One relatively simple process necessary for animal life is the ability for blood to clot to seal a wound and prevent an injured animal (or person) from bleeding to death. Yet the only way this intricate system works is when many complicated chemical substances interact. If only one ingredient is missing or doesn't function in the right way—as in the genetic blood disorder hemophilia—the process fails, and the victim bleeds to death.
How can complex substances appear at just the right time in the right proportions and mix properly to clot blood and prevent death? Either they function flawlessly or clotting doesn't work at all.
At the same time, medical science is aware of clotting at the wrong time. Blood clots that cut off the flow of oxygen to the brain are a leading cause of strokes and often result in paralysis or death. When blood clots, either everything works perfectly or the likely outcome is death.
For evolution to have led to this astounding phenomenon, multiple mutations of just the right kind had to converge simultaneously or the mutations would be useless. Evolutionists can offer no realistic explanation of how this is possible.