Online academic resources for evolution and common ancestry of humans

Thanks. That makes sense. think (though I have not thought very hard yet) that this might be a barely possible but highly unlikely answer in the case that (for example) gorillas and chimps had a set of homologous ERVs that chimps lacked. But so far as I've seen, the things creationists are making a fuss about have a much simpler answer then that --- the ERVs are not in homologous loci, which means that there's really nothing to explain.

My understanding was that the HERV-K family of ERV's was present in humans (hence the name humanERV-K). In fact they are still capable of being transcribed and are known to be involved in some cancers. Usually when this argument comes up it is referring to ptERV sequences, which as others have rightly pointed out, exist in non-homologous loci so are the result of retroviral infection after the human and chimp lineages split.

Hi Malcolm,You are indeed correct in that the HERV-K family of ERVs is present in the human genome. However, I believe Sean Pitman (the author of the article I was quoting) was specifically referring to a specific type of virus within the HERV-K family.See the following paper for further information:"A HERV-K provirus in chimpanzees, bonobos and gorillas, but not humans," Current Biology, 2001.This observation can be explained by incomplete lineage sorting which isn't really ad hoc since it's expected simply from the genetics of populations some of the time.

Yes, in that case you're completely right. That paper is about an ERV found in just one position, so incomplete sorting would be a perfectly adequate explanation. All that's required is that chimps and humans should have diverged before it became fixed in the common ancestral population.