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Isn’t Evolution “Just” a Theory? What is a Theory, Anyways?

Homo erectus fossil

Lots of people say evolution is “just” a theory. But they may not know exactly what a “theory” is. In everyday language, the word ”theory” is often used to mean a “hunch” or “guess.” But in science, the word “theory” has a much different meaning.

So, what is a theory?

To answer that, I need to talk about the Scientific Method. Why? Because Physical Anthropology is a science, and it uses the scientific method to figure things out. 

OK, well, what is science?

Science is a way of explaining things that happen. It’s a way of answering questions about the world. It’s observing things, and then coming up with a hypothesis to explain what happened, and then developing a way to test the hypothesis to see if it really explains what happened. This process that science uses is called the scientific method.

The Scientific Method

With the scientific method, there are 4 basic steps, observation, creating a hypothesis, collecting data, and interpretation. We’ll briefly explore each of these steps. (Note that some science books break things down into different numbers of steps, but they all have the same process.)

Woman scientist looking in a microscope.

So, the first step is observation. You either observe something in the world or use observations made by other researchers. 

The second step is creating a hypothesis. You have to read all the literature (which means books and journal articles) on what you observed, to see what other people have learned about what you observed. Then, you come up with a hypothesis, which is an educated guess, that explains what you observed.

The third step is collecting data. This is when you gather information to test your hypothesis. This means that the evidence you gather will either support your hypothesis or not. 

The fourth step is interpretation. You analyze the data and see if it supports your hypothesis or not. You should look for these four things:

  • Repetition: You need to see if the same thing happens over and over. 
  • Universality: You need to find out, does the same thing happen under all conditions? If part of the situation is changed, does the same thing still happen?
  • Explanations for exceptions: If the same thing does not happen, can we explain why?
  • New data: You need to see if any new data support your hypothesis or not.
Scientist woman analyzing rocks on a laboratory table.

If your data shows that your hypothesis was wrong, then you try another hypothesis. If the data supports your hypothesis, then you test it again. If your hypothesis is still supported, then you publish the results in a journal article so that other scientists can do the same tests and see if they get the same results, too. When you publish your article, you need to make sure to describe your techniques and results precisely, so that other scientists can follow what you did and compare their results to yours. Then, either other scientists have the same results that you do, or their results are different and don’t support your hypothesis. 

If a hypothesis is supported over and over again by multiple researchers, the hypothesis is called a theory. For example, if you drop something, it will fall to the ground, no matter who drops it or where they are in the world. The concept of gravity explains why this happens, and this idea has been tested and retested many times, and all the evidence supports it, so now we have what’s called a theory of gravity.

Now, as I stated before, many people use the word, “theory” to mean a guess or a hunch about something. But in science, a theory is an explanation for something that all the evidence supports. Theories are tested explanations that have NOT been shown to be wrong. Theories can be updated over time as new technology and new research adds to our knowledge, but some theories are so well supported that they are essentially proven, like the theory of evolution.

Image of the inside of a Christian Church, showing decorative walls and pews.

But, science doesn’t answer everything. Science only studies natural phenomena, not supernatural things like ghosts or God. So, there are questions that science can’t answer, such as the meaning of life and the existence of a higher power. The questions are handled by religion and faith. 

In summary, science is a way of answering questions about the world. Since physical anthropology is a science, we use the scientific method to answer questions about humans. The scientific method involves observing something and developing a hypothesis that explains the observation. Then, the hypothesis is tested by collecting data. You see if the data supports the hypothesis or not. If a hypothesis is supported over and over again, then it is called a theory. So, YES evolution is a theory, but it is not a guess. Evolution is not “just” a theory. The idea has been tested and retested over and over again and is so well supported by evidence that it is essentially proven. 

Want to Learn More about Evolution?

Just take my Udemy course, “Exploring Genetics & Evolution Through Physical Anthropology: Anthropology 4U.” 

Thanks for reading!

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