Yay! Going to get some new addition to ‘Creationist Claims about ERVs‘, via this bucket of fail from Answers in Genesis:
The best alternative explanation is that orthologous ERVs were created to occupy similar genomic loci in separate species by a single designer to carry out similar physiological functions.
If ERVs were created in the cell in the beginning, at least some exogenous retroviruses may have been derived from endogenous viruses when viral particles were released from the cell by budding–exogenization. While the ability to exit the host cell and transmit between individuals is designed, uncontrolled infection and deregulated insertion of retroviruses have caused much havoc in the post-Fall world.
You know, good for the YECs. Sure, that statement is demonstrably wrong, but you know what? At least they made a firm, testable prediction, and not the weird ‘you will meet a tall dark man’ predictions ID Creationists have been making since the failure of ‘Darwins Black Box’.
Good on you, YECs.
But heres why theyre wrong.
Viruses, including retroviruses, including endogenous retroviruses, dont speak the same language as humans. Sure they use A, T/U, C, G nucleotides in codons, coding for amino acids that make proteins.
But viruses and humans dont speak this language with the same accent. Its called codon bias, or codon-pair bias.
Several codons can code for the same amino acid. For instance, GCU, GCC, GCA, GCG all code for Alanine. So, in the human genome, you would expect ~25% of all the Alanines to use GCU, ~25% to use GCC, ~25% to use GCA, and ~25% to use GCG, right? Nope. For some reason, the human genome prefers GCC over GCG. Four times as many Alanines are coded by GCC as GCG. Humans have a GCC ‘accent’.
Viruses have their own codon ‘accents’ as well. And even though the differences should, theoretically, mean nothing (an Alanine is an Alanine is an Alanine), one way we can attenuate viruses to make better vaccines is to force them to use codons they dont like.
Thus one of the ways we know ERVs are a later addition to the human genome, and didnt originate in the human genome, is that retroviruses have a different codon ‘accent’ than humans. They dont fit. For example, if you were listening to a recording of Martin Luther King Jrs. ‘I have a dream’ speech, when suddenly you are accosted by ABBAs ‘Dancing Queen, which would you think is more likely?
a– ABBA was a later addition to MLKs speech when someone accidentally recorded over the original speech.
b– ABBA stole ‘Dancing Queen’ from MLKs ‘I have a dream’ speech.
Obviously, A. ‘Dancing Queen’, while in English, the same language MLK was speaking, has a different accent, different cadence, different tone, than MLKs speech. We know one didnt come from the other. They were two independent recordings mushed together.
Human genome is like ‘I have a dream’.
ERVs are like ABBA.
Boy I did not think out this analogy before I started typing…