We had 2 cats. One of them was dying of cancer. Pretty horrible. When his moment came, our other cat came in, sniffed on him one time, and then never gave a **** about it again.
Other animal species (including many primates) treat sex as a friendly socialisation rather than for pleasure or very intimate socialisation like humans, kinda like a big hug between good friends, so try to think of it as a human in denial that their friend is dead, so is hugging and kissing their body to try and get them to respond.
Are you literally retarded. They are taking pictures during the burial. You know, which humans did, and also a time later after the land has been covered up.