I'll review it for grammar errors later tonight, if you want, but the biggest thing I see right now is that you need to learn to vary your sentence lengths. Most of your sentences seem to fall within the same length, which makes your paper read in a dry, boring fashion. Additionally, I'd suggest varying how active your sentences read (structurally): right now, using the subject-verb at the beginning makes everything repetitive.
Examples:
Taxonomists attempt...
Common traits can range...
Behavior is...
Humans tend...
This, of course, is MHO. Take it for what it's worth.
Rob