Experimental human guinea pigs are not named after the animal associated with medical testing.
Human volunteers selected for observation under trial were usually desperate for money and would receive the nominal daily fee of one guinea for their trouble.
A guinea was a forty-shilling piece first minted in 1664, so called because it was minted from West African, Guinea, gold.
The guinea pig animals are misnamed, because they are from Guyana in South America and not Guinea in West Africa.
Subjects of human experiments are often called “guinea pigs”.