Welcome to another new day for Biology Tips Daily, offering tips and tricks to help you ease into the biology mastery.
Today's tip starts out as a question with an obvious answer: Is evolution totally random?
You might have heard this statement before, especially from the doubters of Darwin's magnificent ideas about evolution. How can something that is random produce order and complexity one might reasonably ask?
The answer is that randomness alone is highly unlikely to produce order, let along design complex, competently functioning organisms. That's seems obvious. If you stick car parts together at random, I'll bet you can't drive that car. Of course, Darwin did not make the randomness argument and no rational proponent of any evolutionary theory makes that argument either.
On the other hand, it is certainly true that there is "randomness" in evolutionary processes. Primary among them is the randomness of genetic mutations with regard to the adaptive needs of organisms. Simply because a particular mutation might enhance an organism's ability to survive or increase its capacity to reproduce more in the current or future environments, does not guarantee that particular mutation's imminence or even likelihood.
Hmm...If evolution is not random, then is it "non-random" or ordered in some way? The short answer is "yep". Casual observation shows that organisms are not random assemblages of parts, processes, and behaviors. They are combinations of parts, processes, and behaviors that work in particular environments.
We would all agree that a nuclear submarine is designed to move at great speed and at great depth in water. Imagine trying to drive a nuclear submarine down the freeway. You would be much better off walking down the freeway (except for the crazy drivers and the exhaust). Try finding a tow truck large enough to accommodate your nuclear sub. The point here is that a nuclear submarine is designed for an aquatic environment and completely useless in a terrestrial environment.
Now imagine an organism the size of an elephant with the wings of a hummingbird and the dietary habits of a goldfish. Pretty unlikely combination, don't you think, except in the fertile imagination of Dr. Seuss? Now imagine an organism the size of an elephant with four stout legs and the dietary habits of, we don't know...an elephant. More likely, eh? Since organisms are also composed of parts, processes, and behaviors that work in particular environments, certain combinations are unlikely.
So how can it be that mutations are random with respect to the survival and reproductive needs of organisms yet organisms appear to be well designed? The answer to that question is Darwin's great contribution to science and to the intellectual, social, and cultural history of humankind. It is a non-random process called natural selection.
A mutation can be preserved and even spread by natural selection if it increases the chances of survival and/or reproduction of its bearers in the current environment. In other words, if a mutation causes you to fit your environment well you have a better chance of surviving and reproducing compared to others without the mutation which don't fit the environment as well. Over the course of generations, the better adapted forms in the population will increase in frequency compared to less well adapted forms as will the genetic mutation itself.
As you might imagine, since mutations are random with respect to the survival and reproductive needs of organisms, must mutations must not be helpful. That's right, most mutations are either near neutral or downright deleterious so they are eliminated. But the very rare mutation that actually enhances survival and/or reproduction can be preserved and spread in a population over generations by the non-random process natural selection. Apparently, natural selection, the creative force of evolution, is not random at all.
That wraps up our evolution discussion today. Until then, keep up your study and use what you have learned.
Until then, stay tuned for more biology tips.
Seize the Day!
Dr. Wayne Huang
"The Rapid Learning Coach"
BioTips@RapidLearningCener.com
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