What is a uniquely human challenge? what part of the body is reponsible for this?

I believe its control of emotions. Humans have the most complex emotional responses than any other species on earth. Therefore the endeavour to make emotions and reason congruous are a uniquely humans challenge. The part of the humans responsible for emotions and reason is the limbic system of the brain. It constitutes the hippocampus, amygdala, limbic cortex and septal area.

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.

what is this saying?