This is a touchy subject, so I want to keep it based purely on scientific publications. What kind of evidence is there on the subject of outbreeding of populations and health? In zoos animals are breeded within a bloodline to maintain the identity or a breed. This can be bad, since this can lead to inbreeding. In human populations, has outbreeding ever been linked to either improved or worsened health state? I would assume improved genetic health, since deleterious alleles are more likely to be masked.