We Never Know
No Slack
And for this picture... Here's an explanation.What "homosexual behaviours" are you referring to, then?
Humans beings use sex toys on occasion, to pleasure themselves. Like with the dog and the soccer ball. But that doesn't mean we also don't have sexual orientations involving someone of the same or opposite sex, right?
"Since cow-cow mounting is an accurate sign that the time is right for taking the cow being mounted (“mountee”) to be bred, and that estrus is imminent in most mounting cows (“mounters”), selection for this behavior was probably coincidental."