How did mutations change the way scientists viewed evolution?

when scientists discovered that genes can actually regenerate thus producing a more complex gene by mutation some started coming up with theories that will actually explain to the world how man regenerated from a simple living thing to a more complex living thing

Explanation:

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.

b. read the phase at the intersection of any given temperature and pressure.