I summarised this thread back in message 209, I don't think anything of substance has been posted since then that needs me to expand, so I'll simply repeat:
Science can answer why questions unless:
a) You have a silly notion of reality (dualism)
orb) You have a silly definition of why (purpose only)
Actually, I will change something, my last message finished "have I missed anything?" but since the collected posts of the silly side haven't managed to scrape together anything that would challenge either point I don't think it's necessary any more.