The Theory of Evolution
In flesh and blood, you have been genetically fine-tuned as a product of natural selection. Without evolution, there would be no biodiversity hotspots like tropical rainforests.
This is because life evolved in some of the toughest conditions like an overabundance of water and nutrient deficient soils.
Over time, plants, animals and fungi have developed immunity to harmful bacteria and viruses from these harsh conditions. This is because whatever doesn’t work just doesn’t survive.
Evolution does the work. This is why we find some of the most resistant chemicals for medicine in tropical rainforests.