Gandalf said to Bilbo about Beorn; He lives in an oak-wood and has a great wooden house; and as a man he keeps cattle and horses, which are nearly as marvellous as himself. They work for him and talk to him. He does not eat them; neither does he hunt or eat wild animals.

This is where the similarity ends in my opinion.

Beren is not recorded as ever having changed himself into any other shape or skin. This was achieved by the skills of both Felagund and Lúthien.

These are the only two instances where Beren was changed in form, neither of which has any relation to Bears and neither he managed himself. Therefore I do not believe that this ability was anything to do with Beren at all.

So, where does this leave Beorn? We still can't answer how he managed to skin-change from Man to Bear.

Gandalf again to Bilbo:

We cannot doubt either that he is a man, although Gandalf stated;

In addition, Tolkien says in his letters that Beorn's lifespan was no greater than that of an ordinary Man. It's very unlikely, then, that he survived much beyond TA 3000. (See Letters #144, dated 1954). In the same letter, Tolkien explains that despite his remarkable abilities, Beorn definitely belonged to the race of Men: 'Though a skin-changer and no doubt a bit of a magician, Beorn was a Man'.

This also dispels the Maia myth that is frequently suggested.

So at least there is some confirmation of the magician theory. Yet it is also clear that Beorn must have been the first of his line or people to have this ability, hence the people being known as Beornings.

My theory is complete speculation; Beorn has no known ancestors, though he is from the race of Men. Is it impossible to imagine that Beorn may have been both of Men, yet raised by Bears? He has an intense dislike of Goblins, who may have been responsible for attacking his family home in the mountains of the North. This is not dissimilar to Kiplings, 'Jungle-Book?', where Wolves rear the young Mowgli. A book Tolkien would have read as he penned his early thoughts. Beorn could only have learnt his skill from the Bears he was akin too, over years having been in their company, been fed on milk and honey and assuming the ability to control his own form. Possibly Radagast may have had a hand in his upbringing, although this idea is not developed, only that Gandalf says;

I do not believe in the link with Beren, or Beren's genetic ability to skin-change. He was never responsible for his form changing and only managed this by the skills of others and their enchantments upon him. Beorn is skilled in skin-changing; he has a natural ability to do this at will. Only through magic of his own or that of the animals he is akin to can he do this.

Comments and Discussion

By "no known descendants" do you mean "no known ancestors?" His known descendant is his son Grimbeorn the Old, mentioned to Frodo by Gimli in the chapter "Many Meetings". -- [JohnCowan?]

I rather think the author of the essay meant "no known descendants with the ability to change skin"... -- ChW

Meanwhile I have spoken with RayinBangor, you were right he meant ancestors and asked me to correct it... -- ChW

True enough, I had meant 'ascendents' as relating to no known relatives with such ability in the ascendency... -- Rayinbangor

Your welcome -- DtC