How did the Sapiens species in the Homo genus come to develop an immune system

Question: How did the Sapiens species in the Homo genus come to develop an immune system
- Keywords:
  development
Asked by Wrichik1999 to Laura, Carmen, Daniel, Noel, Steph on 6 Mar 2015.
- Noel Carter answered on 6 Mar 2015:
  
  The immune system evolved long before any of the hominids
  see the following image

Question: How did the Sapiens species in the Homo genus come to develop an immune system