There have been a number of great scientific revolutions over the last few hundred years, but none more revolutionary than that of Darwin’s theory of evolution. When he published his book “On the Origin of Species” in the 19th century, it overturned millennia of religious doctrines about the place of humanity in the natural world.
Today, evolutionary biology is one of the most well-established theories in all of science. The basic principles of evolution are quite easy to grasp, but applying these principles to the natural world takes a lot more work. However, anyone can understand how evolution and natural selection work in just a few minutes.
When Charles Darwin came up with his theory, he based it on a few simple observations. First of all, he noticed the obvious fact that children resemble their parents. This is because parents pass on their traits to their offspring through heredity. Tall parents tend to have tall children, dark-haired people have children with dark hair, and so on.
Second, Darwin noticed that there are always limited resources in the environment. There is usually not enough food for every organism in a population, for example. This suggests that there is a continual competition for these resources among the different members of that population.
Finally, he also noticed that certain traits made some organisms better suited to obtain the resources they needed. For example, a stronger animal might be able to fend off competitors and capture more prey, or a taller organism might be able to reach more leaves on a tree. However, this competition is not always an overt one involving physical strength and dominance.
From these three simple facts about the world, Darwin deduced the idea of evolution through natural selection. Since organisms are always competing for resources, and some organisms are better-positioned to triumph in such a competition, they will naturally tend to have more offspring than others.
By passing on their traits to their children, those creatures that are fitter and better-suited to the environment will gradually see their traits become more common in a population. Over time, therefore, populations tend to change in response to various external pressures, and it is this process that creates all the diversity we see in the biological world.
Of course, there were certain weaknesses in Darwin’s theory as it was originally presented. For one thing, he had no idea how traits were passed from parent to child. It was not until the structure of DNA was discovered in the 1950s that scientists began to understand exactly how heredity works.
Evolutionary biology is now widely accepted by virtually all scientists who study the natural world. In the future, its reach may even be extended to other planets. If life is discovered on Mars or elsewhere in the solar system, scientists will finally be able to compare our form of life to an entirely different form. This may provide answers to some of the most difficult and complicated questions in all of science.