Attack of the lizard people

While we’re all waiting for the new series of Doctor Who to start, ABC television has been kindly showing repeats of the previous season. Which actually is a tradition they’ve kept pretty much for as long as the show’s been on the air.

Two of the episodes they’ve repeated recently involved the Silurians, intelligent reptiles who retreated to underground refuges before humans developed intelligence, and which first appeared in the original series of Doctor Who, with much hokier costumes, back in 1970.

Silurians from Doctor Who, 2010
Silurians from the Doctor Who episode 'The Eleventh Hour', 2010 (BBC)

Needless to say, the science in this is spectacularly wrong. But as is so often the case, the way it’s wrong is itself instructive.

  1. First, there’s their name. The Doctor claims they’re formally called Homo reptilia. Now, the scientific name for a species uses binomial nomenclature, made out of the genus and the species names. Homo is the genus to which humans belong, in the family Hominidae, the order Primates and the class Mammalia. Whereas reptiles are the class Reptilia. Taxonomy forms a branching structure, so a reptile, no matter how human it looks, can’t be in the same genus as mammals like us.
  2. Then there’s their unofficial name: the Silurians. This is stated to be a misnomer, but there actually was a Silurian period in Earth’s prehistory. Except it was from 443.7-416 million years ago, long before reptiles or other vertebrates evolved, let alone left the sea (to find out more, see 600 Million Years at the Melbourne Museum).
  3. So when could they have been around? Well, the obvious place to start when you’re talking about reptiles ruling the Earth is the age of dinosaurs, between 230 and 65 million years ago. However, the Silurians also refer to humans as apes, which evolved around 29-34.5 million years ago. So there’s a bit of a gap there…
  4. The other clue the Silurians give is that they hid underground to avoid an approaching asteroid that never actually hit the Earth, instead going into orbit and becoming the Moon. This one is really interesting: in 1970, this “capture theory” was a leading contender for explaining the formation of the Moon. But at a conference in Hawaii in 1984, it and other theories were replaced by the “impact hypothesis”, which says that the Moon was formed by an actual collision with an object about the size of Mars. This is believed to have happened around 4.5 billion years ago, long before life of any kind formed on Earth. But let’s be fair: we know it’s wrong now, but when the Silurians were first created, it was a pretty good idea.
  5. Now, to biology. Intelligent, humanoid reptiles are themselves quite a cliché, but it’s actually unlikely that evolution would produce something that looks so much like humans (the female Silurians even seem to have breasts, yet these are meant to be reptiles!). I’d go into more detail, but Darren Naish explains it much better on his blog Tetrapod Zoology (I particularly like the idea that they’d be more birdlike, or Avisapiens).
  6. There’s probably a lot more to say about the biology, but I’ll just mention one more thing: the long, flexible tongue with a venomous sting on the tip. Now, as we’ve seen, nothing else about them seems to match real science, so how can we really say what’s acceptable? Well, we can at least say is that nothing else in the world seems to have this biology. The obvious comparison is with snakes, which do have a long tongue, but their venom comes from modified saliva glands behind their eyes, and is then channeled through tubes in the fangs.

So no, not so accurate. But at least they dropped the third eye and the heat ray.


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