Answer 1:
It seems that your question presupposes that we
all have feelings. Think about it. How do you know that I have feelings? You can ask that of any other person. Although it is a basic assumption that most people are conscious and not zombies without feeling, many philosophers propose thought experiments that show we can logically show how our own feelings are the only things we can really know.
People have feelings because it makes
our lives richer. Can you imagine eating a
delicious ice cream sundae but not have the
experience (feelings, consciousness, or any other
favorite word that's hard to define) of how good
it tastes?
This question relates to an answer I provided earlier in the year: Why are people and dolphins the only mammals that have sex for pleasure? Your question gets at the
heart of what many cognitive scientists in the fields of neuroscience, philosophy, and computer science are trying to address. This great mystery in science is consciousness. In particular, your question is related to the mind-body problem. The issue here is what, if any, neural states in our physical brain lead us to have subjective experiences in our mind, which are called qualia by many people in the field of cognitive science.
Besides humans and dolphins, other mammals
such as certain monkeys have sex too. Sex usually
leads to euphoric pleasures that are related to
the release of certain neurotransmitters in our brains. These neurotransmitters help us relax and make us feel good.
The mammals you mention all have neocortex, which is associated with
higher levels of consciousness. For example, ants
do not have neocortex. Higher levels of
consciousness probably lead us to do certain
things for the simple pleasures, such as art,
food, and sex.
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