The horizontal theory of evolution has been proposed for decades and is not that controversial.

Just as biological scientists use hosts to introduce new genes or DNA into cells, there may have been RNA super virus or bacteria that did this in the distant past.

Many unrelated species share identical genes. Modern humans were found to have some feline genes that are hard to explain how they got there.

I imagine a bacterial "flu" that picked up some of Dna and went on to infect another type of animal. If the infection spread to the reproductive organs and in turn the gamete cells the next generation might have some "alien" dna from the bacteria's prior host.

In a way this is the idea behind the monster movie "Alien" and"The Thing".



Socialogicly we often classify people as being like other animals.
I'm not saying we detect actual gene similarities but it is something we do.
Actually I prefer cat people to lizard people. Walrus people are nice but not my favorite.

The human genome project may still hold some surprises regarding humans having genes of animals other than just primates and tiny fragments of feline genes.