Goats are among the earliest animals domesticated by humans. Vaccines are effective in humans and other animals. Among those are two which deal with the difference between humans and animals. Benzene causes cancer in animals including humans. Nicolas Hartsoeker postulated the existence of animalcules in the semen of humans and other animals. They serve as service animals for disabled humans. Ectopic gestation exists in mammals other than humans. They offered definitions of the human being and schemes for classifying types of humans. Hedgehogs suffer many diseases common to humans. Their role in causing diseases in humans and mammals is understudied. They also sometimes lick humans, which may indicate affection. Their psychology seems in many ways similar to that of humans. They are capable of galloping faster than running humans. Their symptoms are similar to those experienced by humans. The leg bones are thicker than those of modern humans.