Rapunzel: How strong is your hair?

Rapunzel, Rapunzel, let down your hair, so that I may climb thy golden stair.

Fairyology Episode 6

rapunzel_tower.jpg

Its been a while since I last dissected a fairytale to its bare scientific bones so here we are again. This time we’re discussing the wonder that is Rapunzel.  So as per usual lets do a quick recap of the story and see what we’re working with. A pregnant wife had severe cravings for green veggies. So her husband goes to the garden of a witch and steals her the veggies she wants. The witch then comes to their house and tells them the price of the veggies is her child. When the baby is born the witch steals her and puts her in a 70ft tower with no doors and just one window. The baby is called rapunzel and her hair grows and grows so much that the witch uses it to get in and out of the tower. One day Rapunzel is singing her tower which attracts the attention of a prince. They fall in love and he continues to visit her in secret. One day the witch catches them and she blinds the prince and casts Rapunzel out into the wilderness. They search for each other and eventually find each other and Rapunzel’s tears brings back the princes sight (1).

So I have a couple of questions, firstly how long would it take for her hair to be long enough for the witch and the prince to climb up the tower?

Well an interesting fact about hair growth is that your ethnicity can influence your hair type and in turn how fast it grows. A 2005 study stated that Asian hair grows the fastest and African hair grows the slowest. In all the various renditions of Rapunzel she has always been Caucasian. This study stated that female Caucasian hair grows at a rate of 5ft per year. Therefore it would take 14 years to grow 70ft worth of hair! Although my very simple maths does not account for a gradual slowing of hair growth as it got longer. This study also stated that diet influenced rate of hair growth and eating lots of fruits and vegetables can increase hair growth. So maybe thats Rapunzels magic secret!  As to how the witch got up the tower in those 14 years whilst her hair was growing well I wouldn’t like to say but she is a witch so maybe a broomstick or some secret stairs?!

My second question is what must her hair must have been made from to carry the weight of a fully grown human being?

A project completed by the natural history museum in London all about hair showed that a single strand of hair could support 100g of weight. The whole head of hair could support 12 tonnes of weight! Although I’d like to see someone try pick up that much weight with just their hair. Weight for weight its not as strong as steel but more like aluminum. Which is pretty awesome.

All in all hair is pretty cool, so go you Rapunzel and your wondrous locks! Hope you’ve enjoyed this episode of fairyology!

ThatBiologist Everywhere!

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Source

(1) – http://web.archive.org/web/20120122211814/http://german.berkeley.edu/poetry/rapunzel.php

 

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