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The theory of evolution describes how species develop over a period through a process called natural selection. It was formulated by British naturalist Charles Darwin, who presented his ideas on the theory of evolution in his book, “On the Origin of Species”. His ideas were based largely on his observations from his survey expedition, which included stops in Australia, South America and many more places.

However, Charles Darwin was not the first or the only scientist who developed the theory of evolution. British biologist Alfred Russel Wallace articulated the theory of evolution, but it had little impact. Similarly, French biologist Jean-Baptiste Lamarck came up with another theory that says that organisms pass on their traits to their offspring. He believed that organisms change their behaviour and bodies, much like athletes change their bodies through exercising and training. For example, Lamarck believed that giraffe necks grow longer by their continuous efforts to stretch them to reach the delicious leaves located high in trees.

Conversely, Charles Darwin had a different view of the giraffe's long neck, according to Quanta magazine. He believed that giraffe species had different neck lengths, and those giraffes with naturally long necks were more successful in obtaining their food, causing their future generations to have longer necks. The main difference between Darwin's and Lamarck's theory is that Darwin did not believe that giraffes stretched their necks and passed on this characteristic to the next generation. Let us understand the theory of evolution, as described by Charles Darwin in his book mentioned above.

Darwin's theory of evolution

Charles Darwin proposed a model in which each species has its unique differences, which differ from their common ancestor. Over generations, species change their hereditary traits from their ancestor, which is called evolution. Many people might not know that Darwin introduced the concept of evolution and, along with it, explained the mechanism behind it. His mechanism logically explains how the population grows over time. His idea of natural selection is based on the following observations.

1. Characteristics are heritable

Species inherit their traits from their parents, which means parents pass them to their offspring. Though Darwin didn’t know about the concept of genes, he somehow figured out many characteristics are passed from parents to children.

2. More children are produced than survive

Organisms produce more children than the environment can support, which means there are limited resources, and offspring have to compete with each other to survive.

Based upon the two observations, Darwin concluded the following things.

• Some organisms inherited traits from their parents that are more beneficial to them. For example, these traits help them to better survive and reproduce, which means they will have more offspring.

• And as they have more offspring, these beneficial traits will begin to pass on to the next generation. Over generations, organisms adapt to the environment, and those whose traits are helpful for the environment thrive.

Darwin’s model allowed him to describe what he had observed during his travels. Let us take an example to understand natural selection in more detail. In a group of mice, some are black, while others are tan. This group moved into a new place where there were black rocks, and Hawk could easily see the tan rats. So, a large population of tan rats will be eaten, while black ones will be less eaten. From the above example, we can deduce that natural selection, as proposed by Darwin, doesn’t favour beneficial traits but those that better suit the environment. It also emphasizes that natural selection starts from inherited variation in the species. This variation is due to random mutation in organisms.

Darwin on human evolution

Charles Darwin's theories were used by researchers later on to understand human evolution. Scientific evidence shows that the first apes emerged around seven million years ago. These apes were gorillas and chimpanzees, who were intelligent creatures. These creatures gave rise to the lineage of apes known as Homo, which started our species. According to scientists, the crucial developmental starts with the full-time bipedalism of apes- The ability to walk on two legs which enabled them to make tools for hunting and construction. Homo genus invented fire and clothing and gradually developed complex languages and many more. However, researchers are still struggling with which home species came first, as many existed (at the same time) according to the fossil fuels record.

Future of human evolution

Humans are expected to evolve with significant changes in physical and cognitive abilities in the next 1000 to 10,000 years. With the increase in the interconnectedness of the world, we will witness a homogenous population with less genetic diversity. Some researchers suggest that we might develop physical features such as small brains and tall height. However, many factors influence how humans will evolve in the next 10,000 years, but one thing that is certain is that humans' choices and decisions will decide their evolution.

The bottom line

At last, the theory of evolution gives a framework that explains how the earth and organisms evolved over time. The theory of evolution is being refined with the emerging evidence, which is further solidifying its role in biology.

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