Xenotransplantation has a long history in the scientific community.
Animal tissue has been used as a substitute for human tissue as far back as 1682. The first time xenotransplantation was applied was when a portion of dog skull was implanted into the skull of a Russian nobleman to repair damage. The graft was removed after a threat of excommunication was made by the Russian Church. Several attempts at xenotransplantation were made over the next two centuries. Many of the attempts failed due to incompatibility of the tissues.