It's amazing how quickly people leap to conclusions in the field of evolutionary biology. Fact: a portion of the placenta's protein sequence is very similar or identical to a virus. Unsubstantiated (and pretty wild) conclusion: the placenta is the product of that virus. We would never accept that kind of mythology in software, medicine, law, etc. – why do it here?
Former biochemist here. There may be flaws in the study (i haven't read it), but none of what you're gesturing to strikes me as evidence of "jumping to conclusions". A couple thousand basepairs is a row (a fair assumed length for encoding proteins) is plenty enough to draw conclusions about evolutionary provenance, and this is totally common.
For lots of ho-hum reasons that don't require any spectacular justification, you are full of virus DNA -- it's just mostly never mentioned in popsci articles that come under your skeptical lens :)
The parent link is a journalistic version of the information, not the scientific paper(s) with the evidence.
Besides, the closest equivalent in software is:
If you have ~20 lines of code, written twice with the same function (perhaps crossing multiple functions in the same order), written with identical style and syntax, with maybe some variable names being slightly different.
In a copyright case, would you believe that these originate from different authors?
> conclusion: the placenta is the product of that virus. We would never accept that kind of mythology in software
Seems like a very reasonable hypothesis if that virus is a retrovirus [1]:
> Endogenous retroviruses (ERVs) are endogenous viral elements in the genome that closely resemble and can be derived from retroviruses.
> ...not all ERVs may have originated as an insertion by a retrovirus but that some may have been the source for the genetic information in the retroviruses they resemble.
