Whenever possible, I like to avoid ending sentences with prepositions because some people can be very picky about it. However, I am struggling with this one sentence in particular:
"The hypothesis proposes that the selection against aggression led to other physiological and psychological changes that may not have been directly selected for."
The only alternative I can think of is "....for which were not directly selected", but in my opinion that sounds very awkward. Any suggestions for a better way to phrase that sentence? I believe that it would be acceptable to leave it as it is, but I would prefer not to if possible.