Hygiene instinct? Dogs regularly roll in and eat rotten dead things. The more disgusting the better. They eat their own shit as well. You sure you want to keep going with this er… ‘logic’?
they cannot masturbate as we do; they have to rub their genitals against something, be it our legs or any other thing, such as another animal genitals, which is more pleasant than rubbing against any other thing.
Dogs don’t hump because they are horny and need something to ‘rub against’ to quell their urges. A male dog who is humping a human or something else (unless there is actual penetration) does not have an erection. If they did you’d see it, it’s pretty fucking obvious. It’s about domination.
Female dogs also hump to dominate. But I’m guessing you’ve assumed every dog they’ve seen humping is a male.
I can assure you that dogs absolutely masturbate. It doesn’t matter that they don’t have “hands”. They just do it with their mouths. Ya know, because they can reach their heads between their legs…
I’m beginning to wonder if you have ever even seen a dog.