Understanding Natural Selection: Darwin’s Groundbreaking Ideas
Charles Darwin, an English naturalist of the 19th century made an in depth study of nature for over 20 years. He made his observations on animal distribution and therefore could also study the relationship between living and extinct animals and as a result, found that these living animals share similar traits. The traits are not only the same between them but also with the opposite species that existed many years ago and among which some became extinct.
Charles Darwin is recognized as the Father of Evolution because of his contribution to the establishment of the idea of evolution. His theory helped in removing all the traditional old beliefs which said that the formation of varied species was a supernatural phenomenon or act of the Almighty. Darwin’s evolutionary theory of survival gave a more rational explanation of the formation of the latest species. As per survival , various species originated from one species as a results of adaptation to the changing environment.
The Theory of Evolution
Darwin Darwin had the subsequent ideas regarding the idea of natural selection:
Species keep on evolving or changing with time. As the environment changes, the requirements of an organism also change and they adapt to the new environment. This phenomenon of adjusting over a period of your time as per the natural requirements is named adaptation..
As per Darwin’s theory, only the upper changes are naturally selected and therefore the lower ones are eliminated. Thus, a progressive evolution can not be expected from all the adaptations. For example, people living in tropical countries have more melanin in their body to guard them from the daylight.
Almost all organisms share common ancestry with some organisms. As per Charles Darwin’s theory, all organisms had one common ancestor at some point in time and kept on diverging ever since. His theories that were evolutionary supported the convergent theory and divergent theory of evolution along with the examples.
He also studied that the birds of Galapagos Island (Darwin’s finches) developed different beaks as per the supply of the food. This proved adaptive radiation. Similarly, he also observed the Australian Marsupials which showed a number of marsupials emerging from an ancestor.
According to Darwin , evolution may be a very slow and gradual process. He concluded that evolution happened over a really long period of your time . As we mention the period of time in evolution we usually ask billions of years. The generation of a species from another takes an extended period of your time . It is a really steady process because the changes and adaptation take an extended time to stabilize and provide rise to a replacement species.
Natural Selection Takes Place in Four Alternative Ways as Follows:
Variation – The changes accumulated over a period of time in an organism usually gives rise to a new species.
Inheritance – It is the passing on of the variations over generations which ultimately leads to speciation.
A High Rate of Growth of Population – This gives rise to more number of organisms being reproduced by a species than the environment can support which might lead to the extinction of that particular species.
Differential Survival and Reproduction – The superior variations cause survival of a specific organism and therefore the inferior or negative variation results in extinction. The superior variations are those inherited during reproduction.
FAQs on Darwin’s Contributions to the Theory of Evolution
1. What was Charles Darwin's main contribution to the theory of evolution?
Charles Darwin's primary contribution was proposing a credible mechanism for evolution, which he called natural selection. Before Darwin, many scientists believed species could change over time, but no one had explained how. Darwin's theory provided a logical, testable explanation that life evolves due to the differential survival and reproduction of individuals with heritable traits that are better suited to their environment.
2. What key observations led Darwin to propose the theory of natural selection?
Darwin based his theory on several critical observations made during his travels and studies. These can be summarised as follows:
- Overproduction: Organisms produce more offspring than can possibly survive.
- Struggle for Existence: Because resources like food and space are limited, there is competition among individuals.
- Variation: Individuals within any population show natural variations in their characteristics. No two individuals are exactly alike.
- Differential Survival and Reproduction (Survival of the Fittest): Individuals with variations best suited to their environment are more likely to survive, reproduce, and pass those advantageous traits to their offspring.
3. How does the phrase “survival of the fittest” relate to Darwin's theory of natural selection?
The phrase “survival of the fittest,” coined by Herbert Spencer and later adopted by Darwin, is often misunderstood. In the context of Darwin's theory, “fittest” does not mean the strongest, fastest, or most aggressive. Instead, it refers to an organism's reproductive fitness—its ability to survive in its current environment and produce viable offspring. An organism is considered “fit” if its inherited traits make it better adapted to its environment, thereby increasing its chances of passing those traits to the next generation.
4. What examples from his voyage on the HMS Beagle supported Darwin's ideas on evolution?
During his voyage, Darwin observed several key pieces of evidence. The most famous examples come from the Galápagos Islands:
- Darwin's Finches: He observed several species of finches on the islands, each with a uniquely shaped beak. He hypothesised that they all descended from a common ancestor from the mainland and their beaks had adapted over generations to suit different food sources available on different islands (e.g., insects, seeds, cacti).
- Galápagos Tortoises: Darwin noted that tortoises from different islands had distinct shell shapes. For instance, tortoises on islands with abundant ground vegetation had dome-shaped shells, while those on islands where food was higher up had saddle-shaped shells, allowing them to stretch their necks.
5. What is the difference between natural selection and artificial selection, and how did the latter help Darwin formulate his ideas?
The key difference lies in the selective agent. In natural selection, the environment “selects” which individuals survive and reproduce based on their adaptive traits. In artificial selection, humans are the selective agent, intentionally breeding plants or animals for desired characteristics (e.g., higher milk yield in cows or specific colours in flowers). Darwin studied artificial selection, particularly in pigeon breeding, and used it as a powerful analogy. He reasoned that if humans could cause such significant changes in a short time, then a similar process, driven by nature, could produce the vast diversity of life over millions of years.
6. Did Darwin's original theory explain everything about evolution? What were its limitations?
No, Darwin's theory was revolutionary but incomplete. The main limitation was its lack of a mechanism for inheritance and the origin of variation. Darwin observed that traits were passed down and that variations existed, but he did not know about genes, DNA, or mutations. He couldn't explain how traits were inherited or how new variations arose in a population. It was only with the later rediscovery of Gregor Mendel's work on genetics that these gaps were filled, leading to the Modern Synthesis of evolutionary theory.
7. How did Darwin apply his theory of evolution to explain the origin of humans?
In his 1871 book, 'The Descent of Man', Darwin extended his theory of natural selection to human evolution. He proposed that humans were not specially created but had evolved from an earlier, non-human ancestor. He presented evidence based on the anatomical similarities between humans and other primates, like apes, suggesting a common ancestry. He argued that traits like bipedalism, intelligence, and complex social behaviour could also be explained through the process of natural selection acting over millions of years.
