This subsides after a day or so, and the victim begins to feel better. But the victim is actually dying. The person's clotting protein has been used up, and can no longer plug leaks in the circulatory system. An autopsy of Karl Schmidt revealed that, even as he prepared to go back to work, he had been hemorrhaging from small leaks all over his body. People tend to categorize snakes as either venomous or harmless, but, as colubrids demonstrate, the reality is a continuum, from completely harmless, to mildly venomous, to deadly.
Viperid venoms are messy - tearing apart tissues and melting cells.
This is all terra incognita. But researchers exploring the molecular evolution of snake venoms have begun to make progress. First, we know that snake venoms evolved primarily to subdue or kill prey. The defensive role for venoms probably had very little to do with their evolution. One piece of evidence that supports this is that many bites to humans are dry, where no venom is injected.