Here is a simple explanation of the logic behind the experiment- for a more scientifically complete explanation, read the long form. The point of this is just to let you get a chance to experiment with evolution on your own, and get a tiny hint of what’s out there.
Simply put, the genetic evidence for evolution is overwhelming. Our DNA is much more similar, in many different ways, to a chimp than to a mouse, more similar to a mouse than to a fish, more similar to a fish than to a yeast, and more similar to a yeast than to a bacteria. Some Creationists dismiss this evidence by saying that God, when He created us all from scratch, made us more physically similar to chimps than to fish, so it makes sense that our DNA should be more similar.
If we want to figure out whether the similarities in DNA are because we evolved that way (meaning we have a common ancestry with other animals) or because they were created that way (meaning everything was created at approximately the same time by the same creator), we need to find something in the DNA that has no function, because then God would have no reason to make it more similar in similar species, but if animals share a common ancestry, then it should still be similar in closely related species.
One thing that fits this description is the third nucleotide of codon. This is essentially just every third letter, or nucleotide, in a gene’s DNA sequence. The third letter/nucleotide is different from the first two because, a lot of the time, it can change without changing the protein that the gene makes (for a better explanation, see the long form below). A letter/nucleotide needs to be there, but it often it doesn’t matter whether it is A, T, G, or C. Because the sequence of the third nucleotide doesn’t matter, there is no reason for God to have made these letters/nucleotides more similar in similar species. If this third letter/nucleotide follows evolution’s rules, then that is strong evidence that evolution occurred, as opposed to God creating everything from scratch.
We can find the actual sequence of genes in several species at free on websites such as www.ncbi.nlm.nih.gov/nuccore or ensembl.org. NCBI has primarily raw sequence, while ensemble lets you browse the genome of different animals, which is pretty cool. If you download and compare the sequences (google clustalW2 or multalin to find websites that will help you align them) you find that closely related species like humans and chimps have very similar sequences at every third letter/nucleotide (see the picture near the bottom), while less similar animals like zebrafish don’t.
So, the third nucleotide does, in fact, fit perfectly with the predictions that evolution makes. This does not prove anything about the existence of God, it just suggests that if He does exist, he either intentionally made it look like evolution happened, which would be dishonest, or He used evolution as part of His creation process.
Short form:
In order to distinguish between the genes of closely related animals being more similar because they evolved from a common ancestor or because they are simply similar animals, determine whether the third nucleotide of codons in highly conserved genes, which often have no functional significance, follow evolutionary patterns. NCBI nucleotide database, ensembl.org, multalin and/or clustalW2 are good tools to accomplish this.
Long form:
Evolution predicts that genes and proteins should be more similar between animals that underwent speciation relatively recently (like humans versus chimps) than between animals with distant speciation events (like humans versus fish). This has been found to be true. The creationist counter-argument is that humans and chimps were created more similar than humans and fish, so their genes should be more similar. The key to differentiating between these two hypothesis is to find a detectable difference between genes that has no functional significance. Without functional significance, there is no reason for a creator to make the difference more similar in similar species. One example of this kind of difference is the third nucleotide of a codon.
In order to make a protein, cells generally go from DNA to RNA to protein. The nucleotides of an RNA molecule are translated into the amino acids of a protein through a code based on sequences of three nucleotides (for example, the nucleotides AUG code for the amino acid methionine). Since there are 4 different nucleotides there are a total of 64 possible 3 nucleotide combinations. However, there are only 20 amino acids (plus a stop codon) that need to be coded for, so there is a lot of room for redundancy (in other words, multiple codons code for the same amino acid). Most, but not all, of the redundancy happens at the third nucleotide of a codon, for example CUU, CUC, CUA, and CUG all code for leucine. Changing from one codon to another functionally redundant one shouldn’t affect the fitness of an individual. If a nucleotide in CUU, leucine, was mutated to adenosine, the result would be:
1st nucleotide: AUU- isoleucine
2nd nucleotide: CAU- histadine
3rd nucleotide: CUA- leucine
Therefore, in highly conserved genes, where a change in the protein would generally be detrimental, the third nucleotide of a codon is more likely to be mutated, because its mutation often results in no change to the protein and therefore will not decrease the fitness of an individual. Because the third nucleotide of a codon can change without altering protein function, it can be used to test evolution versus creationism.
Evolution’s prediction: In highly conserved genes, the third nucleotide of a codon will be more similar between two closely related species.
Creationism’s prediction:
Scenario #1: The creator created the genes of animals from independent sources: the redundant third nucleotide of a codon should be randomly distributed between species.
Scenario#2: The creator created the genes of animals from one source and tailored them to fit individual animals: the redundant third nucleotide of a codon should be identical between species.
Scenario#3: The creator intentionally ordered the coding sequence of the genes to appear that evolution happened, when in fact it didn’t: the redundant third nucleotide of a codon should follow the evolutionary model
Scenario#4: The creator used evolution or a method indistinguishable from evolution to create genes: the redundant third nucleotide of a codon should follow the evolutionary model
The test:
Go to http://www.ncbi.nlm.nih.gov/nuccore a repository of sequences that is free and open to the public.
Search for the scientific name of a species of interest (e.g. Homo sapiens, Pan troglodytes [chimp] Danio rerio [zebrafish])and a highly conserved gene (I used sec23a, a gene required for protein export, but there are lots of them, generally housekeeping genes are highly conserved, so google “housekeeping genes”). The more similar the protein sequence is between the species you test, the easier the data will be to interpret.
One of the results should hopefully be your gene of interest with “mRNA” or “complete cds” at the end. This will take you to the protein and nucleotide sequence. Under the “FEATURES” section there will be a “CDS” tag followed by two numbers, e.g. “224..2521” this is the numbers of the sequence you are interested in. Go to the sequence at the bottom of the page and copy those nucleotides, the first three nucleotides should be ATG for any gene with complete sequence. Save the sequence somewhere, and repeat for the same gene in different species, at least two similar species and one evolutionarily distant one- I suggest human, chimp, and zebrafish because they fit the criteria and have pretty good databases.
Once you have your sequences, go to http://multalin.toulouse.inra.fr/multalin/multalin.html (or google multalin or clustalw2) for a tool that will help you align and compare the sequences. The sequences need to be entered in this format:
>sequence1
ATG…..
>sequence2
ATG…
>sequence3
ATG…
Then just hit the start button.
If all worked correctly you should see an alignment of the sequences, which should be mostly identical, and you can determine whether nucleotides at positions that are multiples of three follow an evolutionary pattern. The result should be pretty obvious. Evolution predicts human and chimp should be very similar at the third base compared to zebrafish. In my test I got:
12 of the first 20 codons are functionally identical but contain different nucleotide sequences. Of the 12, human and chimp sequence agrees 100% of the time, while human and fish agree 0% of the time, indicating that humans and chimps are more closely related than humans and fish, consistent with evolution.
Discussion:
The results are consistent with evolutions predictions. For creationism’s predictions, the results are only consistent with scenarios #3 and #4. If scenario #3 is correct, then the creator is being deceitful. If scenario #4 is correct, then there is no functional difference between evolution and creationism.
So, either God is a liar, or He used evolution.
