What a remarkable find! I can't imagine the time and materials it took just to create this. I think what always amazes me with artifacts like this are the extra touches like the polished wood. I wonder if it broke and was discarded?
Here's a link to Otzi, the iceman they found preserved in Austria who is dated about 3,500 BCE, the same as this axe.
http://earthsky.org/human-world/see-what-5000-year-old-otzi-the-iceman-looked-like
He was 5'3", about 110 lbs, and worn out at 46. With him was the only copper axe of that era yet found.