If there are books of evidence as you say and you can't take one piece of that evidence and use it to show evidence for evolution than I doubt that any of it can be put together.
One piece of evidence?
Sure, I'll give you that. As a matter of fact, I'll give you objective empirical evidence.
Just keep in mind something for me will you? There is no one piece of evidence that "proves" evolutionary theory. Evolutionary theory is nothing more than a scientific model that explains the diversity of species on this planet. There is no "one" piece of evidence holding together the ToE, it's the preponderance of evidence that does so. Keep that in mind, will you please?
Ok, now that that's out of the way- here's one piece of objective empirical evidence-
Allele Frequencies change over time.
An allele is simply a dna coding that that occupies a specific location on a chromosone. For example (like the one given in the article) a single gene may control the color of flower petals, however there may be many variations (alleles) for different colors of the petals (red, yellow, white, etc).
Now you can look around and see various colors of roses. What controls those colors? Alleles (variations). If there were no coding variation, then all roses would be a single color.
Now, take that simple example and expand it to other items, such as human eye color, hair color, uncut hair length, etc etc etc. As you can see, there are many allele variations.
Now back to my evidence- Allele frequencies change over time. For example, if 10% of a population has a given allele (coding variation for say, blue eyes) then among memebers of that population 1 in 10 chromosones will carry that allele. 9 out of 10 will be occupied by other variations of the gene.
Now take it a bit further and say that 20% carries the allele for green eyes, 20% carries the allele for hazel eyes, 10% carries the allele for violet eyes and the rest (40%) carry the allele for brown eyes.
Now, quite simply, Im going to put a common sense question to you, given the above information-
What is going to happen to the alleles (and the frequency of certain alleles) when the various eye-colored people start intermixing and reproducing?
Depending on who mates with who, the
frequencies of any given allele will change over time in the population at large.
Please keep in mind- the above is a
grossly oversimplified version of the process, but I think it serves
both things that you have asked for-
1 One piece of evidence. To boot, this evidence is a concrete fact. Allele frequencies do, in fact, change over time.
and
2 layman's terms
Does allele frequency variation "prove" evolutionary theory? Not at all. But it does serve to demonstrate how variations can arise. Given enough variations over time (coupled with selection, drift, migration, mutation, etc), and you might start seeing offspring that little resemble their ancient ancestors.
