Komodo Dragons Evolved To Eat Pygmy Elephants

Posted May 29th, 2006 at 8:12 pm in Books, Evolution, Nature
Komodo Dragon

I’m reading The Song of the Dodo: Island Biogeography in an Age of Extinction by David Quammen. It’s an excellent book.

In what I’m reading now, Quammen spends some time discussing dwarfism and gigantism and the factors that cause it. (It’s complex, I won’t try to recap). In one of the most fascinating things I’ve come across in a while, he discusses the historical diet of Komodo Dragons (which are really just mind boggling huge monitor lizards).

The question, you see, is what would allow a Komodo Dragon to get so mind boggling huge. A problem arises. While they currently eat deer, goats, and pigs, these animals have only recently arrived to the islands on which Komodos live. Thus the lizards have been around much longer than their food.

One of the disadvantages to becoming as big as a Komodo Dragon is the amount of food needed. Lots and lots of food. Small birds, furry rodents, and buzzing insects just won’t cut it.

It seems there’s only one big animal in the fossil record worth eating if you’re a Komodo Dragon — pygmy elephants.

There are actually two species of small elephant known from the fossil record, occuring in the areas where Komodos now exist. The smaller of the two was only 5 foot high, around the size of a modern cow. The ancestral Komodo Dragons first arriving would likely already have been large monitor lizards. At first, juvenile elephants would have been their meal ticket to survival as the selective pressure to grow bigger pushed their gigantism.

The hypothesis on the historical food source of Komodo Dragons has been advocated by no less than Jared Diamond. (Yes, the ecologist and Guns, Germs, and Steel Jared Diamond). It was originally suggested by an earlier biologist named Walter Auffenberg, who conducted the landmark study on Komodo Dragons in the early ‘70s. Diamond reviewed the evidence and made a case for this hypothesis.

If this hypothesis is false, the fossil record has left no trace of what ancestral Komodo Dragons feasted on. But the idea is intriguing. To me it’s these little tantalizing wonders that make science so fun. I mean, whose heart doesn’t warm a little at the thought of a monstrously big monitor lizard crunching on the bones of a baby pygmy elephant?

And so of course that raises the next question. How did elephants arrive on an island in the first place?

The answer is just as worthy of it’s own post but in short, they swam. Quammen also devotes some discussion to this fascinating topic, including well documented accounts of modern elephants swimming at sea. There were a couple that were documented swimming from a small island to Sri Lanka in 1954. A few years later, a mother and her calf made the same swim in the opposite direction. Reports of elephants swimming to islands exist elsewhere in India, Cambodia, and Kenya.

A more sensational example, which may or may not be true, is an elephant which was reported to have been lost overboard from a ship approaching South Carolina in 1856, and to have swum the remaining 30 miles to shore.

But the best evidence comes from the fossil record. For example, the Channel Islands off the coast of California (I’ve been there to see Island Scrub-Jay by the way) sported a species of pygmy mammoth (yes, the irony is ripe). Scientists assumed that a land bridge was responsible for their presence, yet a closer look revealed that the water between the island and the mainland was deep and that no land bridge ever existed. Also telling is that many other species around during the Pleistocene which left good fossils on the mainland do not occur on the islands. If such a land bridge existed, their absence is not to be expected.

So there you have it. Two good hypothesis that Komodo Dragons ate pygmy elephants and that elephants colonized islands by swimming. See — science is fun!

6 Responses to “Komodo Dragons Evolved To Eat Pygmy Elephants”

  1. I read about half this book earlier in the year and loved it (didn’t finish largely because spring break ended). I think that work that Quammen does explaining evolutionary concepts to the lay reader in quite understandable terms is vitally important (even despite the fact that he sometimes takes swipes at literary critics (which I’m in grad school to become)).

  2. Yes, his writing is wonderful. I would use the word vivid to describe his prose. He strings words together in ways that make me envious.

    While I really liked Guns, Germs, and Steel by Jared Diamond (and frankly find his ideas on that subject matter more profound because of their implications for how they shaped humanity), his writing is nowhere near as entertaining as Quammen’s.

    I’ll have to post an excerpt one day to provide an example of just how good a writer he is.

  3. I read GGS about six months ago, and I actually think of GGS and SotD as doing about the same thing (i.e., thinking about how geographic/climatological factors have such a huge impact on the development of species/civilization). In fact, after I started reading SotD, I felt like I had already read the sequel.

  4. Kyle, I see your point, though Quammen is incredibly interested in the science of ecology, particularly as it relates to islands and the distribution of species, while Diamond was focused on the inherit characteristics that shaped the evolution of the human species — particularly inanimate things about the geography of continents that had enormous implications for the evolution of humans and the crops and livestock we developed.

    Diamond’s book was great intellectual stuff, but I’ve found Quammen’s writing more fun. I think he writes about a subject (ecology) which has the potential to bore those not steeped in its ways, in a manner that really captures the imagination.

  5. Such strange animals…

  6. [...] was more like a dinosaur or a dragon. It could probably eat a small child. (Speaking of which, in this fascinating article, it’s hypothesized that Komodo Dragons used to eat pigmy elephants. That sounds [...]

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