Scientists reporting in the journal Nature took on the task of explaining how snakes could have evolved their fearsome fangs from regular teeth—a question all the more puzzling since some snakes’ fangs are located at the front of their mouth, whereas other snakes have fangs near the back of their mouth.
Both front and rear fangs develop from separate teeth-forming tissue in the back of the mouth.
Examples of front-fanged snakes include the vipers, night adders, cobras, rattlesnakes, and coral snakes. But these famous snakes are in the minority. Other snakes, including rat snakes and grass snakes, have fangs in the back of their mouth.
Researchers at Leiden University looked at fang development in 96 embryos from eight snake species, all of them living today, in search of an answer for why fangs evolved in a different location in the different species.
The team’s research revealed that both front and rear fangs develop from separate teeth-forming tissue in the back of the mouth, as opposed to non-venomous snakes (and humans), for whom all upper teeth and all lower teeth sprout from a single upper and a single lower dental tissue.
For snakes with frontally located fangs, the fangs are displaced toward the front as the embryo develops by the rapid growth of the upper jaw. On other snakes, the fangs remain in place, and the mouth grows in front of them as a result.
So how have evolutionists explained the divergence? “If you want to eat a very dangerous prey, like a big rat with razor-sharp rat teeth, then it would be more advantageous to have your fangs in front of the mouth so you can just bite it quickly and then let go,” explained lead researcher Freek Vonk.
According to herpetologist David Kizirian of the American Museum of Natural History, this explanation “sheds light on one of those nagging questions in herpetology—how did a diversity of fang types among snakes evolve?” Yet explaining why a biological feature may confer an advantage to its owner isn’t the same as giving evidence that it evolved or how it evolved!
Vonk added, “The snake venom system is one of the most advanced bioweapon systems in the natural world. There is not a comparable structure as advanced, as sophisticated, as for example a rattlesnake fang and venom gland.” While we may wonder what fangs and venom glands were originally designed for (if they were present before the fall—but see item #4 below), there is ample evidence that it was indeed designed. Coming up with a story about why it would be advantageous to have fangs in a certain location doesn’t explain how the genetic information for fangs and a venom system could have appeared out of nowhere.
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