I am an Aquarius, a fact that I use to excuse a lot of quirky behavior.

One typical Aquarian trait is that I always want to theorize on why things happen or what motivated somebody to do something. I like to theorize about anything and everything, and writing it down like this I can see what a bore I must be at parties!

Sometimes I am right on the money with my theories. Often, with more information, I realize that I did not fully understand the circumstances and my theory goes up in smoke. And many times, my theories are completely crazy and hairbrained (although even these are not always wrong!).

My point is, in the context of everyday English, the word theory means something unproven, possibly biased, possibly impossible.

In science, the word theory has an almost opposite meaning. For an idea to rise to the level of theory, it must have been held up against scientific data and proven. A theory is bigger than a mere fact. A theory explains a fact.

Fact: when you throw a ball into the air, it comes back down. Theory: Gravity pulls things to the earth.

As we learn more, theories can be modified but their basic truth remains.

Another Aquarius, with a slightly larger readership than me, was Charles Darwin. He proposed his Theory of Natural Selection (a.k.a. Theory of Evolution) in 1859 in “On the Origin of Species.” Darwin was a naturalist, as was his grandfather.

Darwin voyaged to the Galapagos Islands and collected specimens which would eventually lead to his “Aha! Moment.” On each island he found birds and animals with adaptations unique to the island. For example, the shape and size of beaks of the finches on each island reflected the kind of food available to them.

Darwin originally thought that all of the different specimens were different types of birds, but once back in England a specialist confirmed that he had collected about 16 different species of the same kind of bird. He realized that the distinct species would have evolved over time due to mutations, isolation and natural selection from a common ancestor.

It’s been 95 years since the “Scopes Monkey Trial” happened down the road in Dayton, but there continues today confusion and skepticism about the Theory of Evolution. Here are a few key points of the theory:

• The world is constantly changing and organisms must adapt and change to survive;

• Our common biology leads to the hypothesis that all organisms descend from one or several common ancestors. This is accepted by scientists, although the ancestor has not yet been identified;

• Evolution is gradual. Darwin suggested that the world was much older than it was thought at that time in order for so much diversity to have developed. He was correct about the age of the earth. However, it has since been proven that evolution can happen either gradually or quickly. You know how they tell you to finish all your antibiotics even after you start feeling better? That is to prevent your disease from surviving the treatment and then quickly evolving and becoming resistant to subsequent doses.

• Changes can be inherited across a species; each individual does not evolve individually; and

• Evolution occurs through “Natural Selection.” This is often mislabeled “survival of the fittest.” It might be better to say “survival of the best adapted.”

Natural selection is the process whereby individuals with the best adaptations — the chameleon with the best camouflage or the shark with the biggest teeth — will be healthier and survive longer, allowing them more of a chance to pass on these beneficial genes to their offspring. And those offspring which inherit the desirable genes will again have a better chance to produce offspring. So that eventually what started as a deviation or mutation from the normal will become the new genetic normal. This is how a species originates.

It is perfectly acceptable to tell a child that they are tall like their grandfather or smart like their great-grandmother. It is normal to comment on a dog breed’s tendencies: Golden Retrievers were bred to be lovable and dependable while Border Collies were bred to herd sheep. We all know that certain types of cows give more milk and certain sheep give better wool. Humans have been imitating natural selection for hundreds of years.

Why then do we balk at acknowledging that the giraffe with the longest neck or the eagle with the sharpest talons would have certain advantages for survival? And that those who survive the longest or most successfully will have more offspring? And that having more offspring provides more chances to pass those advantageous genes on? And that over generations, two populations that live in distinct habitats may have developed different traits for survival, leading to physical differences between them?

After all, a nocturnal bat that lives in a dark cave needs better echolocation than a day-flying bat that lives in a tree and can use its eyes to see. A forest elephant needs to be smaller so it can navigate through the trees, whereas a savanna elephant needs its height to look for predators in the tall grass or to graze on trees.

These traits, passed down through generations, are the result, and the evidence, of evolution.

Kathryn Hunter is from McMinn County and holds a bachelor’s degree in Forest Resource Management from the University of Idaho and a Master of Forestry from Yale University. She has worked with the USDA Forest Service locally as well as living and working in natural resource management and protected area conservation in eight foreign countries.

Kathryn Hunter is from McMinn County and holds a bachelor's degree in Forest Resource Management from the University of Idaho and a Master of Forestry from Yale University. She has worked with the USDA Forest Service locally as well as living and working in natural resource management and protected area conservation in eight foreign countries.

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