Thinking that eating other mammals is a core problem.

"Just remember that you're standing on a planet that's evolving
And revolving at 900 miles an hour.
It's orbiting at 19 miles a second, so it's reckoned,
The sun that is the source of all our power.
Now the sun, and you and me, and all the stars that we can see,
Are moving at a million miles a day,
In the outer spiral arm, at 40,000 miles an hour,
Of a galaxy we call the Milky Way."
Monty Python....

You get to decide. We are lucky to have the choice to direct our own lives, within limits. For most of mankind's existence, an individual's purpose was usually dictated by the society they lived in. For most of history, a person's life didn't belong to him -- now it does -- at least in societies that have embraced Western culture. Thanks to the enlightenment ideas that led to capitalism, we are now prosperous enough to have many choices. It is unfortunate that many have chosen to undercut the ideas and system that gave us such prosperity and choices.

I was thinking about this question one day when I found the answer staring it in my face. Sex is the purpose of life. That’s right. It’s essentially to fuck.