Evolution of Venomous Snakes
Snakes emerged during the Cretaceous period from lizards, but Dr Bryan Grieg Fry at the University of Melbourne believes, "that almost all snakes share a common, venomous, ancestor". Venomous snakes have similar classes of protein in their venom, suggesting that in the vast difference of habitats, snake’s venom derived from a common origin.
Venom itself also evolved, its
toxins and proteins being reborn from other proteins in tissues throughout the
snake’s body. snake-venom toxins were derived originally from proteins
in the brain, eye, lung, heart, liver, muscle, mammary gland, ovary and testis.
By tweaking the proteins from other body tissues, snakes developed a way to
create more specific and highly potent toxins.
Venom is still evolving today in medicine, having a beneficial effect on the body. For example, some poisons reduce blood pressure so quickly that the victim dies. But by changing and reproducing some components in venom, scientists can make a drug that reduces blood pressure.
Further Questions:
What other types of medicine can venom be substituted in?
Did venomous and poisonous snakes also evolved from the same ancestor?
Which venom is the most potent?
Links:
http://www.independent.co.uk/news/science/whats-your-poison-527683.html
http://www.fathom.com/course/10701017/session2.html
http://animals.howstuffworks.com/snakes/snake4.htm
http://www.animalcorner.co.uk/venanimals/ven_about.html
http://www.popsci.com/scitech/article/2008-03/evolution%E2%80%99s-most-effective-killer-snake-venom
http://evolutionblog.blogspot.com/2005/04/evolution-of-snake-venom.html