Why Is Rhinoceros Horn A Sought After Commodity?

Some consider it to have medicinal properties, relieving rheumatic and other pains. Some believe that a horn placed beneath the bed of a pregnant woman will relieve labour. And an owner of a horn may rent it out for this purpose on many occasions at about $50 each time.
Also drinking cups are made out of rhino horns and these are reputed to be able to neutralize or reveal the existence of poison. Some think that poison in the drink will cause the cup to crack or the potion to froth.
It seems that the practice of making "poison-proof" drinking cups from rhino horns began about the late fourth century C.E. At that time it was believed that the mythical unicorn could detect poison with its horn. Naturally, people were anxious to obtain such horns, and the demand was satisfied by selling rhino horns as genuine unicorn horns.
The particular demand, however, for rhino horn arises because of its reputed quality as an aphrodisiac, something to restore the waning sexual power in man. The rhino may copulate over a period of several hours, and so it has been suggested that this has inspired men to try to gain some of this power by eating the horn.