Have you ever noticed that humans are actually really gross?  There isn't a fluid or an odor that comes out of us that isn't pretty much disgusting.  Did a human leak something out of themselves somewhere?  Yeah, you don't want to touch that.  It's gross and it smells bad and it's probably sticky.  Not to mention we're pretty much all crawling with germs.  It's a wonder we ever want to touch each other at all.  

It's a good thing we at least invented stuff like soap and toilet paper and toothpaste and  deodorant, all of which are relatively recent inventions, by the way.  That's one of the primary reasons I wouldn't want to travel back in time.  I bet the stench of this place was freaking nasty.  I suppose people at the time probably just got used to the bad smell.  But come on.  Would you really want to go anywhere near a large group of unwashed people?  I've been to a couple of concerts where there were a lot of hippies and I can tell you that was a raunchy smell.  Now imagine that on a global scale.  Yeah, I'll stay here in the present, thank you very much.