For those of you saying all mens teams do this: NO. Not true. You'd never hear the guys on my team say crap like "I don't consider them to be human" or whatever.
Maybe your teammates wouldn't say crap like that around you because they know you're a tight-ass.
I read some of the email quotes and immediately recognized the type of humor they were getting at, even out of context. Every single one of the offending quotes was facetious. "I don't consider them to be human" is, to me, quite obviously hyperbole. Half insult, half phony posture. Yes, it's at someone's expense (lots of jokes are), and no, it's not an indicator of a possible rapist (at all). It's intended to be over the line. My team would practically get into competitions to craft the most vulgar and insulting email, and the more people you could insult, the better, including those on the email chain. That kind of humor only comes through in an email amongst a group of people who are very comfortable and familiar with each other. On the other hand, if someone clips out a quote and stomps over to tell teacher, then you wind up having to explain your inside jokes to everyone on the planet.
Someone got a bug up their ass and ruined the team's season for nothing, and the school newspaper cheered. How sad.