New research conducted by Associate Professor Bryan Fry from the University of Queensland School of Biological Sciences shows that tiger snake venom hasn’t changed in over 10 million years, and that’s because it hasn’t had to. "This study is a great example of the human medical benefits that can come from studying evolution." As Fry explained in a release, if the animals had any variation in their blood clotting proteins, “they would die because they would not be able to stop bleeding.” 
 
 But as Charles Darwin pointed out over 150 years ago, evolution tends to thrive on variability, where only the “fittest” survive. Dr Fry's team studied the venom of 16 tiger snake populations from across Australia including five island populations in the Bass Strait, and venoms from 11 other snakes in related genera. "A long-held belief is that snake venom varies with diet -- that is, as the snakes evolve into new species and specialise on new prey, the venom changes along with it," he said. “Our research has shown that tiger snakes and their close relatives have toxins that are almost identical, despite this group of snakes being almost 10 million years old. We worked out the reason was [sic] that the toxins target a part of the blood clotting cascade that is almost identical across all animals. So we have a new addition to the theory of venom evolution; that when the target [prothrombin] itself is under extreme negative selection pressure against change, then the toxins themselves are under similar such pressure [to also not change].” 
 
 The stubbornness of this venom to resist evolutionary change, however, may be of benefit to humans. "The level of conservation in the toxin sequences is not only really unusual, but this is why the corresponding tiger snake antivenom is so useful in treatments against bites from many Australian snakes that affect the blood in the same way," Dr Fry said. That's because tiger snake antivenom has an extraordinary level of cross reactivity against other snake species, and can therefore neutralise the lethal effects on humans in snakebite cases. Advertisement 
 
 “No other antivenom in the world is so spectacularly effective against such a wide range of snakes this way and now we know why,” explained Fry.
– With its exceedingly deadly venom unchanged over the past 10 million years, the Australian tiger snake has essentially defeated evolution. Researcher Bryan Fry says in a press release it's "really unusual" for venom to remain unchanged over such a long period of time. Typically, predators and prey evolve as they find solutions to each other's evolutionary changes, Gizmodo reports. Not so with the tiger snake, which Fry says represents "a novel twist to the chemical arms race which most snake venoms evolve under" and "a new addition to the theory of venom evolution." A study published in the current edition of Comparative Biochemistry and Physiology Part C explains why. Tiger snake venom targets a protein called prothrombin, which handles heavy blood clotting. The venom's effect on prothrombin is what makes it so deadly, which means animals should be under a lot of evolutionary pressure to adjust. However, prothrombin is so important in its current form that any possible mutations to it are just as deadly. As Fry explains, animals with a prothrombin mutation "would not be able to stop bleeding." All of which is a long way of saying tiger snakes "hit the jackpot" with their venom. Surprisingly, tiger snake venom does possess one benefit to humans: Antivenom developed to combat it is effective against an unusually wide range of venomous snake bites. (Scientists found a potential new use for spider venom.)