Answer:
To prevent illness, in reproduction and in beauty.
Step-by-step explanation:
Learning how the human body works, doctors around the world can prevent some illness, and to invent some vacines to some virus. In reproduction, they discover new technologies of having babies, like the artificial reproduction, the artificial insemination, etc. In beauty, the doctors can help to reduce weight knowing the interactions of some products among them and with the body. Also can change the skin appereance.