WWII Syringe for direct interhuman blood transfusion Image Credit: Wiki

It was in 1667 that a French physician by the name of Jean-Baptiste Denys administered the first fully-documented human blood transfusion to a human being. The physician used the blood of a sheep to give a transfusion to a 15-year old boy. Soon after he administered sheep's blood again, this time to a labourer, and both of his patients made full recoveries.

The reason given for their survival is the very small amount of blood that was used. Had they been given a larger amount of animal blood they certainly would have died.

Thankfully we have come a long way since then in understanding how blood transfusions work. Today components of human blood are used to save many lives around the globe.