Why are Santa's elves small?

JRR Tolkien's elves are tall and imposing. JK Rowling's house elves are small but not crafty. So where do Santa's elves fit in with the other elves? Sally Le Page was tasked with getting to the bottom of this magical mystery and she started by finding out more about the origins of the Christmas elves from fantasy literature expert, Dimitra Fimi, from the University of Glasgow...

Dimitra - Definitely from the 1860s and on, we see a lot of images of Santa accompanied by elves who helped him make the toys. So that goes back to traditional beliefs about elves helping people. We have in older times brownies or hobs or hobgoblins: the elves can make things in the traditional belief.

Sally - So you've mentioned hobgoblins and brownies and fairies. Do you think that these are different entities and we are just getting a bit looser in how we are naming them?

Dimitra - They were always looser. So the names have always fluctuated. If anything, today, we more or less stick to elf or fairy and these are the most widespread, the most commonly known ones. So it's actually become less variable.

Sally - That suggests that to look at a biological cause for how they're related to each other and why Christmas elves are small, actually we shouldn't pay too much attention to the English name that we give them.

Dimitra - No, not at all. No. It's about their nature. It's about what they do and what is their role in the way we understand the world around us.

And that means I need to know who the Christmas elves are most closely related to if I want to find out why they're so small and who better to ask than a biologist who specialises in both evolutionary family trees and magical creatures, Dominic Evangelista, from (rather aptly) Adelphi University. And it turns out he has been tackling this very question...

Dominic - I collected all of this data about all of these different kinds of elves and other creatures, which we hypothesised were closely related. This was information on their morphology - so how they look - information on their behaviour. And we have one group in our tree that we call the true elves. These are where the elves from Lord of the Rings like Elrond and Legolas, this is where they go. They're large, tall, very humanoid. We had another grouping, which we can call dwarves, and these are generally less humanoid. Dwarves are obviously shorter than the true elves. And then we had a final grouping in our tree that we call the pixies. This is a new nomenclature, excuse me, gnome-enclature...anyway. The pixies are small, but they have different kind of magical powers than either dwarves or elves.

Sally - For our discussion, the most important grouping are the dwarves. Obviously with dwarves we think of Snow White and the seven dwarves, but you've put Christmas elves in with the dwarves. Can you explain your reasoning behind that?

Dominic - Yeah. That's probably our most interesting finding here. When you think about it, it does make a lot of sense. You mentioned Snow White's seven dwarves, and I think there's a lot of similarities between Snow White's seven dwarves and Christmas elves. They're both very short. They're both kind of cheerful. Well, I guess some of them are cheerful.

Sally - A few are grumpy.

Dominic - Yeah, that's true. At least one. And if we're comparing to other dwarves, like in Lord of the Rings, these are creatures that like to build things; they're very crafty. They're good with their hands. They have have lots of tools. And that is, I think, the main feature of Christmas elves.

Sally - Did they come from an ancestral elf-like creature that was small and then stayed small, or was the ancestral relative of all of these groups tall and Christmas elves have since evolved to be small?

Dominic - This is a good question. Currently with the knowledge that we have presently, the answer to this question is not really known. It could go either way. Every species on Earth, including Christmas elves and the other magical creatures, they are products of both their ancestry and who they originated from and products of their modern adaptations. So it's unclear yet if Christmas elves' form is more adaptive to their current conditions or their form is inherited from their ancestor.

So the question remains are Christmas elves small because they evolved from small dwarves and so it's all just chance, or is there an adaptive advantage to being small? I figured elves are somewhat like humans, so I should speak to someone who has looked at how and why body size has changed in the various human species across the millennia. And that led me, Manuel Will from the University of Tübingen.

Manuel - There's one really cool thing that we could use also for the elves. It's the so-called 'hobbit' from Flores

Sally - Of course!

Manuel - Homo floresiensis, from the island of Flores in Southeast Asia. And that one is really cool not just because it's dubbed 'the Hobbit', which I like a lot, but also it only stood about a bit more than one metre. So these creatures lived on the Earth around a hundred thousand years ago. That's already when our species Homo sapiens existed.

Sally - Do you think that it's possible to know if Christmas elves just evolved from another dwarf-like creature that was small and so are small by chance or whether it was because of an adaptation?

Manuel - I think that's super difficult to disentangle because it's basically unknown, but I would venture for another kind of explanation. It is an adaptive explanation, which I think could explain the small body size in elves and it's so-called 'island dwarfism'. So again, we talk about dwarves here as well, but also about islands. And there's a really cool thing with many animals, not just humans, that when you see them living on isolated islands, there's a cool thing that normally larger-bodied animals when they get to these islands, they get smaller, they 'dwarf', so to speak. That probably has to do with the fact that on these islands, it's much more difficult to get enough food to sustain large bodies, but also at the same time, there's less pressure of predators, so things that might kill and eat you yourself. Normally a good buffer against that is having a large body, but you don't even need that anymore. And funnily enough, that still the most parsimonious explanation for why Homo floresiensis is so small, likely because it's an adaptation to the island living on Flores.

Sally - So the real life hobbits started off a little bit bigger and then became smaller as they evolved isolated on this island?

Manuel - Exactly. Because the current idea about the family tree of Homo floresiensis is that Homo floresiensis is a descendant of Homo erectus, which is much older and much larger. It's not definitely proven, but it's certainly my favourite hypothesis. And it could work for the elves. Where the elves live, that is also a very isolated environment where maybe they don't get enough food from Santa, but certainly there's also no predators there for them, right? So maybe they just don't have to have big bodies.

And I think we've solved it. Comparing Christmas elves to Tolkien's elves turns out to be a red herring and Santa's elves have actually evolved from dwarves, which explains why they're so good at crafting things. And so Father Christmas probably took a small group of dwarves to the North Pole where they were then cut off from mixing with the other dwarf species, and over time they shrank in size due to island dwarfism.