What do hitting a tennis ball and a heartbeat have in common?

They both make objects go through mediums using much force.

Explanation:

For example, hitting a tennis ball makes the tennis ball (object), go through the air (medium) from you swinging your arm (force).

Your heartbeat carries oxygenated blood (object) away from the heart in arteries (medium) using the great force of the heart valves (force).

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.

some scientists like gregory adcock agree with thorne's theory of regional continuity.

others, like chris stringer and ian tattersall, believe thorne's results may be contaminated or misinterpreted.