Ive always wanted a ferret.  When I was little, because of this (1m59s):

Now, because of stuff like this:

Ferrets arent just super cool pets, they also have a very rare ‘gift’– While all organisms genomes are littered with pirate DNA and endogenous retroviruses, endogenous lentiviruses have only been found in three creatures: Bunnies, lemurs, and now, ferrets!

Endogenous Lentiviral Elements in the Weasel Family (Mustelidae)

Lentiviruses are ‘complex’, in that they have the basics retroviruses need to survive, LTRs, gag, pol, and env, plus some bonus genes.  In this case, vif, tat, and rev (relatives of genes found in HIV).  The researchers determined this lentivirus settled into the ferrets genome 8-11 million years ago, but they couldnt figure out yet whether it is more related to HIV or the cat variant, feline immunodeficiency virus (it sorta sits right between their branches on a phylogenetic tree).

What does this mean?  Of course, lots of fun stuff, evolutionarily, but we might also have gained some new tools– It turns out you can infect ferret cells with HIV.  By studying how this endogenous lentivirus works, we might figure out how to make ferrets a good animal model for HIV (we aint got one).  Or maybe, learning more about this ferret lentivirus could help us make better gene therapy vectors (we loves us some lentiviral vectors, but at this point, we just have HIV).

…

I want a ferret.