. Hence, it is concluded that evolution is closely linked with the similar biochemistry existing in various organisms.


Fossils as the biological evidence

Fossils play a key role in providing evidences for evolution. Fossils found under the rocks and forests are the clear indication of the existence of various life forms from ages. In addition, the age of fossils indicate the fact that different organisms have undergone extinction at different times. After analysing the different fossils, it is found that some of the samples look new and some of them look very old this tells the true story the evolution. In other words, evolution is a continuous and longterm process.


The comparative anatomy and morphology as evidence of evolution

It is another evidence-based upon the similarity of body structures and organs of various species. For instance,  the family of dinosaurs with its modern-day counterparts such as crocodile and archaeopteryx look similar. If we take wings of closely related species into account, they look similar but they perform different functions in 2 different species. This phenomenon is known as homologous organs. For instance, consider the 3 species - birds, bats, and insects, they all have wings but the purpose to which they use them may slightly vary. From the evolution point of view, if we ask ourselves why they have a common type of wings?  the answer is simple, they might have shared a common winged ancestors that inherently passed through many generations.  Another classic example of homology is the forelimbs of whales, humans, birds, and dogs. All of these look different despite they are in the same position (frontal region). This is because each organism`s needs are different and the wings have been modified depending on the purposes. On the other hand, all these bones had the same number of fragments, similar shape, and types of bones. So it is almost unlikely that such similar structures would have evolved independently without the influence of genes from the common ancestry. But in some cases, organisms present similar structures but they do not serve useful functions; this is categorized as the evolutionary leftovers or " vestigial structures. For instance, the tailbone of humans, hind leg bones of whales, and the snakes having an underdeveloped leg.



Family tree of dinosaurs and their living counterparts


Analogous features and evolution

One of the examples of analogous features is the eye of a human and the octopus look very similar but in fact, the eye of the octopus is superior to the human eye because they lack the blind spot that we have. However, the octopus and the human are not very closely related descents as they reside far away from each other on the phylogenetic tree of life. Such difference shows there is not only a genetic connection between the nearest species but it can also exist between the 2 distant species.


Embryology as a source of evolution 

The appearance of an embryo in a CT-scan of various species makes us wonder. This is because we don’t often notice a big difference here even if we observe the scanning reports of different species. This sort of similarity can exist if there is some kind of a common evolutionary influence among these. We need to remember the fact that, we all have evolved from a single cell, then the cell divided to form a group of cells resulting in an embryo that has small eyes, ears, a slender body, tail, etc. At this stage most of the organisms look similar, one of the examples shown here in the picture a reptile embryo begins transformations from a fish-like appearance and then it becomes an amphibian-like embryo and finally turns into reptiles. The same sequence looks prominent in human beings also.

Embryology As A Source of Evolution





Course List