Evidences For Evolution


Evolution is the most interesting area in the field of Biology and it is the consequence of interaction between many internal and external factors surrounding the organisms. However, different biologists opine differently on evolution. Some scientists have argued that evolution is a result of environmental forces and a few argued that it is ourely because of the  genetic tendency within the organisms. Evolution is the gradual and overall influence of both internal and external factors on the living organisms. Some of them are the series of genetic and  environmental factors composing both the biotic and abiotic aspects within them. 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. Let us explore how the evolution is linked with all these factors.



Genetics and environemnt 

Genetics and heredity are 2 of the strongest supporting factors of evolution.Our genes have a direct influence on the transmission of inherited traits from parents to the children. The transmission of inherited characters between the generations is a continuous process  during which process of inheritance creates 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 including physical stature, emotions,  intelligence, skin colour and the colour of eyes etc. Because , though parents and children look alike, we can still find some differences between the 2 and this is because of the way the external influences strike on the organisms. 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. Additionally , we can find more number of people with fair complexion among those living near sea shore areas . The fair complexion is linked witht he humidity and sunlight in that area. 


Biochemical organization of organisms  

From the biochemical viewpoint, the process of translation of all the genetic information 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, no matter which species they belong to. Hence, it is concluded that there are evolutionary similarities between different species based on their genetic material.


Fossils as the biological evidence

Fossils play a key role in providing evidences for evolution. Fossils are formed by the decaying of dead matter that accumukated in between various layers of earth. Fossils found under the rocks and forests are the clear indication of the existence of various life forms from ages. In addition, variety of fossils  depends upon the age of decaying . Since different organisms have undergone extinction at different times, we find them in variety of ways. After analysing the different fossils, it is found that some of the samples look new and some of them belongs to stone age and this tells the true story the evolution. In other words, evolution is a continuous and long-term process where fossils are good indicators of the phenomenon.


The comparative anatomy and morphology as evidence of evolution

Anatomy is another evidence for evolution. Evolutionary process is determined by the similarity of body structures among  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 2 closely related species into account, they look similar, but they perform different functions among the 2 species under study and the 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 tail bone 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 . They look very similar in both , however, when we watch carefully , 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 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




  1. What is evolution?

  2. Explain the role of homologous organs in understanding the phenomenon of evolution.

  3. How is environment and genetics linked with evolution?

  4. Explain about the embryology as the source of evolution.

  5. What are fossil fules and how can they help in evolution ?


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