Evolutionary History

Evolutionary history begins with the emergence of our species. It is a process by which an organism changes over time, adapting to its environment, gaining or losing traits, and ultimately becoming a new type of being. Evolutionary history is also responsible for the extinction of other species as well as our continued existence. Evolutionary history has been a key factor in helping shape life today and will continue to shape life in the future. Despite this reality, most people are not familiar with evolutionary history because it is typically taught through biology lessons at school or occurs on some level in other subjects such as geology or anthropology.

What is Evolution?

Evolution is a process by which an organism changes over time, adapting to its environment and ultimately becoming different species. Evolutionary history includes this process along with the extinction of other species or our continued existence. Evolutionary history is caused by natural selection, genetic drift, gene flow, as well as other evolutionary forces (see below).

Sources of Evolutionary History:

Natural Selection: This is a naturally occurring force that occurs across all species in nature. Natural selection is used to help make organisms better suited for their surroundings and it occurs over time when more favourable traits are passed onto offspring while unfavourable traits are not passed on to the next generation. 

Genetic Drift: This is a naturally occurring force that occurs across all species in nature. Genetic drift is used to help make organisms better suited for their surroundings and it occurs over time when populations are small enough that traits can change randomly throughout the population and evolution takes place. 

Gene Flow: This is a naturally occurring force that occurs across all species in nature. Gene flow is used to help make organisms better suited for their surroundings and it occurs over time when other populations are utilised to give offspring favourable traits or when migration from one population to another leads to genetic diversification through interbreeding and evolution takes place.

Natural Selection, Genetic Drift, and Gene Flow vs. Human Evolution:

The process of natural selection, genetic drift, and gene flow cannot be directly linked to human evolution. Human evolution is the result of many different factors and these three factors are merely some of those that have shaped human evolution into what it is today. Humans do not evolve in a simple manner from other species, but rather humans’ existence is the result of a complex set of processes that has given rise to our species. These processes include natural selection, genetic drift, gene flow, and artificial selection.

Artificial Selection: This is an artificially created force that occurs across all species in nature. This force is caused by humans who use artificial selection to help make organisms better suited for their surroundings and it occurs over time when humans purposefully breed organisms to gain other favourable traits while they are breeding.

Today, evolutionary history helps shape life in many different ways on a global scale. Selective breeding is being used to help improve crops as well as livestock. Natural selection, genetic drift, gene flow, and artificial selection all play a role in the improvement of these species.

Human Evolution: An Overview

Early humans used basic tools such as rocks or sticks to help them hunt large game such as animals. These same early humans eventually began living in groups in order to protect themselves from predators and to provide for themselves. The evolutionary history of modern man began around 100,000 years ago when our species evolved from the African ancestor population. Prior to this, our ancestors were generally small-brained and uniform in appearance. From this ancestor population, our species evolved into a different kind of being through natural selection, genetic drift, gene flow, and artificial selection – humans. It was through these factors that humans developed larger brains and became the species we are today. The concept of natural selection applied to our species is used to explain how humans came to have such large brains in small bodies. Humans rapidly evolved larger bodies and smaller brains in order to live in complex social groups and survive with the changing climate and environment. This concept is referred to as directional selection, which involves natural selection that favours one trait over another, increasing this favoured trait over time as long as there is positive directional selection. This type of selection was also applied to humans since it favoured increased brain size over body size, thus resulting in humans’ large brains, but small bodies.

Evolutionary history of vertebrates through geological periods:

100,000 to 25,000 years ago: oldest animal skeletons are found. One large species of dinosaurs roamed the earth and were contemporaries with early man at this time. Some of the most famous dinosaurs such as Tyrannosaurus Rex and Brachiosaurus were also contemporaries with early man at this time.

25,000 to 5,000 years ago: Two humans are thought to have made the first crude stone tools from flakes or blades. A small number of these early humans migrated out of Africa and into Asia where they eventually populated the Middle East and Europe. Some of these early humans were also contemporaries with the last of the dinosaurs which existed to this day.

10,000 to 2,000 years ago: Humans in central Asia began domesticating dogs from wolves. In Africa and India, cattle are domesticated from wild oxen. Primitive rice farming began in China around 10,000 years ago. The invention of the wheel takes place 5,500 years ago in Mesopotamia (modern day Iraq). Humans begin domesticating pigs and goats around this time as well.

7,500 to 5,500 years ago: Farming spread quickly throughout Europe and India due to a warming climate that allowed people to grow plants in more diverse regions. By 5,000 years ago, humans in the Middle East had domesticated sheep, goats, and pigs. Rice farming also begins in Asia around this time. From 5,000 to 3,000 years ago there is a transition from archaeological evidence of hunting and gathering to that of farming. Around this time in history man’s food supply dramatically increases since it is now more reliable with a more stable food source. This transition not only allowed for increased population growth but also led to some major societal changes as well.

2,500 to 2,000 years ago: By the end of this period many of the world’s great civilizations had begun their rise including those in Egypt and Mesopotamia (modern day Iraq). The Black Sea is also linked to the Mediterranean for the first time and regional trade flourishes. By 2,000 years ago, farming practices spread to China and rice cultivation began there. Cows are also domesticated in India by this time as are horses and llamas in South America.

Conclusion:

It is very important to understand how evolution works in order for students to properly comprehend the process. It is also important for students to understand the reason why humans have evolved in this manner, since that was a result of our past environment and not a result of evolution itself. As we continue to travel through time, we will see that although evolution is natural, it isn’t perfectly predictable and sometimes takes a drastic change towards the other direction.