See [this post](http://www.reddit.com/r/AskReddit/comments/25fvj5/what_is_the_greatest_weakness_of_humans/) from /r/AskReddit that was one of the top posts for the past month.
The options below are top 5 answers from the AskReddit thread.
Your vote: No external armor. Just flesh blood bags.
Redditpoll.com