The Unexpected Revelation of Venom’s Origin

Venomous lizards have long been a topic of fascination for scientists and nature enthusiasts alike. While the Gila monster and the Mexican beaded lizard were previously thought to be the only living venomous lizards, a recent discovery has shed new light on the prevalence of venomous traits in these reptiles. According to a study published in the journal Nature, there may be more than 1,500 species of venomous lizards, challenging previous beliefs about the origins of venom in reptiles.

Traditionally, scientists believed that snakes evolved venom between 60 million and 80 million years ago, while lizards were thought to have developed venom around 100 million years ago, independently of snakes. However, genetic analysis conducted by Bryan Fry at the University of Melbourne revealed that snakes and lizards share nine toxins in their venom, suggesting a common evolutionary origin for venom in these reptiles. By tracing the genetic code of snake and lizard venom, Fry and his colleagues determined that venom originated from a single ancestor approximately 200 million years ago.

The common ancestor of snakes and venomous lizards possessed venom glands on both its upper and lower jaws. Over time, snakes evolved to have venom glands only on their upper jaw, while some lizards, like the Gila monster and the Komodo dragon, retained glands on their lower jaw. This unique configuration of venom glands in lizards, resembling „two pieces of macaroni on either side of the jaw with hoses leading to the teeth,“ as described by Fry, highlights the diverse evolutionary paths taken by different reptile species.

Contrary to popular belief, the effects of a Komodo dragon’s bite, previously attributed to bacterial infection, are now believed to be caused by venom. The rapid onset of symptoms such as a drop in blood pressure, loss of clotting ability, amplified pain, and loss of consciousness align more closely with venomous effects rather than bacterial infection. While lizard venom is as potent as snake venom, the method of delivery differs significantly. Lizards dilute their venom by mixing it with saliva and mucus in their mouths, making it less concentrated and therefore less harmful to humans. However, for small prey like mice, lizard venom can be deadly.

In conclusion, the discovery of a wide variety of venomous lizards challenges our understanding of the evolution of venom in reptiles. By uncovering the shared genetic traits between snakes and lizards, scientists have traced the origins of venom back to a common ancestor millions of years ago. This newfound knowledge not only enhances our understanding of the natural world but also highlights the intricate and diverse adaptations that have allowed these fascinating creatures to thrive in their environments.