"It works in a close animal" is a necessary though far from sufficient condition for "it" working in humans. The point of doing animal trials is to filter out drugs that don't even fulfill that condition. Look at the "in mice" twitter account. How many potential Alzheimer treatments and cures for cancer have been touted in the last decade that proved effective in mice? How many of them turned out to be promising in humans? You need to keep that ratio in mind whenever you feel like conjecturing something.

And keep in mind we're talking here about behavioral differences driven by possibly the most complex organ that diverged the most from other animals'.