On Evolution: Common Misconceptions and Deceptions

There are some critical misunderstandings of evolution out there, and I’d like to help clear some of them up.

Ray Comfort is offering $10,000 to the first person who provides evidence of a ‘living transitional form’, and he defines this as a species giving birth to an entirely different species, such as a squirrel giving birth to a bird, or a chicken giving birth to a snake.  Now, I personally think Ray is being patently dishonest, but this raises a good point about what people seem to think evolution is all about.

Let’s say that you are a paleontologist, and you have discovered fossils of a previously undocumented animal.  What you are looking at is a snapshot in time, as it were.  A ‘species’ is just that - it is a group of animals with particular shared characteristics, and when you look at a particular species, you are actually seeing the ‘current version’ of that genetic lineage.  If you take our hypothetical fossil find, you can determine approximately when that creature was alive.  However, if you were to find fossils of that species’ descendants from 5 million years later, they will likely be markedly different.  The key is time - the original species didn’t ‘give birth’ to the new species in a single generation, there were simply changes piled upon changes piled upon more changes, until eventually the animals were so different that they could no longer be considered the same species.

Bear in mind, though, that there are a great many factors which can affect these changes.  Ultimately, the only way that a species will NOT evolve is if there are virtually no changes in the animals’ environment, and this is highly improbable.  

For one thing, predator/prey relationships drive tremendous amounts of change, which can lead ‘evolutionary arms races’, such as the relationship between the cheetah and the gazelle as Richard Dawkins so eloquently described in his book ‘The Greatest Show On Earth’:

“If we are going to postulate a designer of the cheetah, he has evidently put every ounce of his designing expertise into the task of perfecting a superlative killer.  One look at that magnificent running machine leaves us in no doubt.  The cheetah, if we are going to talk design at all, is superbly designed for killing gazelles.  But the very same designer has equally evidently strained every nerve to design a gazelle that is superbly equipped to escape from those very same cheetahs.  For heaven’s sake, whose side is the designer on?  When you look at the cheetah’s taut muscles and flexing backbone, you must conclude that the designer wants the cheetah to win the race.  But when you look at the sprinting, jinking, dodging gazelle, you reach exactly the opposite conclusion.  Does the designer’s left hand now know what his right hand is doing?  Is he a sadist, who enjoys the spectator sport and is forever upping the ante on both sides to increase the thrill of the chase?  Did He who made the lamb make thee?”

Another key point:  Natural Selection is driven by changes in gene frequencies within a population.  Gene mutations which confer a benefit of some kind to a particular species in a particular environment are more likely to spread throughout the population, and gene mutations which hinder an animal’s change of surviving and reproducing will tend not to spread.  The majority of mutations have either no effect or a neutral effect, and these mutations can often lead to much of the brilliant diversity that we see within many species.

This concept can be demonstrated in the relationship between rattlesnakes and some species of California Ground Squirrels:  Rattlesnakes have venom which helps them to immobilize potential prey.  In some environments, their primary prey is a type of ground squirrel.  Over thousands of years, some of the squirrels are born with a gene mutation which makes them resistant to the snake’s venom.  The squirrels born with this gene will have a much better chance of surviving and reproducing, which will increase the frequency of the gene within the overall population, which in turn will produce more and more squirrels with this resistance.

This change can have a dramatic effect on the snake population.  As it becomes more and more difficult for the snakes to find enough food, the gene frequencies in the snake population will start to shift as well.  Over time, genetic mutations can cause the snake’s venom to become more potent, thus granting the snake a better chance of eating, surviving, and reproducing.  Eventually, mutations within the squirrel population will increase the animal’s resistance to the toxin, and the snakes will mutate more potent venom, et cetera and ad nauseum.

Another common lie being told by Creationists is this distinction between ‘macro-evolution’ and ‘micro-evolution’ - they claim that life forms can ‘adapt’ and thus they accept ‘micro-evolution’, but they also claim that the species will never ‘change’ into another species.  As demonstrated above, this is partially based on a misunderstanding/ignorance of the natural selection process; however, it is worth noting that they do accept that natural selection occurs, but that there is something which prevents speciation from occurring.  As stated above, though, a ‘species’ is just a name that we tack onto the ‘version’ of the life form being observed, and is not a concept which nature is obliged to adhere to.  It is true that, most of the time, a species is defined as a group of life forms which are sexually compatible, but this method for defining a species is problematic for many reasons.

First, it completely ignores all asexual forms of reproduction entirely, which includes such life forms as bacteria, viruses (yes, viruses are classified taxonomically), yeasts, and many types of plants and fungi.  If there are this many exceptions to the rule, then it isn’t much of a rule.

Next, it is important to understand that this method of classification does not necessarily mean that the species are chemically or genetically incompatible, but instead there are often physical differences which make reproduction impossible or unlikely.  These changes can occur when a single species is separated from each other and each group winds up in a different environment for a long period of time.

Here is an example:  Let’s say that a particular species of mouse is separated into two groups - one group stays in the original environment (let’s say a dry desert), and the other group ends up in an environment with lots of trees and lots of ground predators.  The mice in the second group, in order to survive, would start to adapt to quickly moving up and down tree trunks, as well as for finding food and shelter under those circumstances.  It is entirely plausible that these mice would, over time, exhibit physical changes in the legs, feet, and other areas of the body to accommodate their new environment.  After tens or hundreds of thousands of years, they would have necessarily had selective pressures to alter the physical shape and structure of the reproductive system.  If the two groups came back into contact after this, they likely would be unable to physically reproduce, and could therefore be classified as two distinct species - even if the DNA were still completely compatible.

I hope that this helps shed some light on this fascinating topic.  If you are interested in learning more about how evolution works, I highly recommend that you check out http://talkorigins.org/faqs/comdesc/


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