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I recently read a couple studies that concluded the 25% of genetic similarity between cows and reptiles is actually primarily due to TEs (transposable elements) rather than common ancestry.

Here's the link to the study for more information: https://www.theatlantic.com/science/archive/2017/10/how-a-quarter-of-the-cow-genome-came-from-reptiles/542868/

Now, I'm a strong believer in evolution, but I'm wondering if there's even the slightest possibility that the 97-99% number floating around when it comes to human and chimp/bonobo genetic similarities isn't exactly accurate, especially with the existence of TEs. I supposed my question is, simply put, could TEs serve as an alternative explanation to common ancestry for humans and modern apes? Also would this undermine the ERV/retrovirus remains argument as well?

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Never say never in biology. But it is not plausible that TEs explain the similarity in great apes (including humans).

Much (most?) of the argument for similarity is and has always been due to essentially identical coding sequences, which are mostly not affected by TEs.

More convincingly, the high degree of synteny between great ape genomes (including humans) is extremely unlikely if generated by independent random processes. For example, there is only one major difference in the gross ordering of elements on the chromosomes between humans and chimps.

The bovine/reptile similarity from TEs is mostly noticeable because it's on a background of quite low similarity at the coding level, and essentially no similarity at the synteny level. The BovB element is <20% of the cow genome. I don't know of high-level similarity numbers for the overall genomes of those organisms because I don't think the genomes are even alignable enough to compute those statistics, but I imagine they are quite low.

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  • $\begingroup$ Thank you for your answer! Is it likely that TEs could at least be used to explain away the same ERV remains in human/primate genomes or is even that unlikely? $\endgroup$
    – Mihir Dhawan
    Commented May 1, 2023 at 5:16
  • $\begingroup$ @MihirDhawan since you seem to be new to the Stack Exchange network, please read What should I do when someone answers my question? in the help center. $\endgroup$
    – MattDMo
    Commented May 1, 2023 at 14:57
  • $\begingroup$ @MihirDhawan Certainly, humans and great apes are quite closely related so they have quite similar TE profiles, both active and defunct. Perhaps I am not understanding the question? In other words, they share TEs rather trivially through common descent, rather than through horizontal transmission (which is what makes that bovine case interesting). If what you are asking is "does horizontal TE transfer occur between apes and humans?", then that should probably be a separate question, as it's a bit different in scope. $\endgroup$
    – Maximilian Press
    Commented May 1, 2023 at 16:49
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    $\begingroup$ @MaximilianPress Yes, I think that's what I'm trying to ask--does horizontal TE transfer happen between apes and humans. Thanks again, I'll post it as a new question! $\endgroup$
    – Mihir Dhawan
    Commented May 1, 2023 at 22:50

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