> A related question: what are the evolutionary advantages to love and
> What non-human species do you think have these experiences?
The evolutionary advantage of love is obvious - it binds a mating pair together for a long time, perhaps life-long, with an aim to give the offspring the best chance of survival through the partnership. You can clearly see the role-splitting for males/females in today's society. The conscious experience of "love" is currently thought to be brought about by one substance alone - I forget the name, it's complicated. This substance is highly addictive, and is only manufactured in the company of the other mate. "Broken Hearts" and "Missing you" are both sensations attributed to withdrawal from this substance. A great way of coercing a couple into staying together for the good of the next generation, eh?
Friendship is also an easy one. Strength by numbers. Also resources - "it's not what you know, but who you know". The consolidation is highly advantageous to all involved.
The question about other species relates to the consciousness question,
which bugs thinkers the world over. We just don't have the necessary
technology at present to detect consciousness, so we can't say whether or
not any other species EXPERIENCE at all. However, our intuition, almost
universally in my experience, indicates otherwise. Ask yourself - is there
something behind that dog's eyes? Is he really here, just like me? Our
primal brain centres jump straight back with a resounding "Yes!". There's
some reason for this, whatever it is, and so given the total lack of data on
consciousness, I think the primal intuition will have to make do for now -
it's all we got.
So, dogs are conscious, but where is the line drawn - are fish ? are bacteria ? There's no way of saying. Again, look into the eyes of the species in question and appeal to your primal brain, there's really no other option at this time.
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