The Hito Hito no Mi is a Zoan-type Devil Fruit that allows its user to transform into a human hybrid and a full human at will. It was eaten by Tony Tony Chopper.
By consuming the fruit, Chopper has been given human intelligence, allowing him to understand and communicate in human language. The fruit has also given Chopper the ability to perceive concepts that a reindeer would not comprehend, such as medicine. It also allows him to transform into human/reindeer hybrid forms.
So how about if the fruit were eaten by a human being? Would the effects of Hito Hito no Mi kick in?
And it looks like Chopper ate that fruit by accident?