So let me get this straight.
If a male dog fucks a female dog then it's natural and ok.
If a male dog fucks a female wolf then it's natural and ok.
If a male dog fucks a sheep then it's also natural.
So if a female woman shows a male dog her naked ass and the dog mounts her, how is that any different or the dog less informed or consenting?
It doesn't add up, logic is against you.
Oh, and for your information some chimps or gorillas have tested a human IQ of 93 or something. That's well within normal human capacity, Bush has 96 or something.
And that's even for human IQ, not taking in mind the differences in brain biology, organs of perception and environment.
You don't need language to give consent, understandable action is enough to sign a contract according to the Contract Law.