You could ask, why does "The Wolfman" look like Hyde?
"The Werewolf of London" was made in 1935 by Universal, and the makeup bears a strong resemblance to Mr. Hyde.
The Mr. Hyde of the 1931 version is not meant to resemble a wolf, but a Neanderthal Man.
He actually looks more simian (ape-like) to me.
I understand March's simian appearance as Hyde was used to emphasize the duality of man, and the duality of "good doctor" Jekyll- his 'alter ego' Hyde is uninhibited, rampant, animalistic and primitive.
'I guess I'm the girl nobody remembers'
The director, Rouben Mamoulian, has said that Hyde WAS the primitive - the Neanderthal - brought forh.
shareHe looked more cro-magnon than the wolf man, with the wide nose and huge, flaring nostrils.
"I promise you, before I die I'll surely come to your doorstep"