What scientists just found out is that the HERB-1 was the cause of the potato famine which destroyed Ireland's population so badly the island still has not reached pre-famine levels. Additionally (and of interest to geographers and historians) is that scientists mapped the genome of the blight. Looking at the evolution of the pathogen revealed that a sudden period of evolution occurred at the same time the Spaniards were conquering the New World. The great social disruption and collapse of New World civilizations allowed crops to rot and the potato blight pathogen to spread, evolve, and grow throughout the Western Hemisphere. The great leap in evolution allowed the blight to occur much earlier than it could ever have if the crops were maintained. A ticking time bomb of crop disease was set for about 300 years the moment American Indians starting dying.
Human-environment and human-human interaction is amazingly complex. We will still be discovering how our actions in the past and present will impact humans across the globe for centuries to come.