Did you know that castor is Latin for “beaver” and that castor oil is so called because it was extracted from beavers’ groins before it was discovered in plants? No? Neither did I until recently. Following the castor oil challenge that started in the U.S. castor oil has grown in popularity amongst the natural hair community. Of all oils, castor oil has one of the highest proportions of polyunsaturated fatty acids. They form 89% of its fatty acid content.