Why are the Bene Gesserit tonsured/bald in the movie?

Question

The opening paragraphs of Dune explicitly state that the Bene Gesserit Reverend Mother has a full head of hair:

The old woman was let in by the side door down the vaulted passage by Paul’s room and she was allowed a moment to peer in at him where he lay in his bed.

By the half-light of a suspensor lamp, dimmed and hanging near the floor, the awakened boy could see a bulky female shape at his door, standing one step ahead of his mother. The old woman was a witch shadow—hair like matted spiderwebs, hooded ’round darkness of features, eyes like glittering jewels.

Has David Lynch (Alan Smithee) offered an explanation on why Gaius Helen Mohiam and the other Bene Gesserit (with the exclusion of Jessica and Princess Irulan (why?)) are tonsured/bald in the film adaptation?

Answer 1

I recall exactly the same about the movie, that Gaius Helen, the old Bene Gesserit who tested Paul Atreides (by putting his hand in that scary box) was tonsured bald. The passage in the book, according to the quote in the question, was different. Let's put that aside for a moment though.

In the book, and the movie, Lady Jessica and Princess Irulan were trained as Bene Gesserit. Neither were tonsured bald in the movie initially. That changed when Lady Jessica drank the liquid (I forgot the name, it was a sandworm exudate, or perhaps melange-related), as part of accepting the role of Reverend Mother for the rebel Arrakis community. At that time, several things happened:

• The transition was a traumatic process. That was clearly the case for Lady Jessica; in the movie, she screams in pain.
• Becoming a Reverend Mother caused Lady Jessica to give birth prematurely to her daughter, Alia. That was stated explicitly as a consequence of her transition in the book.
• Lady Jessica also wore one of those non-hairpiece things, around her now tonsured head.

This would be a rationale that would keep the movie consistent with the book:
Some women are Bene Gesserit, but not all Bene Gesserit are Reverend Mothers.

Once a Bene Gesserit becomes a Reverend Mother, perhaps her hair falls out. It would be consistent with the other traumatic effects endured as part of the transition e.g. spontaneously aborting. Similarly, one of the central themes of Dune was that only women were "strong enough" to drink the sandworm exudate, but that Paul would be the first male who could do this, yet not die. Also, the powers of Bene Gesserit include clairvoyance, maybe telepathy and psychokinesis. They were trusted advisers to royalty, led communities, like a religious order. Both are associated with physical asceticism, including tonsure and black garb, in our historical past. (Maybe the hair interfered with their mental prowess and faculties, so that it fell out, or at the very least, was tonsured?)

There are a few problems. The first is Gaius Helen of course. If she were a Reverend Mother, she would not have had hair in the beginning of the book. If she were not a Reverend Mother, she would have had hair in the movie. The situation was reversed though. I can't reconcile that inconsistency.

The other issue is Alia, Paul's younger sister. She wasn't a Reverend Mother yet she didn't have hair in the movie. Alia was a special case though. She was born prematurely, matured at an unnaturally rapid rate, had exceptionally strong Bene Gesserit powers, greater than even those of Gaius Helen. It would make sense that Alia wore the same black velvet gown and tonsure (though without that non-hairpiece) as the Reverend Mothers did.

Answer 2

I don't think you'll find any in universe explanation. For me the baldness of Reverend Mothers is just a creative license to allow the audience to recognize the status of reverend mother as first sight, also conveying the hierarchical structure of the Bene Geserit.

In the book you have all the narrative, descriptions and inside thoughts of the characters guide you to recognize the evolution of Jessica's character, specially after transforming the water of life and experience the sum of all her female memories... That's really dificult to convey in a film... Sometimes a thousand words are much much better than an image.

By making reverend mothers bald you provide the audience with an easy way to spot and grasp the change that has taken place inside Jessica, at the beginning of the film she was just an apprentice, the next time she meets Mohiam, she is her equal. For the audience, at the start of the film Mohiam is bald and clearly superior to Jessica who is not... When Jessica becomes bald the audience can easily identify the "increase" in status because it can be associated with that first moment in the movie in which the "bald" woman was completely in control.

Answer 3

From what we have observed only reverend mothers are bald. Considering that Lady Jessica wasn't bald until she became one it logically points to the only common denominator, the Water of Life. Since the water of life is a poison we can safely assume that the deadly nature of the water makes their hair fall out. Although considering that they can manually alter their metabolism I would think that they could make their hair grow back if they so desired but instead choose not too, either being beyond caring or like me, thinking it makes them look mystical.