Evolution invented death. Death is the mechanism by which evolution continually improves and modifies life to deal with new challenges. We see this plainly in pesticides and antibiotics. Initially quite effective at killing a target species, these lose effectiveness with each passing generation as resistance develops. Humans are no different. Foods that are harmful when first introduced will become less harmful with each passing generation as susceptible individuals are weeded out. Thus, when we look for cause and effect for disease, we should first suspect something introduced recently rather than something introduced hundreds or thousands of generations previously.