Evolution is a process by which living beings transform themselves from their current form to another form that is better suited to cope with the immediate environment. The theory of evolution was first proposed by British scientist and naturalist Charles Darwin in 1859 by publishing a book named ‘On the Origin of Species’. Earlier to that he jointly published some papers with his fellow scientist and geologist Alfred Russel Wallace, regarding the evolution of species.
Later though they independently published their works. Wallace mainly worked on the geographical diversities, spanning different regions of the world. He primarily did extensive fieldwork in the Amazon River basin, and then in the Malayan Archipelago. But here are specific points to highlight the essential principles of evolution as proposed by Charles Darwin, also known as Darwinism.
According to Charles Darwin, the first principle of evolution is genetic variation among the population. No two offspring of the same parents look the same or has exactly similar traits or interest. Even similar or look-alike twins have different characteristics. This is because though they have the same origin, their genes vary. This, according to Darwin, leads to random mutation of genes, which evolves into more suitable species, who can adopt themselves the changed atmosphere and environmental conditions. Geographical variation among the population is caused by genetic drift in population across locations. In different places genes tend to adopt the geographical and climatic condition of the native locality, thus giving a different set of adaptability to the ethnic population, different from population of other lands. Genetic variation within a community is measured in terms of percentage of variation in gene loci.
Heredity is the process of passing of traits from parents to their descendants. The process of reproduction does this. Reproduction is a natural power of all living beings to produce offspring similar to them, either through sexual, as in genetically complex animals and plants, or through asexual methods, as in simpler organisms. According to Darwin, variation between individuals leads to the possibility of accumulation of change and cause different species to evolve through natural selection. The study of this branch of science is also called Genetics. Inherited qualities are passed from parents to their children through a molecule known as Deoxyribose Nucleic Acid or in short DNA, that contains the genetic code and is handed down to offspring from parents. But, as mentioned earlier, inheritance does not mean merely copying of traits. DNA from two individuals do vary from child to child, and thus paving the way to mutation, migration, genetic drift and evolution.
The third and probably the most important principle of Darwinian Evolution is the principle of Natural Selection. It is sometimes referred to as the cornerstone of Darwinism. Darwin first proposed this theory in a joint publication with Wallace in the year of 1858. He subsequently elaborated the theory in his book, which was published in the year of 1859. According to Darwin: - “Though all beings are fertile, their number remains more or less constant.” In other words, he means to say that though all beings have the potential more than a sufficient number of issues, their number remains constant by way of natural selection. Or, putting things differently, Darwin speaks of ‘Survival of the fittest’. That means for a given species, though more than sufficient quantity individuals are produced, only the ‘fit’ members of the gang survive. They are the future torch-bearers, who has the responsibility to carry on the reproduction course of the future generation and thus contribute to the process of evolution.
Over time, the process of natural selection and as such, the evolution of species takes place. It may take days, years, decades or millions of years to evolve a species into another. While viruses, and in some cases microbes like bacteria, evolve very rapidly may take a few months or years, whale evolution took millions of years. Whale, being a mammal, developed fins like fish and their nostrils migrated to the back of their skull. This evolution took millions of years.
1. On the other hand, viruses develop new strains within days. Bacteria immune to the old type of antibiotics are evolved over the years as scientists need to develop new types of antibiotics to combat them. So, we see that time is also a huge factor in the process of evolution and natural selection.
2. Adaptation to environmental changes: Adaptation is a significant issue in the biological perspective, especially concerning evolution. It has more or less three related meanings. First of all, it is the process of fitting an organism into its changing environment. Then, it also means a stage reached by the species or organism by the above process. And finally, it also may mean an adaptive role that an individual member of the species may play in participating in this process. Adaptation is a process of biological fitness or co-adaptivity of two species also. For example, pollinating flowers and nectar seeking insects. Thus, adapting to the environment is a significant factor in evolution as species evolve into newer species only to adapt to the changing climate.
These, in short, are five major principles of evolution as proposed by Charles Darwin. Together they are sometimes referred to as VISTA. We must keep in mind that in the era of Darwin, genetics and molecular biology was not developed to that extent to give scientific proof to the theory of evolution. Scientists, after Darwin further enhanced his theories and gave birth to a new school of studies known as Neo-Darwinism. Among them, we can consider George John Romanes (1848 to 1894) as one of the forerunners.
While previously, Neo-Darwinism was viewed as the history of the modern synthesis in the early 20th Century. However, scientist now differs in their opinion as consider Neo-Darwinism often to denote the modern theory of evolution and genetics.