Evolution of Animals: How Life Changed over Millions of Year

Ever wonder why people have hands, fish have fins, and birds have wings? Or why do certain creatures resemble their old cousins so much while others have entirely different appearances? Evolution has the key to the solution.

The gradual process of change that takes place in living things over millions of years is called evolution. Animals don't change during their existence. Rather, minor alterations are passed on from parents to their offspring, and subsequently to their offspring's offspring. These alterations can accumulate over a very long period of time to produce an animal that is completely different from its forebears.

Table of Contents:

• How Did Life Begin?
• From Water to Land
• What Happened to the Dinosaurs?
• Why Do Animals Change?
• Some Animals Barely Changed
• Conclusion

How Did Life Begin?

According to scientists, life on Earth originated in the water around 3.5 billion years ago. The earliest living species were quite small and basic, unlike modern mammals. Some of these basic living forms gradually evolved into more complex ones over time. Simple animals initially emerged in the oceans some 600 million years ago. They lacked both shells and bones. Some animals eventually acquired stronger bodies that improved their chances of survival.

>From Water to Land

The transition of some marine animals to land was one of the most significant shifts in the history of animals. about fish developed powerful fins that functioned almost like limbs about 375 million years ago. Those fins gradually developed into regular legs over millions of years. In order to breathe air, these animals also developed lungs. They evolved into the first amphibians, which are aquatic and terrestrial creatures. Reptiles evolved from amphibians. Reptiles were more suited to live on land. They lay eggs with hard shells and had scaly skin to retain moisture. Of all the reptiles, dinosaurs were the most well-known.

What Happened to the Dinosaurs?

For over 165 million years, dinosaurs inhabited the planet. Then, a huge asteroid struck Earth about 66 million years ago. The majority of dinosaurs were unable to survive due to the significant changes in the climate. But a tiny percentage did, and over millions of years, they gradually changed into birds. Thus, it is true that modern birds are descended from dinosaurs. Early mammals, which are small, furry animals, were also present on Earth at this time. These animals had greater room and food after the extinction of the dinosaurs. Over time, they gradually dispersed and evolved into the diverse range of mammals that we are familiar with today, including humans, whales, elephants, and bats.

Why Do Animals Change?

Animals change mainly because of survival. In the natural world, animals that are more adapted to their environment tend to live longer and produce more offspring. These infants frequently inherit the same beneficial characteristics. Those characteristics become more prevalent over several generations. Charles Darwin, a biologist, originally described this process, known as natural selection, in 1859.

Here is a basic illustration. Consider rabbits residing in a region covered in snow. Predators find it more difficult to identify those with somewhat whiter fur. They pass on the white fur, produce more offspring, and live longer. Over time, most rabbits in that area become white. That is natural selection working quietly in the background.

Some Animals Barely Changed

Not every animal has changed a lot. Some look almost the same as they did millions of years ago. The crocodile, for example, has looked similar for over 80 million years. Scientists sometimes call these animals living fossils. Their bodies worked so well for survival that there was simply no need for big changes.

Conclusion

The process of evolution takes time. It's a slow, complex procedure that takes a long time. However, the effects are felt in every hand, wing, claw, and fin that surrounds us. Every living thing has a unique tale of transformation and survival. Understanding evolution makes it easier to see how all life on Earth is interconnected in ways that date back millions of years.