Healers

All people have some form of healer within their society.  Humans, with the help of The Ciar - Kob, Fae, and Gnomes and Eldar, have taken the profession to new standards of excellence.
The relatively recent flourishing of human civilization is a direct result of the prominence of healers in human society. Healers are considered sages. They work tirelessly to serve others and hospitals are literally the center of human settlements.  Things like city planning and agricultural research are performed by human healers with specialties in administration or research.  
Human healers are responsible for the invention of vaccines, wound mending technologies, and advances in surgery which heal infirmity and genetic deformity.