[@Jbcool] It's not explicitly stated that they Aren't, so much as there's nothing that even hints at that being the case. It doesn't take longer for them to heal, there's no mention of them having weaker bones or the like. If anything, there's evidence suggesting they're even more resilient than humans, because half their race somehow manages to live for centuries while injecting the absolute maximum level of drugs possible into their systems. A human doing that would die in a fraction of our estimated maximum lifespan.