Humans Aren’t Evolving by Natural Selection Anymore (Part 1)

natural selection part 1 Deel

By Dr. Gary L. Deel, Ph.D., J.D.
Faculty Director, School of Business, American Public University

This is the first part of a two-part series on natural selection.

More than 150 years ago, Charles Darwin explained the diversity of biological life on Earth through his brilliant theory of natural selection, also known as evolution. Darwin described how the environment shaped organisms from one millennium to the next as it selected the fittest ones for survival.

Misunderstandings about Darwin’s Theory of Evolution

One common misunderstanding with Darwin’s theory of evolution is his use of the expression “survival of the fittest.” When Darwin wrote this phrase, he did not mean “fittest” as in being the most muscular or being in the best physical shape, as we often use the term “fit” in conversation today. Rather, he was implying the extent to which an organism “fits” its environment so it is able to survive long enough to procreate and pass on its genes to future generations.

Here’s an example: Polar bears have evolved to live in the Arctic where their white fur allows them to blend in with the snow and ice of the region, so they can effectively hunt and fish to feed themselves and their young. A polar bear is therefore “fit” for the Arctic environment.

The lineage of Arctic bears has been shaped over millions of years and thousands of generations, such that the bears are influenced by their environment to select genes that cause white fur. Other bears, say, with brown fur, would not be as successful hunting in the near all-white Arctic and would not survive in the Arctic. In much the same way, a polar bear would likely not survive long if it were transplanted to a forest in a more temperate climate with green and brown foliage.

Another misunderstanding about evolution comes from confusion about the way in which Darwin proposed that an environment over eons would shape the organisms that inhabit it. Some people have mistakenly thought Darwin proposed evolution as a force that somehow changes organisms during their lifetimes. This is not at all what Darwin posited, and is not consistent with our understanding of biological science.

Rather, an organism’s genes are relatively fixed throughout its life, barring random mutations, degradation through aging, and so on. Sure, organisms can adapt their behaviors to environments, but most species cannot change their physical appearance or other immutable characteristics, nor can the environment suddenly change such characteristics of the species that live within it. For example, a brown bear living in the Arctic will not change its fur to white, and the Arctic environment cannot create such a spontaneous change in a bear’s genetics either.

Environments Hone the Characteristics of Generations

But what the environment does do is hone the characteristics of the next generation of organisms that inhabit it by affecting which members of the current generation will make it far enough in their own lives to create offspring.

Imagine five bears living in the Arctic a million or so years ago. Four were born with white fur, and one was born with brown fur. Such random variations come with bisexual reproduction.

As these bears grow up and become independent, they must obviously rely on their abilities to hunt and fish to survive. The four white bears can hide and sneak up on seals and other prey to ensure successful hunting. But the brown bear sticks out in his environment, and his prey can see him coming in time to get away.

Because of this poor fit to its environment, the brown bear will likely starve to death before he ever reaches sexual maturity and finds a mate to reproduce. And because the brown bear never has offspring, he will not pass on his dominant gene for brown fur.

Now, it’s entirely possible that the white bears might carry a recessive gene for brown fur. When they reproduce, there is still a non-zero chance that they will have one or more cubs with brown fur.

But unfortunately, the fate of those cubs will probably be similar to that of all brown bears in the Arctic. In this way, the Arctic environment systematically eliminates brown bears, not through change in one organism, but by changes over many, many generations.

That said, the important thing to note about evolution through natural selection is that it only works if the mismatch between organism and environment is substantial enough to block the organism from reaching reproductive age and procreating. If the organism gets that far, then any environmental impediments prior to that point are moot.

For example, let’s imagine that rather than being solitary animals, Arctic bears are communal mammals that share and support each other like wolves or primates. In such a scenario, a brown bear’s odds of survival might be much higher.

As long as the brown bear has pack mates that are white and effective hunters, the brown bear might be able to survive through his white bears sharing kills with all of the group members. And if most brown bears could make it far enough to procreate this way, then natural selection is effectively canceled by the cooperation of the group to protect those members that otherwise would not survive on their own.

And that brings us to the point of this article, which is that modern human societies have effectively halted evolution by natural selection for the human race. In the second part, we’ll look at how this has come to be and what it means for the future.

About the Author

Dr. Gary Deel is a Faculty Director with the School of Business at American Public University. He holds a J.D. in Law and a Ph.D. in Hospitality/Business Management. Gary teaches human resources and employment law classes for American Public University, the University of Central Florida, Colorado State University and others.

#APU expands access to quality #highereducation & prepares our students for #service & #leadership in a diverse & global society.

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