Chickens Have Something Important to Say About Evolution (after the clucking is done).
Rhode Island Red, Bantam, Leg Horn, it doesn’t matter, chickens have been dealt a foul blow. They’re tired of being associated with the stupid mind-twister, “Which came first, the chicken or the egg?” The chicken, an animal known for its stupidity and ability to run around without its head, deserves a little respect for helping to clarify an evolutionary enigma.
What’s that, you’re not sure of the answer? If you are a Creationist or IDer, you can be forgiven. After all, you believe God made all species (kinds) less than 10,000 years ago, end of discussion. But if you are of the secular persuasion or are of a liberal Christian theology there is no excuse for your hesitation in answering. After all, it’s seventh grade level evolution, or is it?
Most educated people choose “egg” because they know mutations (changes in an organism’s DNA) occur during fertilization when parental genes are combined and duplicated in processes called meiosis and mitosis. Fortunately for all life, this process is imperfect and mistakes (mutations) occur. Therefore, the fertilized egg may have a slightly different genome (DNA) from that of its parent’s genome. This is classic evolution but is it speciation? Not yet. Probably not enough change has occurred for speciation.
Before we continue, we need a concise definition of speciation. Speciation is: the genetic change in one population of animals away from its parent population so that the two populations are no longer able to mate and bear offspring. There are exceptions, a new concept called symbiogenesis.
Symbiogenesis: the creation of a new species of animal or plant by the combination of the DNA of two different species. This may occur during simple ingestion of one animal by another or parasitism. If the genes of one animal or plant are combined with the genes of another, they can create a totally new organism like the ubiquitous lichen, which is part algae and part fungus. The lichen did not exist until this combination of DNA occurred.
Getting back to the egg problem: Surprise! The bird that laid the first chicken egg was also a chicken. Although its genome, its DNA, was almost identical to that of the chicken egg it laid, the small difference was barely enough to notice. In fact, it was too small to change the bird from one species into another. This kind of slow evolution cannot create a new species in one generation. Over the course of many generations the accumulation of multiple small mutations may be enough to create a new species. The first-generation offspring is never sufficiently different from its parent’s generation to be classified as a new species distinct from the parent.
In summary, you would not have noticed any overt, and obvious physical change between any two consecutive generations of chickens, except perhaps for tiny accumulations of DNA mutations and tiny physical variations. But eventually, those little mutations (microevolution) would have added up to an actual change of species (macroevolution), allowing a non-chicken to evolve into a modern chicken. That’s evolution, and it’s been happening ever since the first glob of pre-life organic material started replicating itself. The “Which came first question is really a bogus question because the question incorrectly assumes that the egg should contain enough genetic change to hatch out a new species immediately. It never does. The genetic difference between parent and offspring is never great enough to create a new species. Evolution happens all the time but speciation takes a whole lot longer.
I know I have been repeating myself, but here I go again:
Another way to think about the slow pace of speciation is to consider a roll of movie film. Cut out one frame and compare it to the immediate preceding and following frames and you probably will not be able to detect any difference in them unless there had been a scene change. The small changes in the three frames are usually so slight (especially when filmed in slow motion) that no difference is detectable except by very close examination. A change is usually not evident by examining adjacent frames but is evident by examining widely separated frames. This is exactly how evolution and speciation works.
The next time someone asks you the chicken/egg question, you’ll have an answer. I realize the answer wasn’t as simple as you thought? But, don’t try to explain all this to someone who doesn’t really care. Just say, “evolution takes a long time, too long to wait for an omelet.”